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THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

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ROGER   BACON 


OXFORD   UNIVERSITY   PRESS 

LONDON      EDINBURGH      GLASGOW      NEW    YORK 
TORONTO       MELBOURNE      BOMBAY 

HUMPHREY  MILFORD  M.A. 

PUBLISHER   TO  THE  UNIVERSITY 


ROGER  BACON 

ESSAYS 

CONTRIBUTED  BY  VARIOUS  WRITERS 
ON  THE  OCCASION  OF  THE  COMMEMORATION 
OF   THE   SEVENTH    CENTENARY   OF    HIS    BIRTH 

COLLECTED  AND  EDITED 
BY 

A.  G.  LITTLE 


OXFORD 
AT   THE   CLARENDON    PRESS 
1914 


PREFACE 


V/Z 

loo 

HlLf- 


The  Commemoration  of  the  Seventh  Centenary 
of  Roger  Bacon's  birth  was  undertaken  by  an 
Executive  Committee,  consisting  of  Sir  Archibald 
Geikie,  O.M.,  K.C.B.,  then  President  of  the  Royal 
Society  (Chairman),  Cloudesley  Brereton,  Sir  Wil- 
liam Crookes,  O.M.,  now  President  of  the  Royal 
Society,  F.  A.  Dixey,  J.  P.  Gilson,  Sir  George 
Greenhill,  A.  G.  Little,  F.  Madan,  Sir  William  Osier, 
Professor  Poulton,  Lieutenant-Colonel  Hime  (Secre- 
tary), Sir  Alfred  B.  Kempe  (Treasurer).  A  General 
Committee,  consisting  of  subscribers  and  collabor- 
ators, was  formed  under  the  presidency  of  the  Right 
Honourable  the  Earl  Curzon  of  Kedleston,  Chancellor 
of  the  University  of  Oxford. 

The  proposals  of  the  Committee  were  (i)  to  erect 
a  statue  of  Roger  Bacon  (by  Mr.  Hope  Pinker)  in 
the  University  Museum  ;  (2)  to  issue  the  present 
memorial  volume  of  essays  ;  (3)  to  raise  a  fund  for 
the  publication  of  Roger  Bacon's  works. 

As  regards  the  last  object,  the  hopes  of  the  Com- 
mittee have  been  only  partially  realized.  Arrange- 
ments have  been  made  for  editing  the  pseudo-Aristo- 
telian Secretum  Secretorum  with  Bacon's  introduction 
and  commentary  (by  Robert  Steele),  Bacon's  medical 
treatises  (by  E.  Withington  and  A.  G.  Little),  and 
probably  the  Communia  Mathematicae  (by  Robert 
Steele  and  Professor  D.  E.  Smith).  Anything  beyond 
these  will  have  to  be  carried  out  by  private  enter- 


vi  PREFACE 

prise,  or  through  the  formation  of  a  Roger  Bacon 
Society. 

The  volume  of  Commemoration  Essays  now 
issued  corresponds  with  the  plan  already  announced 
except  in  two  particulars.  Sir  William  Osier  being 
unfortunately  compelled  to  postpone  his  promised 
article  to  a  future  occasion,  Mr.  E.  Withington  most 
generously  contributed  at  very  short  notice  the 
article  on  Roger  Bacon  and  Medicine,  which  is  based 
on  his  introduction  to  the  forthcoming  edition  of 
Bacon's  medical  treatises.  The  second  alteration  is 
the  addition  of  the  Appendix  containing  a  list  of 
Roger  Bacon's  works  and  those  attributed  to  him, 
which  it  is  hoped  may  encourage  further  researches. 

On  behalf  of  the  Executive  Committee  I  desire  to 
thank  the  writers  of  the  following  articles  for  their 
gifts.  Each  writer  is  responsible  for  his  own  article 
and  for  that  alone.  The  work  of  the  editor  has  been 
confined  mainly  to  ensuring  some  uniformity  in  the 
spelling  of  proper  names,  to  correcting  the  final 
proofs  (with  the  invaluable  assistance  of  the  staff 
of  the  Press),  and  to  cutting  out  from  some  essays 
statements  which  occurred  elsewhere.  A  certain 
amount  of  repetition  is  inevitable  in  a  volume  of  this 
kind,  nor  is  it  a  disadvantage  to  have  the  same 
facts  represented  in  different  connexions.  Differences 
of  opinion  are  equally  inevitable  ;  no  attempt  has 
been  made  to  reconcile  them,  and  it  is  surprising 
that  so  many  estimates  of  Roger  Bacon's  manifold 
activities  do  not  present  greater  divergences. 

A.  G.  L. 


CONTENTS 

PAGE 

I.  Introduction  :  On  Roger  Bacon's  Life  and 
Works.  By  A.  G.  Little,  M.A.,  Lecturer  in 
Palaeography  in  the  University  of  Manchester        i 

IL  Der  Einfluss  des  Robert  Grosseteste  auf  die 

WISSENSCHAFTLICHE      RiCHTUNG      DES      ROGER 

Bacon.  Von  Universitatsprofessor  Dr.  Ludwig 
Baur  (Tiibingen) 33 

in.  La  Place  de  Roger  Bacon  parmi  les  Philosophes 

DU     Xllie     SIECLE.        Par     FRAN9OIS      PiCAVET, 

Secretaire  du  College  de  France,  Directeur  a 
rficole  pratique  des  Hautes-fitudes  .  .       55 

IV.  Roger  Bacon  and  the  Latin  Vulgate.  By  His 
Eminence  Francis  Aidan  Cardinal  Gasquet, 
D.D.,  O.S.B.,  President  of  the  International 
Commission  for  the  Revision  of  the  Vulgate     .       89 

V,  Roger  Bacon  and  Philology.    By  S.  A,  Hirsch, 

Ph.D loi 

VI.  The  Place  of  Roger  Bacon  in  the  History  of 
Mathematics.  By  David  Eugene  Smith, 
Professor  of  Mathematics,  Teachers'  College, 
Columbia  University      .         .         .         .         -153 

VII.  Roger  Bacon  und  seine  Verdienste  um  die 
Optik.  Von  Geheimer  Hofrat  Professor 
Dr.  EiLHARD  Wiedemann  (Erlangen)      .         .     185 

VIII.  Roger  Bacons  Lehre  von  der  sinnlichen  Spezies 
UND  voM  Sehvorgange.  Voh  Dr.  Sebastian 
VoGL  (Passau) 205 


viii  CONTENTS 

PAGE 

IX.  Roger  Bacons  Art  des  wissenschaftlichen 
Arbeitens,  dargestellt  nach  seiner  Schrift 
De  Speculis.  Von  Dr.  J.  Wurschmidt 
(Erlangen)    .......     229 

X.  Roger  Bacon  et  l'Horreur  du  Vide.  Par  Pierre 
Duhem,  Membre  de  ITnstitut  de  France,  Pro- 
fesseur  a  I'Universite  de  Bordeaux  .  .         .     241 

XL  Roger  Bacon  :  His  Relations  to  Alchemy  and 
Chemistry.  By  M.  M.  Pattison  Muir,  M.A., 
Fellow,  and  formerly  Praelector  in  Chemistry, 
of  Gonville  and  Caius  College,  Cambridge         .     285 

XII.   Roger  Bacon  and  Gunpowder.     By  Lieutenant- 
Colonel  H.  W.  L.  HiME,  (late)  Royal  Artillery  .     321 

XIII.  Roger  Bacon  and  Medicine.    By  E.  Withington, 

M.A.,  M.B 337 

XIV.  Roger  Bacon  in  English  Literature.     By  Sir 

John  Edwin  Sandys,  Litt.D.,  LL.D.,  F.B.A., 
F.R.S.L.,  Public  Orator  in  the  University  of 
Cambridge    .......     359 

Appendix.  Roger  Bacon's  Works,  with  references  to 
the  MSS.  and  Printed  Editions.  By  A.  G. 
Little  .......     373 


I 

INTRODUCTION 

ON  ROGER  BACON'S  LIFE  AND  WORKS 

By  a.  G.  little 

Writing  in  1267  Roger  Bacon  says  :  '  I  have  laboured 
much  at  sciences  and  languages,  and  it  is  now  forty  years 
since  I  first  learnt  the  alphabet  :  I  have  always  been 
studious,  and  except  for  two  of  those  forty  years  I  have 
always  been  in  studio.'  ^  The  last  phrase  probably  means 
'  at  a  university  '.  Boys  generally  went  to  Oxford  at  the 
age  of  twelve  or  thirteen.  It  may,  then,  be  inferred  that 
Roger  Bacon  was  born  about  1214. 

The  tradition  that  he  was  born  near  Ilchester  is  preserved 
by  John  Rous,^  the  Warwick  antiquary,  who  was  a  student 
at  Oxford  about  1440,  was  interested  in  the  history  and 
legends  of  his  university,  and  had  some  knowledge  of  Roger 

'  Op.  Tert.  (Brewer),  p.  65  ;  cf.  Gasquet's  Fragment  in  Engl.  Hist. 
Rev.  xii.  507 '  Exceptis  duobus  annis  quibus  recreationem  et  solatium 
quietis  sumpsi,  ut  melius  postea  laborarem  '. 

-  Hist.  Regum  Angliae  (ed.  Heme,  1716),  pp.  29,  82.  According 
to  Atkyns,  Ancient  and  Present  State  of  Gloucestershire,  p.  147,  Friar 
Bacon  was  bom  at  Todgmore  bottom,  in  the  parish  of  Bisley.  '  He 
was  educated  at  St.  Mary's  Chapel,  now  St.  Bury  Mill  on  Stroud 
river  in  the  parish  of  Hampton,  wherein  is  a  room  at  this  day  called 
Frier  Bacon's  study.'  It  may  be  noted  that  the  nuns  of  Holy 
Trinity  at  Caen  held  Hampton  or  Minchin -Hampton.  Gilbert  Baco 
appears  as  witness  in  one  of  their  charters,  while  William  Bacon  and 
Roger  his  son  were  concerned  in  a  benefaction  to  the  Abbey  of 
St.  Stephen,  Caen,  in  the  twelfth  century.  Round,  Cal.  of  Doc. 
France,  nos.  447,  453;  cf.  no.  551.  John  Dee's  statement  that 
Bacon  '  was  named,  as  some  think,  David  Dee  of  Radik '  appears, 
as  Bridges  justly  says,  'to  rest  on  no  authority  but  that  of  John 
Dee's  very  erratic  imagination ' :  Opus  Majus,  i.  xxxiv. 

1689  B 


2  ROGER  BACON 

Bacon's  works.  In  one  place  he  calls  him  '  friar  Roger 
Bacon  of  the  English  nation  and  the  county  of  Dorset  '  ; 
in  another,  '  that  famous  clerk  friar  Robert  (sic)  Bacon  of 
the  minorite  order,  by  birth  an  Englishman,  of  noble  family 
of  the  inhabitants  of  the  county  of  Dorset  near  Ilchester.' 
Ilchester  is  in  the  county  of  Somerset,  but  only  some  five 
miles  from  the  boundary  of  Dorset.  And  in  support  of 
the  tradition  it  may  be  noted  that  in  1166  one  Roger  Bacon 
held  two  parts  of  a  knight's  fee  in  Dorsetshire,  given  to  him 
by  his  father-in-law,  William  son  of  John  of  Harptree,' 
The  name  Roger  is  also  found  in  the  twelfth  and  thirteenth 
centuries  among  the  Bacons  of  the  Bessin  in  Normandy,^ 
the  Bacons  of  Norfolk,^  and  the  Bacons  of  Essex,"*  and  there 
is  little  doubt  that  these  were  branches  of  the  same  family. 

Roger  Bacon  tells  us  little  about  his  family.  His  mother 
v>'as  still  alive  in  1267  :  his  elder  brother  ('  my  rich  brother ') 
had  succeeded  to  the  estates,  but  having  supported  the 
king's  cause  during  the  Barons'  War  had  been  driven  out 
with  his  relatives  and  reduced  to  poverty.^  Another  brother 
Bacon  describes  as  a  '  scholar  '.^ 

It  is  generally  supposed  that  Roger  was  related  to  Robert 
Bacon,  the  famous  Dominican  doctor,  who  died  in  1245. 
Matthew  Paris  tells  how  Friar  Robert  Bacon  of  the  Order 
of  Preachers,  in  a  speech  before  the  king  at  Oxford,  June  24, 
1233,  denounced  the  royal  favourites,  the  Bishop  of  Win- 

'  Red  Book  of  the  Exchequer,  i.  219.  I  am  indebted  to  Professor 
Powicke  for  this  reference. 

°  Round,  Cal.  of  Doc.  France,  p.  160.  Delisle,  Excheq.  Roll  of 
Normandy  {1184),  p.  31.  Red  Book  of  the  Exchequer,  ii.  645  (1172). 
Stapleton,  Observations,  ii.  Ixxix.  Palgrave,  Rot.  Cur.  Reg.,  ii. 
191-2,  374. 

^  Rot.  de  Finibus,  p.  443  (1208)  ;    Rot.  Litt.  Claus.,  i.  254,  ^^^, 

534.  535- 

''  Roberts,  Cal.  Genealog.,  pp.  424,  634  ;  Close  Rolls,  18  Ed.  I, 
m.  17  d.  :  34  Ed.  I,  m.  3  d.  schd. 

■^  Op.  Tert.  (Brewer),  p.  16;   cf.  E.H.R.,  xii.  502. 

*  op.  Tert.  (Brewer),  p.  13. 


LIFE  AND  WORKS  3 

Chester  (Pierre  des  Roches)  and  Pierre  de  Rievaulx  :  where- 
upon seeing  the  king  inchning  to  reason,  a  witty  clerk  of 
the  court  [clericus  de  curia),  namely  Roger  Bacun,  said  : 
'  My  Lord  King,  what  is  most  injurious  and  dangerous  to 
sailors  crossing  a  strait  ?  '  The  king  replied  :  '  They  know 
that  do  business  in  great  waters/  The  clerk  said  :  '  I  will 
tell  you,  my  lord  :  Petrae  ct  Rupes.'  "■  Was  this  clerk  the 
famous  Roger  ?  In  his  writings  he  does  not  appear  as 
iocundus  in  sermone,  and  though  he  had  some  knowledge 
of  the  inner  working  of  a  chancery,^  there  is  no  evidence  that 
he  was  ever  a  clerk  in  the  royal  court.  That  he  was  already 
a  student  at  Oxford  some  years  before  this  may  be  inferred 
from  his  statement  that '  Edmund  Archbishop  of  Canterbury 
first  lectured  on  the  book  of  Elenchs  at  Oxford  in  my  time  'J 
Edmund  Rich  was  consecrated  archbishop  April  2,  1234,  ^^^ 
had  ceased  to  lecture  at  Oxford  some  years  earlier.  Grosse- 
teste,  who  exercised  the  most  permanent  influence  on  his 
intellectual  development,  was  lecturing  in  the  schools  of 
the  Franciscans  at  Oxford  from  about  1230  to  1235,  when 
he  became  Bishop  of  Lincoln.'* 

Bacon  took  the  degree  of  M.A.  at  an  unknown  date,  and 
acquired  fame  by  his  lectures  at  Oxford  and  Paris.  He 
wrote  many  elementary  treatises  for  students.^  '  Men  used 
to  wonder  before  I  became  a  friar  {in  alio  statu)  that 
I  lived  owing  to  my  excessive  labours.'  '^  To  this  period 
probably  belong  his  commentaries  on  the    Physics  '  and 

'  Chron.  Majora,  iii.  244-5. 

-  E.  H.  R.,  xii.  501  '  Videmus  enim  in  curiis  prelatorum  et  princi- 
pum  quod  una  littera  transit  per  multas  manus  antequam  examinata 
scriptura  bullam  recipit  aut  sigillum  ' ;  cf.  Op.  Tert.  (Brewer),  p.  57. 

^  Comp.  Stud.  Theol.  (Rashdall),  p.  34. 

*  Lanercost  Chron.,  p.  45  ;   Eccleston  (ed.  Little),  p.  61. 
^  E.H.  R.,  xii.  500. 

*  Op.  Tert.  (Brewer),  p.  65. 

^  A  reference  to  the  Seine  (MS.  Amiens  406,  f.  47,  col.  a)  shows 
that  the  second  series  of  quaestiones  on  the  Physics  was  composed 
in  Paris. 

B  2 


4  ROGER  BACON 

Metaphysics,  preserved  in  the  Amiens  MS.  No.  406  :  they 
are  in  the  prevalent  dialectic  style,  and  perhaps  might  be 
put  into  the  class  of  works  which  Bacon  afterwards  ridiculed 
as  '  horse-loads  '.  His  lectures  on  the  pseudo- Aristotelian 
treatise  De  plantis  (preserved  in  part  in  the  same  MS.)  were 
delivered  at  Paris,  where  his  Spanish  students  laughed  at 
him  for  bungling  over  a  word  which  he  thought  was  Arabic 
and  they  told  him  afterwards  was  Spanish.' 

There  is  some  evidence  that  he  went  to  Paris  before  1236. 
For  he  says  that  he  began  his  Epistola  de  accidentibus 
senectutis  at  the  suggestion  of  two  wise  men,  namely 
John  of  Chatillon  (?)  and  Philip  Chancellor  of  Paris. ^ 
There  were  two  chancellors  of  the  name  of  Philip  in  the 
thirteenth  century :  Philip  de  Greve,  who  died  in  1236 
(and  was  buried  in  the  Franciscan  Church  at  Paris), ^  and 
Philip  de  Thoiry,  Chancellor  1280-4.  Since  Bacon  refers 
to  the  Epistola  as  already  published  in  1267,'*  it  is  clear  that 
the  Philip  referred  to  must  be  Philip  de  Greve.  Further, 
the  earliest  extant  MS,,  which  contains  an  early  version  of 
the  work,  states  that  the  letter  was  sent  to  Pope  Innocent  IV 
(1243-54).^  It  bears  internal  evidence  of  having  been  an 
early  work  ;  for  it  was  written  at  a  time  when  the  author 
did  not  know  Greek.  Incidentally  Bacon  mentions  in  it 
that  he  had  been  in  partibus  Romanis. 

Bacon  was  certainly  in  Paris  before  1245  :    for  he  says 

'  Op.  Maj.  (Bridges),  iii.  82  ;  Op.  Tert.  (Brewer),  p.  91  ;  Comp, 
Studii  Phil.  (Brewer),  pp.  467-8. 

-  MS.  Bibl.  Nat.  Paris,  6978,  f.  27'^ :  the  MS.,  which  is  anonymous, 
has  recently  been  identified  by  Mr.  Steele.  '  Et  hanc  incepi  ad 
suasionem  duorum  sapientum,  scil.  Johannis  Castellomati  {or 
Castelloniaci)  et  Philippi  Cancellarii  Parisiensis.'  John  of  Chatillon, 
O.F.M.,  was  in  Paris  1273  (Lecoy  de  la  Marche,  La  Chaire  fvam^.y 
p.  515)  :  John  of  Chatillon,  Count  of  Blois,  received  privileges  from 
Innocent  IV  (Baluze,  Miscell.,  i.  215). 

^  Brit.  Mus.  MS.  Add.  33956,  f.  71. 

*  Op.  Maj.  (Bridges),  ii.  209. 

5  MS.  Bibl.  Nat.,  6978. 


LIFE  AND  WORKS  5 

that  he  had  seen  with  his  own  eyes  Alexander  of  Hales/ 
who  died  in  that  year.  He  twice  heard  William  of  Auvergne 
(who  died  in  1248)  dispute  on  the  Intellectiis  A  gens  before 
the  whole  university.^  He  also  heard  Master  John  de 
Garlandia  (j  1252)  denounce  ignorant  etymologists.^  And 
he  was  in  France  in  1251,  when  he  saw  the  leader  of  the 
Pastoureaux.'*  We  do  not  know  when  or  where  he  entered 
the  Franciscan  Order,  nor  the  reasons  which  moved  him 
to  take  this  step.  Possibly  he  felt  the  need  of  the  protection 
of  a  powerful  organization.  He  was  clearly  of  mature 
years,  and  it  is  natural  to  suppose  that  he  was  influenced 
by  his  admired  friend  and  master,  Friar  Adam  Marsh. 

A  tradition  preserved  in  the  Register  of  the  Grey  Friars 
of  London  is  perhaps  worth  mentioning,  namely  that  John 
of  Parma  '  wrote  to  Friar  Roger  Bakon  the  treatise  beginning 
Innominato  Magistro  ' .^  This  is  a  well-known  letter  ^ 
written  by  Bonaventura  while  he  was  lecturing  at  Paris 
and  when  John  of  Parma  was  general  minister,  i.  e.  between 
1248  and  1257.  The  '  unnamed  master  '  appears  to  have 
had  some  thoughts  of  joining  the  Order,  but  to  have  been 
shaken  by  a  Dominican  who  attacked  the  Franciscans  for 
not  observing  the  Rule.  The  Dominican  was  rebuked  by 
the  English  provincial  minister,  from  which  it  may  be 
inferred  that  he  was  an  Englishman.  Though  at  least  one 
of  Bonaventura's  arguments,  that  namely  in  favour  of 
studying  philosophy  in  general  (*  for  without  practical 
knowledge  of  other  sciences  the  Holy  Scriptures  cannot  be 
understood  '),  would  have  appealed  to  Bacon,  and  though 
there  is  no  chronological  difficulty,  there  is  no  evidence  to 
support  the  identification  of  the  '  unnamed  master  '  with 
Roger  Bacon. 

'  Op.  Min.  (Brewer),  p.  325. 

-  Op.  Maj.  (Bridges),  iii.  47  ;   Op.  Tert.  (Brewer),  p.  74. 

^  Comp.  Siudii  Phil.  (Brewer),  p.  453. 

*  Op.  Maj.  (Bridges),  i.  401.  ^  Mon.  Franc,  i.  533. 

^  Bonaventiirae  Opera  Omnia,  viii.  331-6  (ed.  Quaracchi). 


6  ROGER  BACON 

It  may  be  mentioned  that  Roger  Bacon  never  became 
a  doctor  of  divinity  (in  spite  of  early  statements  to  the  con- 
trary)/ and  it  is  doubtful  whether  he  was  ever  in  holy  orders. 

Before  he  joined  the  Franciscans  he  had  already  cut 
himself  adrift  from  the  traditional  methods  and  objects 
of  study  {neglecto  sensu  vulgi)  and  struck  out  a  line  for 
himself.  He  had  already  become  convinced  of  the  inadequacy 
of  logic  and  of  the  need  for  the  acquisition  of  positive 
knowledge.  *  During  the  twenty  years  (he  says  in  1267)  ^ 
in  which  I  have  laboured  specially  in  the  study  of  wisdom, 
after  abandoning  the  usual  methods,  I  have  spent  more 
than  2000/.  on  secret  books  and  various  experiments,  and 
languages  and  instruments  and  mathematical  tables,  &c.' 
Though  a  libra  Parisiensium  was  only  equivalent  to  a  third 
of  a  pound  sterling,^  it  is  difhcult  to  believe  that  a  Mendicant 
Friar,  even  so  hardy  a  beggar  as  Bacon  evidently  was  when 
the  interests  of  science  were  concerned,  can  have  obtained 
so  large  a  sum  :  it  must  have  included  his  private  means 
171  alio  statu. 

'  He  is  called  '  magister  '  in  Amiens  MS.  406 — evidently  Master 
of  Arts.  No  thirteenth-century  document,  so  far  as  I  know,  refers 
to  him  as  Doctor  or  Master  of  Theology.  The  Chron.  XXIV  Gene- 
ralium,  written  c.  1370,  but  containing  earlier  matter,  calls  him 
S.  Theol.  Mag.  (p.  360).  On  the  other  hand,  Bartholomew  of  Pisa, 
who  is  very  careful  to  distinguish  between  friars  who  were  masters 
of  theology  and  friars  who  were  not,  always  refers  to  him  as  fraier, 
never  as  magister  :  Conform.,  i.  338  (ed.  Quaracchi)  '  Frater  Rogerius 
Bachon,  in  omni  facultate  doctissimus,  in  eisdem  scribendo  mirabilis 
apparet  scientiarum  diversitate  imbutus  '  (the  first  appearance  of 
his  traditional  epithet  'mirabilis'):  cf.  pp.  341,  547,  'fratrem 
Robertum  {sic)  Bachon.' 

■  Op.  Tert.  (Brewer),  p.  59. 

^  This  is  Bacon's  estimate  in  the  interesting  passage  quoted  by 
Charles,  Roger  Bacon,  p.  305,  from  MS.  Royal  7,  F.  VIII,  f.  4: 
'  Primum  enim  speculum  consistit  60  libris  parisiensium  quae  valent 
circiter  20  libras  sterlingorum  :  et  postea  feci  fieri  melius  pro  10  libris 
parisiensium,  scil.  pro  quinque  marcis  sterlingorum  [£2,  6s.  8<^.]  ;  et 
postea  diligentius  expertus  in  his  percepi  quod  meliora  possent  fieri 
pro  duobus  marcis,  vel  20  solidis,  et  adhuc  pro  minore.' 


LIFE  AND  WORKS  7 

His  health  broke  down,  and  for  ten  years  [c.  1256-66)  he 
had,  '  owing  to  many  infirmities,'  to  withdraw  from  taking 
any  pubUc  part  in  university  affairs.'  He  was  not,  as  is 
often  alleged,  imprisoned  or  banished  at  this  time.^  We 
have  a  glimpse  of  him  in  Paris  during  this  period  listening 
to  a  tale  of  magic. ^  He  seems  to  have  been  in  the  habit  of 
supplying  new  masters  of  arts  at  their  inception  or  inaugural 
disputation  with  problems  in  geometry  which  none  of  their 
hearers  could  solve.*  He  was  mainly  occupied  in  investiga- 
tions and  experiments  in  physics,  especially  optics,  in  making 
lenses,  in  constructing  astronomical  tables,  and  elaborating 
his  theory  of  the  propagation  of  force. ^  He  devoted  his 
leisure  to  instructing  boys  in  mathematics,  sciences,  and 
languages  :  ^  one  of  them,  John,  who  came  to  him  poor  and 
eager  to  learn,  about  1260,  at  the  age  of  fifteen,  he  supported 
through  alms  begged  from  friends  and  instructed  gratis  for 
the  love  of  God,  and  afterwards  employed  as  his  messenger 
to  the  pope.^  He  kept  himself  thoroughly  informed  on  what 
was  going  on  in  the  world,  and  uses  contemporary  political 
and  social  events  to  illustrate  his  points.  The  Children's 
Crusade  and  the  Revolt  of  the  Pastoureaux  afford  him 
instances  of  '  fascination  '.^  The  quarrels  between  Henry  III 
and  the  barons  in  England,  the  relations  of  the  English  and 
French  kings,  the  struggle  between  Empire  and  Papacy  and 

'  E.  H.  R.,  xii.  500. 

-  The  error  arose  from  a  misunderstanding  of  the  words,  '  a  decern 
annis  exulantem  quantum  ad  famam  studii  quam  retroactis  tempori- 
bus  obtinui.'    Op.  Tert.  (Brewer),  p.  7. 

^  Liber  Exemplorum,  ed.  Little  (Brit.  Soc.  of  Franciscan  Studies,  i), 
p.  22. 

"*  Op.  Tert.  (Brewer),  p.  139. 

^  Ibid.,  pp.  36,  T)S  ;   Charles,  p.  305. 

''  Op.  Tert.  (Brewer),  p.  159. 

'  Op.  Tert.  (Brewer),  pp.  61-3,  89,  iii,  135,  139,  221,  270; 
E.  H.  i?.,xii.  506  ;  Op.  Tert.  (Little),  pp.  61,  82  ;  Op.  Min.,  p.  320  ; 
Op.  Maj.,  ii.  171,  iii.  23. 

^  Opus  Maj.  (Bridges),  i.  401. 


8  ROGER  BACON 

final  overthrow  of  the  Hohenstaufen  by  Charles  of  Anjou, 
the  Crusades  of  St.  Louis,  the  agitation  of  William  of 
St.  Amour  in  the  University  of  Paris,  are  among  the  subjects 
he  alludes  to.'  He  draws  attention  to  the  cruelties  of  the 
Teutonic  knights  and  points  out  how  fatal  these  were  to  the 
efforts  of  the  friars  to  convert  the  heathen  Slavs  to  Chris- 
tianity.^ He  knew  of  the  great  German  friar  Berthold  of 
Regensburg  :  '  The  magnificent  work  he  is  doing  in  preaching 
is  of  more  value  than  that  of  almost  all  the  other  friars 
together.'  ^  He  was  profoundly  interested  in  the  discoveries 
of  the  great  travellers  of  the  time,  especially  William  de 
Rubruck  :  '  I  have  perused  his  book  diligently  and  conferred 
with  the  author,  and  with  many  others  who  have  investigated 
the  geography  of  the  East  and  South.'  ^  In  speaking  of 
mechanical  discoveries  :  '  I  have  not  seen  a  flying  machine,' 
he  says  in  one  place,  '  and  I  do  not  know  any  one  who  has 
seen  one  ;  but  I  know  a  wise  man  who  has  thought  out  the 
principle  of  the  thing.'  ^ 

Among  the  learned  he  made  many  friends,^  such  as  the 
mysterious  Peter  de  Maricourt,^  and  the  unnamed  homo 
sapientissimus,  who  has  been  identified  on  doubtful  grounds 
with  the  Franciscan  William  de  Mara.^  The  enemies  he 
made  by  his  bitter  tongue  were  more  important  people, 
chief  among  them  being  Albert  the  Great, ^  who  probably 

'  Ci.Comp.  StudiiPhil.  (Brewer),  pp.  399,  429 ;  Op.  Tert.  (Little), 
p.  19;  Op.  Maj.  (Bridges),  pp.  321,  386. 

-  Op.  Maj.  (Bridges),  iii.  12 1-2. 

^  Op.  Tert.  (Brewer),  p.  310. 

*  Op.  Maj.  (Bridges),  i.  303,  305,  356-74,  400. 

^  De  Secretis  Operihus  Artis  et  Naturae  (Brewer),  p.  533. 

^  Cf.  Op.  Tert.  (Brewer),  p.  58. 

^  e.g.  Op.  Tert.  (Brewer),  pp.  35,  43,  46-7.  See  Picavet,  Essais,  &c. 
(Paris,  1913),  cap.  xii. 

^  Op.  Tert.  (Brewer)  ;  Op.  Min.,  pp.  32,  317  ;  S.  Berger,  Quam 
notitiam  Linguae  Hebraicae  habuerint  Christiani,  &c.,  p.  35. 

^  Op.  Tert.  (Brewer),  pp.  30,  37-42  ;  Op.  Min.,  pp.  327-8  :  these 
passages  probably  refer  to  Albert  rather  than  to  Aquinas.     Bacon 


LIFE  AND  WORKS  9 

was  thinking  of  Bacon  when  he  denounced  those  critics 
who  were  too  idle  to  pubhsh  works  of  their  own  and  only 
read  the  works  of  others  to  find  fault  with  them.'  Bacon 
himself  admits  that  he  wrote  nothing  or  next  to  nothing 
of  importance — confining  himself  to  letters  to  friends  who 
asked  his  opinion  on  special  points.^  This  is,  however,  an 
exaggeration.  Though  he  received  no  command  to  write 
from  his  superiors,^  who  were  naturally  nervous  of  encourag- 
ing independent  talent  at  a  time  when  the  publication  of 
the  '  Introduction  to  the  Eternal  Gospel  '  had  shaken  the 
Order  to  its  foundations,*  the  list  of  his  writings  which 
may  be  assigned  to  this  period  is  not  inconsiderable.  It 
probably  includes  the  De  Speculis  and  the  De  Mirahili 
Potestatc  Artis  et  Naturae,  certainly  the  long  astronomical 
work  De  Computo  Naturali  (a.  d.  1263-4)  ^^^  the  Meta- 
physical (a  treatise  which  in  its  present  fragmentary  form 
gives  a  very  poor  impression  of  Bacon's  capacity  to  deal 
with  questions  of  pure  philosophy),  and  probably  a  version 

was  indignant  that  he  should  be  quoted  as  an  '  authority  '  in  the 
schools,  and  regarded  his  influence  as  pernicious  mainly  because 
of  his  ignorance  and  neglect  of  languages  and  mathematics,  and  the 
sciences  based  on  mathematics :  he  reiterates  that  he  is  not  moved 
by  personal  feeling — indeed,  he  praises  him  as  '  studiosissimus ' 
(Brewer,  p.  327) — but  attacks  him  only  '  propter  amorem  veritatis  et 
propter  utilitatem  communem '  (ib.  p.  30) .  That  his  hostility  was  not 
a  Franciscan's  jealousy  of  a  Dominican  is  proved  by  the  fact  that  he 
simultaneously  denounces  Alexander  of  Hales.  (On  pp.  326-7  of 
Brewer,  for 'Nam  quum  intra vit',  &c.,  read:  'Immoquoniamintravit 
ordinem  fratrum  minorum,  fuit  de  eo  maximus  rumor  non  solum 
.  .  .  sed  propter  hoc  quod  novus  fuit  Ordo  Minorum.') 

^  Mandonnet,  Siger  de  Brabant,  i.  246;  Alberti  Magni  Opera 
Omnia,  ed.  Borgnet,  viii.  803-4  (Politics). 

-  Op.  Tert.  (Brewer),  p.  13. 

^  Ibid. 

■•  Cf.  Seppelt,  Der  Kampf  der  Bettelorden,  &c.,  Breslau,  1907  ; 
and  the  decree  against  publishing  unauthorized  writings  in  the 
General  Constitutions  of  the  Franciscan  Order,  1260  :  Archiv  f.  Lit. 
II.  Kirchengesch.,  vi.  no. 

5  Cf.  Op.  Tert.  (Little),  p.  56. 


10  ROGER  BACON 

of  the  important  physical  treatise  De  Multiplicatione 
Specierum,  or  On  the  propagation  of  force.  The  last  two 
seem,  however,  to  have  been  written  after  Bacon  had  come 
into  communication  with  Guy  de  Foulques,  the  future 
Clement  IV. 

Bacon's  great  opportunity  came  in  1266.  Guy  de  Foul- 
ques, Archbishop  of  Narbonne  (1259)  and  Cardinal-Bishop 
of  St.  Sabina  (1261),  heard  of  Bacon's  writings  from  Raymond 
de  Laon,  a  clerk  in  the  cardinal's  service,  and  commissioned 
Raymond  to  obtain  them,  probably  at  the  end  of  1264.' 
Guy  was  elected  Pope  under  the  title  of  Clement  IV  on 
February  5,  1265.  In  March  1266,  Sir  William  Bonecor  or 
Boncquor,  who  had  been  employed  in  negotiations  with  the 
Holy  See  and  with  Spain,  and  who  (as  Matthew  Paris  notes) 
was  well  versed  in  the  manners  and  customs  of  the  Spaniards, 
was  sent  by  Henry  III  as  special  envoy  to  Clement  IV, ^ 
and  to  his  hands  Bacon  entrusted  a  letter  for  the  pope, 
which  has  not  been  preserved.^  The  pope,  having  noted  the 
viva  voce  explanations  which  the  learned  knight  supplied, 
wrote  to  Bacon  from  Viterbo  on  June  22,  1266,  bidding 
him  send  a  fair  copy  of  the  works  which  Raymond  de  Laon 
had  previously  mentioned,  secretly  and  without  delay, 
notwithstanding  any  constitution  of  the  Franciscan  Order 
to  the  contrary.'^ 

Bacon's  gratitude  was  boundless.  '  The  Head  of  the 
Church  has  sought  out  me,  the  unworthy  sole  of  its  foot  .  .  . 
I  feel  myself  elevated  above  my  ordinary  strength  ;  I  con- 
ceive a  new  fervour  of  spirit.    I  ought  to  be  more  than  grate- 

'  It  is  often  said  that  Guy  de  Foulques  heard  of  Bacon  when  he 
was  legate  in  England  (1264) ;  he  failed,  however,  to  gain  admittance 
to  England  and  got  no  further  than  Boulogne. 

-  Matt.  Paris,  Chron.  Maj.,  v.  555,  576.  Pat.  Rolls,  50  Hen.  Ill, 
m.  24.    Sir  W.  Bonecor  is  frequently  mentioned  in  the  public  records. 

"  Can  it  have  been  the  Metaphysica  de  viciis  contracHs  in  studio 
theologie  ? 

"  The  letter  is  printed  in  Brewer,  Op.  Iiied.,  p.  i. 


LIFE  AND  WORKS  ii 

ful  since  your  Beatitude  has  asked  me  for  that  which  I  have 
most  ardently  desired  to  communicate,  which  I  have  worked 
at  with  immense  toil  and  brought  into  light  after  manifold 
expenses.'  '  He  explains  to  the  pope  in  some  detail  the 
various  difficulties  which  he  had  had  to  face  :  weak  health, 
want  of  money,  lack  of  assistants,  the  obstacles  thrown  in 
his  way  by  his  superiors,  the  impossibility  of  finding  com- 
petent and  trustworthy  copyists,  and  his  own  methods  of 
composition.  '  Anything  difficult  I  have  to  write  four  or 
five  times  before  I  get  what  I  want.'  -  The  pope  was  wrong 
in  thinking  that  the  work  was  already  written  :  nothing 
worthy  of  his  Holiness  was  written,  and  the  whole  had  to 
be  composed  from  the  beginning.  His  first  project  was  an 
elaborate  one,  including  a  systematic  and  scientific  treatment 
of  the  various  branches  of  knowledge  ;  he  worked  at  this, 
writing  parts  of  the  Communia  Naturaliuni  ^  and  Communia 
Mathematicae,  for  some  months  ('  till  after  Epiphany ', 
i.  e.  January  6,  1267),  but  found  it  impossible.  He  then 
started  again  on  a  more  modest  scale  and  wrote  in  the  next 
twelve  months  the  preliminary  treatise  known  as  the 
Opus  Majus,'^  which  was  supplemented  by  the  Opus  Minus, 
and,  subsequently,  by  the  Opus  Tertium.^ 

The  Opus  Minus  and  the  Optis  Tertium  were  both  of  them 
introductions  to  and  summaries  of  the  Opus  Majus  with  some 
additions  (chiefly  on  the  dangerous  subjects  of  alchemy  and 
astrology)  and  further  elucidation  of  special  points.  The  Opus 
Majus  Bacon  sometimes  calls  Tractaius  praeambulusinconiva.- 
distinction  to  the  great  systematic  work  on  all  the  sciences 

'  Op.  Teri.  (Brewer),  pp.  7-8  ;  Brewer's  Introduction,  p.  xxv. 

-  Op.  Tert.  (Brewer),  pp.  13-17  ;   E.H.R.,  xii.  501. 

^  Mr.  Steele  has  pointed  out  that  part  of  this  was  written  before 
the  Opus  Majus  :   Com.  Nat.,  p.  13. 

'  E.H.R.,  xii.  501-3. 

^  I  hope  to  discuss  on  another  occasion  Father  Mandonnet's 
ingenious  and  paradoxical  theory  on  '  La  composition  des  trois 
Opus':  Revue  neo-scolastique  de  philosophic,  19 13. 


12  ROGER  BACON 

which  he  hoped  to  write/  more  often  Persuasio.^  It  was 
a  treatise  written  with  the  definite  object  of  persuading 
the  practical  man  of  the  practical  usefulness  of  '  wisdom  ', 
of  scientific  knowledge  and  method.  The  parts  into  which 
it  is  divided  are  entitled  '  On  the  Usefulness  of  the  Study 
of  Languages',  'On  the  Usefulness  of  Mathematics',  and 
so  forth,  and  at  the  end  of  each  section  the  author  points 
out  practical  appHcations  which  were  likely  to  appeal  to 
the  ruler  of  the  Church  ;  thus  a  knowledge  of  Hebrew  and 
Greek  is  necessary  for  understanding  the  meaning  and 
establishing  the  correct  text  of  the  Bible,  a  knowledge  of 
Arabic  is  useful  to  convict  the  infidel,  a  knowledge  of  geo- 
graphy would  save  missionaries  from  much  waste  labour 
and  many  dangers,  a  knowledge  of  optics  would  lead  to 
the  construction  of  instruments  which  would  increase  the 
power  of  vision,  and  would  enable  a  leader  to  make  and 
use  burning-glasses  and  destroy  the  cities  and  armies  of 
the  enemy. 

An  admirable  sketch  of  the  course  of  thought  in  the 
Opus  Majus  was  given  by  the  late  Professor  Robert  Adamson 
in  an  address  delivered  at  the  Owens  College,  Manchester, 
in  1876,^  and  is  here  reproduced.  '  You  will  find  it  consist ', 
says  Professor  Adamson,  '  mainly  in  three  things  :  ist,  A 
criticism  of  the  spirit  in  which  scientific  studies  were  then 
pursued  ;  2nd,  an  attempt  at  a  classification  of  the  sciences  ; 
3rd,  an  exposition  of  a  new  scientific  method.  ...  As  it 

'  e.g.  Op.  Tert.  (Brewer),  p.  19,  'In  tractatu  praeambulo  et 
separate  a  singulis  tractatibus  particularibus.'    Cf.  21,  22,  23,  &c. 

-  e.g.  E.H.R.,  p.  507:  '  Persuasio  igitur  quam  mitto  habet 
septem  partes,'  &c.  Op.  Maj.,  iii.  36  ;  i.  305  '  praesens  persuasio' 
distinguished  from  '  scriptura  perf ecta  quam  requiritis  '  ;  p.  325,  '  in 
hac  persuasione '  distinguished  from  '  principaliori  tractatu  '.  See 
also  the  titles  in  the  Digby  MS. 

^  Roger  Bacon:  the  Philosophy  of  Science  in  the  Middle  Ages 
(Manchester,  Cornish,  1876).  It  is  out  of  print.  The  following 
pages  arc  reprinted  with  the  kind  permission  of  Mrs.  Adamson. 


LIFE  AND  WORKS         *  13 

stands  at  present  the  work  consists  of  [six]  parts/  of  which 
the  contents  are  as  follows  : 

'  Part  I  is  an  exposition  of  the  causes  which  have  hindered 
the  progress  of  true  philosophy  among  the  Latins.  These 
Offendicula,  as  Bacon  calls  them,  are  four  in  number : 
(i)  Dependence  on  authority  {fragilis  ct  indignae  auctoritatis 
exemplum) ;  (2)  Yielding  to  established  custom  [consuetii- 
dinis  diuturnitas) ;  (3)  Allowing  weight  to  popular  opinion 
{vulgi  sensus  imperiti)  ;  (4)  Concealment  of  real  ignorance 
with  pretence  of  knowledge  [propriac  ignorantiae  occultatio 
cum  ostentationc  sapientiae  apparentis).  As  Bacon  bitterly 
says,  the  prevailing  mode  of  argument  in  his  time  was  : 
"  this  is  affirmed  by  our  superiors  ;  this  is  the  customary 
opinion  ;  this  is  the  popular  view  ;  therefore  it  must  be 
admitted."  It  may  seem  but  a  small  thing  for  a  writer  to 
reject  authority,  but  one  must  reflect  on  what  that  meant 
in  Bacon's  time.  It  meant  absolute  revolt  against  the 
whole  spirit  of  scholasticism  ;  it  was  the  assertion  of  freedom 
of  thought,  of  the  claim  of  science  to  push  forward  to  its 
conclusions,  regardless  of  fancied  consequences,  with  im- 
plicit trust  in  the  grand  law  that  all  truth  is  ultimately 
harmonious.  Over  and  over  again  Bacon  dwells  upon  the 
baneful  influence  of  authority,  and  speaks  of  it  in  terms 
that  remind  one  strongly  of  his  namesake.  He  points  out 
that  the  Fathers,  after  all,  were  men,  and  used  the  same 
faculty  of  reason  that  men  now  possess.  He  implores  his 
contemporaries  to  consider  that  their  authorities  not  only 
fall  into  error,  but  spend  great  part  of  their  labour  in  refuting 
one  another,  which  would  not  be  the  case  if  they  were  in- 
fallible. And  finally  generalizing  his  argument,  he  makes 
the  weighty  observation,  that  authority  may  compel  belief, 
but  cannot  enlighten  the  understanding  {credimus  auctoritati, 
sed  non  propter  earn  intelligimus) .  He  is  willing  that  all 
honour  should  be  paid  to  the  ancients  ;  but,  as  he  says, 
those  who  are  younger  in  order  of  time,  enjoy  the  labours 
of  those  who  have  gone  before  them  ;  Quanta  juniores,  tanto 
perspicaciores,  a  maxim  which,  it  seems  to  me,  may  rank 
with  Francis  Bacon's  famous  apophthegm,  antiquitas  seculi, 
juventus  mundi. 

'  This  strong  opposition  to  Authority  extends  itself  to  all 
that  rests  on  custom  or  popular  opinion.     Bacon,  indeed, 

•  Part  VII,  on  Moral  Philosophy,  was  first  edited  by  Bridges  in 
1897. 


14  ^  ROGER  BACON 

has  a  true  savant's  contempt  for  the  profanum  vulgus. 
"  Whatever  ",  he  stoutly  declares,  "  seems  true  to  the  many, 
must  necessarily  be  false."  The  common  people,  however, 
are  not  guilty  of  the  fourth  fault,  concealment  of  ignorance 
and  assumption  of  knowledge  ;  that  is  the  peculiar  property 
of  the  learned  professors.  ... 

'  On  the  whole,  then,  in  this  first  part  we  can  see  Bacon 
dehberately  rejecting  the  whole  spirit  and  method  of 
scholasticism.  He  has  said  himself  off  from  contemporary 
philosophy,  and  now  proceeds  to  evolve  the  system  of 
knowledge  which  ought  to  be  substituted  for  it. 

'  Before  beginning  his  task  he  has  to  come  to  terms  with 
the  great  scholastic  study,  Theology  ;  this  he  does  in  the 
Second  Part  of  his  work.  It  is  not  very  easy  for  us  to  realize 
Bacon's  position  with  regard  to  the  question  of  the  relation 
between  Philosophy  and  Theology.  He  does  not  seem  to 
have  entered  with  much  earnestness  on  the  matter,  and 
sometimes  he  is  a  little  inconsistent.  He  takes  up  the  usual 
position  that  all  knowledge  is  revealed  in  the  Scriptures, 
but  is  there  only  implicitly,  and  thus  philosophy  has  a  place 
alongside  of  theology  as  its  exponent.  "  The  end  of  all  true 
philosophy",  says  he,  "  is  to  arrive  at  a  knowledge  of  the 
Creator  through  knowledge  of  the  created  world."  A  better 
definition  has  seldom  been  given.  Theology,  further,  has 
need  of  philosophy  to  prove  its  principles,  otherwise  infidels, 
who  do  not  accept  the  Scriptures,  could  never  be  convinced 
of  the  truth  of  the  Christian  faith.  There  is  much  in  this 
proposition  that  requires  more  careful  handling  than  Bacon 
has  given.  Evidently,  however,  the  problem  is  not  one  of 
the  highest  interest  for  him. 

'  Part  HI.  The  third  part  of  the  Opus  lays  the  first 
stone  of  the  new  building.  In  order  to  obtain  real  know- 
ledge we  must  study  what  Bacon  calls  Grammar,  what  we 
should  call  Philology,  for  Bacon  has  a  wide  idea  of  Grammar. 
In  particular  the  Greek,  Hebrew,  Chaldaic,  and  Arabic 
languages  must  be  mastered,  for  the  Scriptures  and  the  best 
philosophical  works  are  written  in  these  tongues.  There 
were  translations  no  doubt  ;  the  Bible  has  been  translated, 
Aristotle  had  been  translated.  But  Bacon  never  wearied  in 
pointing  out  how  miserably  defective  these  translations 
were.'  Of  Aristotle,  in  especial,  he  declared  that  if  he  had 
the  power  he  would  burn  every  book,  so  miserable  had  been 

'  [Bacon  certainly  exaggerated  the  badness  of  the  later  translations : 
cf.  Mandonnet,  Siger  de  Brabant  (2nd  ed.),  i.  40-     A.  G.  L.] 


LIFE  AND  WORKS  15 

the  execution.  There  is  no  doubt  that  Bacon  was  right 
in  this  criticism,  and  the  history  of  some  of  the  Latin 
translations  is  sufficient  to  make  their  worthlessness  in- 
teUigible.  In  many  cases  they  were  translated  from  the 
Arabic  by  wretched  Arabic  scholars  ;  while  the  Arabic 
versions  were  not  generally  from  the  original  Greek.  Most 
frequently  they  were  from  Syriac  translations,  through 
which  a  knowledge  of  Aristotle  first  penetrated  to  the  Arabs. 
Thus  the  steps  would  be  :  Original  Greek,  Syriac  version, 
Arabic  translation  of  the  Syriac,  Latin  version  of  the  Arabic. 
It  is  not  wonderful  that  in  too  many  cases  Aristotle  was 
indeed  "  translated  ",  and  that  there  should  be  found  in 
his  harder  works  what  Bacon  calls  "  horrible  difficulties  ". 

'  Bacon  himself  knew  Greek  well.  Among  his  unprinted 
works  ^  is  a  fragment  of  a  Greek  grammar  ;  and  so  easy 
did  he  think  the  language  that  he  professed  himself  able 
to  teach  any  one  to  read  the  ordinary  authors  within  three 
days.  For  this  boast  he  has  been  much  blamed  ;  Prantl, 
the  historian  of  Logic,  with  all  the  German  capacity  for 
hurling  hard  names,  calls  him  "  a  swindler  and  a  charlatan 
like  his  celebrated  namesake  ".  I  think  it  probable  that 
the  particular  passage  in  the  Opus  Tertium  has  been  some- 
what misunderstood,  and  that  we  must  not  interpret  the 
language  very  strictly. 

'  The  Fourth  part  of  the  Opus  is  in  some  respects  the 
most  remarkable.  In  it  Bacon  handles  mathematics,  their 
utility  for  science  and  for  theology.  It  is  for  what  he  says 
here  that  one  would  claim  highest  credit  for  him.  Mathe- 
matics he  calls  the  gate  and  key  of  the  natural  sciences, 
the  alphabet  of  philosophy.  In  it  alone  do  we  have  perfect 
and  complete  demonstration.  While  therefore  mathematics 
is  necessary  for  all  science  whatsoever,  it  is  particularly 
needful  and  useful  for  natural  philosophy.  "  Physicists", 
says  Bacon,  "  ought  to  know  that  their  science  is  powerless 
unless  they  call  in  the  aid  of  mathematics."  (Naturales 
mundi  sciant  quod  languebunt  in  rebus  naturalibus,  nisi 
mathematicae  noverunt  potestatem. — De  Coelestibus  MS.)  ^ 
This  opinion  is  not  taken  up  loosely,  not  thrown  out  by 
chance  ;  it  is  grounded  on  a  broad  and  comprehensive  theory 
of  natural  action.  For,  according  to  Bacon,  all  natural 
phenomena,  all  generation,  change,  transformation,  must 

'  [Printed  in  1902,  ed.  Nolan  and  Hirsch.] 

'  [Charles,  Roger  Bacon,  137,  note:  Steele,  Opera  hadenus  inedita, 
Fasc.  IV,  p.  342,] 


i6  ROGER  BACON 

be  regarded  as  the  result,  the  effect,  of  the  exercise  of  force 
by  material  agents.  Matter  and  Force,  in  short,  are  his 
fundamental  physical  ideas.  Now  Force,  according  to  him, 
is  invariably  subject  to  mathematical  law.  It  is  propagated, 
or,  as  he  calls  it,  multiplied,  uniformly  and  regularly  in  space 
and  time,  and  can  consequently  be  expressed  by  lines  and 
figures.  Geometry  is  therefore  absolutely  necessary  in  order 
to  explain  the  action  of  natural  agents  ;  all  natural  philo- 
sophy is  ultimately  mathematical.' 

*  This  is  a  wonderful  step  in  advance  of  any  preceding 

'  '  The  following  passages  may  be  cited  in  support  of  what  is  here 
said  : 

'  (i)  "  Omnis  res  naturalis  producitur  in  esse  per  efificiens  et  mate- 
riam,  in  quam  operatur,  nam  haec  duo  concurrunt  primo.  Agens 
enim  per  suam  virtutem  movet  et  transmutat  materiam,  ut  fiat  res. 
Sed  virtus  efficientis  et  materiae  sciri  non  potest  sine  magna  mathe- 
maticae  potestate,  sicut  nee  ipsi  effectus  producti.  .  .  .  Et  sic  potest 
ostendi,  quod  nihil  in  rebus  sciri  potest  sine  geometriae  potestate.  .  .  . 
Omne  enim  efficiens  agit  per  suam  virtutem,  quam  facit  in  materiam 
subjectam  .  .  .  et  haec  virtus  vocatur  similitudo,  et  imago,  et  species, 
et  multis  nominibus  .  .  .  et  haec  species  facit  omnem  operationem 
hujus  mundi  ;  nam  operatur  in  sensum,  in  intellectum,  et  in  totam 
mundi  materiam  per  rerum  generationem,  quia  unum  et  idem  fit  ab 
agente  naturali  in  quodcunque  operetur,  quia  non  habet  deliberatio- 
nem,  et  ideo  quicquid  ei  occurrat  facit  idem." — Op.  Maj.,  p.  66  [ed. 
Bridges,  i.  no].  The  same  at  greater  length  in  the  De  Multiplicatione 
Specierum. 

'  (2)  "  Circa  vero  geometricalia,  respectu  rerum  et  scientiarum 
sciendarum,  consideravi  quod  res  omnis,  quae  fit  in  hoc  mundo,  exit  in 
esse  per  efficiens  et  materiale  principium,  ex  quo  producitur  per  vir- 
tutem efhcientis,  et  ideo  tota  originalis  rerum  cognitio  dependet  ex 
parte  efficientis  et  materiae." — Opus  Tert.  {Op.  Ined.  [Brewer]), 
pp.  107-8. 

'  (3)  "  Nee  mirum  si  omnia  sciantur  per  mathematicam,  et  omnia 
per  hanc,  quia  omnes  scientiae  sunt  annexae,  licet  quaelibet  simul  cum 
hac  habet  suam  proprietatem.  Unde  quaelibet  habet  potestatera  in 
aliam,  nee  potest  una  sciri  sine  alia.  .  .  .  Et  necesse  est  omnia  sciri  per 
hanc  .scientiam,  quia  omnes  actiones  rerum  fiunt  secundum  specierum 
et  virtutum  multiplicationem  ab  agentibus  hujus  mundi  in  mate- 
rias  patientes  ;  et  leges  hujusmodi  multiplicationum  non  sciuntur 
nisi  a  perspectiva,  nee  alibi  sunt  traditae  adhuc  ;  cum  tamen  non 
solum  sint  communes  actioni  in  visum,  sed  in  omnem  sensum,  et  in 
totam  mundi  machinam,  et  in  coelestibus  et  in  inlerioribus." — Op. 
Ined.  [Brewer],  p.  37.' 


LIFE  AND  WORKS  i7 

thinker.  The  mere  enunciation  of  such  a  thought  is  sufficient 
to  secure  for  Bacon  a  high  place  among  those  who  have 
written  on  scientific  method.  It  by  no  means  detracts  from 
his  merit  to  say,  as  Prantl  says,  that  Grosset^te  was  an  able 
mathematician  ;  for  Grossetete,  so  far  as  we  know,  made 
no  such  appUcation  of  his  mathematical  knowledge.  How- 
ever imperfectly  Bacon  realized  his  great  conception,  and 
it  must  be  remembered  how  weak  the  instrument  then  was, 
and  how  little  was  prepared  for  its  application,  he  at  all 
events  threw  out  a  fruitful  thought,  of  which  modern 
physical  science  is  but  the  exemplification. 

'  So  highly  does  Bacon  estimate  mathematics  that  he 
makes  logic  entirely  subordinate  to  it.  This  attempt  to 
show  that  logic  deals  essentially  with  quantities,  and  is 
therefore  mathematical  in  character,  is  both  bold  and 
subtle.'  He  will  not  allow  that  logical  is  synonymous  with 
demonstrative.  Mathematics  alone  can  give  absolute 
certainty  {in  sola  mathcmatica  est  certitudo  sine  diihitatione) ; 
demonstration  is  in  essence  mathematical.  To  logic,  indeed, 
Bacon  is  rather  unjust.  He  advances  against  it  arguments 
similar  to  those  afterwards  employed  by  Locke.  Logic, 
he  says  in  effect,  is  innate  ;  we  reason  perfectly  well  with- 
out it. 

'  The  Fifth  part  of  the  Opus  Majus  treats  at  great  length 
of  Perspective  or  optics.  One  can  readily  understand  how 
this  should  be  for  Bacon  the  very  type  of  physical  science. 
It  was  exactly  conformed  to  mathematical  law  ;  in  fact, 
one  may  say  that  his  grand  idea  of  all  physical  science  as 
mathematical  in  nature  was  simply  an  inference  from  what 
was  so  palpable  in  optics.  It  is  not  necessary  to  enter  into 
the  details  of  the  treatise,  which  begins  with  the  psychology 
of  perception,  then  takes  up  the  anatomy  and  physiology 
of  the  eye,  and  finally  discusses  at  great  length  vision 
in  a  right  line,  the  laws  of  reflection  and  refraction,  the 
construction  and  properties  of  mirrors,  lenses,  and  burning- 
glasses.    There  is  not  much  advance  beyond  Alhazen.- 

'  Part  VI.  Of  all  the  parts  of  the  Opus  Majus,  the  sixth 
is  the  most  important.  It  treats  of  experimental  science, 
domina  omnium  scientiarum  et  finis  totius  speculationis. 
Without  experience,  as  Bacon  constantly  repeats,  nothing 
can  be  known  with  certainty.     Even  the  conclusions  of 

^  'Op.  Majus,  60'  [ed.  Bridges,  i.  102]. 

-  [On  this  cf .  the  remarks  of  Bridges,  Introduction,  pp.  Ixxii-Ixxiii, 
and  the  articles  of  Wiedemann,  Vogl,  and  Wurschmidt  in  this  volume.] 
1689  C 


i8  ROGER  BACON 

mathematical  physics,  reached  by  argument  from  certain 
principles,  must  be  verified  before  the  mind  can  rest  satisfied. 
To  this  great  science  all  the  others  are  subsidiary ;  they  are 
to  it  ancillae  or  handmaids,  an  expression  that  curiously 
reminds  one  of  Francis  Bacon.  The  reasoning  in  favour 
of  experience  is  well  worth  quoting  at  length.  "  There  are 
two  modes  in  which  we  acquire  knowledge,  argument  and 
experiment.  Argument  shuts  up  the  question,  and  makes 
us  shut  it  up  too  ;  but  it  gives  no  proof,  nor  does  it  remove 
doubt,  and  cause  the  mind  to  rest  in  the  conscious  possession 
of  truth,  unless  the  truth  is  discovered  by  way  of  experience, 
e.g.  if  any  man  who  had  never  seen  fire  were  to  prove 
by  satisfactory  argument  that  fire  burns  and  destroys 
things,  the  hearer's  mind  would  not  rest  satisfied,  nor 
would  he  avoid  fire  ;  until  by  putting  his  hand  or  some 
combustible  thing  into  it,  he  proved  by  actual  experiment 
what  the  argument  laid  down  ;  but  after  the  experiment 
had  been  made,  his  mind  receives  certainty  and  rests  in 
the  possession  of  truth,  which  could  not  be  given  by  argu- 
ment but  only  by  experience.  And  this  is  the  case  even  in 
mathematics,  where  there  is  the  strongest  demonstration. 
For  let  any  one  have  the  clearest  demonstration  about  an 
equilateral  triangle  without  experience  of  it,  his  mind  will 
never  lay  hold  of  the  problem  until  he  has  actually  before 
him  the  intersecting  circles  and  the  lines  drawn  from  the  point 
of  section  to  the  extremities  of  a  straight  line.  He  will 
then  accept  the  conclusion  with  all  satisfaction."  [Op.  Maj., 
p.  445  [ed.  Bridges,  ii.  167].) 

'  This  important  passage,  it  seems  to  me,  marks  a  distinct 
advance  in  the  philosophy  of  science.  The  science  of  that 
time  proceeded  wholly  per  argumentu7n  ;  verification  was 
unknown.  Not  only,  however,  does  Bacon  recognize  the 
necessity  for  experiment,  for  observation  at  first-hand,  but 
he  has  a  clear  appreciation  of  the  true  nature  of  scientific 
verification.  He  has  already  expounded  his  ideal  of  physical 
science,  the  application  of  mathematics  to  determine  the 
laws  of  force  and  to  deduce  conclusions  from  these  laws  ; 
but  he  is  perfectly  aware  that  these  general  conclusions 
must  be  tested  by  comparison  with  things,  must  be  verified. 
The  function  of  experimental  science  is,  in  a  word.  Verifica- 
tion. "  This  Science ",  says  Bacon,  "  has  three  great 
prerogatives  in  respect  to  all  the  other  sciences.  The  first 
is — that  it  investigates  their  conclusions  by  experience. 
For  the  principles  of  the  other  sciences  may  be  known  by 
experience,    but    the    conclusions    are    drawn    from    these 


LIFE  AND  WORKS  19 

principles  by  way  of  argument.  If  they  require  particular 
and  complete  knowledge  of  those  conclusions,  the  aid  of 
this  science  must  be  called  in.  It  is  true  that  mathematics 
possesses  useful  experience  with  regard  to  its  own  problems 
of  figure  and  number,  which  apply  to  all  the  sciences  and 
to  experience  itself,  for  no  science  can  be  known  without 
mathematics.  But  if  we  wish  to  have  complete  and 
thoroughly  verified  knowledge,  we  must  proceed  by  the 
methods  of  experimental  science."  [Op.  Maj.,  p.  448.')  As 
an  example  of  his  method  Bacon  analyses  the  phenomena 
of  the  rainbow  in  a  thoroughly  scientific  manner. 

'  The  second  and  third  prerogatives  (though  not  of  such 
importance)  may  also  be  mentioned.  The  second  is — 
that  Experimental  Science  attains  to  a  knowledge  of  truth 
which  could  not  be  reached  by  the  special  sciences  ;  the 
third — that  Experimental  Science,  using  and  combining  the 
results  of  the  other  sciences,  is  able  to  investigate  the  secret 
operations  of  Nature,  to  predict  what  the  course  of  events  will 
be,  and  to  invent  instruments  or  machines  of  wonderful  power. 

'  From  the  whole  spirit  of  this  great  work,  of  which  what 
has  been  given  is  but  an  inadequate  summary,  we  may  gather 
a  fairly  accurate  idea  of  what  Bacon  attempted  to  perform. 
We  see  in  it  strong  opposition  to  the  current  modes  of 
thought,  a  well-grounded  rejection  of  authority  and  of  the 
syllogistic  method  as  then  conceived,  an  attempt  at  a 
classification  of  the  sciences,  a  clear  perception  of  the  neces- 
sity for  studying  nature  at  first-hand,  a  comprehensive 
idea  of  natural  philosophy,  and  the  foreshadowings  of  a  new 
method  of  research  ;  in  all  points,  in  short,  an  almost  exact 
parallel  to  what  was  presented  four  centuries  later  in  the 
De  Augmcntis  and  Novum  Organiim.' 

Part  VII  on  Moral  Philosophy  was  unknown  to  Professor 
Adamson.  It  bears  obvious  marks  of  haste  (Bacon  was  un- 
able to  revise  the  later  sections  before  sending  the  work  to 
the  pope)  ;  ^  it  consists  largely  of  quotations  from  the 
dialogues  of  Seneca,  which  Bacon  had  just  discovered  after 
a  search  of  more  than  twenty  years, ^  and  it  incorporates 
many  pages  of  Bacon's  Metaphysics,'^  and  is  perhaps  the  least 

'  Ed.  Bridges,  ii.  172-3.  =  Op.  Tert.  (Little),  p.  61. 

^  Op.  Tert.  (Brewer),  p.  56. 

*  For  portions  of  Metaphysics  included  see  Steele's  edition  of 
Metaphysica  (Introduction),  and  Little,  Op.  Tert.,  p.  xxix. 

C  2 


20  ROGER  BACON 

satisfactory  portion  of  the  work.  Yet  in  the  few  pages 
devoted  expressly  to  political  philosophy  we  find  the  curiously 
modern  idea  that  the  aged  poor  should  be  maintained  by 
the  State.^ 

The  Opus  Majus  and  Opus  Minus,  together  with  two 
versions  ^  of  the  De  MuUiplicatione  Specierum  and  a 
separate  treatise  on  Alchemy,^  were  sent  to  the  pope  by  the 
hand  of  Bacon's  young  pupil  John,  apparently  early  in  1268/ 
It  is  doubtful  whether  the  Opus  Tertium  was  ever  sent. 
Clement  IV  died  November  29,  1268. 

About  this  time  Bacon  seems  to  have  returned  to  Oxford, 
where  he  wrote  (perhaps  now,  perhaps  earlier)  his  Introduc- 
tion and  Notes  to  pseudo- Aristotelian  Secretum  Secretorum.^ 
To  this  period  also  belong  the  Greek  and  Hebrew  Grammars,^ 
and  a  fragment  generally  known  as  Compendium  Studii 
Philosophiae.  The  latter  was  written  when  the  Papal  See 
had  been  vacant  many  years,  but  during  the  pontificate  of 
Gregory  X,  i.  e.  about  1272  ;  ^   it  professes  to  deal  with  four 

'  Op.  Maj.  (Bridges),  ii.  251. 

"'  Op.  Tert.  (Brewer),  p.  38  ;  Op.  Teri.  (Little),  pp.  34-5  ;  Op.  Tert. 
(Brewer),  p.  99  '  Tractatum  de  speciebus  .  .  .  quern  dupliciter  misi 
vobis,  et  tertio  modo  incepi  sed  non  potui  consummare '. 

^  Op.  Tert.  (Little),  p.  82  ;   Com.  Nat.  (Steele),  p.  298. 

*  Father  Mandonnet  in  Roger  Bacon  et  la  composition  des  trois 
'  Opus  ',  pp.  14-16  (Extrait  de  la  Revue  neo-scolastique  de  philosophie , 
fev.  et  mai  191 3),  points  out  that  the  references  to  the  capture  of 
Bagdad  in  Op.  Maj.,  Parts  IV  and  VII  (Bridges,  i.  266  ;  ii.  389-90), 
imply  that  Bacon  was  writing  Part  IV  in  1267,  and  Part  VII  in  1268. 
Bacon  refers  to  the  sending  of  the  Compendium  to  the  pope  in  Camp. 
Studii  Phil.  (Brewer,  p.  424). 

'''  Sec.  Secretorum  (ed.  Steele),  p.  10.  '  In  illo  anno  (1264)  et 
sequentibus  fuerunt  maximeturbationes  mundi,'  &c. :  cf.  ibid.,  p.  39. 

^  Edited  by  Nolan  and  Hirsch,  Cambridge,  1902.  These  were  not 
written  at  the  time  of  the  composition  of  the  Op.  Tert.  (ed.  Brewer), 
pp.  65,  88.  The  Greek  Grammar  is  connected  with  the  Comp.  Studii 
Phil.  (ed.  Brewer,  p.  495). 

'  Brewer,  pp.  399,  414.  Clement  IV  died  November  29,  1268  : 
Gregory  X  was  elected  September  i,  1271,  and  consecrated  March  27, 
1272;  died  January  10,  1276. 


LIFE  AND  WORKS  21 

points  :  (i)  the  value  of  knowledge  in  speculation  and 
practice  ;  (2)  the  question  what  parts  of  knowledge  are 
essential ;  (3)  the  methods  of  acquiring  knowledge  ;  (4)  the 
impediments  to  knowledge  and  how  to  avoid  or  remedy 
them.  It  includes  violent  attacks  on  all  estates  of  the  world 
— the  papal  court,  all  religious  orders  without  exception, 
the  clergy  and  universities,  kings  and  princes,  and  lawyers  :  ' 
then  follows  a  dissertation  on  the  study  of  languages,  in 
the  midst  of  which  the  treatise  breaks  off.  It  is  doubtful 
whether  this  treatise  was  intended  to  form  part  of  the 
encyclopaedic  work  on  all  the  sciences,  which,  to  judge  from 
the  fragments  of  it  that  remain,  was  written  more  scholastico, 
in  a  much  more  impersonal  way.  These  fragments  were 
composed  partly  before  and  partly  after  the  Opus  Majus  : 
they  incorporate  whole  sections  of  the  works  sent  to  the  pope, 
and  probably  a  number  of  dissertations  which  Bacon  wrote 
originally  for  the  pope,  but  excluded  from  the  final  drafts  of 
the  Opus  Majus,  Opus  Minus,  and  Opus  Tertium.  A  sketch 
of  contents  which  Bacon  drew  up  for  the  encyclopaedic 
work  may  be  given, ^  with  the  warning  that  Bacon  himself 
rarely  adhered  to  his  own  plans. 

The  work  was  to  consist  of  four  volumes,  dealing  with  the 
principal  branches  of  knowledge  ;  the  first  or  introductory 
book  of  each  volume  dealt  with  the  general  principles  of  the 
branch  of  knowledge  under  discussion  ;  the  remaining  books 
beingdevoted  to  the  specialsciencesformingthe  branch;  thus : 

Vol.  I,  Grammar  and  Logic. 

(No  further  details  given  in  Bacon's  sketch.) 

Vol.  II,  Mathematics  :  Book  i,  General  Principles,  or 
Communia  Mathematicae :  Books  ii-vi,  Special 
Mathematical  Sciences. 

'  His  quarrel  with  the  lawyers  went  very  deep  :  he  held  that 
they  were  destroying  the  Church,  which  had  become  a  great  legal 
institution  and  lost  its  spirituality  :  see,  e.  g..  Op.  Tert.  (Brewer), 
pp.  84-8  ;   Conip.  Studii  Phil.  (Brewer),  pp.  418-25. 

-  Com.  Nat.  (ed.  Steele),  pp.  i,  3. 


22  ROGER  BACON 

Vol.  Ill,  Physics  and  Natural  Philosophy :  Book  i, 
Communia  Naturalium  :  Book  ii,  On  Heavenly 
Bodies  :  Book  iii,  On  the  Elements  and  Inanimate 
Compounds  :  Book  iv,  On  Vegetables  and  Animals. 
Or  (a  slightly  different  scheme)  : '  Books  ii,  iii,  and  iv 
are  to  treat  of  the  seven  natural  sciences,  (i)  Optics, 
(2)  Judicial  and  Practical  Astronomy,  (3)  Barology, 
(4)  Alchemy,  (5)  Agricultural  Chemistry,  (6)  Medicine, 
(7)  Experimental  Science. 

Vol.  IV,  Metaphysics  and  Morals. 
(No  further  details  given.) 

It  is  impossible  to  say  how  much  of  this  great  work  was 
written  :  it  is  not  easy  to  say  how  much  exists.  The  diffi- 
culty is  increased  by  Bacon's  incorrigible  habit  of  beginning 
according  to  one  scheme,  and  then,  when  he  grew  dissatisfied 
or  lost  interest,  beginning  afresh  on  another  scheme,  using 
the  same  material  (slightly  altered)  but  in  a  different 
connexion.  However,  we  may  say  with  certainty  that 
a  fragment  of  the  Communia  Mathematicae  ^  exists,  perhaps 
in  two  recensions  ;  the  greater  part  of  the  Communia 
Naturalium  and  of  the  De  Coelestibus.^  The  substance  of 
some  of  the  other  parts  will  be  found  in  various  works  of 
Bacon  :  e.g.  barology  is  one  of  the  subjects  of  the  Tractatus 
trium  verborum^  Medicine  is  dealt  with  in  a  number  of 
short  treatises,^  and  alchemy  is  expounded  in  the  (fragmen- 
tary) Opus  Minus,^  in  the  Opus  TertiumJ  and  elsewhere. 

'  Com.  Nat.,  p.  i,  n.,  pp.  5-9. 

"  An  edition  is  being  prepared  by  Mr.  Steele  and  Professor  D.  E. 
Smith. 

^  Edited  by  Steele,  Opera  hactenus  inedita,  fasc.  ii,  iii,  iv. 

*  Printed  Frankfurt,  1603  :  a  new  edition  is  being  prepared  by 
Monsieur  J.  A.  Col. 

^  In  the  De  Erroribus  Medicorum  occurs  the  phrase  '  Hoc  est 
principaliter  intentum  quantum  ad  peccata  philosophic  que  redun- 
dant in  theologicam ',  which  suggests  that  the  treatise  may  be 
connected  with  the  group  of  treatises  written  for  Clement  IV. 

*  Ed.  Brewer,  pp.  313-15,  359-89.  ^  Ed.  Little,  pp.  80-9, 


LIFE  AND  WORKS  23 

In  1277  occurred  the  great  catastrophe  of  Bacon's  life. 
The  University  of  Paris  had  for  years  been  distracted  by 
philosophical  and  theological  quarrels,  and  by  struggles 
between  the  secular  masters  and  the  mendicant  orders 
in  the  faculty  of  theology.  On  January  18,  1277,  Pope 
Gregory  X  ordered  the  Bishop  of  Paris  to  inquire  into  and 
report  on  the  '  errors  '  which  disturbed  the  pure  streams  of 
wisdom  in  the  university.'  Stephen  Tempier  before  he 
became  bishop  had  been  Chancellor  of  the  Church  and 
University,  in  which  capacity  he  had  been  noted  for  his 
arbitrary  and  tyrannical  measures.  He  now  in  conjunction 
with  certain  masters  of  theology  seized  the  opportunity  of 
attacking  progressive  and  independent  thought  in  all 
directions  in  a  decree  issued  March  7,  1277.-  This  begins 
by  declaring  that  students  in  arts  exceeding  the  limits  of 
their  proper  faculty  presumed  to  discuss  in  the  schools 
certain  execrable  errors  enumerated  below  :  for  they  say 
that  these  things  are  true  according  to  philosophy,  but  not 
according  to  the  Catholic  faith,  '  as  though  there  are  two 
truths  and  as  though  there  may  be  truth  in  the  sayings  of 
damned  gentiles  contrary  to  the  truth  of  holy  scripture.' 
All  maintaining  these  errors  or  attending  lectures  in  which 
they  are  taught  are  excommunicated  unless  within  seven  days 
they  confess  to  the  bishop  or  the  chancellor,  in  which  case 
they  will  be  punished  according  to  their  faults.  Various 
books  of  magic  are  then  condemned,  and  a  like  sentence 
passed  on  all  who  teach  or  attend  lectures  on  such  subjects. 
Then  follows  a  list  of  219  condemned  errors.  Enumerated 
in  the  wildest  confusion,  these  include  doctrines  not  only 
of  the  Averroist  artists  but  of  the  Dominican  theologians — 
not   only  of   Siger  de   Brabant   but   of  Thomas   Aquinas. 

'  Chart.  Univ.  Paris.,  i,  no.  471.  On  the  whole  subject,  see 
Mandonnet,  Siger  de  Brabant,  i,  chap,  ix  (2nd  ed.,  Louvain,  191 1). 

=  Chart.  Univ.  Paris.,  i,  no.  473  ;  Mandonnet,  Siger  de  Brabant, 
ii.  175-91- 


24  ROGER  BACON 

Some  of  them  may  have  been  directed  against  Bacon  : 
e.  g.  Error  150  is, '  That  a  man  ought  not  to  be  content  with 
authority  in  order  to  have  certainty  on  any  question.' 
Error  151  is,  '  In  order  that  a  man  may  have  certainty  of 
any  conclusion,  he  ought  to  be  based  on  principles  known 
by  himself.'  Several  of  them  are  directed  against  the  belief 
in  astrology  :  e.  g.  143, '  Different  signs  in  the  heaven  signify 
different  conditions  in  men  both  of  spiritual  gifts  and  of 
temporal  things ; '  No.  206,  '  That  health,  sickness,  life,  and 
death  are  attributed  to  the  position  of  the  stars  and  the 
aspect  of  fortune ; '  No.  154,  '  That  our  will  is  subject  to  the 
power  of  heavenly  bodies  ;  '  No.  167,  '  That  from  signs 
(in  the  heavens)  future  events  of  various  kinds  can  be 
predicted.' 

Bacon,  like  his  contemporaries,  was  a  thorough  believer 
in  astrology  :  indeed,  when  the  earth  was  regarded  as  the 
centre  of  a  spherical  and  limited  universe,  it  was  impossible 
not  to  believe  that  the  motions  of  the  heavenly  were  followed 
by  corresponding  changes  in  terrestrial  bodies.  But  Bacon 
is  always  insisting  that  though  those  influences  work  un- 
hindered in  the  inanimate  world,  they  are  in  the  case  of 
man  limited  by  the  freedom  of  the  will  :  they  affect  only 
temperament ;  they  may  incline  a  man  to  a  particular  course 
of  action,  they  cannot  compel  him,  because  the  will  is  free.^ 
Bacon  differs  from  most  of  his  contemporaries  in  the 
thoroughness  with  which  he  investigated  the  subject  :  he 
frequently  rebukes  those  who  argued  (very  wisely)  that 
the  complexity  of  the  subject  was  too  great  to  permit  of 
any  certain  results ;  -  he  read  and  compared  the  authorities, 

'  e.g.  Op.  Maj.  (Bridges),  i.  240  ;  Op.  Terf.  (Little),  p.  4  ;  Comp. 
Stiidii  Phil.  (Brewer),  p.  422. 

-  Cf.  Op.  Maj.  (Bridges),  i.  394.  Also De  Eyroribus  Mediconim  (MS.). 
The  following  passage  from  Pecham's  Canticum  Pauperis  pro 
Dilecto  (ed.  Quaracchi,  p.  136)  is  interesting  as  containing  a  clear 
allusion  to  Bacon  :  '  Audita  proinde  laude  mathematicae  .  .  .  eius 
gymnasia  introivi  .  .  .  illiciebar  tamcn  paululum  ilia  mathematicae 


LIFE  AND  WORKS  25 

compiled  astronomical  tables,  and  studied  history  to  estab- 
lish the  effects  of  constellations  and  comets ;  and  he  did  not 
shrink  from  applying  the  science  to  the  elucidation  of  the 
foundations  of  religions.' 

His  attitude  to  magic  is  more  individual.  While  showing 
up  unmercifully  charlatans  and  swindlers,  he  points  out  that 
many  things  are  considered  magical  which  are  merely  the 
result  of  some  unknown  power  of  art  or  nature  :  thus  the 
magnet  must  appear  magical  to  people  who  know  no  better. 
What  power  again,  if  any,  have  incantations  and  charms  ? 
What  is  the  explanation  of  the  wonderful  power  of  words  ? 
*  All  the  miracles  since  the  world  began,  almost,  have  been 
wrought  by  words.'  It  was  unreasonable  to  prohibit  the 
study  of  these  things  on  the  ground  that  a  knowledge  of 
them  would,  in  the  hands  of  bad  men,  produce  evil  results. 
Antichrist  would  certainly  know  all  about  them,  and  we 
must  be  prepared  to  meet  him.  The  whole  question  of  the 
'  magical  sciences  '  should  be  investigated  by  competent 
men  specially  licensed  by  the  pope.^ 

A  criticism  of  the  decree  of  the  Bishop  of  Paris  was  soon 
issued  under  the  name  of  Speculum  Astrononiiae,  which  has 
been  generally  ascribed  to  Albertus  Magnus  and  printed 
among  his  works  ;  -^  it  embodies,  however,  the  views  of  Bacon 
on  astrology  and  magic,  and  was  probably  written  either 
by  him  or  under  his  inspiration/    As  to  the  books  of  necro- 

parte,  quae  ex  motu  siderum  colligit  praesagia  futurorum.  Con- 
siderans  vero  illam  non  demonstrationibus  deduci,  sed  experimentis 
frivolis  inniti,  sciens  etiam  ex  illius  negotii  peritissimis,  efficaciam 
siderum  super  habentes  liberum  arbitrium  esse  inter  possibile  et 
necessarium,  posseque  sapientem  sideribusdominari,  vidi  a  signis  coeli 
non  esse  metuendum  .  .  .  vanaque  reputavi  opera  et  risu  digna  ',  &c. 

'  Op.  Maj.,  i.  253-69,  289  ;   Op.  Tert.  (ed.  Little),  p.  14. 

■'  Op.  Tert.  (Brewer),  pp.  96-9;  Op.  Tert.  (Little),  pp.  15-18; 
De  Potestate  Artis  et  Naturae  (Brewer),  pp.  523  et  seq. 

'  Alberti  Magni  Opera  Omnia,  ed.  Borgnet,  x.  629  et  seq. 

*  See  Mandonnet,  '  Roger  Bacon  et  le  Speculum  Astronomiae ' 
[Revue  neo-scolastique,  aout  19 10). 


26  ROGER  BACON 

mancy,  says  the  writer,  it  would  be  better  to  keep  them 
than  to  destroy  them.  Many  of  the  books  condemned 
contain  nothing  against  the  CathoHc  faith  ;  '  nor  is  it 
perhaps  just  that  people  who  have  never  touched  them 
should  presume  to  judge  them.'  It  was  an  open  repudiation 
of  ecclesiastical  authority. 

Towards  the  end  of  1277  John  of  Vercelli,  Master-General 
of  the  Friars  Preachers,  and  Jerome  of  Ascoli,  Minister- 
General  of  the  Friars  Minor,  met  in  Paris  to  devise  measures 
for  allaying  the  scandalous  quarrels  between  the  Dominican 
and  Franciscan  Orders.  They  decreed  among  other  things 
that  the  friars  of  both  Orders  should  abstain  from  mutual 
detractions  ;  '  and  any  friar  who  was  found  by  word  or 
deed  to  have  offended  a  friar  of  the  other  Order  should 
receive  from  his  Provincial  such  punishment  as  ought  to 
satisfy  the  offended  brother.'  '  Roger  Bacon  had  certainly 
offended  the  leading  Dominicans,  and  if  he  had  also  attacked 
members  of  his  own  Order  with  almost  equal  vehemence, 
this  would  not  make  the  latter  less  willing  to  give  him  up 
as  a  sacrifice  to  their  rivals. 

'  This  Minister  General  brother  Jerome  (in  the  words  of 
the  Franciscan  Chronicle  of  the  XXIV  Generals  ^)  by  the 
advice  of  many  friars  condemned  and  reprobated  the 
teaching  of  Friar  Roger  Bacon  of  England,  master  of  sacred 
theology,  as  containing  some  suspected  novelties,  on  account 
of  which  the  same  Roger  was  condemned  to  prison, — 
commanding  all  the  friars  that  none  of  them  should  maintain 
this  teaching  but  should  avoid  it  as  reprobated  by  the 
Order.  On  this  matter  he  wrote  also  to  Pope  Nicholas  (III) 
in  order  that  by  his  authority  that  dangerous  teaching  might 
be  completely  suppressed.' 

The  teaching  and  the  novelties  are  not  defined  by  the 
chronicler,  but  we  may  infer  that  the  causes  of  Bacon's 
imprisonment  were  his  contempt  for  authority,  his  attacks 

'  '  Chron.  XXIV  Gen.'  in  Anal.  Franc,  iii.  365. 
"  Anal.  Franc,  iii.  360. 


LIFE  AND  WORKS  27 

on  the  Dominicans  and  on  his  own  Order,  his  defence  and 
practice  of  the  '  magical  sciences  ',  in  magic  being  included 
the  unknown  powers  of  art  and  nature. 

It  is  generally  supposed  that  Bacon  remained  in  prison 
from  the  end  of  1277  till  1292.  Raymond  Gaufredi,  a  sup- 
porter of  the  spiritual  friars,  was  elected  General  Minister 
by  the  anti-Italian  party  at  Rieti  at  Whitsuntide  in  1289  : 
he  visited  a  number  of  provinces  and  released  some  friars 
unjustly  imprisoned  in  the  March  of  Ancona  in  1290.  It  is 
possible  that  Roger  Bacon  was  set  free  at  this  time,  or  at 
the  General  Chapter  at  Paris,  May  25,  1292.  Jerome  of 
Ascoli,  Roger  Bacon's  enemy,  who  had  ascended  the  papal 
throne  as  Nicholas  IV,  died  on  April  4,  1292  ;  on  the  other 
hand,  Raymond  Gaufredi  was  accused  of  heresy,  and  had 
difficulty  in  maintaining  his  position  at  the  Chapter  of  1292.' 
The  tradition  that  Roger  owed  his  deliverance  to  Raymond 
Gaufredi  is  supported  by  a  note  appended  to  the  summary 
made  by  Raymond  of  an  alchemical  work  of  Bacon's  : 
'  And  Roger  on  account  of  this  work  by  command  of  the 
said  Raymond  was  seized  by  the  friars  of  the  Order  and 
imprisoned ;  but  Raymond  released  Roger  from  prison 
because  he  taught  him  this  work.'  '^  This  would  become 
intelligible  if  we  might  substitute  '  Jerome  '  for  the  first 
'  Raymond  '.  It  is  certain  that  Roger's  last  dated  work 
was  written  in  1292.  This  is  a  fragment  called  Compendium 
Studii  Theologiae,^  of  which  perhaps  only  the  beginning  was 
written.    Once  more  he  deals  with  the  causes  of  error,  first 

'  On  the  general  situation  see  K.  Balthasar,  Geschichte  des  Arniuts- 
stveites  (Miinster  i.  W.,  191 1),  pp.  174-84. 

-  '  De  Leone  Viridi,'  printed  in  Sanioris  Medicinae,  &c.  Frankfurt, 
1603,  pp.  264-85.    Cf.  MS.  Bibl.  de  I'Arsenal  (Paris,  2872,  f.  401). 

'  Ed.  by  Dr.  H.  Rashdall,  Brit.  Soc.  Franc.  Studies,  vol.  iii. 
Bacon  refers  to  other  parts  of  the  work  which  do  not  seem  to  be 
extant  :  pp.  36,  51.  Perhaps  the  version  of  the  De  Multiplicatione 
Specieritm  in  Brit.  Mus.  MS.,  Royal  7,  F.  VIII,  ff.  2-12,  and  MS. 
Angelica  1017  in  Rome  belonged  to  this  Compendium. 


28  ROGER  BACON 

among  which  is  undue  reliance  on  authority,  and  then 
proceeds  to  the  estabHshment  of  truths  :  this  part  is  occupied 
with  a  discussion  of  the  misunderstandings  and  the  real 
meanings  of  the  terms  used  ;  before  this  discussion  is 
finished  the  work  breaks  off.  It  may  be  noticed  that  Roger 
at  the  end  of  his  life  goes  back  to  his  early  reminiscences — 
the  teaching  of  that  '  utter  fool  '  (stultissimus)  Friar  Richard 
of  Cornwall  in  1250,  and  the  lectures  of  St.  Edmund  of 
Canterbury  in  his  early  days  at  Oxford.' 

'  The  noble  doctor  Roger  Bacon  ',  says  John  Rous,^  '  was 
buried  at  the  Grey  Friars  in  Oxford,  a.  d.  1292,  on  the 
feast  of  St.  Barnabas  the  Apostle  '  (June  11).  There  seems 
to  be  no  authority  for  placing  his  death  in  1294. 

Though  Roger  Bacon  was  in  opposition  to  the  general 
tendencies  of  his  age,  it  is  a  mistake  to  suppose  either  that 
he  stood  alone  in  his  own  lifetime  or  that  his  influence  was 
negligible  after  his  death.  Professor  Baur  of  Tiibingen  has 
recently  edited  among  the  Philosophical  Works  of  Grosse- 
teste  ^  a  Summa  Philosophiae,  falsely  ascribed  to  Grosseteste, 
really  written  by  an  unknown  Englishman  soon  after  1265 — 
that  is,  at  the  very  time  that  Roger  Bacon  was  engaged  on 
the  Opus  Majus.  This  work,  if  not  by  Bacon  himself — 
which  seems  impossible — was  composed  by  some  one  in  the 
very  closest  sympathy  with  him  ;  the  whole  drift  of  thought 
and  often  even  the  very  expressions  are  reminiscent  of  Bacon. 
Dr.  Rashdall  has  pointed  out  that  the  germs  of  the  two 
rival  schools  of  the  later  Middle  Ages,  the  Realism  of  Duns 
Scotus  and  the  Nominalism  of  Ocham,  are  to  be  found  in 
Bacon.'*     The  influence  of  his  physics  is  obvious  in  Pecham 

'  Comp.  Siudii  TheoL,  pp.  34,  52. 

-  Hist.  Regiim  Angliae,  p.  82.  Cf.  Royal  MS.  13,  C.  I,  f.  151  : 
'Anno  Christi  1292  obiit  Rogerus  Bacon  professor  theologie  et  quasi 
eruditus  ut  magister  in  octo  scienciis  ubi  alii  clerici  non  potuerunt 
preter  vii  scire '  (MS.  '  scie  '). 

'  In  Beitrdge  ziir  Geschichte  der  Philosophic  des  Mittelalters, 
Band  IX,  Miinster  i.  W.,  1012.  ■•  Comp.  Studii  TheoL,  pp.  22-3. 


LIFE  AND  WORKS  29 

(a  not  very  grateful  pupil),  and  hardly  less  marked  in  Giles 
of  Rome  and  John  Dumbleton.'  It  would  be  interesting 
to  examine  how  far  it  can  be  traced  in  Raymond  Lull, 
Arnold  de  Villeneuve,  Walter  Burley,  Thomas  Bradwardine, 
and  even  Duns  Scotus.-  Again,  many  others  besides  Bacon 
were  advocating  the  study  of  Greek  and  Oriental  languages. 
The  English  Franciscan  William  de  Mara  was  evidently 
an  admirable  Hebrew  scholar.^  Both  the  Dominican  and 
Franciscan  Orders  had  colleges  for  the  study  of  Oriental 
languages  before  the  end  of  the  century,*  and  in  1312 
Clement  V  in  the  Council  of  Vienne  endeavoured  to 
provide  for  the  establishment  and  endowment  of  chairs 
of  Hebrew,  Greek,  Chaldaic,  and  Arabic  in  the  Roman 
Curia  and  the  Universities  of  Paris,  Oxford,  Bologna,  and 
Salamanca.^  This  effort  was  not  very  successful  in  the 
universities,  but  among  the  English  Franciscans  it  is  possible 
to  trace  a  thin  but  continuous  line  of  Greek  and  Hebrew 
learning  during  the  fourteenth  century.  Henry  de  Costesy, 
lector  to  the  Franciscans  at  Cambridge,  c.  1330,  is  perhaps 
the  most  eminent  of  these  scholars.^ 

Direct  allusions  to  Bacon  are  few  until  the  period  of  the 
Renaissance.  William  Herbert,  lector  to  the  Franciscans 
at  Oxford,  obtained  some  of  his  manuscripts  (two  are  still 
extant)  for  the  friary  at  Hereford.^  Pierre  Dubois  at  the 
beginning  of  the  fourteenth  century  had  assimilated  his 

'  See  Professor  Duhem's  article  in  this  volume. 

^  Cf.  R.  Seeberg,  Die  Theologie  des  J  oh.  Dims  Scotus,  Leipzig,  1900, 
pp.  12,  605. 

^  The  Toulouse  MS.  402  ought  to  be  edited. 

■*  Golubovich,  Bihl.  Bio-Bibliog.,  i.  365  ;  Mortier,  Hist,  des 
Maitres  Generanx,  i.  518  seq. 

^  Chart.  Univ.  Paris.,  ii,  no.  695.  Cf.  also  bull  of  Honorius  IV, 
Jan.  23,  1286:  ibid.,  i,  no.  527. 

"  M.  R.  James  in  Camb.  Modern  Hist.,  vol.  i,  and  Catalogue  of 
MSS.  at  Christ's  College,  Cambridge,  no.  11. 

^  M.  R.  James,  '  Library  of  the  Grey  Friars  of  Hereford  j'  (Brit. 
Soc.  Franc.  Studies,  vol.  v). 


30  ROGER  BACON 

teaching  on  '  experience  ',  and  recommends  the  study  of  his 
mathematical  works. '  The  early  alchemical  treatise  De 
Lapide  Philosophorum,  popularly  attributed  to  Thomas 
Aquinas,  quotes  '  Rogerius  in  libro  De  Infiuentiis  '  (i.  e.  the 
DeMultiplicationeSpecierum).^  William  Woodford  at  Oxford, 
towards  the  end  of  the  century,  refers  to  his  curious  book 
on  Old  Age.^  About  the  same  time  Franciscan  chroniclers 
placed  him  among  the  famous  natural  philosophers  of  the 
Order  and  praised  his  universal  learning.''  In  the  fifteenth 
century  disputants  quoted  him  in  the  schools  at  Oxford,^ 
and  an  official  letter  of  the  University  mentioned  him 
among  the  '  modern  Oxonians '  who  had  kept  untarnished 
the  brightness  of  Oxford's  fame.^  Cardinal  Pierre  d'Ailly 
incorporated  a  passage  from  Bacon's  work  on  geography 
{Opus  Majus,  iv)  in  the  Imago  Mundi,  a  passage  which  so 
impressed  Columbus  that  he  annotated  it  fully  and  quoted 
it  in  a  letter  to  Ferdinand  and  Isabella  :  ^  thus  the  Opus 
Majus  at  second-hand  became  one  of  the  authorities  which 
inspired  him  to  undertake  his  great  voyage  of  discovery. 
And  it  would  appear  that  through  the  medium  of  Paul  of 
Middelburg,  Bacon  influenced  Copernicus.^ 

The  extant  manuscripts  of  Bacon's  works  show  that  the 

'  De  Recuperatione  Terrae  Sanctae,  ed.  Langlois. 

-  Zetzner,  TheatrumChem.  (1659),  iii.  267.  Alchemists  in  the  later 
Middle  Ages  often  quote  Bacon  or  the  numerous  spurious  works 
attributed  to  him  :  e.  g.  George  Ripley  in  The  Marrow  of  Alchymie  ; 
cd.  W.  Salmon,  1707,  p.  646. 

^  Brown,  Fasc.  Rer.  Expet.,  i.  p.  197. 

*  Bart.  Pisan.  De  Conform.,  i.  338  (ed.  Quaracclii) :  Bodl.  MS. 
Can.  Misc.,  525,  ff.  202^,  2031':  Opuscules  de  critique  historique,  i.  287. 

s  Lambeth  MS.  221,  ff.  281,  306^ 

*  Ibid.,  f.  308^. 

^  Opiis  Majus  (Bridges),  i.  pp.  xxxiii,  292:  Thacher,  Christopher 
Columbus,  iii.  480:  Select  Letters  of  Columbtis  (Hakluyt  Soc), 
pp.  xliii.  140. 

*  Optis  Majus  (Bridges),  i.  pp.  xxxiv,  285  :  John  Dee's  Playne 
discourse  and  humble  advice  on  the  reform  of  the  Calendar,  MS. 
Corp.  Chr.  Coll.,  Oxford,  254,  ff.  141-54. 


LIFE  AND  WORKS  31 

'  Doctor  mirabilis '  never  wanted  admirers.  Thus  of  his 
treatise  on  Optics  {Opus  Majus,  v)  (to  give  one  instance) 
I  have  found  some  twenty-seven  manuscripts,  ranging  from 
the  thirteenth  to  the  seventeenth  century.  The  treatises 
on  Optics  and  Mathematics  were  probably  the  most  popular 
in  the  Middle  Ages,  and  here  Bacon,  though  he  made  fresh 
applications  of  the  sciences,  was  rather  the  interpreter  of 
the  Arabian  scientists  to  the  western  world  than  an  original 
investigator.  For  the  most  original  sides  of  his  work,  for  his 
experimental  science  and  his  principles  of  textual  criticism, 
the  Middle  Ages  had  little  understanding.  Bacon  has 
the  merit  of  having  pointed  out  the  lines  of  intellectual 
advance  which  the  world  was  to  follow  two  centuries  after 
his  death. 


II 

DER  EINFLUSS  DES  ROBERT  GROSSETESTE 
AUF  DIE  WISSENSCHAFTLICHE  RICH- 
TUNG  DES  ROGER  BACON 

Von  LUDWIG  BAUR 

I 

Wenn  man  den  Begriff  '  Lehrer '  im  strengen  Sinn  des 
Wortes  nimmt  und  nur  diejenigen  Manner  unter  die  '  Lehrer ' 
des  Roger  Bacon  rechnet,  welche  durch  personlichen  miind- 
lichen  Unterricht  ihm  in  der  Philosophie  und  Theologie  die 
wissenschaftliche  Richtung  gaben,  so  ist  es  schwer,  ja 
unmoglich,  die  Lehrer  des  Roger  Bacon  erschopfend  und 
sicher  zu  bestimmen.  Der  Begriff  des  Lehrers  ist  zudem 
im  Mittelalter  in  mehrfacher  Hinsicht  etwas  dehnbar.  Er 
verlangt  auch  nicht  notwendig  einen  erheblichen  Alters- 
unterschied  zwischen  dem  Lehrer  und  seinem  Schiiler : 
auch  zwischen  Freunden  gleichen  Alters  kann  ein  Lehrer- 
bzw.  Schiilerverhaltnis  bestehen.  Und  nicht  immer  war 
es  ein  in  seiner  Dauer  oder  in  der  Auswahl  der  Facher 
genau  umgrenztes  Verhaltnis. 

Da  Roger  Bacon  in  keiner  seiner  zahlreichen  Schriften 
direkt  und  bestimmt  die  Lehrer  nennt,  deren  miindlichem 
Unterricht  und  unmittelbarer  Leitung  er  seine  Kenntnisse 
in  den  verschiedenen  Zweigen  menschlichen  Wissens  und 
seine  wissenschaftliche  Richtung  iiberhaupt  verdankt,  so 
konnen  die  Namen  derselben  nur  indirekt  aus  seinen 
Andeutungen,  aus  seinem  Studiengang,  aus  dem  Charakter 
seiner  Schriften,  der  Eigenart  seiner  wissenschaftlichen  Pro- 
blemstellungen  und  Losungsversuche  erschlossen    werden. 

1689  D 


34  ROGER  BACON 

Gerade  bei  Roger  Bacon  gilt,  dass  oft  diejenigen,  die  seine 
personlichen  Freunde  waren,  zugleich  auch  seine  bedeu- 
tenden  und  einflussreichen  Lehrer  wurden.  Wenigstens 
sagt  er  selbst  :  '  Quaesivi  amicitiam  omnium  sapientum 
inter  Latinos  et  feci  iuvenes  instrui  in  Unguis  et  figuris  et 
numeris  et  tabulis  et  instrumentis  et  in  multis  neces- 
sariis.'  ' 

Es  erscbeint  als  glaubwiirdig,  wenn  man  annimmt,  oder 
wenigstens  vermutet,   dass   Roger   Bacon  wahrend   seiner 
Studienzeit    in    Oxford   Richard   Fitzacre,   Edmund   Rich 
(den  hi.  Edmund  v.  Canterbury),  den  Dominikaner  Robert 
Bacon  (seinen  Onkel  ?)  zu  Lehrern  gehabt  habe.     Lehrer 
und  zugleich  Freunde  (trotz  des  erheblichen  Altersunter- 
schiedes)  wurden  ihm  dort  Robert  Grosseteste  und  Adam 
de  Marisco.    Als  er  —  vor  1245  —  nach  Paris  iibersiedelte,  da 
sah  er,  wie  er  selbst  erzahlt  {op.  ined.,  ed.  Brewer,  325),  noch 
den  Alexander  v.  Hales  (f  1245)  mit  eigenen  Augen.     Er 
horte    Wilhelm     von    Auvergne    (t  1248)    noch    iiber    den 
intellectus    agens    vor  der  ganzen  Universitat  disputieren. 
Indes  ob,  oder  wie  weit  ihn  mit  den  beiden  Genannten  noch 
ein  eigentliches  Schiilerverhaltnis  verband,  ist  nicht  mehr 
zu  sagen.     Auch  mit  dem  hi.  Bonaventura  scheint  er  zu 
Paris  in  personliche   Beriihrung  gekommen  zu  sein,  wenn 
anders  die  Annahme  richtig  ist,  dass  sich  der  Brief  Bona- 
venturas  '  ad  magistrum  innominatum  '  an  Roger  Bacon 
gerichtet  habe.^    Jedenfalls  aber  bestand  dieses  '  Schiiler- 
verhaltnis ',  wenn  sich  je  ein  solches  zwischen  Bonaventura 
und   Roger   Bacon    herausbildete,   ausschliesslich    fiir    das 
Gebiet  der  Theologie  und  Aszetik.  —  Aus  Bacons  Schriften 
selbst  wird  man  entnehmen  diirfen,  dass  er  zu  Paris  (bzw. 
Oxford)   zu   seinen   Lehrern   sowohl   als   Freunden   zahlen 
diirfte :    Campanus  von  Novara ;  den  Astronomen,  Mathe- 

'  Opus  Teftium  (Brewer),  p.  58. 

'  Vgl.  G.  Delorme  in  Dictionnaire  de  Theologie  catholique,  ii,  s.  v. 
'Bacon,  Roger.' 


EINFLUSS  DES  ROBERT  GROSSETESTE        35 

matiker  und  Computisten,  Johannes  von  London;  den 
grossen  Mathematiker  aus  der  Picardie,  Petrus  von  Mari- 
court,  der  ihm  zugleich  wert voile  optische  Kenntnisse 
vermittelte.  Fiir  seine  Ausbildung  in  den  Sprachen  wurde 
ihm  die  Freundschaft  mit  Magister  Nicolaus  (Graecus  ?), 
Hermannus  Alamannus  und  Robert  Grosseteste  wertvoll. 
Amalrich  von  Montfort  und  Adam  de  Marisco  gesellten  sich 
dazu.'  Wie  weit  nun  der  wissenschaftliche  Einfluss  dieser 
Manner  auf  Roger  Bacon  bestimmend  wurde,  lasst  sich 
solange  nicht  in  wissenschaftlich  einwandfreier  Weise  fest- 
stellen,  als  wir  nicht  in  den  Stand  gesetzt  sind,  durch 
Vergleichung  ihrer  Schriften  diesen  Einfluss  exakt  zu 
bestimmen.  Vorerst  konnte  man  nur  die  vagen  Vermu- 
tungen  wiederholen,  welche  Roger  Bacons  Biographen 
durch weg  iiber  seine  Lehrer  und  deren  Einfluss  ausstellten. 
Anders  verhalt  sich  das  mit  seinem  beriihmtesten  Lehrer 
Robert  Grosseteste,  dessen  philosophische  Werke  durch  den 
Verfasser  dieser  Arbeit  zum  erstenmal  vollstandig  und  in 
einer  kritischen  Ausgabe  der  wissenschaftlichen  Bearbeitung 
zuganglich  gemacht  wurden.-  Sie  ermoglichen  eine  genaue 
Feststellung  des  wissenschaftlichen  Einflusses,  den  Robert 
Grosseteste  auf  seinen  Schiiler  Roger  Bacon  ausgeiibt  hat. 
Derselbe  ist  grosser,  als  man  bisher  ahnte,  und  manch  ein 
Lorbeerblatt,  das  man  bisher  in  den  wissenschaftlichen 
Ruhmeskranz  des  Roger  Bacon  eingeflochten  hatte,  muss 
nicht  ihm,  sondern  seinem  Lehrer  Robert  Grosseteste  zu- 
erkannt  werden.  Es  bestiitigt  sich  auch  hier  das  Urteil 
P.  Mandonnets,  dass  ein  vergleichendes  Studium  der  Wissen- 
schaft  des  Roger  Bacon  mit  der  seiner  Zeitgenossen  die  allzu 

'  Roger  Bacon  macht  die  Genannten  namhaft  im  Opus  Tert. 
(ed.  Brewer),  ii.  13,  17. 

"  Lud.  Baur,  Die  philosophischen  Werke  des  Robert  Grosseteste, 
Bischofs  von  Lincoln,  Miinster  ( Aschendorff ) ,  191 2  (Beitrage  zur 
Geschichte  der  Philosophic  des  Mittelalters,  hgb.  v.  CI.  Baeumker 
U.S.W.,  IX.  Bd.).  Demnachst  erscheint  in  derselben  Sammlung  : 
L.  Baur,  Die  Philosophie  des  Robert  Grosseteste,  Bischofs  v.  Lincoln. 

D  2 


36  ROGER  BACON 

optimistischen  Werturteile  iiber  ihn  bedeutend  herabsetzen 
und  den  Wert  seiner  Ideen  und  Theorien  auf  ein  gerechtes 
Mass  zuriickfiihren  werde.^ 

II 

Robert  Grosseteste  iibernahm  nach  seiner  Riickkehr  von 
Paris  ca.  1224-6  (?)  auf  Bitten  der  eben  damals  in  Oxford 
angekommenen  Minderbriider,  speziell  des  Frater  Agnellus 
V.  Pisa,  die  Aufgabe,  den  Franziskanernovizen  Unterricht 
in  den  Wissenschaften,  so  weit  dieser  notwendig  erschien, 
zu  geben.^  Es  kann  kaum  zweifelhaft  sein,  dass  auch  andere 
Schiiler  diesen  Unterricht  besucht  haben  werden.  Jeden- 
falls  ist  eine  ganze  Anzahl  spaterer  Franziskanerlehrer  zu 
Oxford  aus  Grossetestes  Schule  hervorgegangen.^ 

Sicher  war  dies  der  Fall  bei  Roger  Bacon,  der  von  Grosse- 
teste in  mannigfacher  Hinsicht  seine  wissenschaftliche  Rich- 
tung  empfing.  Wir  konnen  nicht  sagen,  wie  weit  die 
wissenschaftlichen  Anschauungen  Bacons  auf  milndliche 
Anregungen  durch  Grosseteste  zuriickgehen.  Aber  wir 
konnen  auf  Grund  der  Schriften  Grossetestes  und  Bacons 
diejenigen  Lehrpunkte  bezeichnen,  welche  die  wissen- 
schaftliche Art  des  Roger  Bacon  in  zweifelloser  Abhangig- 
keit  von  seinem  Lehrer  zeigen. 

Grammatik  und  Sprachensfudium 
Man  riihmt  dem  Roger  Bacon  allgemein  nach,  dass  er 
die  Wichtigkeit,  ja  Unerlasslichkeit  des  philologischen 
Studiums  und  der  Sprachenkenntnis  fiir  die  verschiedenen 
Wissenszweige,  besonders  aber  fiir  das  Theologiestudium, 
als  erster  erkannt  und  in  hochst  temperamentvoller  Weise 

'  P.  Mandonnet,  Siger  de  Brabant  ei  V averrhoisme  latin  au  XIII^ 
siecle,  Fribourg,  1899,  p.  260. 

-  Thomas  v.  Eccleston  (ed.  Little,  1909),  p.  60, 

^  Vgl.  das  hochst  verdienstUche  Buch  von  A.  G.  Little,  The  Grey 
Friars  in  Oxford,  Oxford,  1892,  pp.  139  fif.;  H.  Felder,  Geschichte 
der  wissenschaftlichen  Studien  im  Framiskanerordeti  bis  um  die 
Mitte  des  ij.  Jahrhunderts,  Freiburg  i.  Br.,  1904. 


EINFLUSS  DES  ROBERT  GROSSETESTE        37 

literarisch  vertreten  habe.  In  der  Tat  braucht  man  nur 
die  einschlagigen  Seiten  seines  Opus  Majus,  des  Opus  Minus, 
des  Opus  Tertium,^  des  Compendium  Studii,  oder  seiner 
griechischen  Grammatik  (ed.  Nolan  and  Hirsch,  1902)  zu 
lesen,  um  zu  erkennen,  wie  sehr  dieses  Lob  berechtigt  ist. 
Roger  Bacon  betrachtet  es  als  ein  unumstossliches  Axiom 
fiir  das  akademische  Studium,  '  Notitia  linguarum  est  prima 
porta  sapientiae  '  {Op.  Tert.,  cp.  28,  ed.  Brewer,  102).  Gram- 
matik und  Sprachenkunde  miissen  demnach  die  Grundlage 
aller  wissenschaftlichen  Ausbildung  sein.^  Roger  Bacon 
riihmt  deshalb  auch  von  sich  selbst  :  *  lam  a  iuventute 
laboravi  in  scientiis  et  Unguis.'  ^ 

Dieses  Interesse  Bacons  an  den  philologischen  Studien 
gibt  sich  in  verschiedener  Weise  in  seinen  Schriften  kund  : 
Er  iiberschiittet  jene  Manner  mit  Lob,  welche  die  Sprachen 
—  Latein,  Griechisch,  Hebraisch,  Chaldaisch,  Arabisch  — 
beherrschen,  oder  ihr  Interesse  am  Sprachenstudium 
irgendwie  dokumentierten :  Boethius,"*  Beda,^  Robert 
Grosseteste,  Adam  Marsh,  Thomas  Wallensis^  werden  als 
die  weisesten  Manner,  als  '  maiores  clerici  de  mundo  et 

'  Die  Einwendungen  K.  Werners  gegen  die  Echtheit  des  von 
Brewer  publizierten  Opus  Tertium  halte  ich  mit  H.  Hover  fiir 
nicht  stichhaltig.  Vgl.  Hover  im  Jahrb.  f.  Philos.  u.  spekul.  Theol., 
XXV.  (1911),  215  ff. 

"  The  Greek  Grammar  of  Roger  Bacon,  ed.  Nolan,  xxviii ;  daselbst 
weitere  Belegstellen.  ^  Op.  Tert.,  cp.  20,  ed.  Brewer,  65. 

*  Op.  Tert.,  cp.  10,  ed.  Brewer,  33  ;  Op.  Maj.,  iii,  ed.  Bridges,  i.  67  ; 
The  Greek  Grammar  .  .  .,  ed.  Nolan,  29. 

^  Op.  Min.,  ed.  Brewer,  332  ;   Greek  Grammar,  41. 

^  Op.  Maj.,  iii,  ed.  Bridges,  i.  67-73  '<  Op.  Tert.,  cp.  10,  ed.  Brewer,  33; 
cp.  25,  ibid.,  91  ;  Greek  Grammar,  118.  Roger  Bacon  sagt  selbst: 
'  Doctores  autera  non  desunt  .  .  .  Graecum  vero  maxime  concordat 
cum  Latino  et  sunt  multi  in  Anglia  et  Francia,  qui  hie  satis  instructi 
sunt.'  Und  :  '  Multi  inveniuntur,  qui  sciunt  loqui  Graecum  et 
Arabicum  et  Hebraeum  inter  Latinos,'  Op.  Tert.  (Brewer),  cp.  33-4. 
Unter  seinen  Landsleuten,  die  im  13.  Jahrh.  sich  mit  der  griechischen 
Sprache  vertraut  machten,  sind  zu  nennen  :  Daniel  Morlai,  Michael 
3cotus,  Robert  Grosseteste,  John  Basingstoke,  Adam  de  Marisco,  Wil- 
helm  de  Mara.   V.  Nolan,  a.  a.  O.,  xliii ;  Bacon,  Camp.  Studii,  vi.  434. 


38  ROGER  BACON 

perfect!  in  scientia  divina  et  humana  '  gepriesen  um  ihrer 
sprachlichen  und  grammatischen  Kenntnisse  willen.  An- 
dererseits  werden  diejenigen  schwer  getadelt,  welche  keine 
Sprachenkenntnisse  besitzen,  oder  sich  um  ein  philologi- 
sches  Wissen  nicht  kummern. 

Roger  Bacon  wird  nicht  miide,  immer  wieder  auf  die 
grosse  Bedeutung  hinzuweisen,  welche  die  grammatischen, 
linguistischen  und  philologischen  Kenntnisse  als  Grund- 
bedingung  der  Vermittlung  der  Gedanken  fremder  Volker 
und  ihrer  Literaturen  fiir  den  Theologen,  Philosophen, 
Exegeten  besitzen.  Er  verlangt  deshalb  vom  Theologen 
eine  eindringende  Kenntnis  der  lateinischen,  griechischen, 
hebraischen,  chaldaischen  und  womoglich  auch  der  arabi- 
schen  Sprache.  Dabei  unterscheidet  er  drei  Stufen  der  zu 
fordernden  Hohe  sprachlicher  Kenntnisse.' 

Einen  Hauptgrund  fiir  den  von  ihm  so  oft  beklagten 
Mangel  an  einer  griindlichen  Sprachenkenntnis  seiner  Zeit 
erkannte  Roger  Bacon  darin,  dass  die  richtige  wissen- 
schaftliche  Unterrichtsmethode  und  Lernmethode  fehlte  ; 
und  diese  fehlte,  well  man  keine  richtigen  Grammatiken 
hatte,  wahrend  das  praktisch  und  unmethodisch  erlernte 
Sprechen  der  lateinischen,  griechischen  und  arabischen 
Sprache  mehr  verbreitet  war.^  Daher  schrieb  Bacon  selbst 
eine  griechische  Grammatik,  in  welcher  er  eine  ausgebreitete 
Kenntnis  der  alten  Grammatiker  verrat.  Auch  eine  hebrai- 
sche  Grammatik  hat  ihn,  wie  Hirsch  mit  guten  Griinden 
dargelegt  hat,  zu  ihrem  Verfasser.' 

Vor  allem  aber  suchte  Bacon  eine  philologische  Methode 

'  Nolan,  a.  a.  O.,  xlv  ;   Bacon,  Comp.  Studii  Phil.,  vi.  433  f. 

-  Mit  der  ihm  eigenen  Obertreibungssucht  sagt  Roger  Bacon 
hieriiber  :  '  Paucissimi  sunt,  qui  sciunt  rationem  grammaticae 
ipsius,  nee  sciunt  docere  earn  ;  nam  non  sunt  quattuor  Latini, 
qui  sciant  grammaticam  Hebraeorum  et  Graecorum  et  Arabum.' 
Er  fiigt  hinzu  :  '  bene  enim  cognosco  eos,  quia  et  citra  mare  et  ultra 
feciinquiriet  multuminhis  laboravi.'    Op.  Tert.,  a.  a.  O.,  Nolan,  xliv. 

'  The  Greek  Grammar  of  Roger  Bacon  and  a  fragment  of  his  Hebrew 
Grammar,  ed.  by  Nolan  and  Hirsch,  Cambridge,  1902,  S.  197  ff. 


EINFLUSS  DES  ROBERT  GROSSETESTE        39 

auszubilden,  in  welcher  die  philologischen  Regeln  der  Uber- 
setzungskunst,derHandschriftenkunde,Textkritikundphilo- 
logischen  Hermeneutik  zu  ihrem  Rechte  kommen  sollten. 
Bei  der  grossen  Fehlerhaftigkeit  der  bestehenden  Uber- 
setzungen  biblischer  und  profaner  Schriften  verlangt  er 
Feststellung  des  handschriftlich  fundierten  Vulgatatextes, 
neue  direkt  aus  der  Ursprache  der  betr.  Schrift  hergestellte 
Ubersetzungen,  oder  Korrektur  der  bestehenden  Uberset- 
zungen  und  Ausgleich  strittiger  Ubersetzungen  durch  Zuriick- 
gehen  auf  den  Urtext.  In  Anlehnung  an  Augustinus  und 
Hieronymus  versucht  er  Regeln  einer  philologischen  Text- 
kritik  aufzustellen  ;  ein  nach  solchen  Regeln  systematisch 
angelegtes  Bibelkorrektorium  schwebt  ihm  stets  als  Ideal 
vor.'  Als  Grundregeln  stellt  er  auf  :  Feststellung  und  Er- 
klarung  der  Texte  nach  dem  Urtext,  einerseits,  nach  den 
altesten  auffindbaren  Handschriften  andererseits.  —  Die 
libersetzer  miissen  die  betreffenden  Sprachen  nicht  nur 
oberflachlich  und  rein  praktisch  konnen,  sondern  Gram- 
matik  und  Sprachi^io;«  durch  und  durch  beherrschen,  um 
audi  die  sprachlichen  Nuancierungen  des  fremden  Idioms  in 
der  Uebersetzung  zum  Ausdruck  bringen  zu  konnen.  Noch 
mehr !  Sie  miissen  auch  geistig  dem  Inhalt  der  betr. 
Schriften  gewachsen  sein.  Davon  hangt  die  Richtigkeit, 
Zuverlassigkeit ,  der  wissenschaftliche  Wert  der  Lexika, 
Korrektorien,  Ubersetzungen  und  Kommentare  ab. 
Auf  die  positiven  Einzelvorschlage,  die  Roger  Bacon  zur 

'  tJber  die  Bibelkorrektorien  des  13.  Jahrh.  s.  Trochon,  Essai  sur 
I'histoire  de  la  Bible  dans  la  France  chretienne  au  moyen  age,  Paris, 
1878  ;  F.  P.  Martin,  La  Vulgate  latine  au  XIII''  siecle  d'apres  Roger 
Bacon,  Paris,  1888;  Denifie  im  Archiv  f/ir  Literatur  u.  Kirchengesch. 
des  Mittelalters,  iv.  (1888),  270  ff.  ;  S.  Berger,  De  I'histoire  de  la 
Vulgate  en  France,  Paris,  1887  ;  Derselbe  in  Revue  de  Theologie  et  de 
Philosophie,  1883  ;  vgl.  auch  Museon,  viii.  (1889),  444  ff.  ;  ix.  (1890), 
301  ff. ;  Magenot  im  Dictionnaire  de  la  Bible,  art.  '  Correctoires ' ; 
Gasquet,  '  English  Bibhcal  Criticism  in  the  Thirteenth  Century,'  in 
Dublin  Review,  January,  1898,  p.  7  ;  G.  Delorme  in  Dictionnaire  dc 
Theologie  catholique,  ii,  s.v.  'Bacon,  Roger.' 


40  ROGER  BACON 

Verbesserung  des  arg  verschlechterten  Pariser  Vulgata- 
Textes  machte,  brauchen  wir  nicht  einzugehen.  Auch  seine 
Versuche,  die  friiheren  Bibelkorrektorien  der  Franziskaner 
und  Dominikaner  durch  ein  nach  seinen  philologischen  Grund- 
satzen  gearbeitetes  Korrektorium  zu  ersetzen,  konnen  in 
diesem  Zusammenhang  iibergangen  werden.  Nur  ein  ihm 
eigentiimlicher  Gedanke  sei  noch  erwahnt  :  sein  sprachge- 
schichtlicher  Gedanke,  alle  Sprachen  auf  eine  Ursprache 
zuriickzufiihren,  wie  etwa  die  Dialekte  einer  Sprache  auf 
einer  gemeinsamen  Sprache  beruhen. 

Von  diesen  Grundsatzen  und  philologischen  Kenntnissen 
des  Roger  Bacon  wird  man  ein  gut  Teil  zuriickfiihren 
miissen  auf  die  Anregungen,  die  ihm  das  Studium  der 
exegetischen  Schriften  des  hi.  Augustinus  und  Hieronymus, 
sowie  der  friiheren  Bibelkorrektorien  geboten  hatte/  Aber 
es  kann  doch  auch  nicht  zweifelhaft  sein,  dass  das  Interesse 
des  Roger  Bacon  an  Grammatik,  Sprachenstudium  und 
philologischer  Kritik  von  der  Schule  des  Robert  Grosseteste 
angeregt  und  grossgezogen  worden  ist,  und  dass  es  von 
der  ganzen  Gruppe  der  sprachenkundigen  Manner  gefordert 
wurde,  die  Robertus  Lincolniensis  umgaben  :  Nicolaus 
Graecus,  John  Basingstoke,  Adam  Marsh,  Wilhelm  de 
Mara  u.  a.  Wer  sein  unmittelbarer  Lehrer  im  Griechischen, 
Hebraischen,  Chaldaischen  und  Arabischen  gewesen  ist, 
wissen  wir  nicht.  Und  wie  weit  Bacon's  grammatische 
Kenntnisse  des  Griechischen  etwa  auf  direkte  Unter- 
weisung  durch  Robert  Grosseteste  zuriickgehen  mogen, 
lasst  sich  nicht  sagen.  Er  selbst  behauptet  von  Grosseteste, 
dass  dieser  nicht  so  viel  Griechisch  gewusst  habe,  als  fxir 
Anfertigung  selbst andiger  Ubersetzungen  notig  gewesen 
ware.^     Nur   die   unterste    (dritte)    Stufe   der   von   Bacon 

'  Vgl.  Denifle,  '  Die  Handschriften  der  Bibelkorrektorien  im 
13.  Jahrhundert.'^ycA./.  Literaturu.  Kirchengesch.,  iv.  (1888),  270  fif. ; 
292  ff. 

-  Comp.  Studii  Phil.,  viii.  472  ;  Nolan,  Ivii  ;  F.  G.  Stevenson, 
The  Life  of  Robert  Grosseteste,  London,  1899,  S.  224. 


EINFLUSS  DES  ROBERT  GROSSETESTE        41 

unterschiedenen  Sprachenkenntnisse  will  er  seinem  Lehrer 
im  Griechischen  zugestehen.  Ich  habe  an  einer  anderen 
Stelle '  nachzuweisen  versucht,  dass  dies  zwar  fiir  die  friihere, 
aber  wohl  kaum  mehr  fiir  die  spatere  Lebenszeit  des  Robert 
Grosseteste  zutraf. 

Sicher  ist,  dass  Roger  Bacon  die  Anregung  fiir  seine 
Wertung  der  Sprachenkenntnisse,  und  vor  allem  seine  Uher- 
setzungsgrundsdtze,  von  Robert  Grosseteste  erhalten  hatte. 
Dass  dieser  wenigstens  indirekt  auch  auf  seine  grammatischen 
Kenntnisse  anregend  einwirkte,  scheint  die  Bemerkung  des 
Roger  Bacon  nahezulegen,  der  es  nicht  unterlasst,  hervor- 
zuheben  :  Grosseteste  ' .  .  .  fecit  libros  grammaticae  Graecae 
de  Graecia  et  aliis  congregari.'  - 

Dass  seine  Vorliebe  fiir  die  Sprachen  und  seine  philologi- 
schen  Ubersetzungsgrundsatze  auf  Grosseteste  zuriickgehen, 
kann  um  so  weniger  einem  Zweif el  unterliegen,  als  Bacon  {Greek 
Grammar,  ed.  Nolan  118)  selbst  gelegentlich  auf  die  Kom- 
mentare  des  Lincolniensis  zu  Dionysius  Pseudoareopagita 
hinweist.^  In  der  Tat  entsprechen  die  grammatischen, 
philologischen,  textkritischen,  lexikalischen  Bemerkungen, 
die  Grosseteste  in  den  Einleitungen  und  Kommentaren  zu 
den  genannten  Schriften  niedergelegt  hat,  ganz  dem  spater 
von  Roger  Bacon  entwickelten  Gedankengang.  Beachtens- 
wert  ist  jedenfalls  schon  die  Betonung  des  exegeiischen 
Studiums  im  theologischen  Lehrplan  und  seine  deutliche 

'  L.  Baur,  Die  philosophischen  Wevke  des  Robert  Grosseteste,  Miinster 
(Aschendorff),  191 2,  S.  42*  f. 

-  O^.  Tey^.  (Brewer),p.9i.  Nolan,  a.  a.  O.,  Ix.  Natiirlich  kommt  f iir 
Roger  Bacon  noch  mehr  der  Donatus  graecus  des  John  Basingstoke 
in  Betracht,  der  seiner zeit  die  byzantinische,  in  Athen  iibliche 
Grammatikmethode  befolgte. 

^  So  sagt  er  :  '  Et  est  "  arete  "  virtus  gratuita,  "  dynamis  "  vero 
virtus  naturalis,  qua  diversitate  ignorata  a  multis  latinis  accipitur 
una  pro  aha  in  scripturis  autenticis,  sicut  Dominus  Robertus  sanctae 
memoriae  quondam  episcopus  Lincolniensis,  doctor  famosissimus 
exposuit  in  suis  Commentariis  super  libros  Dionysii  et  corrigit 
ceteros  translatores.'    Nolan,  a.  a.  O.,  118. 


42  ROGER  BACON 

Bevorzugung  vor  dem  systematischen  der  Sentenzen  in 
einem  Brief e  des  Grosseteste  (ca.  1246).' 

In  seinen  Kommentaren  zu  der  Areopagitica  (speziell 
zu  De  divinis  noniinibus)  gibt  Grosseteste  eine  Art  gram- 
matischer  Einleitung  in  die  griechische  Sprache.  Er  be- 
handelt  hier  die  Lautlehre,  Vokale,  Konsonanten,  Diph- 
thonge,  Aussprache  der  griechischen  Buchstaben,  ferner  die 
Genusregeln,  Konstruktionseigentiimlichkeiten,  Composita, 
signifikante  Wortverbindungen,  verschiedene  Bedeutungen 
desselben  Ausdrucks  (Synonymik) ,  Idiomunterschiede  zwi- 
schen  der  lateinischen  und  griechischen  Sprache,  Nament- 
lich  betont  er,  wie  sehr  es  notwendig  sei,  von  den  lateinischen 
Ubersetzungen  zum  Urtext  vorzudringen  :  einerseits,  um 
eine  gute  Ubersetzung  zu  erlangen,  andererseits,  um  eine 
richtige  Erklarung  der  Texte  geben  zu  konnen.  Wer  sich 
nur  an  die  lateinische  Ubersetzung  halte,  der  werde  niemals 
oder  nur  mangelhaft  den  wahren  Sinn  eines  Autors  erkennen, 
wahrend  dieser  denjenigen  nicht  verborgen  bleibe,  die 
wenigstens  einigermassen  (mediocriter  vel  etiam  tenuiter) 
die  griechische  Sprache  verstehen.  Diese  allein  seien  auch 
imstande,  die  feineren  Nuancierungen  der  Gedanken,  die  in 
dem  Idiom  der  fremden  Sprache  verborgen  liegen,  aufzufin- 
den  und  in  der  anderen  Sprache  wiederzugeben.  Auch 
konnen  sie  bei  zweifelhaften  und  mehrdeutigen  Ausdriicken, 
oder  Ubersetzungen,  ihre  Konjekturen  machen. 

Die  Ubersetzung  selbst  hat  vor  allem  einen  einwandfreien, 
gesicherten  Text  und  ein  richtiges  Verstandnis  des  Textes 
seitens  des  tJbersetzers  zur  Voraussetzung.  Um  einen  guten 
Text  zu  haben,  verwendet  Grosseteste  immer  eine  grossere 
Anzahl  griechischer  Handschriften.  Ob  er  dabei  auch  schon 
die  von  Roger  Bacon  gegebenen  Regeln  der  Textkritik 
anwandte  lasst  sich  aus  diesen  Ausfiihrungen  nicht  fest- 
stellen.  Doch  ist  es  durchaus  wahrscheinUch.  Bei  seinen 
Ubersetzungen  verfuhr  Grosseteste  so,  dass  er  zunachst 
'  Roberti  Grosseteste  Epistolae,  ed.  Luard,  pp.  346-7. 


EINFLUSS  DES  ROBERT  GROSSETESTE        43 

mehrere  lateinische  tJbersetzungen,  so  weit  solche  bestan- 
den,  vergleichsweise  nebeneinander  —  und  diese  zugleich  in 
verschiedenen  Handschriften  —  beniitzte.  Diese  verglich 
er  dann  mit  dem  griechischen  Text  und  brachte  entspre- 
chende  Korrekturen  an.  Wo  sich  Verschiedenheiten  in  den 
Ubersetzungen  herausstellten,  da  suchte  er  diese  Verschie- 
denheiten zu  erklaren  teils  palaeographisch,  teils  durch 
Zuriickgehen  auf  den  griechischen  Text. 

Endlich  gibt  er  auch  gewisse  grundsatzliche  Anweisungen 
und  Rcgeln  fiir  das  Uhersetzen,  insbesondere  fiir  solche  Falle, 
wo  das  lateinische  Idiom  sich  mit  dem  Griechischen  nicht 
ohne  weiteres  deckt,  wie  z.  B.  bei  den  zusammengesetzten 
Wortern.    Er  sagt  dariiber  {De  divin.  nomin.,  p.  i)  : 

'  Oportet  autem  huiusmodi  dictiones  Graecas  compositas, 
cum  non .  habent  correspondentes  compositiones  in  Latino 
nee  aequipollentes  eis  dictiones  simplices,  transferre  in  dic- 
tiones simplices  idem  significantes  cum  dictionibus  Graecis, 
ex  quibus  hunt  Graecae  compositiones.  Cum  vero  inveniuntur 
in  Latino  Graecis  correspondentes  et  aequipollentes,  conve- 
nientissime  transferuntur  in  huiusmodi  compositas.  Ouando 
vero  possunt  fingi  compositiones  non  multum  absonae 
Latinitati,  convenienter  etiam  in  huiusmodi  fit  translatio, 
ut  si  dicantur  compositae  '  bonidecenter,  sacridecenter, 
boniformiter,  omnisciens,  omnibonus  '  et  huiusmodi.  Mens 
enim  auctoris  et  venustas  sui  sermonis  per  huiusmodi  com- 
positiones, ut  existimo,  magis  est  dilucida.  Existimo  etiam, 
quod  diligenter  consideranti,  quae  dictiones  in  Latino 
diversimode  positae  habent  sibi  correspondentes  in  Graeco 
compositas  et  fingenti,  ut  patet,  ex  simplicibus  Latinis 
correspondentes  compositiones  licet  Latinitati  absonas,  sicut 
nos  fecimus  in  principio  expositionis  angelicae  hierarchiae, 
patcbit  dilucidius  et  mens  auctoris  et  venustas  sermonis. 
Ideo  non  incongruum  nobis  videtur,  si  breviter  tangamus 
quae  diversimode  positae  dictiones  in  Latino  habent  in  Graeco 
aequipollentes  sibi  quoad  sensum  dictiones  compositas.'  ' 

Hochst  beachtenswert  sind  auch  die  lexikalischen  Notizen, 
welche  sich  in  diesen  Kommentaren  Grossetestes  iiberaus 

■  Zum  Ganzen  vergl.  L.  Baur,  Die  philosophischen  Werke  des 
Robert  Grosseteste,  Munster,  191 2,  S.  37*  H. 


44  ROGER  BACON 

zahlreich  vorfinden.  Es  liesse  sich  daraus  unschwer  das 
griechisch  -  lateinische  Lexikon  rekonstruieren  —  wenig- 
stens  zum  Teil,  —  das  diesem  Oxford-Lincolner  philologisch 
interessierten  gelehrten  Kreise  zu  Gebote  stand.  Das 
wiirde  sicher  eine  bedeutende  und  ergebnisreiche  Erganzung 
sein  zu  der  hoch  interessanten  Studie  '  Uber  ein  griechisch- 
lateinisches  Lexikon  des  13.  Jahrhunderts  '  (MS.  London, 
College  of  Arms,  Arundel,  ix),  das  vor  einigen  Jahren  M.  R. 
James  (in  den  Melanges  offerts  a  M.  Emile  Chatelain  par 
ses  Sieves  et  ses  amis,  Paris,  1910,  S.  396-411)  veroffentlichte. 
Mit  gut  en  Griinden  weist  James  jenes  Lexikon  dem  Kreise 
Grossetestes  zu.  Der  Zusammenhang  der  grammatisch- 
lexikalischen  Kenntnisse  des  Roger  Bacon  mit  diesem 
Kreise  ist  durch  die  oben  angefiihrte  Stelle  aus  seiner 
griechischen  Grammatik  zur  Evidenz  erwiesen. 

Ill 

Noch  viel  deutlicher,  als  auf  dem  Gebiete  der  Grammatik, 
Linguistik,  Philologie  und  Textkritik  zeigt  sich  der  starke, 
bestimmende  Einfluss  des  Robertus  Lincolniensis  auf, die 
wissenschaftliche  Richtung  seines  Schiilers  auf  dem  Gebiete 
der  Naturerkenntnis  und  Naturphilosophie,  Manch  ein 
Gedanke  und  origineller  Erklarungsversuch,  den  man  Roger 
Bacon  zum  Verdienste  anrechnet,  geht  tatsachlich  auf 
Robert  Grosseteste  zuriick.  Es  ist  hier  nicht  der  Raum  zur 
Verfiigung,  um  das  in  ausfiihrlichem  Beweisgang  darzulegen. 
Ich  werde  den  Beweis  in  meinem  bald  erscheinenden  Buch, 
Die  Philosophie  des  Robert  Grosseteste,  erbringen.  In 
diesem  Artikel  moge  es  geniigen,  kurz  die  Punkte  namhaft 
zu  machen,  an  welchen  eine  solche  richtunggebende  Einfluss- 
nahme  des  Lehrers  gegeniiber  dem  Schiiler  tatsachlich 
stattgefunden  hat.  Natiirlich  will  damit  der  fruchtbare 
Einfluss  der  arabischen  Literatur  auf  Bacons  Natur- 
philosophie in  keiner  Weise  verkleinert  werden. 

I.  Es  ist  bekannt,  dass  Roger  Bacon  an  den  verschieden- 


EINFLUSS  DES  ROBERT  GROSSETESTE        45 

sten  Stellen  seiner  Schriften  auf  die  Frage  der  Kalenderreform 
zu  sprechen  kommt '  und  dieselbe  als  dringend  notwendig 
bezeichnet :  so  z.  B.  in  seinem  (nicht  edierten)  Computus, 
im  Opus  Majus,  ed.  Bridges,  i.  276  ;  Opus  Tert.,  cp.  70, 
ed.  Brewer,  281  ff.,  287  ff.  Die  Art,  wie  er  die  Forderung 
einer  Kalenderreform  begriindet,  der  Sinn,  in  welchem  er 
diese  Forderung  erhoben  wissen  will,  stimmen  vollkommen, 
oft  sogar  wortlich  iiberein  mit  dem,  was  Robert  Grosseteste 
in  seinem  gleichfalls  noch  unedierten  Computus  -  in  derselben 
Hinsicht  forderte  und  begriindete.  Vor  allem  machen  beide 
den  ganz  identischen  Vorschlag  :  {a)  Um  zu  einer  besseren 
Kalenderrechnung  zu  kommen,  muss  man  vor  allem  die 
Grosse  des  Sonnenjahrs  richtig  bestimmen  und  die  in  der 
bisherigen  Kalenderrechnung  gemachten  Fehler  vermeiden. 
Man  muss  die  wahre  astronomische  Grosse  des  Sonnenjahrs 
der  Rechnung  zu  Grunde  legen.  [h)  Auch  ohne  Verifizierung 
der  astronomischen  Grosse  des  Sonnenjahrs  soil  der  Tag  des 
Friihlingsaequinoctiums  nicht  nach  dem  alten  Osterkanon 
und  nach  veralteten  astronomischen  Tafeln,  sondern  ein- 
fach  durch  das  Beobachtungsinstrument,  oder  auf  Grund 
verifizierter,  neuer  Tafeln  bestimmt  werden.  (c)  Auf  Grund 
von  dem,  was  Grosseteste  bzw.  Bacon  iiber  die  Berechnung 
der  Primationen  ausfiihrte,  soil  der  richtige  Tag  des  ersten 
Vollmondes  nach  dem  Friihlingsaequinoctium  wahrheits- 
getreu  festgestellt  werden  und  dieser  Tag  soil  dann  als 
Osterterminus  fiir  die  Bestimmung  des  Osterfestes  dienen. 

2.  Wahrend  Grosseteste  seine  ganze  Naturphilosophie  in 
seiner  Lichttheoric  zusammenfasst,  hat  diese  '  Lichtmeta- 
physik  '  auf  Roger  Bacon  nicht  einen  so  ausschlaggebenden 
Einfiuss  ausgeiibt.  Nur  gelegentlich  finden  sich  verwandte 
Gedanken  bei  ihm.     Dagegen  hat  sich  Roger  Bacon  einen 

'  Vgl.  Kaltenbrunner,  'Die  Vorgeschichte  der  gregorianischen 
Kalenderreform,'  Sitz.-Ber.  der  K.  K.  Akadeniie  d.  Wiss.,  philol.- 
hist.  KL,  Bd.  Ixxxii,  Wien,   1876,  S.  289-414. 

"  t'ber  diesen  Computus  vgl.  L.  Baur,  Die  philosoph.  Werke  des 
Robert  Grosseteste,  Miinster,  1912,  S.  O5*  flE. 


46  ROGER  BACON 

wichtigen  Grundgedanken  der  Naturerklarung  des  Grosse- 
teste  zu  eigen  gemacht,  welcher  bei  diesem  mit  seiner 
Lichtmetaphysik  aufs  engste  verkniipft  erscheint  :  namlich 
die  grundsdtzliche  methodische  Auffassung  der  Naturwissen- 
schaft,  und  die  Erkldrung  des  Wirkens  und  Werdens  in  der 
Natur.  Roger  Bacon  vertritt  in  seinen  verschiedenen 
Schriften  immer  wieder  die  Ansicht,  dass  der  Naturforscher 
die  Natur  durch  Mathematik  und  Experiment  erklaren 
miisse.  Wenn  er  die  Naturwissenschaft  auf  fruchtbare 
Weise  und  in  wissenschaftlicher  Art  betreiben  soil,  so  muss 
dies  mit  der  richtigen  Methode  geschehen.  Diese  ist  die 
mathematische.  Speziell  die  Geometrie  ist  fiir  die  Natur- 
erkenntnis  von  der  allergrossten  Wichtigkeit.'  Die  Bedeu- 
tung  der  Mathematik  erstreckt  sich  iibrigens  auf  samt- 
liche  Wissenschaften.  Roger  beweist  dies  daraus,  dass  die 
mathematischen  Kenntnisse  uns  angeboren  seien  (vgl. 
Plato  !),  ja  geradezu  die  apriorischen  Voraussetzungen  des 
wissenschaftlichen  Denkens  iiberhaupt  bilden  {Op.  Mai., 
ed.  Bridges,  i,  103).  Sie  sei  unter  alien  Wissenschaften 
geschichtlich  am  friihesten  erfunden  worden  (ebd.,  i.  104). 
Sie  sei  die  leichteste  Wissenschaft  (ebd.),  Daher  sei  es  auch 
methodisch  allein  richtig,  vom  Bekannten  zum  Unbekannten 
(vom  Leichteren  zum  Schwereren)  voranzuschreiten,  d.  h.  also 
im  Studiengang  mit  der  Mathematik  zu  beginnen  (natiirlich 
nach  der  Grammatik).  Endlich  erhalten  die  iibrigen 
Wissenschaften  durch  die  Mathematik,  bzw.  genauer  durch 
die  Geometrie,  eine  Gewissheit  ohne  Zweifel  und  eine  Wahr- 
heit  ohne  Irrtum  (ebd.,  i.  106). 

Ohne  Mathematik,  sagt  Bacon,  ist  es  unmoglich,  zu  einer 
richtigen  Erkenntnis  iiber  die  Dinge  dieser  Welt  zu  kommen. 
Denn  jedes  Naturding  wirkt  durch  die  ihm  innewohnenden 
Krafte.  Diese  aber  wirken  nach  Linien,  Winkeln  und 
Figuren.^ 

'  Op.  Tert.,  cp.  58,  ed.  Brewer,  227  ;   Op.  Min.,  ed.  Brewer,  321. 
-  Dieser  Satz  kommt  bei  Bacon  wiederholt  vor,   so  namentlich 


EINFLUSS  DES  ROBERT  GROSSETESTE       47 

Die  Proklamierung  des  Grundsatzes,  die  Naturwissen- 
schaft  (bzw.  Naturphilosophie)  more  geometrico  zu  treiben, 
wird  allgemein  fiir  die  Zeit  des  Mittelalters  dem  Roger 
Bacon  als  Verdienst  angerechnet.  Allein  samtliche  von 
ihm  iiber  diese  Frage  vorgetragenen  Gedanken  finden  sich 
der  Sache  nach,  nicht  selten  auch  dem  Wortlaut  nach,  schon 
bei  Robert  Grosseteste  vor.  Bacon  zitiert  ihn  zwar  nicht 
im  einzelnen  Fall,  wo  er  ihm  folgt,  mit  Namen,  aber  er 
riihmt  doch  wenigstens  im  allgemeinen  von  ihm  (ebenso 
von  Adam  de  Marisco),  dass  er  es  verstanden  habe,  durch 
Mathematik  die  Ursache  der  Dinge  zu  finden  und  ihr  Wesen 
zu  bestimmen.'  Die  Abhangigkeit  des  Roger  Bacon  von 
der  Naturphilosophie  des  Robert  Grosseteste  in  vielen 
grundsatzlichen  Fragen  lasst  sich  im  einzelnen  vergleichs- 
weise  dartun,    Wir  fassen  uns  dabei  so  kurz  als  moglich. 

Wenn  Bacon  [Commun.  Nat.,  i.  5,  ed.  Steele,  36)  sagt : 
'  agens  muUiplicat  se  aequaliter  in  omni  parte  [in  omnem 
partem  ?]  et  secundum  omnes  diametros  et  omnes  diffe- 
rentias  positionis,  quae  sunt  sursum,  deorsum,  ante,  retro, 
dextrorsum,  sinistrorsum.  Ergo  undique  exeunt  lineae  in 
omni  parte  ab  agente  tanquam  a  centro.  Sed  lineae  undique 
exeuntes  ab  uno  loco  non  possunt  terminari  nisi  ad  super- 
ficiem  concavam  sphaerae,'  so  ist  das  genau  dasselbe,  was 
Grosseteste  iiber  die  '  sui  multiplicatio  '  des  Lichtes  bzw. 
der  Kraft  in  seinem  Kommentar  zu  den  zweiten  Analytiken 
(ed.  Venet.,  1504,  fol.  33"")  und  in  der  Schrift  Dc  Luce 
(s.  L.  Bauer,  a.  a.  O.,  51  ff.)  ausgefiihrt  hat. 

Da  das  Licht  nach  Grosseteste  das  Wesen  der  Naturdinge 

ausmacht,  so  erfolgt  —  konsequent  nach  seiner  Ansicht,  — 

gerade  so  wie  in  Bacons  Naturphilosophie,  auch  das  Wirken 

und  Werden  der  Dinge  nach  den  Gesetzen  des  Lichtes,  d.  h. 

Op.  Maj.,  iv,  diet.  2,  cp.  i,  ed.  Bridges,  i.  no.  Der  Zusammenhang 
desselben  mit  der  Schrift  des  Grosseteste,  '  De  lineis,  angulis  et 
figuris  '  (s.  Baur,  Die  philos.  Werke  des  Robert  Grosseteste,  S.  59  ff.), 
ist  ganz  unverkennbar.     Vgl.  ebd.,  S.  78*  ff. 

'  Op.  Maj.,  p.  iv,  diet,  i,  cp.  3,  ed.  Bridges,  i.  108. 


48  ROGER  BACON 

nach  Linien,  Winkeln  und  Figuren.  Somit  muss  die  optische 
Geometrie  (Perspectiva)  die  Grundlage  fiir  die  gesamte 
Naturerklarung  abgeben.  Die  geometrischen  Linien,  Winkel 
und  Figuren  beherrschen  das  ganze  Kraftwirken  im  Univer- 
sum,  in  seinen  einzelnen  Teilen,  in  den  Beziehungen  der 
Dinge  und  ihren  Wechselwirkungen. 

Bei  Roger  Bacon  konzentriert  sich  der  Begriff  des 
Naturwirkens  genau  wie  bei  Robert  Grosseteste  in  dem 
Begriff  der  '  multiplicatio  specierum  ',  die  sich  nach  den 
Gesetzen  der  Perspektive  vollzieht. 

Auch  die  '  Perspektive  '  selbst,  von  Roger  Bacon  sehr 
ausfiihrlich,  von  Robert  Grosseteste  nur  ganz  fliichtig  und 
skizzenhaft  behandelt  (eben  nur  insoweit,  als  sie  zum 
Verstandnis  des  Kraft wirkens  oder  der  KraftUnien  dient), 
bietet  eine  Anzahl  paralleler  Gedanken,  vereinzelt  sogar 
fast  wortlich  gleicher  Stellen. 

Die  Unterscheidung  der  Virtus  accidentalis  im  Natur- 
wirken  von  der  Virtus  principaHs,  die  Einteilung  des  Natur- 
wirkens in  ein  Wirken  super  lineis,  super  anguhs  (und  zwar 
per  fractionem,  per  dupUcem  fractionem,  per  reflexionem) 
und  endlich  super  figuris  (namUch  nach  spharischen  und 
pyramidalen  Figuren)  bei  Roger  Bacon  hat  wiederum  ihren 
Vorgang  bei  Robert  Grosseteste. 

Die  Lehrpunkte  iiber  die  Naturwirksamkeit  in  geraden 
Linien,  iiber  die  Starke  der  senkrecht  einfallenden  Kraft- 
linien  und  ihre  Uniformitas,  iiber  den  Einfall  der  Kraftlinien 
im  Winkel  bei  zwei  Medien  von  verschiedener  Dichtigkeit, 
iiber  die  Starke  der  reflektierten  Kraft  bei  poherten  und 
rauhen,  ebenen  und  konkaven  Korpern,  iiber  die  einfache 
und  doppelte  Strahlenbrechung,  iiber  das  Starkeverhaltnis 
der  gebrochenen  gegeniiber  der  reflektierten  Kraft,  der  nach 
rechtshin  gebrochenen  gegeniiber  der  nach  Hnks  gebro- 
chenen, endlich  iiber  das  Wirken  der  Naturkrafte  nach 
Figuren,  in  Kugelform  oder  Pyramidenform  und  die  jeweili- 
gen  Starkeverhaltnisse  —  all  das  wird  von  Roger  Bacon  in 


EINFLUSS  DES  ROBERT  GROSSETESTE        49 

durchaus  iibereinstimmender  Weise  mit  den  Ausfiihrungen 
des  Robert  Grosseteste  behandelt.  Ich  habe  in  meinem 
demnachst  erscheinenden  Buch,  Die  Philosophic  des  Robert 
Grosseteste,  Miinster  (Aschendorff) ,  1914,  den  Nachweis  einer 
nicht  selten  ganz  wortlichen  tJbereinstimmung  erbracht 
und  darf  auf  dasselbe  verweisen. 

Man  hat  es  ferner  als  Verdienst  des  Roger  Bacon  bezeich- 
net,'  dass  er  als  erster  unter  den  Lateinern  des  Mittelalters 
die  Lehre  von  den  Brennkugeln  und  der  ihnen  eigentiimlichen 
Strahlenbrechung  in  Angriff  genommen  habe.  Aber  auch 
hier  ist  es  wieder  der  anregende  Einfluss  des  Robert  Grosse- 
teste gewesen,  der  unverkennbar  auf  Roger  Bacon  stattge- 
funden  hat.  Was  Roger  Bacon  {Op.  Maj.,  ed.  Bridges,  i.  113  ; 
De  multiplicatione  specierum,  ed.  Bridges,  ii.  3,  471  ;  Com- 
mun.  nat.,  i.  5,  ed.  Steele,  30  ff.)  dariiber  schreibt,  ist,  wenn 
auch  nicht  so  ausfiihrlich,  so  doch  der  Sache  nach,  oft  mit  den- 
selben  Redewendungen  schon  bei  Robert  Grosseteste  zulesen.^ 

Auch  in  ihren  Ausfiihrungen  iiber  die  optischen  Tdu- 
schungen  stimmen  beide  iiberein.  Materiell  beruht  ja  das, 
was  sie  dariiber  zu  sagen  haben,  durchaus  auf  alteren 
Vorlagen  :  auf  Euklid,  Ptolemaus,  Heron,  Alkindi,  Alhazen. 
Aber  der  Umstand,  dass  auch  formell  weitgehende  tJberein- 
stimmung besteht,  lasst  den  Schluss  als  berechtigt  erschei- 
nen,  dass  die  Abhangigkeit  Bacons  von  Grosseteste  auch 
fiir  diese  Fragen  als  moglich  bezeichnet  werden  darf. 

Auf  die  nur  teilweise,  allerdings  wieder  vielfach  wortliche 
tJbereinstimmung  in  der  Meteorologie  soil  kein  allzu  grosses 
Gewicht  gelegt  werden,  weil  sie,  wie  es  scheint,  auf  die 
gemeinsame  Quelle,  aus  welcher  beide  offenbar  schopften, 
zuriickzufiihren  ist. 

'  S.  Vogl,  Die  Physik  Roger  Bacons,  Diss.,  Erlangen,  1906,  S.  79  f. 

-  Besonders  bezeichnend  fiir  die  unmittelbare  Abhangigkeit  des 
Roger  Bacon  von  Grosseteste  erscheint  es,  dass  beide  [aus  der 
Schrift  De  proprietatibus  rerum  ?]  dasselbe  Beispiel  wahlen  und 
dabei  den  Ausdruck  '  urinale  '  zur  Bezeichnung  des  kugelformigen 
Glases  verwenden. 

1689  E 


50  ROGER  BACON 

Aber  auf  drei  andere  Roger  Bacon  und  Robert  Grosseteste 
gemeinsame  Lehrpunkte  moge  noch  kurz  verwiesen  werden. 

Hier  ist  zunachst  einmal  an  die  Lehre  von  den  Klimaten, 
ihren  Unterschieden  und  den  Ursachen  dieser  Unterschiede 
zu  erinnern.  Wohl  behandelt  Roger  Bacon  auch  diesen 
Lehrpunkt  —  wie  fast  alle  iibrigen  —  viel  ausfiihrlicher, 
eingehender,  oft  auch  genauer,  als  Grosseteste.  Aber  was  er 
op.  Majus,  ed.  Bridges,  i.  132  ft.,  dariiber  vortragt,  das  hat  — 
wiederum  teilweise  wortUche  —  Anklange  bei  Robert  Grosse- 
teste in  seiner  Schrift  De  natura  locorum.^ 

Weitgehende  und  zwar  ganz  charakteristische  Uberein- 
stimmung  lasst  die  Lehre  der  beiden  Manner  iiber  Ebbe  und 
Flut  erkennen.  Nicht  nur  behandeln  beide  den  Mond  als 
Ursache  der  Gezeiten,  was  ja  an  sich  nichts  Auffallendes 
ware  ;  nicht  nur  denken  beide  die  Art  dieser  Einwirkung 
und  ihre  Folgen  fiir  die  Anschwellung  des  Wassers  ^  bei  der 
Flut  ganz  gleich,  sondern  auch  in  der  physikalischen 
Erklarung  der  betreffenden  Vorgange  besteht  zwischen 
Robert  Grosseteste  {De  7iatura  locorum)  und  Roger  Bacon 
{Op.  Maj.,  ed.  Bridges,  i.  139  ff.)  wieder  eine  auffallende 
Ubereinstimmung.  Beide  ziehen  namlich  die  schon  oben 
erwahnte  Art  des  Naturwirkens  (super  lineis,  angulis  et 
figuris)  zur  Erklarung  heran  :  Die  iiber  dem  Meere  an  einem 
bestimmten  Ort  aufgehenden  Strahlen  des  Mondes  haben 
langere  Linien  und  Pyramiden,  sind  weniger  senkrecht, 
mehr  schief,  fallen  weniger  in  rechten  Winkeln  auf,  werden 
weniger  direkt  zuriickgestrahlt,  starker  gebrochen.  Deshalb 
ist  auch  ihre  Kraft  schwacher.  Anders  ist  es,  wenn  der 
Mond  mitten  am  Himmel  steht  :  dann  haben  seine  Strahlen 
kiirzere  Linien  und  steilere  Pyramiden  :  sie  fallen  mehr 
senkrecht,  werden  mehr  direkt  reflektiert,  weniger  gebrochen 

'  Vgl.  L.  Baur,  Die  philosophischen  Werke  des  Robert  Grosseteste, 
Miinster  (Aschendorff),  1912,  S.  65-72. 

-  Grosseteste  gcbraucht  dafiir  den  Ausdruck  '  augmentatio ' 
und  '  tumor ',  Roger  Bacon  dagegen  '  ebuUitio'  (ed.  Bridges,  i.  139  ff.) 


EINFLUSS  DES  ROBERT  GROSSETESTE       51 

und  sind  deshalb  starker.  1st  der  Mond  erst  daran,  allmahlig 
emporzusteigen,  so  sind  seine  Krafte  noch  schwach  ;  sie 
lassen  die  Dampfe  vom  Meeresgrunde  inmitten  des  Meeres- 
wassers  aufsteigen,  sind  aber  noch  nicht  stark  genug,  um 
sie  vollig  an  die  Luft  herauszuziehen,  oder  sie  aufzusaugen 
{consumere).  Daher  verdrangen  diese  Dampfe  die  Meeres- 
wasser  von  ihrer  Stelle,  weil  sie  ja  korperlich  sind  und  nicht 
mehrere  Korper  an  einem  Ort  des  Raumes  sein  konnen. 
Sie  bringen  Blasen  {ampullae)  und  Anschwellungen  {tumores) 
oder  Aufwallungen  [ehullitio,  sagt  Roger)  hervor.  Daher 
steigt  das  Meer.  Wenn  der  Mond  zur  Mitte  des  Himmels 
emporgestiegen  ist,  so  ist  auch  seine  Kraft  grosser,  so  dass 
er  die  Dampfe  aufzuzehren  [consumere)  imstande  ist.  Auf 
seinem  Hohepunkt  angekommen  lost  er  sie  auch  voU- 
standig  auf.  Da  mit  dem  Aufhoren  der  Ursache  auch  die 
Wirkung  aufhort,  so  fiiesst  das  Meereswasser  wieder  an 
seinen  Ort  zuriick,  damit  kein  Vacuum  entsteht. 

Auch  die  Schwierigkeit  wird  von  beiden  aufgeworfen  und 
iibereinstimmend  behandelt  :  wie  diese  Einwirkung  des 
Mondes  auf  den  entgegengesetzten  Vierteln  der  Erde  zu- 
gleich  erfolgen  konne.  Beide  weisen  den  Erklarungsversuch 
des  Albumazar  (oder  Alpetragius  ?)  zuriick,  der  diese  Er- 
scheinung  aus  der  gleichen  (chemischen)  Zusammensetzung 
der  entgegengesetzten  Erdviertel  ableiten  wollte.  Beide 
suchen  die  Erklarung  mittels  der  Theorie  der  Strahlen- 
reflexion  zu  finden.  Grosseteste  stellt  sich  das  in  etwas 
dunkler  Wendung  des  bei  Bacon  (ed.  Bridges,  i.  141) 
deutlicher  ausgedriickten  Gedankens  so  vor,  dass  die  Mond- 
strahlen  gegen  den  Sternhimmel,  der  als  dichter  Korper 
aufgefasst  wird,  ausgestrahlt,  und  von  diesem  wie  von  einem 
Spiegel  auf  das  entgegengesetzte  Erdviertel  refiektiert 
werden.  Roger  Bacon  fiigt  (a.  a.  O.)  hinzu,  dass  diese  re- 
flektierten  Strahlen  allerdings  schwacher  wirken,  als  die 
direkten,  und  dass  sie  deshalb  auch  eine  schwachere  Flut 
bewirken. 

E  2 


52  ROGER  BACON 

Die  auffallendste  well  ganz  charakteristische  Beein- 
fiussung  Bacons  durch  Robert  Grosseteste  lasst  sich  fest- 
stellen  hinsichtlich  ihrer  Warmetheorie.  Bei  beiden  beruht 
dieselbe  auf  einer  Art  Atomistik,  auf  der  Bewegung,  Zer- 
streuung,  Strahlung  und  Strahlensammlung,  als  ihren  wich- 
tigsten  Erklarungsfaktoren. 

Besonders  auffallend  ist  ihre  gleichlautende  Erklarung 
der  Warmeerzeugung  durch  die  natiirliche  und  gewaltsame 
Bewegung,  die  beide  in  Anlehnung  an  Aristoteles  unter- 
scheiden.  In  alien  Fallen  ergibt  sich  —  so  fiihrt  Grosseteste 
aus  ^  —  eine  Zerstreuung  der  molekularen  Teilchen  infolge 
der  Bewegung.  In  dem  gewaltsam  Bewegten  ist  eine  doppelte 
Bewegungskraft  wirksam  :  eine  natiirliche  und  eine  gewalt- 
same. Beide  suchen  die  einzelnen  Telle  eines  korperlichen 
Gegenstandes  nach  verschiedenen  Seiten  hin  zu  bewegen. 
Die  Folge  dieser  verschiedenen  Richtungstendenz  ist  eine 
Zerstreuungstendenz  {disgregatio  materiae)  in  den  Mole- 
kularteilen  dieses  Korpers.  Daraus  entwickelt  sich  Warme. 
Bei  der  Aufwartsbewegung  sind  die  Richtungstendenzen 
der  natiirlichen  und  gewaltsamen  Bewegung  einander  direkt 
entgegen,  weshalb  daraus  die  denkbar  grosste  Zerstreuungs- 
tendenz und  darum  auch  die  denkbar  grosste  Warme  sich 
ergibt.  Bei  schiefer  oder  seitwartiger  Bewegung  ist  diese 
dagegen  geringer. 

Ganz  dasselbe  gilt  nun  aber  auch  fiir  die  natiirliche 
Bewegung.  Auch  sie  entwickelt  Wiirme  aus  denselben 
Ursachen.  Diese  entsteht  daraus,  dass  die  natiirliche 
Bewegung  nach  der  Erdmitte  zu  erfolgt.  Nun  aber  tritt 
auch  hier  neben  die  natiirliche  Richtungstendenz  noch  eine 
gewaltsame,  ihr  entgegengesetzte,  hinzu.  Dass  eine  natiir- 
liche Richtungstendenz  dem  Erdmittelpunkt  entgegen  vor- 
handen  sei,  wird  als  zugegeben  betrachtet.  Eine  gewalt- 
same Bewegung  und  divergierende  Richtungstendenz  aber 

'  Robert  Grosseteste  in  der  Schrift  De  calore  soHs  bei  L.  Baur,  Die 
philos.  Werke  des  Robert  Grosseteste,  S.  80  f. 


EINFLUSS  DES  ROBERT  GROSSETESTE        53 

entsteht  dadurch,  dass  der  schwere  Korper  als  Gauzes 
sich  dem  Erdmittelpunkt  zu  bewegt.  Seine  kleinsten  mate- 
riellen  Telle  behalten  innerhalb  des  Gesamtkorpers  beim 
Fallen  gleichen  Abstand  von  einander,  fallen  also  in  genau 
parallelen  Linien  nach  unten.  Selbst  ins  Unendliche  fort- 
gefiihrt  treffen  sich  diese  niemals  in  einem  Punkte  —  also 
auch  nicht  im  Erdmittelpunkt.  Wahrend  also  die  Moleku- 
larteile  des  Korpers  natiirlicherweise  dem  Erdmittelpunkt 
zu  streben,  werden  sie  tatsachlich  nicht  dem  Erdzentrum 
zu  —  also  gegenseitig  in  einem  spitzen  Winkel  —  son- 
dern  parallel  bewegt.  So  entsteht  auch  hier  wieder  eine 
doppelte  Richtungstendenz  und  daraus  die  Warme.  Doch 
ist  in  diesem  Fall  die  Gegensatzspannung  nicht  so  stark 
wie  im  ersten  Fall  der  gewaltsamen  Bewegung.  Deshalb 
bringt  die  natiirliche  Bewegung  unter  alien  Bewegungs- 
formen  die  geringste  natiirliche  Warme  im  Bewegten 
hervor. 

Diese  Gedanken  finden  bei  Roger  Bacon  [Op.  Maj.,  ed. 
Bridges,  i.  168)  ihre  nahezu  wortliche  Wiederholung,  ebenso 
wie  die  Lehre  des  Robert  Grosseteste,  dass  als  weitere 
Ursache  der  Warme  die  Strahlensammlung,  collectio  radio- 
rum,  wie  beim  Brennglas,  oder  bei  der  Warme  in  Talern, 
in  Erwagung  zu  ziehen  sei,  genau  so  wieder  von  Roger 
Bacon  [Op.  Maj.,  ed.  Bridges,  i.  113  f.)  vertreten  wird. 

Aus  dem  Gesagten  darf  mit  voller  Sicherheit  der  Schluss 
gezogen  werden,  dass  die  wissenschaftliche  Richtung  des 
Roger  Bacon,  die  so  deutlich,  ja  so  exklusiv  auf  Philologie 
und  Naturwissenschaft  eingestellt  ist,  dass  Bacon  nicht 
mehr  zum  Verstandnis  und  zu  einer  gerechten  Wertung  der 
spekulativen  Wissenschaft  zu  kommen  vermag,  in  ganz 
hervorragender  Weise  auf  seinen  Lehrer  Robert  Grosseteste 
zuriickgeht.  Von  ihm  und  Adam  de  Marisco  hat  er  auch 
die  Geistesrichtung  empfangen,  die  alles  Wissen  in  Unter- 
ordnung  unter  die  Theologie  betrieben  wissen  wollte  und 
innerhalb    der    Theologie    eine    starke    Bevorzugung    des 


54  ROGER  BACON 

Schriftstudiums,  der  Exegese,  erkennen  lasst  und  einen 
stark  aszetischen,  mystischen,  fast  mochte  man  sagen  in- 
tuitionistischen  und  traditionalistischen  Zug  verrat.  Es 
ist  durchaus  richtig,  wenn  P.  Hugo  Hover  schreibt  :  '  Der 
hohe  Wert,  den  Robert  Grosseteste  dem  Sprachstudium 
und  den  experimentellen  Wissenschaften  beilegte,  die  Unter- 
ordnung  alles  Wissens  unter  die  Theologie  und  das  Studium 
der  hi.  Schrift,  spiegeln  sich  in  den  Werken  Bacons  getreu 
wieder.' ' 

'  P.  Hugo  Hover,  Ord.  Cist.,  'Roger  Bacons  Hylomorphismus  als 
Grundlage  seiner  philosoph.  Anschauungen,'  in  Jahrh.f.  Philosophie 
tmd  spekul.  Theologie,  hgb.  v.  E.  Commer,  xxv.  (191 1),  207  (auch 
separat  erschienen).  Vgl.  noch  G.  M.  Mauser,  Ord.  Praed.,  '  Roger 
Bacon  und  seine  Gewahrsmanner,'  in  Zeitschr.  f.  Philos.  und  spekul. 
Theol.,  xxvii.  (191 3),  i  ff. 


Ill 


LA  PLACE  DE  ROGER  BACON  PARMI  LES 
PHILOSOPHES  DU  XIIP  SlfeCLE^ 

Par  FRANgOIS  PICAVET 

Le  neuvieme,  le  dixieme,  le  onzieme  et  le  douzieme 
siecle  nous  presentent  des  penseurs  remarquables,  surtout 
chez  les  Byzantins,  les  Arabes  et  les  Juifs.^  Au  xiii®, 
une  civilisation  nouvelle  apparait  dans  I'Occident  chretien. 
Elle  absorbe  les  acquisitions  anterieures  de  I'humanite 
et  elle  y  joint  son  apport  propre.  Elle  a  de  grands  savants, 
des  philosophes  marquants,  des  theologiens  originaux. 
Aussi  le  XIIP  siecle  est-il  une  periode  importante  dans 
I'histoire   de   Thumanite   et   dans   celle   du   christianisme, 

'  M.  Little  a  donne,  dans  le  volume  III  des  publications  de  la 
British  Society  of  Franciscan  Studies  de  191 1,  un  De  Operibiis  Rogeri 
Bacon.  J'ai,  dans  les  Essais  sitr  I'histoire  generate  et  comparee  des 
theologies  et  des  philosophies  medievales,  191 3,  Paris,  Alcan,  reuni 
une  partie  des  recherches  que  j  'ai  faites  ou  dirigees  sur  Roger  Bacon  : 
ch.  i  et  ii,  Enseignement  et  recherches  &,  I'ilficole  des  Hautes  ifitudes 
et  a  la  Faculte  des  Lettres  ;  ch.  x,  Editions  faites  et  a  f aire  de  Roger 
Bacon  (pp.  209-32)  ;  ch.  xi,  Le  maitre  des  experiences,  Pierre  de 
Maricourt,  L'exegete  et  le  theologien  vantes  par  Roger  Bacon 
(pp.  233-54)  ;  ch.  xii,  Jean  disciple  de  Roger  Bacon  (pp.  255-64)  ; 
ch.  xiii,  Quelques-uns  de  ceux  que  combat  Roger  Bacon,  Alexandre 
de  Hales,  Albert  le  Grand,  S.  Thomas  (pp.  265-78)  ;  ch.  xiv.  Deux 
directions  de  la  theologie  et  de  I'exegese  catholiques  au  xiiie  siecle, 
S.  Thomas  d'Aquin  et  Roger  Bacon  (pp.  279-94).  La  Revue  des  Deux 
Mondes  doit  publier  le  i"""  juin  un  article  sur  la  formation  intellectuelle 
de  Roger  Bacon.  Une  bibliographie  complete  a  ete  donnee  dans  ces 
diverses  publications,  auxquelles  il  faut  joindre  VEsquisse  d'une  histoire 
generate  et  comparee  des  philosophies  medievales,  2«  ed.,  Paris,  Alcan. 

-  Esquisse  d'une  histoire  generate  et  comparee  des  philosophies  medie- 
vales, 2*  ed.,  Paris,  Alcan,  ch.  vii,  pp.  141-77. 


56  ROGER  BACON 

dans  I'histoire  des  arts,  des  sciences,  des  lettres,  comme 
dans  celle  des  religions  et  des  philosophies.' 

II  est  grand  pour  I'histoire  du  christianisme,  car  le 
catholicisme  y  atteint  son  plein  developpement  en  theo- 
logie  et  en  philosophie.  C'est  a  lui  que  reviennent  les 
Peres  du  Concile  de  Trente  pour  lutter  au  xvi^  siecle 
contre  la  Reforme  ;  c'est  de  lui  que  se  reclame  Leon  XIII 
au  XIX®  pour  combattre  la  philosophie  moderne,  en  em- 
pruntant  au  prealable  a  la  science  tout  ce  qui  peut  entrer 
dans  les  conceptions  orthodoxes.- 

Que  le  xiiie  siecle  doive  figurer,  dans  I'histoire  de  I'hu- 
manite,  a  cote  des  siecles  de  Pericles,  d'Auguste,  de  Leon  X 
ou  de  Louis  XIV,  on  le  voit  d'abord  par  I'examen  de  ce 
que  furent  les  papes,  les  souverains  temporels,  et  les  peuples 
qui  obeissent  a  leur  direction  ou  les  provoquent  a  Taction. 
Innocent  III,  Gregoire  IX,  Innocent  IV,  Urbain  IV, 
Nicolas  IV,  Boniface  VIII  dirigent,  a  peu  pres  sans  controle, 
les  affaires  spirituelles  de  la  chretiente,  Parfois  ils  sont 
sur  le  point  de  regir  le  temporel  comme  le  spirituel,  avec 
I'aide  des  ordres  mendiants,  dont  Taction  est  alors  si 
considerable  dans  la  predication  et  dans  Tenseignement, 
dans  le  gouvernement  et  la  surveillance  des  esprits  :  '  Le 
pape,  ecrit  Roger  Bacon  (Bridges,  ii.  227),  est  le  mediateur 
entre  Dieu  et  les  hommes,  le  legislateur  et  le  souverain 
pontife  qui  a  plein  pouvoir  dans  les  choses  temporelles 
et  spirituelles,  comme  un  Dieu  humain  qu'il  est  permis 
d'adorer  apres  Dieu.'  Les  souverains  laiques,  Philippe- 
Auguste,  Frederic  II,  S.  Louis,  Alphonse  X,  Philippe  le 
Bel,  ne  sont  pas  inferieurs  aux  Papes.  Frederic  II  aspire 
a  creer  une  royaute  universelle  qui  s'etendrait  de  la  Baltique 
a  la  Mongolie.     S.  Louis  est,  sous  la  forme  chretienne,  un 

'  Franfois  Picavet,  Esquisse,  ch.  viii,  La  raison  et  la  science  dans 
les  philosophies  medi6vales,  pp.  178-215. 

-  Esquisse,  ch.  ix.  La  restauration  thomiste  au  ixe  siecle,  pp.  216- 
288  ;  Essais,  ch.  xviii,  Thomisme  et  modernisme  dans  le  monde 
catholique,  pp.  346-67, 


SA  PLACE  PARMI  LES  PHILOSOPHES  57 

(des  hommes  qui,  a  travers  les  siecles,  ont  le  plus  aime 
la  justice  et  le  plus  travaille  a  son  triomphe.  En  France, 
en  Angleterre,  en  Italic,  en  Flandre,  les  peuples  participent 
de  plus  en  plus  a  la  vie  politique. 

Quant  aux  arts,  I'epoque  est  merveilleuse  par  ses  cathe- 
drales,  ses  forteresses  feodales,  ses  hotels  de  ville,  ses 
beffrois  et  ses  ponts,  par  bien  d'autres  edifices  qui  en 
sent  restes.  Comme  au  temps  de  Phidias,  I'architecture 
est  completee  par  la  peinture  et  la  sculpture/  La  musique, 
religieuse  et  profane,  s'ajoute  aux  autres  arts.  Les  langues 
nationales  se  forment  en  Angleterre,  en  Allemagne,  en 
France,  en  Espagne  et  en  Portugal,  provoquant  I'appari- 
tion  et  preparant  la  croissance  de  litteratures  nouvelles 
dont  I'une  au  moins,  avec  Dante  et  la  Divine  Comedie, 
atteint  presque  du  premier  coup  la  perfection.^ 

I 

C'est  dans  les  Universites  et  les  ficoles,  dont  le  nombre 
et  I'importance  s'accroissent  singulierement,  c'est  chez 
les  seculiers  et  les  reguliers,  surtout  parmi  les  Franciscains 
et  les  Dominicains,  que  se  produit  le  travail  scientifique, 
theologique  et  philosophique.  On  pourrait  done  distinguer 
les  maitres  d'apres  le  groupement  auquel  ils  se  rattachent. 
Mais  il  vaut  mieux  suivre  la  chronologic,  en  tenant  compte 
tout  a  la  fois  des  livres  composes,  des  questions  traitees 
et  de  I'activite  des  principaux  personnages.^ 

'  Sur  I'art  du  xiii«  siecle,  on  peut  voir  Adolfo  Venturi,  Storia  del- 
I'arte  italiana,  Milano,  Hoepli,  vol.  iii  a  viii ;  Male,  L'art  religieux 
du  xiii^  siecle,  Paris,  Colin. 

-  Sur  la  musique,  voir  Hugo  Riemann,  Gesch.  der  Musiktheorie  im 
ix.-xix.  Jahrhundert,  1898  ;  J.  J.  Abert,  Die  Musikanschauung  des 
Mittelalters  und  ihre  Grundlagen,  Leipzig,  1905  ;  J.  Combarieu, 
Histoire  de  la  musique,  Paris,  Colin,  vol.  i. 

^  Douais,  Essai  sur  I' organisation  des  etudes  dans  I'ordre  des  Freres 
Pre'cheurs,  Paris,  1884  ;  Denifle,  Die  Universitciten  des  Mittelalters 
bis  1400,  Berlin,  1885;  Denifle  et  Chatelain,  Chartularium  Univer- 
siiatis Parisiensis.Paxis,  1889-97,  4  vols.  in-4° ;  H.  Felder,  Geschichte 


58  ROGER  BACON 

Une  premiere  division  conduit  du  debut  du  xiii^  siecle 
a  I'annee  1228,  ou  Guillaume  d'Auvergne  est  nomme  a 
I'eveche  de  Paris  ;  une  seconde  mene  jusqu'en  1257,  jusqu'au 
moment  ou  les  ordres  mendiants  triomphent  de  TUniver- 
site  de  Paris  ;  la  troisieme  va  jusqu'a  la  mort  d'Albert  le 
Grand  en  1280  ;  la  derniere  laisse  entrevoir  deja  les  direc- 
tions que  suivront  les  successeurs  des  grands  hommes  du  xiii® 
siecle  et  se  termine  en  1315  a  la  mort  de  Raymond  LuUe. 
Sans  doute  certaines  questions  comme  celles  du  pouvoir 
spirituel  et  du  pouvoir  temporel,  de  I'Evangile  eternel, 
des  rapports  entre  Chretiens  et  Juifs,  ont  ete  discutees 
pendant  tout  le  xiii^  siecle  ;  certains  hommes,  que  Ton 
place  dans  une  periode,  ont  aussi  deploye  leur  activite 
dans  les  epoques  qui  precederent  ou  qui  suivirent.  Mais 
si  ces  divisions  ne  correspondent  pas  d'une  fagon  exacte 
a  la  realite,  elles  ont  cependant  I'avantage  de  favoriser  les 
recherches  et  de  faciliter  I'exposition  des  doctrines.' 

Dans  la  premiere  se  presentent  d'abord  David  de  Dinant, 
Amaury  de  Bennes,  et  les  Albigeois.  On  recueille  et  on 
rassemble  les  traductions  d'oeuvres  grecques  et  byzantines, 
arabes  et  juives.  Les  Universites  entrent  dans  leur  plein 
fonctionnement  et  a  celle  de  Paris  Guillaume  d'Auvergne 
accomplit  son  oeuvre  philosophique.  S.  Francois  d'Assise 
et  S,  Dominique  fondent  et  organisent  deux  ordres  religieux.^ 

d.  wissensch.  Studien  im  Franciskanerorden  bis  um  die  Mitte  des  ij. 
Jahrh.,  Freiburg  im  Breisgau,  1904  ;  H.  Rashdall,  The  Universities 
of  Europe  in  the  Middle  Ages,  Oxford,  1895  ;  Paulsen,  Gesch.  des 
gelehrten  Ujtterrichts,  Leipzig,  1896-7  ;  Hilarin,  Histoire  des  etudes 
dans  I'ordre  de  S.  Francois,  tr.  fran9.  du  P.  Eusebe,  Paris,  Picard. 

'  Sur  les  divisions  de  I'histoire  g^nerale  et  comparee  des  philo- 
sophies medievales,  voir  Esquisse,  ch.  iii,  pp.  42-63  ;  ch.  viii, 
pp.  178-215.  Sur  le  xin«  siecle  on  peut  consulter  les  auteurs  catho- 
liques  et  thomistes,  Stockl,  de  Wulf,  comme  Haureau,  Histoire 
de  la  philosophie  scolastique,  ii.  i  et  2.  Voir  aussi  nos  Essais,  ch.  i, 
ii,  iii,  iv,  ix,  x,  xi,  xii,  xiii,  xiv,  xvi. 

""  Sur  David  de  Dinant,  on  peut  voir  Ueberweg,  ii.  26  ; 
Haur6au,  Histoire  de  la  philosophie  scolastique,  ii.   i,  ch.  iv  (qui  le 


SA  PLACE  PARMI  LES  PHILOSOPHES  59 

Pendant    la    seconde    periode    disparaissent    Guillaume 

d'Auvergne,   Alexandre    de  Hales,   Jean  de  la   Rochelle. 

La  poursuite  et   la  condamnation  du  Talmud  montrent 

les  principes  auxquels  obeissent  les  Chretiens  dans  leurs 

rapports  avec  les  Juifs.     Des  questions  fort  delicates  et 

fort  complexes  sont  soulevees  dans  la  lutte  entre  les  Uni- 

versites  et  les  ordres  mendiants.     L'oeuvre  scientifique  de 

Frederic  II  et  de  ses  collaborateurs  est  terminee.    Aristote 

est  devenu  un  des  maitres  officiels  ;    les  Universites  ont 

en  leur  possession  les  sources  dont  elles  disposeront  pendant 

le  reste  du  siecle.     Mais  aussi  les  Conciles  et  les  Papes 

travaillent   a   formuler   les   regies   sur  lesquelles   reposera 

I'organisation  de  ITnquisition.' 

compare  a  Spinoza),  et  Memoir es  de  I'Ac.  des  Inscriptions,  xxix, 
20  partie;  le  '  Chronicon  Laudun.  canonici',  Recueil  des  Historiens 
de  la  France,  xviii,  p.  715  ;  '  Tractatus  de  unitate  et  uno,'  faussement 
attribue  k  Boece  et  restitue  a  Gundissalvi  par  Correns,  Beitr.  z.  G. 
d.  Ph.  des  Mittelalters,  Bd.  i,  H.  i.  Sur  Amaury  de  Bennes  et  les 
Amauriciens,  voir  Ueberweg,  ii.  26  ;  Haureau,  ii,  i,  ch.  v,  et 
Memoires  de  I'Ac.  des  Inscriptions,  xxix,  2«  partie  ;  Ch.  Jourdain, 
'  Memoire  sur  les  sources  philosophiques  des  heresies  d'Amaury 
de  Chartres  et  de  David  de  Dinant,'  Memoires  de  I'Ac.  des  Inscrip- 
tions, xxvi,  2*  partie  ;  le  '  Chronicon  '  de  I'Anonyme  de  Laon, 
Recueil  des  Historiens ,  xviii ;  Guill.  Brito,  Recueil  des  Historiens ,  xvii ; 
Martini  Poloni  Chro7ticon  (Spicil.  de  Dachery,  iii,  p.  184)  ;  Martene, 
Thes.  nov.  anecdot.,  iv,  col.  163,  164  ;  Contra  Amaurianos  (analyse 
par  Haureau,  public  par  Baeumker)  ;  W.  Preger,  Geschichte  d. 
deutsch.  Myst.  im  Mittelalt.,  i  ;  Delacroix,  Essai  sur  le  mysticisme 
spiculatif  en  Allemagne,  Paris,  Alcan,  1900.  Sur  les  Universites, 
voir  le  Chartulaire  de  Denifle  et  Chatelain,  Denifle,  Rashdall,  Paulsen 
(p.  57,  note  3);  Charles  Thurot,  De  l' organisation  de  I'enseignement  dans 
rUniversite  de  Paris,  1850.  Sur  S.  Francois  d' Assise,  voir  surtout 
Touvrage  de  Sabatier.  Les  publications  de  la  British  Society  of 
Franciscan  Studies  apporteront  d'utiles  renseignements  pour  I'ordre. 
Voir  Douais,  Felder  (p.  57,  note  3)  et  aussi  la  Revue  Thomiste  et  la 
Revue  des  etudes  theologiques  et  philosophiques. 

'  Sur  Guillaume  d'x\uvergne,  voir  N.  Valois,  Guillaume  d'Auvergne, 
sa  vie  et  ses  ouvrages,  Paris,  1880  ;  Baumgartner,  '  D.  Erkenntnissl. 
d.  W.  von  Auvergne,'  Miinster,  1897,  Beitr.  z.  G.  d.  Ph.  des  Mittel- 
alters ;  Billow,  '  De  immortalitate  animae,  Gundissalvi  et  G.  d'Au- 
vergne,' Beitr.,  ii,  3.    Sur  la  condamnation  du  Talmud  et  les  rapports 


6o  ROGER  BACON 

La  troisieme  periode  est  des  plus  fecondes.  Albert  le 
Grand  est  le  maitre  le  plus  ecoute  de  la  chretiente,  avant 
que  S.  Thomas  prenne  la  premiere  place  dans  I'Eglise 
comme  chez  les  Dominicains.  II  y  a  lutte  entre  la  direc- 
tion thomiste  et  celle  que  Roger  Bacon  eut  voulu  donner 
a  r^glise  et  a  la  chretiente,  Les  resultats  scientifiques, 
philosophiques  et  religieux  des  explorations  du  xiii®  siecle, 
ceux  des  recherches  ou  des  meditations  de  Vincent  de 
Beauvais,  de  S.  Bonaventure,  ceux  qu'on  doit  aux  savants 
de  tout  ordre,  apparaissent  en  pleine  lumiere.  A  Constan- 
tinople les  Grecs  reorganisent  les  etudes.  Mais  les  con- 
damnations  prononcees  de  1258  a  1280,  contre  I'Evangile 
eternel  et  les  spirituels,  contre  les  Averroistes  latins,  contre 
des  Franciscains  et  des  Dominicains,  temoignent  que  la 
liberte  de  la  recherche  et  de  la  pensee  sont  singulierement 
restreintes.' 

Dans  la  derniere  periode,  on  ne  trouve  plus  ni  Albert 
le  Grand,  ni  S.  Thomas,  ni  Vincent  de  Beauvais,  ni  S.  Bona- 
venture. Roger  Bacon  ne  conserve  aucune  chance  d'agir 
sur  ses  contemporains.  II  reste  Henri  de  Gand,  Duns  Scot, 
Raymond  Lulle  dont  I'oeuvre  sera  terminee  en  1315.  On 
voit  alors  assez  nettement  ce  qu'ont  fait  pendant  le  xiii<^ 
siecle,  en  theologie  et  en  philosophie,  les  Universites  et 
les  ordres  mendiants,  les  seculiers  et  les  reguliers,  comme 

des  Chretiens  et  des  juifs,  voir  N.  Valois,  op.  cit.  ;  Fran90is  Picavet, 
Esquisse,  2*  6d.,  pp.  247-51.  Sur  les  rapports  des  Universites  et  des 
ordres  mendiants,  voir  les  ouvrages  relatifs  aux  Universites,  Felder 
(p.  57,  note  3)  ;  Mandonnet,  Siger  de  Brabant  et  V Averroi'sme  latin, 
2  vols,  des  Philosophes  beiges,  Louvain,  1908.  Sur  Aristote,  voir 
Jourdain,  Recherches  critiques  sur  I'dge  et  I'origine  des  traductions 
latines  d' Aristote,  Paris,  1849 ;  Haureau,  Denifle  et  Chatelain, 
op.  cit.  Sur  r Inquisition  voir  Lea,  History  of  the  Inquisition,  tr. 
fran9.  de  S.  Reinach,  Paris,  1902. 

'  Sur  la  direction  thomiste  et  la  direction  baconienne,  voir  Frangois 
Picavet,  '  Deux  directions  de  la  theologie  et  de  I'exegese  catholiques 
au  XIII"  siecle,'  Revue  d'histoire  des  religions,  1905  ;  Comptes  rendus 
de  I' Ac.  des  sc.  morales,  1905  ;  Essais,  191 3,  ch.  xiv. 


SA  PLACE  PARMI  LES  PHILOSOPHES  6i 

rinfluence  que  tous  ensemble  ils  ont  exercee  sur  les  arts 
et  sur  la  litterature  profane.  Les  discussions  relatives 
au  pouvoir  spirituel  et  au  pouvoir  temporel,  au  droit  canon 
et  au  droit  romain,  semblent  suspendues  pour  un  temps 
par  la  victoire  de  Philippe  le  Bel,  dont  les  consequences 
seront  considerables  dans  le  domaine  philosophique  comme 
dans  la  vie  religieuse.' 

Quel  fut  done  le  but  que  poursuivirent,  consciemment 
ou  non,  les  penseurs  les  mieux  doues  du  xiii®  siecle  ? 
D'abord  ils  devaient  conserver  les  connaissances  des  Latins 
qui  les  avaient  precedes,  puis  examiner  avec  soin  tout  ce 
qui  leur  venait  du  monde  grec  et  byzantin,  arabe  et  juif. 
Les  donnees  scientifiques  et  philosophiques  s'y  melent 
a  des  conceptions  religieuses  ou  theologiques  qui,  n'etant 
pas  mdme  toujours  orthodoxes  pour  les  Chretiens  orientaux, 
pour  les  Musulmans  ou  pour  les  Juifs,  ne  sauraient  etre 
pour  les  catholiques  que  des  nouveautes  dangereuses  ou 
des  heresies.  Mais  convient-il,  pour  cet  examen,  de  s'en 
rapporter  aux  traductions  deja  faites  ou  faut-il  recourir 
aux  textes  originaux  et  par  consequent  etudier  I'hebreu, 
le  grec  et  I'arabe  ?  Quand  on  a  elimine,  des  auteurs  pris 
en  eux-m6mes  ou  dans  leurs  traductions,  tout  ce  qui 
risque  de  nuire  a  la  purete  de  la  foi,  on  pent  recueillir  les 
elements  d'ordre  scientifique  et  philosophique,  en  notant 
les  liens  parfois  divers  qui  les  unissent  et  la  methode  qui 
servit  a  les  assembler.  Puis  il  y  a  lieu  de  systematiser,  si 
on  le  veut,  les  resultats,  de  provenance  ancienne  ou  recente, 
pour  en  former  une  metaphysique  coherente  dans  ses 
parties    essentielles    et    coherente    avec    toutes   ses    bases 

'  Sur  rinfluence  qu'ont  exercee  les  oeuvres  philosophiques  en  latin 
sur  la  litterature  profane  de  xiii®  siecle,  il  y  a  beaucoup  a  faire. 
On  peut  voir  Gaston  Paris,  La  litterature  franQaise  au  moyen  age, 
3*  ed.,  Paris,  1905.  Sur  les  arts,  voir  Male,  op.  cit.  Sur  les  discus- 
sions relatives  au  pouvoir  spirituel  et  au  pouvoir  temporel,  voir 
Paul  Janet,  Histoire  de  la  science  politique  dans  ses  rapports  avec 
la  morale,  4^  ed.  191 3. 


62  ROGER  BACON 

positives.  La  philosophie  ainsi  construite  est  employee 
a  constituer  une  theologie  plus  comprehensive  et  plus 
riche,  une  doctrine  exegetique  qui  transforme  a  son  tour 
interpretation  des  textes  sacres.  Ainsi  s'enrichissent 
toutes  a  la  fois  les  parties  maitresses  de  la  sagesse.  Mais 
avant  de  proceder  a  cette  systematisation  dont  I'objet 
est  triple,  on  peut  etudier  les  methodes  mises  en  usage 
et  voir,  en  les  pratiquant  soi-meme,  ce  qu'elles  valent 
et  ce  que  valent  les  donnees  transmises,  puis  les  employer, 
qu'il  s'agisse  de  celle  des  mathematiques  ou  de  celle  des 
sciences  experimentales,  a  augmenter  les  connaissances 
positives.  En  ce  cas  la  synthese  philosophique,  portant 
sur  des  acquisitions  deja  anciennes  et  sur  des  acquisitions 
toutes  nouvelles,  devra  etre  parfois  revisee  comme  la 
theologie  et  I'exegese  a  laquelle  elle  est  jointe.  Enfin  pour 
I'utiliser  dans  ces  matieres  essentiellement  religieuses,  on 
se  dira  peut-etre  qu'il  faut,  pour  les  livres  sacres  comme  pour 
les  livres  profanes,  connaitre  les  langues  dans  lesquelles 
ils  sont  ecrits  et  ne  pas  se  contenter  uniquement  de  traduc- 
tions dont  on  ne  saurait  controler  la  valeur.' 

Or  presque  tous  les  penseurs  du  xiii®  siecle  ont  voulu 
user  de  leur  raison  ==  et  en  meme  temps  rester  Chretiens  ^ 
ou  r^tre  mieux  que  leurs  predecesseurs.  Si  Joachim  de 
Flore  travailla  a  I'avenement  de  I'Evangile  eternel,  si  les 
Amauriciens  et  les  Albigeois  voulaient  promouvoir  le  regne 
de  I'Esprit  Saint  et  auraient  ruine,  s'ils  avaient  reussi, 
TEglise    existante,    ses    institutions,    ses    sacrements,    sa 

'  Ce  sont  a  peu  pres  toutes  les  questions  que  s'est  posees  Roger 
Bacon  et  qu'il  a  resolues  d'une  fa9on  afBrmative,  comme  on  le  verra 
par  la  suite  de  I'article. 

=  Esquisse,  oh.  viii. 

^  Sur  les  trois  Imposteurs,  voir  Renan,  Averroes  et  I'Avevroisme. 
C'est  k  peu  pr^s  la  seule  formule  5,  propos  de  laquelle  on  puisse  poser 
la  question  de  savoir  s'il  y  eut  au  xiii«  siecle  des  hommes  complete- 
ment  irreligieux.  Car  les  Averroistes  latins  s'inclinaient  devant  les 
affirmations  port6es  au  nom  de  la  foi. 


SA  PLACE  PARMI  LES  PHILOSOPHES  63 

hierarchic  et  ses  pratiques,  c'etait  pour  donner,  du 
christianisme,  une  forme  plus  parfaite,  comme  les  Chretiens 
avaient  substitue,  par  une  raison  semblable,  leur  religion 
a  I'antique  judaisme.  C'est  en  s'appuyant  sur  la  raison 
et  plus  specialement  sur  le  principe  de  contradiction  que 
David  de  Dinant  et  Amaury  de  Bennes  font  de  Dieu  la 
matiere  ou  I'essence  des  choses,  qu'ils  ramenent  a  I'unite 
le  monde  et  Dieu  dont  seul  le  principe  de  perfection  permet 
d'affirmer  tout  a  la  fois  I'existence  distincte  et  les  rapports 
essentiels.  C'est  au  nom  de  la  raison  et  du  meme  principe 
que  les  Averroistes  latins  se  refusent  a  admettre  Timmor- 
talite  de  I'ame  dont,  en  croyants,  ils  ne  doutent  aucune- 
ment,  qu'ils  suppriment  les  intellects  multiples,  places 
par  Plotin,  en  vertu  du  principe  de  perfection,  a  cote  de 
I'intellect  divin.'  Et  il  faut  noter  encore  le  caractere 
profondement  religieux  de  tons  ces  hommes  que  I'Eglise 
combattit  avec  tant  d'acharnement,  car  dans  I'impossi- 
bilite  pour  eux  de  conserver  I'Un  et  le  Multiple,  c'est  I'Un 
ou  Dieu  qu'ils  continuent  a  mettre  en  premiere  ligne. 

Pour  se  defendre,  I'Eglise  ne  se  borna  pas  a  condamner 
ceux  qui  se  mettaient  en  opposition  avec  elle  dans  le  temps 
present,  elle  leur  chercha  partout  des  complices.  Elle 
frappa  d'abord  le  nouvel  Aristote  et  ses  commentateurs, 
Mais  quand  Jean  Scot  Erigene  eut  ete  declare  le  vrai 
coupable  par  Honorius  III  en  1225,  Gregoire  IX  ordonna, 
des  1231,  d'examiner  si  cet  Aristote  qu'on  enseignait 
a  Toulouse  ne  pourrait  etre  debarrasse  de  ce  qu'il  y  avait 
de  dangereux  en  lui  et  etudie  ainsi  dans  toutes  les  ecoles. 
C'est  ce  que  firent,  de  maniere  a  donner  toute  satisfaction 
a  I'Eglise,  Albert  le  Grand  et  S.  Thomas.  Puis  on  s'attaqua 
au  Talmud  et  aux  Juifs  que  Roger  Bacon  soup9onnait, 

'  Sur  David  de  Dinant  et  les  Amauriciens,  voir  les  ouvrages  cites, 
p.  58,  note  2.  Sur  les  Averroistes  latins,  voir  Renan,  Mandonnet, 
op.  cit.  ;  Francois  Picavet,  Revue  d'hisioire  des  religions,  1902  ; 
Esquisse,  ch.  viii ;    Essais,  ch.  xvi  et  xvii. 


64  ROGER  BACON 

comme  il  soupgonnait  les  Grecs,  de  falsifier  les  livres 
saints  avant  de  les  remettre  aux  catholiques  romains. 
Les  Arabes  devinrent  suspects  a  cause  des  Averroistes 
latins  et  il  fallut  encore  le  travail  de  S.  Thomas  pour 
montrer  ce  que  Ton  pouvait  emprunter  aux  Arabes  et  aux 
Juifs,  surtout  a  Averroes  et  a  son  contemporain  Mai- 
monide.^ 

Apres  1280,  il  se  forma,  semble-t-il,  un  accord  tacite  tout 
au  moins,  entre  ceux  qui  craignaient  les  nouveautes  genera- 
trices d'heresies  et  ceux  qui  entendaient  conserver  les 
doctrines  essentielles,  en  matiere  scientifique  et  philoso- 
phique,  des  Grecs  et  des  Byzantins,  des  Arabes  et  des  Juifs. 
De  plus  en  plus  on  etait  severe  pour  les  ennemis  du  Chris- 
tianisme.  Apres  avoir  fait  des  Croisades  contre  les  Musul- 
mans,  on  en  fit  contre  les  Grecs,  contre  les  Albigeois,  on  en 
precha  contre  Frederic  II  et  bien  d'autres.  LTnquisition 
fut  chargee  de  rechercher  les  heretiques  dans  tons  les 
pays  Chretiens.  Elle  imposa  aux  habitants  des  villes  et  des 
villages  I'obligation  de  denoncer  meme  toute  personne  vivant 
autrement  que  la  generalite  des  fideles.  D'un  autre  cote,  les 
Dominicains,  souvent  charges  de  representer  ITnquisition,  es- 
timerent  vers  1280  que  S.  Thomas  avait  mis  dans  sa  synthese 
tout  ce  qui  est  necessaire  aux  catholiques :  ils  def  endirent  done 
aux  membres  de  leur  ordre  d'attaquer  le  thomisme,  puis  ils 
travaillerent  a  y  gagner  tous  les  reguliers  et  tous  les  seculiers, 
lis  reussirent  dans  cette  double  entreprise  et,  au  moment 
de  la  Reforme,  surtout  pendant  le  Concile  de  Trente,  les 
solutions    thomistes    devinrent    les   solutions    catholiques.^ 

'  Sur  les  condamnations  portees  a  partir  de  1200,  sur  le  role  de 
la  papaute,  voir  Denifle  et  Chatelain,  Chartulaire  ;  Haureau,  ii,  i, 
et  Memoires  ;  Jourdain,  op.  cit.  ;  Mandonnet,  Noel  Valois,  op.  cit.  ; 
Renan,  op.  cit.  ;  Dr.  J.  Guttmann,  Die  Scholastik  des  dreizehnien 
Jahrhunderts  in  ihren  Beziehungen  zum  Judenthum  und  zur  judischen 
Liter attir,  Breslau,  1902. 

'  "Lea.,  Histoire  de  l' Inquisition,  permet  de  suivre  la  marche 
r6alis6e  dans  I'organisation  des  tribunaux  ;    Jourdain,  Philosophie 


SA  PLACE  PARMI  LES  PHILOSOPHES         65 

L'obligation  imposee  aux  Jesuites  par  Ignace  de  Loyola 
d'enseigner  le  thomisme  acheva  de  lui  donner  une  autorite 
preponderante  dans  tout  le  monde  catholique.  En  fait, 
des  que,  vers  la  fin  du  xiii®  siecle,  on  cessa  de  penser  aussi 
librement  qu'on  I'avait  fait  pendant  les  quatre-vingts 
premieres  annees  du  siecle,  c'est  S.  Thomas,  bien  plus 
qu'Aristote,  qui  devint  le  maitre  dont  on  reproduisit  et 
commenta  les  doctrines.' 

II 
Dans  ce  travail  philosophique  d'une  intensite  considerable, 
quelle  fut  la  part  de  Roger  Bacon  ?  II  faut  dire  brievement 
d'abord  ce  que  firent  ceux  dont  le  nom  merite  surtout 
d'etre  rappele  dans  ce  siecle  riche  en  penseurs  de  toute 
espece,  Un  des  premiers,  Guillaume  d'Auvergne^  utilise 
les  ouvrages  des  Byzantins  et  des  Grecs,  des  Arabes  et  des 
Juifs.  Profondement  orthodoxe,  philosophe  et  ami  de  la 
science,  soucieux  d'user  pleinement  de  sa  raison,  il  ne  fait 
appel  a  I'autorite  que  si  elle  est  en  accord  avec  ce  que  lui 
apprennent  la  raison,  I'experience  ou  I'intuition.  Sa  theorie 
de  la  vision  divine  est  d'une  importance  capitale  pour  la 
science  et  pour  la  philosophic,  puisqu'il  en  cherche  la  source 
en  Dieu  dont  les  revelations  se  produisent  incessamment. 

de  S.  Thomas  d'Aquin,  montre  les  progres  du  thomisme,  vol.  ii, 
ch.  iii,  iv.  Canonisation  de  S.  Thomas,  La  sentence  de  1276  est 
rapportee  ;  ch.  iv,  v,  vi,  Le  thomisme  au  Q)ncile  de  Trente,  Dans  la 
Compagnie  de  Jesus,  Le  thomisme  au  xviie  siecle.  Constitutions 
donnees  par  S.  Ignace  a  la  C'^  de  Jesus,  P.  iv.  ch.  xiv.  2  :  In  theologia 
legetur  Vetus  et  Novum  Testamentum  et  doctrina  scholastica 
D.  Thomae. 

'  C'est  la  un  fait  d'importance  capitale  sur  lequel  on  ne  saurait 
trop  insister.  L'union  intime  entre  la  theologie,  la  philosophic  et 
la  science,  realisee  par  S.  Thomas  pour  les  catholiques,  explique,  bien 
mieux  que  I'influence  d'Aristote.  I'opposition  faite  aux  savants  par 
un  certain  nombre  de  catholiques  pendant  le  xvii^  siecle.  Nous 
nous  proposons  de  revenir  sur  ce  sujet  par  la  suite. 

-  Sur  Guillaume  d'Auvergne  voir  les  ouvrages  cites,  note  i,  p.  59. 

1689  F 


66  ROGER  BACON 

En  soutenant  I'unite  de  Dieu,  il  combat  les  doctrines  a 
tendance  manicheiste  ;  en  insistant  sur  la  personnalite  de 
Tame  qu'il  fonde  sur  la  doctrine  plotinienne  de  son  in- 
divisibilite  et  de  sa  parente  avec  la  nature  divine,  il  etablit 
son  immortalite  et  detruit  a  I'avance  la  these  des  Averroistes 
latins.  C'est  un  precurseur  de  Roger  Bacon  comme  d'Albert 
le  Grand  et  de  S.  Thomas. 

Alexandre  de  Hales,  son  contemporain,  acheve  de  con- 
stituer  la  methode  ebauchee  par  Abelard,'  qui  sera  d'un 
usage  constant  dans  les  ecoles  et  chez  les  rtiaitres  jusqu'au 
XVII®  siecle.  Dans  la  Somme  de  theologie,  ou  il  I'emploie, 
il  distingue  nettement,  a  la  fa^on  augustinienne  et  ploti- 
nienne, le  monde  sensible  et  le  monde  intelligible.  Bon 
nombre  des  doctrines  nouvellement  arrivees  en  Occident 
y  prennent  place.  Pour  Jean  de  la  Rochelle,  son  successeur, 
ceux  qui  veulent  aneantir  1' etude  de  la  philosophie  sont  des 
suppots  de  Satan.  II  s'attache  a  I'etude  approfondie  de 
Tame  humaine  et  fait  des  emprunts  a  Aristote,  aux  medecins 
arabes  et  a  Galien,  mais  surtout,  par  S.  Augustin  et  les 
commentateurs  grecs,  a  Plotin  et  a  ses  disciples.^ 

On  ne  pent  separer  I'ceuvre  des  trois  dominicains,  Vincent 
de  Beauvais,  Albert  le  Grand  et  S.  Thomas.  Dans  le  Grand 
Miroir,  Speculum  Majus,  le  premier  corrige  Abelard  qui 
mettait  sur  le  meme  plan  les  autorites  sacrees  et  les  autorites 
profanes.  Au-dessus  de  tout,  il  place  I'Ecriture,  Ancien  et 
Nouveau  Testament.  Puis  en  premiere  ligne,  supremum 
locum,  les  decretales  des  souverains  pontifes,  les  canons  des 

'  Frangois  Picavet,  Abelard  et  Alexandre  de  Hales,  createurs  de  la 
methode  scolastique,  Paris,  Leroux,  1896;  Esquisse,  ch.  viii,  pp.  181-92' 

""  Sur  Jean  de  la  Rothelle,  cf.  Haureau,  ii.  i,  ch.  x  ;  Luguet, 
Joannis  a  Rupella  Summa  de  anima,  Paris  ;  Essai  d' analyse  et  de 
critique  sur  le  texte  itiedit  du  traite  de  I'dme  de  J.  de  la  Rochelle, 
Paris,  1875  ;  ^<^  Summa  de  Anima  di  Frate  Giovanni  delta  Rochelle 
pubblicata  per  la  prima  volta  et  corredata  di  alcuni  studi  del  P.  Teofilo 
Domenichelli,  Min.  Oss.,  sotto  la  direzione  del  P.  Marcellino  da  Civezza. 
Prato.  1882. 


SA  PLACE  PARMI  LES  PHILOSOPHES  67 

conciles  generaux,  les  oeuvres  des  docteurs  sacres,  c'est-a-dire 
de  ceux  qui  furent  canonises  par  I'^glise  et  dont  les  doctrines 
ont  re^u  I'approbation  des  conciles  et  du  Pape.  En  seconde 
ligne  viennent  les  docteurs  prudents  et  catholiques,  mais 
non  canonises  ;  en  troisieme,  les  philosophes,  les  docteurs 
des  gentils,  qui  ont  ignore  la  verite  de  la  foi,  mais  qui  ont 
dit  sur  le  Createur  et  les  creatures,  les  vertus  et  les  vices, 
de  belles  et  merveilleuses  choses,  vraies  pour  la  croyance 
catholique  comme  pour  la  raison  humaine.  Aux  Deflora- 
iiones  anonymes  dont  userent  Alcuin  et  bien  d'autres 
jusqu'a  Guillaume  d'Auvergne,  Vincent  de  Beauvais 
substitue  le  Florilege,  ou  recueil  de  morceaux  choisis 
dont  la  source  est  indiquee.  Meme  il  pense  a  faire  du 
Grand  Miroir  une  oeuvre  analogue  a  nos  modernes 
Encyclopedies,  en  rangeant  sous  un  seul  titre,  Charite, 
Chastete,  tons  les  extraits  qui  y  auraient  quelque  rapport. 
Mais  il  s'est  decide  a  suivre  I'ordre  des  Sommes,  celui  de 
I'Ecriture  meme,  en  pla9ant  d'abord  le  Createur,  puis  les 
creatures,  la  chute  et  la  reparation  de  I'homme,  les  choses 
faites  dans  I'ordre  des  temps.  Sous  son  nom,  il  donne  ce 
que  lui  ont  appris  des  docteurs  modernes  par  leur  enseigne- 
ment  ou  leurs  livres  ;  sous  les  noms  de  leurs  auteurs,  tout 
ce  que  lui-meme  et  ses  collaborateurs  ont  recueilli  dans  les 
oeuvres  anterieures.'  Ainsi  il  a  constitue  un  aide-memoire 
assez  ample,  une  introduction  ou  un  complement  a  I'ceuvre 
plus  personnelle  d'Albert  le  Grand  et  de  S.  Thomas. 

Albert  s'est  propose  tout  a  la  fois  de  faire  connaitre  la 
nature  et  comprendre  Aristote,  sans  separer  d'ailleurs 
I'Aristote  authentique  et  I'Aristote  apocryphe,  sans  distin- 

'  R.  P.  Mortier,  Histoive  des  maiires  generaux  de  I'ordre  des  Freres 
Precheurs,  Paris,  Picard  ;  Boutaric,  '  Vincent  de  Beauvais  et  la 
connaissance  de  I'antiquite  classique  au  xiii«  siecle,'  Revue  des 
questions  historiques ,  9®  annee,  tome  xvii ;  Bourgeat,  Etudes  sur 
Vincent  de  Beauvais,  theologien,  philosophe,  encyclopediste ,  ou  specimen 
des  etudes  theologiqiies ,  philosophiques  et  scientifiques  au  moyen  dge, 
Paris,  1856. 

F  2 


68  ROGER  BACON 

guer  nettement  I'un  et  I'autre  des  auteurs  grecs,  arabes 
ou  juifs  que  connait  alors  I'Occident  Chretien.  S'il  dit 
parfois  que  connaitre  Aristote,  c'est  connaitre  la  nature, 
c'est  qu'il  joint  a  Aristote  tous  ces  penseurs,  surtout  les 
Plotiniens  par  lesquels  il  le  complete.  II  est  si  peu  le  singe 
d'Aristote,  comme  I'appelerent  des  adversaires  de  la  philo- 
sophie  et  de  la  theologie  du  xiii®  siecle,  qu'il  le  combat  et 
que,  dans  ces  matieres  sur  lesquelles  ne  pent  porter  le 
syllogisme,  I'experience  seule  lui  donne  la  certitude.  Enfin 
il  fait  une  place  considerable  au  Pseudo-Denys  I'Areopagite, 
aux  doctrines  mystiques  qui  lui  viennent  encore  par  S.  Au- 
gustin  et  bien  d'autres  sources  plotiniennes,  de  sorte  qu'on 
a  pu  le  considerer  comme  I'un  des  maitres  des  Allemands, 
Eckhart,  Tauler,  Suso  et  I'auteur  de  la  Deutsche  Theologie 
editee  deux  fois  par  Luther.  Au  temoignage  de  son  adver- 
saire  Roger  Bacon,  le  succes  d'Albert  fut  immense  :  '  On 
I'invoque,  dit-il,  dans  les  ecoles  comme  Aristote,  Avicenne  et 
Averroes,  et  il  a  eu,  de  son  vivant,  une  autorite  que  le 
Christ  n'a  pas  eue  pendant  qu'il  vivait.' ' 

Pour  des  causes  diverses  et  multiples,  c'est  cependant 
son  disciple  S.  Thomas  qui  I'emporte  aupres  de  leurs  com- 

'  Voir  Haureau,  ii.  i,  ch.  xi,  xii,  xiii  ;  Hertling, '  Albertus  Magnus,' 
Festschrift,  Coin,  1880  ;  R.  de  Liechty,  Albert  le  Grand  et  S.  Thomas 
d'Aquin  ou  la  science  du  moyen  age,  Paris,  1880  ;  M.  Glossner,  Das 
objective  Princip  der  arist.  schol.  Philos.,  besonders  Albert  des  Gr. 
Lehre  vom  obj.  Ur sprung  der  intellectuellen  Erkenntnisse ,  Regensb., 
1880  ;  Van  Veddingen,  Albert  le  Grand,  le  maitre  de  S.  Thomas 
d'Aquin  d'aprh  les  plus  r&cents  travaux  critiques,  Bruxelles,  188 1  ; 
G.  Endriss,  Albertus  Magnus  als  Interpret  der  aristot.  Metaphysik, 
Miinchen,  1886;  R.  P.  Mandonnet,  'Les  id6es  cosmographiques 
d'Albert  le  Grand  et  de  S.  Thomas  d'Aquin  et  la  decouverte  de 
I'Am^rique,'  Revjie  thomiste,  1893  :  R-  P-  Pierre  Girard,  '  La  Cosmo- 
grapliie  d'Albert  le  Gr.  d'apres  I'observation  etrexp6rience  du  moyen 
age,'  Revue  thomiste,  1904  ;  Noble,  '  Note  pour  I'^tude  de  la  psycho- 
physiologie  d'Albert  le  Grand  et  de  S.  Thomas,'  Revue  thomiste,  1905  ; 
A.  Mansion,  '  L'induction  chez  Albert  le  Grand,'  Revue  nSo- 
scolastique,  1906  ;  R.  P.  Mandonnet,  '  Albert  le  Grand,'  dans  le 
Dictionnaire  de  theologie  de  I'abb^  Vacant. 


SA  PLACE  PARMI  LES  PHILOSOPHES         69 

muns  successeurs.  C'est  que  S.  Thomas  opera,  plus  sure- 
ment  qu'aucun  de  ses  contemporains,  le  depart  entre  ce 
qui  pouvait  etre  adapte  au  catholicisme  et  ce  qui  y  repugnait 
dans  ce  qui  venait  d'arriver  a  I'Occident  latin.  Pour  Aristote, 
en  particulier,  il  a  joint  a  ses  oeuvres  capitales  des  com- 
mentaires  qui  en  donnent  une  bonne  interpretation  litterale, 
pour  laquelle  il  consulte  diverses  versions,  greco-latines  ou 
arabico-latines,  quelques-unes  faites  a  son  intention,  peut- 
etre  meme  vers  la  fin  de  sa  vie  les  manuscrits  grecs,  et  toujours 
les  commentateurs  qui  ont  travaille  a  I'eclaircir.  A  cette 
interpretation  litterale  il  ajoute  une  interpretation  ploti- 
nienne  et  chretienne  par  laquelle  il  attribue  a  Aristote  les 
doctrines  auxquelles  les  Chretiens  tenaient  le  plus  et  qu'on 
rencontre  le  moins  chez  I'Aristote  authentique,  la  Creation, 
la  Providence,  rimmortalite  de  Tame.  Avec  ce  qu'ont 
transmis  au  xiii®  siecle  les  Latins  et  les  Grecs,  les  Arabes 
et  les  Juifs,  avec  ce  qu'ont  rassemble  Vincent  de  Beauvais, 
Albert  le  Grand  et  leurs  contemporains,  avec  le  secours 
de  nombreux  collaborateurs  qui  sont  toujours  a  sa  disposi- 
tion, S,  Thomas  construit,  d'un  point  de  vue  orthodoxe 
et  avec  une  habilete  singuliere,  la  synthese  philosophique 
qui  s'accorde  avec  les  dogmes  et  comprend  les  elements 
scientifiques  et  philosophiques  dont  disposent  alors  les 
Occidentaux.  Ce  systeme,  dont  la  valeur  persistera  tant 
que  les  recherches  exp^rimentales  n'auront  pas  fourni  la 
matiere  d'une  synthese  nouvelle,  S.  Thomas  le  fait  entrer 
tout  entier  dans  la  theologie,  qui  fournira  ainsi  au  Concile 
de  Trente  des  reponses  jugees,  alors  et  aujourd'hui  encore, 
satisfaisantes,  par  les  catholiques,  aux  questions  et  aux 
objections  des  Reformateurs.  Pour  I'histoire  et  I'exegese, 
S.  Thomas  accomplit  une  oeuvre  analogue  :  la  Catena  aurea 
relie  les  quatre  ]fevangiles  comme  s'ils  etaient  le  travail  d'un 
seul  docteur  ;  les  commentaires  sur  chacun  des  livres  saints, 
meme  sur  le  Psautier,  le  Decalogue,  le  Symbole,  I'Oraison 
dominicale,  montrent  qu'ils  contiennent  en  germe  tout  ce 


70  ROGER  BACON 

qui  se  trouve  dans  la  Sonime  et  par  suite  toute  la  philosophic 
thomiste.  Ainsi  une  direction  est  donnee  a  I'^glise  catho- 
lique :  elle  I'accepte  officiellement,  en  theologie  et  en  exegdse, 
au  Concile  de  Trente  ;  elle  la  reprend,  en  philosophie,  avec 
Leon  XIII,  en  1879/ 

A  S.  Bonaventure  on  doit  une  doctrine  mystique  et 
orthodoxe  qui  developpe  tout  ce  qui  vient  de  Plotin  et 
de  S.  Augustin,  du  Pseudo-Denys  et  des  Victorins,  de 
S.  Bernard,  des  Byzantins,  des  Arabes  et  des  Juifs  :  I'ltine- 
raire  de  I'dme  vers  Dieu  en  est  la  partie  essentielle.^ 

De  nombreux  savants  travaillent  au  xiii^  siecle  a  s'as- 
similer  les  donnees  positives  qui  leur  sont  offertes.  II  y  en 
eut  en  Angleterre  autour  de  Robert  de  Lincoln,  en  France 
autour  de  Pierre  de  Maricourt,  le  maitre  des  experiences. 
II  y  eut  en  Italic  une  ecole  d'alchimistes,  etudies  par 
Berthelot,  qui  font  les  experiences  indiquees  par  les  anciens 
et  en  imaginent  de  nouvelles,  qui  remontent  des  pratiques 
aux  doctrines  et  provoquent  les  progres  de  la  technique  que 
revelent  alors  les  arts  de  toute  espece.  Des  physiciens 
constituent,  les  uns,  un  groupe  a  Oxford,  les  autres,  un 
groupe  a  Paris.  Certains  medecins  font  appel  a  I'experience 
et  a  Talchimie  pour  prolonger  la  vie  humaine  et  retarder  les 
accidents  de  la  vieillesse.  II  y  a  des  opticiens,  maitre 
Pierre,  Vitellion,  moins  geometre  et  moins  physiologiste 
que  Roger  Bacon,  commente  par  Kepler  au  debut  du  xvii^ 
siecle ;  il  y  a  des  mathematiciens  celebres,  Sacrobosco 
dont  le  Traite  de  la  Sphere  sera  si  souvent  commente, 
Leonard  de  Pise  qu'on  dira  le  plus  grand  mathematicien 
du  moyen  age,  maitre  Pierre  et  Jean  de  Londres,  maitre 
Campanus  de  Novare  et  maitre  Nicolas,  mentionnes  par 
Roger    Bacon.      Presque    tons    ces    savants    conserverent 

■  Sur  S.  Thomas,  voir  Jourdain,  op.  cit.  ;  Sertillanges,  La  philo- 
sophie de  S.  Thomas,  Paris,  Alcan.  Sur  la  restauration  thomiste, 
Esquisse,  ch.  ix  ;    Essais,  ch.  xiii  ;    Bibliographic  dans  Ueberweg,  ii. 

-■  Opera  omnia  edita  studio  et  cura  P.  P.  collegii  a  S.  Bonaventura, 
ad  Claras  Aquas  prope  Florentiam,  a  partir  de  1882. 


SA  PLACE  PARMI  LES  PHILOSOPHES         71 

bien  des  doctrines  metaphysiques  et  esquisserent  des  con- 
ceptions relatives  a  la  philosophic  des  sciences,  qu'on  re- 
prendra  surtout  au  xviie  siecle.  Pour  la  meme  raison, 
il  convient  de  rappeler  Carpini,  Rubruquis  et  Marco-Polo 
qui  augmenterent  les  connaissances  que  leurs  contempo- 
rains  avaient  de  la  terre  et  preparerent,  avec  de  nouvelles 
decouvertes,  un  agrandissement  ^  de  la  science  sous  plusieurs 
de  ses  formes. 

La  derniere  periode  marque  une  decroissance  dans  la 
speculation  theologique  et  philosophique.  Henri  de  Gand, 
adversaire  de  S.  Bona  venture  et  de  S.  Thomas,  rappelle 
surtout  S.  Augustin,  parfois  les  Arabes  et  Guillaume  d'Au- 
vergne,  avec  la  theorie  de  I'illumination  speciale,  comme 
il  annonce  Duns  Scot  et  Guillaume  d' Occam  par  celle  de  la 
volonte  superieure  a  I'intelligence.  Duns  Scot  s'inspire 
de  tons  les  franciscains  ses  predecesseurs,  y  compris  Roger 
Bacon,  attaque  la  plupart  de  ses  contemporains,  proclame 
en  Dieu  la  predominance  de  la  volonte.  Avec  le  Plotinien 
Ibn  Gebirol — ego  autem  ad  positionem  Avicemhrolis  redeo — 
Scot  soutient  que  toute  substance  creee,  corporelle  ou 
spirituelle,  participe  de  la  matiere  et  que  cette  matiere  est 
une  en  tous.  Sa  doctrine,  d'une  subtilite  singuliere,  sera 
souvent  opposee  au  thomisme.  Avec  Raymond  Lulle 
apparait  le  Grand  Art,  la  methode  logique  qui  combine 
des  idees  generales  pour  en  faire  sortir  des  solutions  meta- 
physiques ou  theologiques.  Mais  c'est  aussi  un  mystique 
curieux,  dont  les  doctrines,  mal  connues  encore,  melent  le 
plotinisme  et  le  christianisme.^ 

'  Berthelot,  Les  origines  de  I'alchimie  ;  Science  et  Philosophie  ; 
Collection  des  anciens  alchimistes  grecs  ;  Introduction  a  I'etude  de 
la  chimie  des  anciens  et  du  moyen  age  ;  Hisfoire  des  sciences,  La  chimie 
au  moyen  age,  3  vols.  Francois  Picavet,  La  science  experimentale 
au  xiii'  siecle  en  Occident,  Moyen  Age,  novembre  1891  ;  et  Esquisse, 
ch.  viii,  pp.  202-9. 

-  Prantl,  Gesch.  der  Log.,  iii ;  Haureau,  Histoire  de  la  scolastique, 
ii.  2  ;   Pluzanski,  Essai  sur  la  philosophie  de  Duns  Scot,  Paris,  1887  ; 


72  ROGER  BACON 

III 

Roger  Bacon  a  expose,  d'une  fa9on  fort  ample  sinon 
toujours  fort  precise,  ce  qui  meritait  d'etre  poursuivi  et 
realise  non  seulement  par  lui  et  ses  contemporains,  mais 
aussi  par  leurs  successeurs,  sous  la  direction  de  la  papaute, 
avec  I'aide  des  grands,  des  princes  et  des  rois.  II  faut, 
dit-il  dans  VOpus  Majus,  faire  I'etude  parfaite  de  la  sagesse, 
arriver  avant  tout  a  la  possession  de  la  verite,  puis  se  servir 
de  la  verite  trouvee  pour  le  gouvernement  de  toutes  choses. 
Avec  elle  et  par  elle,  on  doit  ordonner  I'^glise  de  Dieu, 
organiser  la  republique  des  fideles,  travailler  a  la  conversion 
des  infideles  et  repousser  du  monde  chretien,  mieux  que 
par  1 'effusion  du  sang,  ceux  qui  refusent  de  se  convertir. 
Comme  un  moderne,  Roger  Bacon  fait  de  la  recherche 
de  la  verite  le  but  supreme  et  ultime  ;  comme  un  chretien 
du  xiii®  siecle,  il  entend  qu'elle  serve  a  gouverner,  a  etendre 
et  a  proteger  la  Cite  fondee  sur  les  principes  evangeliques.' 

Mais  I'acquisition  de  la  verite  est  difficile  et  notre  intelli- 
gence est  faible.  II  importe  done  d'ecarter  les  causes  et 
les  occasions  d'erreur,  surtout  les  quatre  obstacles  qui  se 
dressent  devant  tons,  I'autorite  sans  force  et  sans  dignite, 
la  longueur  et  la  puissance  de  I'habitude,  les  prejuges  du 
vulgaire,  la  tendance  a  cacher  son  ignorance  sous  une 
sagesse  apparente — d'autant  plus  que,  de  I'ignorance  ou 

Reinhold  Seeberg,  Die  Theologie  des  J.  Duns  Scotus,  Leipzig,  1900  ; 
M.  de  Wulf,  Histoire  de  la  philosophic  scolastique  dans  les  Pays-Bas 
et  la  principaute  de  Liege.  C'est  Guardia,  dans  la  Revue  philosophique, 
qui  a  surtout  appel6  I'attention  sur  le  mystique,  dont  nous  ne  con- 
naissons  I'oeuvre  qu'imparfaitement.  Probst  a  soutenu  en  19 13 
a  Grenoble  une  these  sur  Raymond  Lulle. 

'  C'est  le  point  de  vue  auquel  se  place  Roger  Bacon,  non  seulement 
dans  les  trois  ouvrages  envoyes  a  Clement  IV,  mais  encore  dans 
le  fragment  public  par  Gasquet,  Historical  Review,  xii,  1897,  dans  le 
Compendium  de  philosophic  publie  par  Brewer  et  dans  le  Compen- 
dium de  theologie  edite  par  Rashdall  dans  la  British  Society  of 
Franciscan  Studies,  vol.  iii. 


SA  PLACE  PARMI  LES  PHILOSOPHES  73 

de  I'erreur,  decoule  la  corruption  des  moeurs/  Comme  il 
n'y  a  qu'un  Dieu,  il  n'y  a  qu'une  sagesse  parfaite.  EUe 
est  contenue  dans  les  Ecritures.  Mais  pour  Ten  tirer,  pour 
constituer  la  theologie  sous  forme  de  sagesse  complete,  il 
faut  recourir  au  droit  canon  et  a  la  philosophic,  dans  laquelle 
sont  comprises  toutes  les  sciences.  Par  I'histoire,  par  des 
faits,  par  des  raisonnements  et  par  des  textes,  Roger  Bacon 
etablit  que  la  theologie  et  la  philosophic  sont  les  deux 
aspects  de  la  supreme  verite,  que,  si  les  patriarches  et  les 
prophetes  en  ont  eu  la  revelation  dans  son  integralite,  les 
philosophes,  les  poetes,  les  sibylles  et  tons  ceux  qui  se  sont 
adonnes  a  la  sagesse  en  ont  eu  une  revelation  suffisante  ; 
elle  I'a  ete  certainement  pour  Aristote  et  pour  Avicenne.^ 

Or  pour  connaitre  Dieu,  le  monde  et  I'homme,  Roger 
Bacon  estime  que  cinq  choses  sont  necessaires  et  suffisantes. 
D'abord  il  faut,  pour  la  pratique  comme  pour  la  speculation, 
etudier  les  langues  etrangeres  par  lesquelles  la  sagesse  est 
venue  en  partie  aux  Latins  et  par  lesquelles  elle  pent  leur 
arriver  complete.  En  second  lieu,  il  faut  recourir  aux 
mathematiques,  fondement  de  toutes  les  sciences,  d'abord 
a  ce  qu'on  pent  appeler  la  metaphysique  des  mathematiques, 
puis  aux  quatre  sciences  speculatives,  geometric,  arithme- 
tique,  astronomic,  musique  ou  acoustique,  et  aux  quatre 
sciences  pratiques  qui  leur  correspondent,  c'est-a-dire  en 
somme  a  neuf  sciences  totalement  ignorees  des  Latins. 
Ensuite  Roger  Bacon  fait  intervenir  I'optique,  qui  suppose 
la  multiplication  des  especes,  identifiee  par  certains  modernes 
avec  notre  propagation  actuelle  de  la  force,  la  science 
experimentale,    qui    emploie,    avec    I'experience    humaine 

'  Pour  ces  causes  de  I'erreur,  il  ne  serait  pas  sans  interet  de  com- 
parer Roger  Bacon  et  Fran9ois  Bacon. 

-  Toute  cette  theorie  de  Roger  Bacon  —  qu'on  retrouve  pendant 
tout  le  moyen  age,  et  qui  permet  aux  Chretiens  d'utiliser  d'autres 
livres  que  les  Ventures  —  a  pour  point  de  depart  r£)vangile  de 
S.  Jean  ou  il  est  dit  que  le  Verbe  est  la  lumiere  qui  eclaire  tout 
homme  venant  en  ce  monde. 


74  ROGER  BACON 

et  philosophique,  I'experience  par  illumination  interieure, 
c'est-a-dire  une  revelation  permanente  et  individuelle.  Et 
il  termine  par  la  morale,  la  plus  noble  des  parties  de  la  philo- 
sophie,  qu'il  ne  distingue  guere  d'ailleurs  de  la  metaphysique 
et  de  la  theologie.  Car  la  theologie  expose,  en  faisant 
appel  a  la  foi  au  Christ,  ce  que  la  morale  et  la  metaphysique 
tirent  des  autres  sciences  et  d'une  revelation  speciale.' 

Dans  VOpus  Minus  et  dans  I'Opus  Tertium,  Roger  Bacon 
acheve  d'indiquer  au  Pape  la  direction  que  I'Eglise  devrait 
suivre.  Dans  le  premier,  Roger  Bacon  signale  les  parties 
de  VOpus  Majus  qui  lui  paraissent  les  meilleures,  et  il  passe 
en  revue  ce  qu'il  appelle  les  sept  peches  de  la  theologie. 
D'abord  elle  est  dominee,  dit-il,  par  la  philosophic  dans 
les  ecoles  et  chez  les  maitres  dont  il  fait  une  si  vive  critique. 
Puis  elle  n'utilise  pas  les  sciences  les  meilleures  et  celles  qui 
lui  seraient  les  plus  precieuses,  les  langues  etrangeres  au 
latin  dont  elle  devrait  sortir  tout  entiere,  la  mathematique 
et  I'optique,  la  science  experimentale  et  morale,  deja  in- 
diquees  dans  VOpus  Majus,  I'alchimie  qu'il  met  sur  le  meme 
plan  ;  elle  se  borne  a  employer  des  sciences  vUes,  la  gram- 
maire  des  Latins,  une  logique  incomplete,  la  partie  la  moins 
valable  de  la  philosophie  naturelle  et  une  partie  seulement 
de  la  metaphysique.  Bien  plus,  ces  sciences  d'une  valeur  in- 
ferieure,  les  theologiens  les  ignorent,  acceptant  une  infinite 
de  choses  fausses,  prenant  pour  certain  ce  qui  est  douteux, 
pour  clair  ce  qui  est  obscur,  recherchant  le  superflu  et 
omettant  le  necessaire,  comme  on  pent  le  voir  par  I'exemple 
des  maitres  les  plus  celebres,  Alexandre  de  Hales  qui  est 
mort,  et  Albert  le  Grand  dont  I'influence  est  encore  si  con- 
siderable et  si  pernicieuse.  En  cinquieme  lieu,  les  theo- 
logiens preferent  le  Livre  des  Sentences  a  I'Ancien  et  au 
Nouveau  Testament.  Et  dans  les  6critures,  dans  la  Vulgate 
qui  est  entre  leurs  mains,  le  sens  litteral  presente  des  faus- 
set6s  infinies,  des  doutes  intolerables  qui  empechent  d'at- 
'  Voir  plus  loin  la  theorie  de  la  double  experience. 


SA  PLACE  PARMI  LES  PHILOSOPHES         75 

teindre  la  verite  et  qui  emportent  les  memes  erreurs  et  les 
memes  incertitudes  pour  I'interpretation  allegorique  :  tout 
cela  provient  de  ce  qu'ils  ignorent  I'hebreu,  le  grec,  I'histoire 
naturelle,  le  latin  meme,  mais  surtout  la  propriete  des  choses 
qui  figurent  dans  les  Ecritures.  Enfin  ils  ne  savent  pas 
davantage  la  generation  des  choses  dont  I'histoire,  partout 
diffuse  dans  I'Ecriture,  est  le  fondement  de  la  philosophie 
naturelle  et  de  la  medecine  :  si  Ton  connaissait,  dit-il  en 
soulevant  un  certain  nombre  de  questions  relatives  a 
I'alchimie,  les  proprietes  de  toutes  les  choses,  on  saurait 
I'Ecriture,  la  philosophie  et  par  consequent  toute  la  sagesse 
divine  et  humaine.' 

A  maintes  reprises  Roger  Bacon  proclame,  dans  VOpus 
Tertium,  I'originalite  de  son  ceuvre  et  la  necessite  de  suivre 
la  direction  qu'il  indique.  Comme  les  sciences  sont  connexes, 
il  faut  en  donner  une  vue  comprehensive,  il  faut  soumettre 
aux  maitres  I'esquisse  generale  et  les  objets  de  la  connais- 
sance,  preparer  a  I'etude  de  la  philosophie  dont  on  ne  peut 
avoir  que  I'idee  la  plus  fausse  et  la  plus  pernicieuse  par 
les  deux  maitres  vantes  dans  les  ecoles,  Alexandre  de 
Hales  et  Albert  le  Grand.  L'erreur  et  la  confusion  dans 
la  theologie  et  la  philosophie  sont  surtout  causees  par 
I'ignorance  des  langues.  Mais  aussi  il  y  a  trop  peu  de  maitres 
pour  les  mathematiques  —  Roger  Bacon  n'en  connait  que 
deux  parfaits  et  deux  bons  ;  il  n'y  en  a  pas  trois  non  plus 
qui  sachent  I'optique.  La  multiplication  des  especes, 
qu'il  a  travaillee  pendant  dix  ans,  est  aussi  importante  que 
I'optique  elle-mSme  ;  I'alchimie  speculative  et  I'alchimie 
operative,  fort  peu  etudiees,  ont  des  rapports  considerables 
avec  la  physique  ;  I'experience  est  le  seul  temoin  certain 
pour  les  sciences  et  toutes  sont  ses  servantes  ;    la  morale 

'  Voir  dans  fimile  Charles,  Roger  Bacon,  sa  vie,  ses  ouvrages,  ses 
doctrines,  Paris,  1861  ;  et  Bridges,  i,  pp.  Ixxiv-lxxviii,  ce  qui  est 
dit  de  I'alchimie  chez  Roger  Bacon.  Voir  aussi  la  publication  de 
Duhem. 


76  ROGER  BACON 

a  une  grande  importance  comme  fin  et  comme  regie  de 
toute  connaissance.  Pour  I'avancement  de  la  philosophic, 
un  seul  homme  ne  peut  suffire  :  il  y  faut  I'aide  des  princes 
et  des  prelats,  il  faut  de  I'argent  pour  les  livres,  pour  les 
instruments,  pour  les  tables  mathematiques  et  astrono- 
miques,  pour  I'etude  des  langues,  pour  la  recherche  et 
I'achat  des  livres,  pour  les  experiences  et  pour  la  formation 
de  coUaborateurs  de  toute  espece.  En  analysant  I'Opus 
Majus,  Roger  Bacon  rappelle  que  la  sagesse  veritable, 
unique  et  parfaite,  est  dans  les  Ecritures,  que  toute  philo- 
sophie  vient  de  Dieu  par  son  action  sur  I'intellect  de 
I'homme,  que  toute  la  sagesse  a  ete  donnee  d'abord  par 
Dieu  aux  patriarches  et  aux  prophetes  ;  que  les  philo- 
sophes  et  les  sages  eurent  des  illuminations  speciales  par 
lesquelles  ils  furent  instruits  sur  Dieu  et  le  salut  de  Fame, 
peut-etre  plus  pour  les  Chretiens  que  pour  eux-memes,  mais 
que  la  philosophie  est  vaine  si  elle  n'est  pas  jointe  a  la  sagesse 
de  Dieu  et  ne  lui  obeit  pas.  A  propos  de  I'etude  des  langues, 
Roger  Bacon  expose  la  puissance  miraculeuse  de  la  parole, 
surtout  si  I'influence  des  astres  y  est  jointe,  I'imposition 
des  mots  et  leur  puissance  significative,  les  signes  artificiels 
et  les  signes  naturels.  La  logique  est  connue  sans  appren- 
tissage  et  tous  les  hommes  raisonnent  naturellement.  Des 
mathematiques,  la  plus  noble  est  I'astronomie  speculative 
et  pratique,  qui  fait  connaitre  les  choses  celestes  dont 
dependent  tous  les  changements  terrestres.  C'est  la  geome- 
tric qui  explique  ces  changements  et  qui  explique  aussi  la 
multiplication  des  especes,  en  ligne  droite  ou  par  des  rayons 
accidentels,  par  refraction  ou  par  reflexion.  Et  Roger  Bacon 
donne  ses  idees  sur  la  matiere,  qui  n'est  pas  egale  a  Dieu, 
sur  les  figures  des  corps,  sur  le  monde,  le  temps,  le  mouve- 
ment  et  I'eternite,  sur  le  vide,  meme  sur  les  explications 
populaires  de  la  transsubstantiation,  parce  que  tout  cela 
a  rapport  a  la  quantite  que  le  geometre  considere.  L'as- 
tronomie  apparait  comme  le  fondement  assure  de  la  chrono- 


SA  PLACE  PARMI  LES  PHILOSOPHES  ^y 

logie  :  aussi  donne-t-elle  le  moyen  de  reformer  le  calendrier. 
A  propos  de  la  musique,  Roger  Bacon  traite  de  I'accentua- 
tion,  du  chant,  de  la  psalmodie,  de  Tharmonie,  du  metre 
et  du  rythme,  de  la  predication  et  de  la  rhetorique,  con- 
tinuant ainsi  a  elargir  le  trivium  et  le  quadrivium  de 
I'epoque  anterieure/ 

Ce  qui  caracterise  peut-etre  le  mieux  Roger  Bacon  comme 
penseur,  c'est  qu'il  est  le  representant  le  plus  complet  de 
la  speculation  au  xiii®  siecle,  puisqu'il  a  poursuivi  la  con- 
naissance  sous  toutes  ses  formes  alors  accessibles,  c'est 
qu'il  pent  etre  rapproche  par  consequent  de  tous  ses  con- 
temporains,  mais  qu'il  pent  I'etre  tout  aussi  bien  des  hommes 
de  la  Renaissance,  de  la  Reforme  et  des  temps  modernes. 

Sans  doute  il  veut  qu'on  s'applique  a  I'etude  de  la  gram- 
maire  latine  ;  mais  il  recommande  qu'on  apprenne  le  grec, 
I'hebreu,  le  chaldeen,  I'arabe  et  meme  la  plupart  des  langues 
que  parlent  les  peuples  avec  lesquel^  les  Latins  sont  en  rela- 
tions. A  la  fagon  des  erudits  de  la  Renaissance,  qu'il  sur- 
passe  meme  par  I'ampleur  de  ses  recherches,  il  compose 
une  grammaire  grecque,  une  grammaire  hebraique,  peut- 
etre  des  vocabulaires  ;  il  est  en  quete  de  manuscrits  et  il 
ecrit  un  latin  bien  plus  voisin  du  leur  que  de  celui  de 
S.  Thomas.  Comme  les  partisans  de  la  Reforme,  il  entend 
qu'on  lise  les  Ecritures  dans  I'original  et  qu'on  tache  d'avoir 
un  texte  correct.  En  moderne  il  signale  les  avantages  de 
I'etude  des  langues  etrangeres  pour  le  commerce,  pour  les 
relations  politiques  avec  les  differents  peuples,  pour  la 
conservation  ou  le  retablissement  de  la  paix,  il  pratique 
I'exegese,  il  apparait  ainsi  comme  un  des  fondateurs  de  la 
philologie  comparee,  de  la  philosophic  du  langage  et  de  la 
critique  sacree.- 

'  II  faut  rapprocher  les  fragments  publics  par  Gasquet,  par  Little 
et  par  Duhem  de  I'Opus  Tertium. 

-  Tout  cela  a  deja  ete  etabli  en  bonne  partie  par  ;fimile  Charles, 
op.  cit.,  2®  partie,  ch.  ii,  '  Essai  d'une  renaissance  au  xiiie  siecle  ' ; 
4«  partie,  I.  Caractere  philosophique  attribue  a  la  grammaire,  Bacon, 


78  ROGER  BACON 

II  n'ignore  pas  la  logique  demonstrative  de  VOrganon 
qu'il  connait  tout  entier.  Mais  il  croit  que  le  raisonnement 
est  naturel  a  rhomme,  que  les  termes  seuls  par  lesquels  on 
en  fait  la  theorie  sont  a  apprendre  dans  les  livres.  Surtout 
il  met  le  raisonnement  au-dessous  de  1' experience  et  vante 
une  forme  de  raisonnement  dont  le  germe  est  dans  la  Rhe- 
torique,  la  Poetique  d'Aristote  et  leurs  commentateurs, 
mais  qui  ressemble,  en  plus  d'un  point,  a  ce  que  nous  nom- 
mons  la  logique  du  vraisemblable  et  aussi  a  ce  qu'est  pour 
M.  Ribot  la  logique  du  sentiment/ 

Pour  les  mathematiques,  il  n'est  pas  inferieur  a  ceux  qui 
en  font  une  etude  speciale  et  il  depasse  les  philosophes  qui 
s'en  tiennent  a  I'antique  quadrivium.  Comme  Descartes, 
il  les  applique  a  la  physique  et  en  tire  I'explication  de  toutes 
choses.  Tout  ce  que  savent  les  astronomes  et  les  astrologues 
de  son  temps,  il  le  sait.  Mais  il  expose,  sur  le  calendrier, 
des  idees  qui  ne  seront  realisees  qu'en  1582.  En  examinant, 
a  la  suite  des  Arabes,  la  duree  attribuee  a  di verses  formes 
religieuses,  il  esquisse  une  histoire  comparee  des  religions 
ou  il  ne  tient  pas  compte  uniquement  de  celles  que  comparent 
les  controversistes  juifs,  Chretiens  et  musulmans.  En  geo- 
graphic, il  utilise  ce  qu'ont  transmis  les  Grecs,  les  Latins 
et  les  Arabes,  mais  il  consulte  les  recits  des  voyageurs  du 
xiii®  siecle  et,  quand  il  le  pent,  les  voyageurs  eux-memes. 
Les  pages  que  Pierre  d'Ailly  a  reproduites  textuellem.ent, 
sans  citer  d'ailleurs  Roger  Bacon,  n'ont  pas  ete  sans  infiu- 

un  des  fondateurs  de  la  critique  sacree  ;  IV.  De  I'erudition  de  Roger 
Bacon.  Voir  Hirsch,  '  Early  English  Hebraists,  Roger  Bacon  and 
his  Predecessors,'  Jewish  Quarterly  Review,  October  1899,  vol.  xii  ; 
J.  L.  Heiberg,  '  Die  griechische  Grammatik  Roger  Bacons,'  Byzan- 
tinische  Zeitschrift,  vol.  ix,  Leipzig,  1900,  pp.  479-91  ;  Edmond 
Nolan  et  Hirsch,  The  Greek  Grammar  of  Roger  Bacon  and  a  Fragment 
oj  his  Hebrew  Grammar,  Cambridge,  at  the  University  Press,  1902. 

'  Roger  Bacon  insiste  sur  cette  forme  de  la  logique  qui  mettrait 
au  second  plan  la  logique  demonstrative,  Charles,  p.  140.  Voir 
Th.  Ribot,  La  psychologic  des  sentiments  ;  La  logique  des  sentiments, 
Paris,  Alcan. 


SA  PLACE  PARMI  LES  PHILOSOPHES         79 

ence  sur  la  decouverte  de  FAmerique.  En  optique,  Roger 
Bacon  resume  Ptolemee,  Avicenne,  Alhazen,  mais  il  est 
superieur  a  Witelo  que  Kepler  commente  au  debut  du 
xvii^  siecle.  Les  savants  utilisent  les  deux  parties  de  VOpus 
Majus,  que  Combach  publie  en  1614,  comme  les  travaux  de 
Scheiner  et  de  Kepler.  Et  Ton  rappelle  Roger  Bacon  quand 
Descartes  traite  de  la  dioptrique  et  des  moyens  de  prolonger 
la  vie  humaine/ 

Avec  Albert,  Roger  Bacon  vante  I'experience;  avec  les 
hommes  de  son  temps,  il  croit  a  Taction  toute-puissante  de 
Dieu,  mais  il  ne  doute  ni  du  pouvoir  de  la  nature,  ni  du 
pouvoir  de  I'homme,  et  il  a  une  confiance  illimitee  dans 
I'observation  et  dans  I'experience  pour  determiner  en 
dernier  ressort  la  valeur  des  conceptions  actuelles  et  des 
affirmations  antiques.  Son  alchimie  et  celle  de  ses  contem- 
porains  rassemblent  tout  ce  qui  a  ete  trouve  par  les  Grecs 
et  les  Arabes,  mais  c'est  en  les  continuant  que  le  xvii®  et 
le  xviii^  siecle  feront  enfin  naitre  la  chimie  positive.  Pour 
la  morale,  Roger  Bacon  s'inspire  des  moralistes  latins  et 
grecs,  notamment  de  Seneque  ;  il  trouve  chez  eux  les  prin- 
cipes  metaphysiques  et  theologiques  du  christianisme, 
m^me  la  puissance  spirituelle  et  temporelle  du  Pape,  vicaire 
de  Dieu  et  Dieu  humain.  II  pose,  comme  I'ideal  supreme, 
I'union  mystique  avec  Dieu,  qui  produit,  autant  que  cela 

'  Charles  a  insiste  sur  toute  cette  partie  de  I'ceuvre  de  Roger  Bacon 
que  nous  connaitrons  mieux  quand  nous  aurons  une  edition  complete 
des  oeuvres.  Voir  aussi  pour  la  geographie  ce  que  dit  Bridges  dans 
les  notes  sur  VOpus  Majus,  en  particulier  i.  290  pour  la  decouverte 
de  I'Amerique  et  aussi,  pour  I'optique,  ii,  pp.  i  et  2.  Voir  aussi 
Essais,  ch.  x.  Ce  chapitre  synth^tise  trois  articles  qui  ont  paru 
dans  le  Journal  des  Savants  en  juillet  1905,  en  septembre  et  octobre 
1912.  C'est  dans  le  Discours  de  la  Methode,  6e  partie,  que  Descartes 
expose,  sur  les  moyens  de  prolonger  la  vie  humaine  et  de  reculer 
les  accidents  de  la  vieillesse,  des  id^es  qui  rappellent  celles  de  Roger 
Bacon.  En  ce  qui  concerne  I'histoire  des  religions,  nous  avons 
d6veloppe  les  idees  de  Roger  Bacon  dans  nos  conferences  des  Hautes- 
£tudes. 


8o  ROGER  BACON 

est  possible  en  cette  vie,  la  christification  et  la  deification 
de  I'individu,  tout  en  exposant  bien  des  solutions  pratiques 
pour  la  vie  actuelle.  Pour  I'education,  il  considere  comme 
indispensable  la  methode  des  ecoles,  conferences  entendues 
et  prononcees,  discussions  auxquelles  on  prend  part  ou 
qu'on  dirige,  mais  il  juge  severement  la  plupart  des  procedes 
dont  usent  les  maitres  et,  pour  sa  part,  les  transforme 
completement.' 

Par  I'ensemble  de  sa  direction  scientifique,  par  le  soin 
qu'il  prend  de  proclamer  la  connexite  de  toutes  les  sciences, 
parties  d'un  tout  qui  accomplissent  leur  oeuvre  propre  en 
s'aidant  cependant  les  unes  les  autres,  par  la  place  qu'il 
fait  a  la  science  pratique  ou  a  I'industrie,  Roger  Bacon  est 
devenu  pour  Haureau  et  Renan,  Littre  et  Bridges,  un 
anc^tre  d'Auguste  Comte,  un  precurseur  du  modeme 
positivisme.  Mais  il  ne  s'est  pas  borne  a  la  recherche  exacte 
et  scientifique  ;  il  n'a  condamne  ni  la  theologie,  ni  la 
metaphysique.  Au  contraire,  les  acquisitions  scientifiques 
doivent  servir  a  les  constituer  d'autant  plus  parfaites  I'une 
et  I'autre  que  les  sciences  seront  elles-m^mes  plus  com- 
prehensives  et  plus  riches  en  verites  incontestees.  Et  cela 
surtout  distingue  Roger  Bacon  des  thomistes  posterieurs 
a  1280,  plus  encore  que  de  S.  Thomas,  pour  qui  la  tache 
du  theologien  et  du  philosophe  sera  a  peu  pres  terminee 
quand  il  aura  fait  la  synthese  des  connaissances  anterieure- 
ment  rassemblees.  D'un  autre  cote,  I'utilite  pratique,  par 
les  applications  industrielles,  n'a  pour  lui  qu'un  role 
secondaire  :  le  but  supreme,  c'est  la  possession  de  la  sagesse 
d'ou  resultera  I'eternelle  beatitude.^ 

'  Pour  la  morale,  dont  le  texte  a  ete  publie  pour  la  premiere  fois 
par  Bridges,  il  faut  se  souvenir  de  ce  qu'a  ecrit  £mile  Charles  qui 
avait  consulte  tous  les  manuscrits  de  Roger  Bacon.  Sur  I'education 
telle  que  I'entend  Roger  Bacon,  voir Essais,  ch.  xii  etch,  xiii,  et  notre 
article  de  la  Revue  des  Deux  Mondes,  du  ler  juin. 

-  Sur  Roger  Bacon  mystique,  on  pent  voir  ce  qui  va  etre  dit  des 
deux  formes  de  I'experience. 


SA  PLACE  PARMI  LES  PHILOSOPHES         8i 

Pour  mettre  pleinement  en  lumiere  rhomme  original  et 
le  penseur  qui  tient  par  toutes  ses  inspirations  au  xiii" 
siecle,  il  semble  qu'il  suffise  de  montrer,  avec  un  peu  plus 
de  precision,  quelle  fut  pour  Roger  Bacon  la  methode  par 
excellence  de  la  recherche  et  de  I'enseignement  et  ce  qu'il 
fait,  pour  la  theologie  et  I'exegese,  de  la  philosophic  qu'il 
a  ainsi  acquise. 

Comme  sources  de  nos  connaissances,  Roger  Bacon  admet 
I'autorite,  le  raisonnement  et  I'experience.^ 

Personne,  pas  meme  Albert  le  Grand  ou  Vincent  de  Beau- 
vais,  n'a  recherche  les  ouvrages  du  passe  avec  autant  de  soin, 
n'a  moins  epargne  son  argent  et  ses  peines  pour  rassembler 
des  manuscrits  et  en  augmenter  sans  cesse  le  nombre.  Mais 
s'il  fait  appel  a  I'autorite  et  au  temoignage,  il  n'admet 
que  I'autorite  qui  vient  de  Dieu  ou  celle  des  hommes  saints 
et  sages  ;  il  condamne  I'autorite  qui  s'attache  a  des  gens 
qui  ne  le  meritent  ni  par  I'emploi  des  procedes  propres  a 
trouver  la  verite,  ni  par  un  genre  de  vie  qui  fasse  supposer 
que  Dieu  leur  a  accorde  des  revelations  speciales.  Aussi 
annonce-t-il  I'intention  de  verifier  par  I'experience  les  affir- 
mations qu'il  doit  a  I'autorite  humaine,  et  il  n'hesite  pas 
a  declarer  fausses  celles  qu'elle  contredit.  Roger  Bacon  ne 
se  contente  pas  des  documents  ecrits,  il  s'efforce  toute  sa 
vie  de  nouer  des  relations  avec  ceux  qu'il  estime  capables 
de  lui  fournir  des  connaissances  nouvelles,  maitres  savants 
ou  hommes  dedaignes  par  eux,  Latins,  Grecs  ou  Hebreux. 
Personne,  dans  ce  xiii*'  siecle  qui  use  tant  des  Universites 
et  des  Ecoles,  n'a  eu  une  confiance  plus  grande  dans  la 
puissance  de  I'enseignement  et  de  la  parole.  Mais  il  se 
reserve  d'examiner  la  valeur  des  le9ons  comme  celle  des 

'  Les  textes  relatifs  a  I'experience  ont  deja  ete  releves  en  partie 
par  Charles,  pp.  1 1 1-15,  comme  ceux  qui  concernent  le  raisonnement 
et  I'experience.  Voir  aussi  Essais,  ch.  xi,  Le  maitre  des  experiences, 
Pierre  de  Maricourt ;  xii,  Jean,  disciple  de  Roger  Bacon ;  xiii,  Ceux 
que  combat  Roger  Bacon. 

1689  G 


82  ROGER  BACON 

ecrits,  en  se  servant  de  I'experience  et  de  I'observation 
toutes  les  fois  que  cela  sera  possible/ 

Roger  Bacon  admet  bien,  comme  ses  contemporains,  qu'on 
utilise  les  traductions  faites  depuis  le  temps  de  Boece 
jusqu'au  xii®  et  au  xiii®  siecle.  II  felicite  Robert  de  Lincoln 
d'avoir  voulu  en  augmenter  le  nombre  et  il  indique,  mieux 
qu'on  ne  fit  jamais,  a  quelles  conditions  doit  repondre  une 
bonne  traduction  :  il  faut  connaitre  la  langue  dans  laquelle 
est  ecrite  I'oeuvre  originale,  celle  dans  laquelle  on  veut  la 
faire  passer  et  la  science  meme  dont  il  y  est  trait e.  Mais, 
comme  des  traducteurs  Boece  seul  a  connu  les  langues, 
Robert  de  Lincoln  seul  a  connu  les  sciences,  il  n'y  a  pas 
de  traductions  qui  repondent  aux  conditions  requises. 
M6me  il  en  est  —  en  particulier  d' Aristote  —  de  si  mauvaises 
qu'il  vaudrait  mieux  qu'elles  n'existent  pas  ou  que  personne 
ne  les  consulte.  En  toute  circonstance,  il  est  done  pre- 
ferable de  recourir  aux  originaux  grecs  et  hebreux,  arabes 
et  syriaques  —  d'autant  plus  qu'une  foule  d'oeuvres  scienti- 
fiques,  philosophiques  et  theologiques  n'ont  jamais  ete  mises 
en  latin,  Aussi  apprend-il  lui-meme  les  langues  qu'il  juge 
bon  de  savoir.  Aussi  insiste-t-il  tout  a  la  fois  sur  la  neces- 
site  d'avoir  des  collaborateurs  qui  les  sachent,  des  protec- 
teurs  riches  et  puissants,  pape,  princes,  rois  et  seigneurs, 
qui  lui  procurent  I'argent  necessaire  a  la  recherche  et  a 
I'achat  des  livres  ignores  des  Latins  afin  d'y  recueillir,  dans 
toute  leur  purete,^  les  connaissances  transmises. 

Roger  Bacon  emploie  le  raisonnement.  Mais  non  seule- 
ment  il  pense  que  la  logique  est  connue  naturellement,  qu'il 
y  a  une  autre  fa9on  de  raisonner  que  celle  dont  on  trouve 
la  theorie  dans  VOrganon,  il  affirme,  en  outre,  que  les 
conclusions  les  plus  certaines  laissent  a  desirer,  si  elles  ne 
sont  pas  verifiees.     Supposez,  dit-il,  qu'on  ait  prouve  par 

'  Essais,  ch.  xii  et  ch.  xiii. 

'  Voir  notre  article  dans  la  Revue  des  Deux  Mondes  du  i^""  juin  sur 
la  formation  intellectuelle  de  Roger  Bacon. 


SA  PLACE  PARMI  LES  PHILOSOPHES  83 

des  arguments  suffisants  que  le  feu  brule,  endommage  les 
choses  ou  les  detruit.  L'esprit  ne  sera  pas  en  repos  tant  que 
I'experience  n'aura  pas  etabli  ce  qu'enseignait  I'argument. 
Quand  elle  I'aura  fait,  Tame,  ayant  acquis  la  certitude,  se 
reposera  dans  la  splendeur  de  la  verite.  M6me  dans  les 
mathematiques,  ou  la  demonstration  est  la  plus  puissante, 
I'experience  est  indispensable  pour  que  I'adhesion  pleine 
et  entiere  soit  donnee  a  la  conclusion.  Si  Aristote  delinit 
la  demonstration  comme  le  syllogisme  qui  fait  savoir,  il 
entend  la  demonstration  avec  accompagnement  d'expe- 
rience/ 

Ainsi  Roger  Bacon  vante  I'experience  comme  Albert  le 
Grand.  II  veut,  en  plus,  qu'on  I'emploie  a  verifier  la  valeur 
des  connaissances  qui  viennent  par  I'autorite  ou  plutot  par 
des  temoignages,  qui  lui  apparaissent  comme  une  observa- 
tion indirecte.  Avec  les  alchimistes,  avec  certains  physiciens, 
surtout  ceux  qui  etudient  la  multiplication  des  especes  et 
I'optique,  avec  certains  medecins  et  astronomes,  Roger 
Bacon  pratique  I'observation  et  I'experience,  mais  il  en  tire 
un  parti  inliniment  plus  considerable,  car  il  en  utilise  les 
resultats  pour  la  constitution  d'une  philosophic  des  sciences, 
d'une  metaphysique  et  d'une  morale,  d'une  exegese  et 
d'une  theologie,  c'est-a-dire  d'une  sagesse  parfaite  qui 
implique  la  connaissance  des  choses  divines  et  humaines. 

Des  trois  modes  de  connaissance,  I'experience  a  seule  une 

valeur    par   elle-meme,    I'autorite    et    le   raisonnement    ne 

valant  que  par  I'experience.     Celle-ci  est  double,  elle  est 

externe  ou  interne.    La  premiere  est  naturelle  et  imparfaite, 

quand  elle  n'a  pas  conscience  de  sa  puissance,  quand  elle 

•ne  se  rend  pas  compte  de  ses  procedes  ;    elle  est  a  I'usage, 

non  des  savants,  mais  de  ces  artisans  qu'interrogent  avec 

tant  de  soin  et  de  profit  maitre  Pierre  et  Roger  Bacon. 

La  seconde,  humaine  et  philosophique,  est  la  science  des 

observations  qui  ne  sont  ni  debiles  ni  incompletes.     Elle 

'  Voir  note  i,  p.  78, 

G  2 


84  ROGER  BACON 

s'etend  de  I'observation  proprement  dite,  de  la  soumission 
patiente  et  perspicace  a  la  nature,  jusqu'a  I'experience  qui 
la  met  a  la  question  pour  lui  arracher  ses  secrets.  Elle  use 
des  sens  ;  elle  y  joint  des  instruments  dont  Roger  Bacon 
voudrait  qu'on  augmente  le  nombre  et  la  portee  ;  elle  utilise 
le  raisonnement  par  analogie,  comme  les  modernes,  en 
particulier  pour  I'explication  de  I'arc-en-ciel  et  pour  la 
decouverte  des  moyens  propres  a  prolonger  la  vie  humaine. 
Le  temoignage  intervient  comme  une  observation  indirecte 
pour  nous  apprendre,  si  elle  est  dirigee  par  des  sages,  ce 
qui  se  passe  la  ou  nous  ne  sommes  pas.  Ainsi  nous  avons 
la  raison  et  la  cause  en  meme  temps  que  le  fait.  Au-dessus 
de  toutes  les  sciences  speculatives,  de  tous  les  arts,  sinon 
au-dessus  de  la  philosophie  et  de  la  theologie,  I'experience 
a,  par  rapport  aux  autres  sciences,  trois  grandes  prerogatives  : 
elle  examine  et  confirme  leurs  conclusions,  elle  fournit  des 
resultats  nouveaux  qui  entrent  dans  les  sciences  existantes, 
elle  provoque  dans  la  science  de  nouvelles  divisions,  elle 
produit  la  connaissance  du  present,  du  passe  et  du  futur, 
elle  amenera  ces  inventions  merveilleuses  plutot  entrevues 
ou  imaginees  que  realisees  a  cette  epoque,  emploi  de  la 
poudre  a  canon  pour  I'attaque  et  la  defense  des  forteresses, 
instruments  pour  naviguer  sans  rameurs,  pour  nager  et 
rester  sous  I'eau,  pour  voler  a  la  fa9on  des  oiseaux,  voitures 
pour  rouler  sans  attelage,  ponts  sans  colonnes  et  sans  piles, 
miroirs  comburants,  verres  qui  utilisent  le  pouvoir  grossis- 
sant  de  surfaces  diverses  et  conduiront  au  microscope  et  au 

telescope,  etc' 

* 
'  II  faut  consulter,  en  meme  temps  que  I'Opus  Majus,  VQpiis  Minus 
et  I'Opus  Tertium,  le  fragment  de  Gasquet,  V Epistola  fratris  Rogerii 
Baconis  de  secretis  operibus  artis  et  naturae,  et  de  nullitate  magiae 
(Brewer) .  La  reimpression  ou  la  publication  des  opuscules  de  Roger 
Bacon  nous  fournira,  il  faut  I'esperer,  des  renseignements  complemen- 
taires  sur  la  theorie  de  la  double  experience  chez  Roger  Bacon. 
Comparez  aussi  notre  'Note  pour  I'Academie  des  Sciences,'  Comptes 
rendus,  p.  615  du  tome  clvii,  seance  du  13  octobre  191 3. 


SA  PLACE  PARMI  LES  PHILOSOPHES  85 

Mais  I'experience  humaine  et  philosophique  est  cependant 
insuffisante,  parce  qu'elle  ne  fournit  pas  pour  les  corps  une 
pleine  certitude  et  qu'elle  n'atteint  aucune  des  choses 
spirituelles.  II  faut  done  que  I'intellect  humain  soit  aide  par 
d'autres  moyens,  par  des  illuminations  interieures,  par  des 
inspirations  divines  qui  portent  sur  le  monde  sensible 
comme  sur  le  monde  intelligible,  qui  achevent  la  science 
comme  la  philosophie  et  la  theologie.  Au  premier  degre 
sont  les  Oluminations  purement  scientifiques  qui  completent, 
en  les  expliquant,  les  resultats  de  I'experience  externe. 
Puis  ce  sont  les  vertus  qui  clarifient  I'esprit,  de  fagon  qu'il 
comprend  plus  facilement  les  choses  morales  et  celles  d'ordre 
scientifique.  Roger  Bacon  rejoint  ainsi  Plotin  par  I'inter- 
mediaire  de  S.  Augustin  et  d'Algazel ;  au  lieu  de  dire  que 
la  science  est  la  condition  necessaire  et  suffisante  de  la  vertu, 
que  tout  mechant  est  un  ignorant,  il  soutient  que  la  vertu 
est  la  condition  indispensable  de  la  science,  que  le  mechant 
ne  pent  arriver  a  la  possession  de  la  verite.  Au  troisieme 
degre  sont  les  sept  dons  du  S.  Esprit  dont  parlent  Isaie 
et  S,  Paul  et  qui  caracterisent  les  perfections  nouvelles  dans 
I'homme  illumine  par  Dieu.  Puis  ce  sont  les  beatitudes, 
qui  presentent  les  memes  resultats  sous  une  forme  nouvelle. 
Ensuite  les  sens  spirituels  fournissent  de  I'Ecriture  des 
interpretations  allegoriques  avec  lesquelles  la  theologie 
reconstruit  le  monde  intelligible.  L'un  des  fruits  en  est 
la  paix  de  Dieu  qui  surpasse  tout  ce  que  donnent  les  sens. 
Enfin  se  produisent  les  ravissements,  les  extases  qui  unissent 
I'homme  a  Dieu,  en  lui  faisant  voir  beaucoup  de  choses  dont 
il  n'est  pas  permis  de  parler,  en  lui  donnant  la  certitude, 
pour  lui  et  pour  les  autres,  sur  les  choses  spirituelles  et  les 
sciences  humaines,  en  le  christifiant  et  en  le  deifiant.' 

Pour  I'enseignement,   Roger  Bacon  ne  cesse  de  recom- 

'  II  faut  rapprocher  ce  qui  est  dit  de  la  science  experimentale  de  ce 
qui  est  dit  de  la  morale,  puis  des  afi&nites  de  la  theologie  et  de  la 
philosophie. 


86  ROGER  BACON 

mander  la  methode  qui  a  pris  avec  Alexandre  de  Hales 
sa  forme  definitive  :  on  ne  saurait  connaitre  ce  que  Ton  veut 
saisir  par  son  intelligence  si  Ton  n'a  entendu  et  fait  des 
conferences,  si  Ton  n'a  pris  part  aux  discussions  et  si  on 
ne  les  a  soi-meme  dirigees.  Et  c'est  pour  cette  raison 
qu'il  accuse  d'ignorance  ceux  qui  se  sont  crees  maitres 
avant  d'avoir  ete  ecoliers,  qu'il  les  rend  responsables  du 
mauvais  etat  des  etudes  et  de  la  corruption  des  moeurs. 
Mais  ces  exercices  necessaires,  il  ne  les  juge  pas  suffisants. 
Roger  Bacon  n'est  pas  plus  satisfait  de  la  maniere  dont  on 
enseigne  la  verite  que  de  la  fa9on  dont  on  la  cherche.  Le 
maitre  devrait  rediger  un  manuel  pour  les  etudiants  et  leur 
faire  des  le9ons  orales  dont  I'importance  est  grande,  en  raison 
meme  de  la  puissance  naturelle  et  surnaturelle  qui  est 
attribuee  a  la  parole.  On  y  joindrait  des  conseils,  une 
direction  constante.  On  suivrait  I'ordre  indique  au  Pape 
en  enseignant  les  langues,  les  mathematiques,  la  multiplica- 
tion des  especes  et  I'optique,  la  science  experimentale  et 
morale,  la  philosophic,  le  droit  canon  et  la  theologie  ;  on 
ferait  pratiquer  I'experience  externe  et  interne.  Le  disciple 
doit,  avant  tout,  avoir  le  coeur  pur  ;  il  doit  etre  docile 
et  attentif ,  travailler  d'apres  les  principes  qui  lui  sont  donnes 
et  les  mettre  en  pratique  dans  des  recherches  personnelles.' 
Pour  les  philosophes  du  xiii^  siecle,  la  science  maitresse 
est  la  theologie,  dont  la  philosophic  et  les  sciences  sont  les 
servantes  ou  les  vassales.  Et  Bacon  use  d'expressions  ana- 
logues. Mais  c'est  aussi,  selon  lui,  la  science  qui  a  besoin, 
pour  se  constituer,  du  droit  canon  et  de  la  philosophic,  des 
mathematiques  sous  toutes  leurs  formes,  de  la  multiplication 
des  especes  et  de  I'optique,  de  la  science  experimentale  et 
de  la  morale.  De  sorte  que  si  la  theologie  est  au  premier 
plan,  comme  il  convient  a  la  science  qui  traite  de  Dieu, 
la  philosophic  et  les  sciences  prennent  une  valeur  singuliere, 
puisqu'elles  sont  indispensables  a  I'acquisitiqn  de  la  parfaite 
'  Essais,  ch.  xii  et  ch.  xiii. 


SA  PLACE  PARMI  LES  PHILOSOPHES         87 

sagesse.  Et  comme  la  science  comporte,  pour  Roger  Bacon, 
les  connaissances  deja  rassemblees  et  celles  qui  restent  a 
decouvrir,  le  theologien  doit  faire  appel  a  1' experience  externe 
et  a  I'experience  par  illumination  interieure  pour  etre  de 
plus  en  plus  renseigne  sur  le  monde  sensible  et  sur  le  monde 
intelligible.  Au  lieu  de  se  constituer  definitivement  comme 
elle  le  fut,  dans  ses  grandes  lignes,  par  S.  Thomas,  la  theologie 
serait  sans  cesse  en  progres  ou  en  accroissement  du  fait 
de  ses  propres  acquisitions,  comme  du  fait  de  I'augmenta- 
tion  des  connaissances  positives  et  philosophiques.' 

Et  comme  Roger  Bacon  veut  que  le  theologien  apprenne 
les  langues  pour  consulter  a  la  source  les  textes  sacres  et 
leurs  commentaires,  on  en  eut  acquis  une  comprehension 
d'autant  plus  exacte  qu'on  eut  pris  des  langues  une  con- 
naissance  plus  appro fondie  et  plus  precise.  L'exeg^se, 
comme  la  theologie,  eut  ete  dans  un  progres  constant — d'au- 
tant plus  qu'elle  aurait  utilise  comme  elle  toutes  les  donnees 
nouvelles  qu'on  aurait  recueilli  dans  le  domaine  scientifique 
et  philosophique. 

Dans  une  de  nos  premieres  publications  relatives  a  Roger 
Bacon,  nous  ecrivions  en  1904  que,  si  I'Eglise  avait  suivi  la 
direction  dans  laquelle  il  voulait  I'engager,  il  n'y  aurait  eu 
place  ni  pour  une  Renaissance  parfois  hostile  au  christia- 
nisme,  ni  pour  une  Reforme  qui  se  separat  completement 
du  catholicisme,  ni  pour  une  lutte  ouverte  ou  une  rupture 
complete  entre  les  theologiens,  les  philosophes  ou  les  savants, 
entre  les  exegetes  et  les  partisans  de  la  critique  historique. 
On  pourrait  tout  aussi  bien  marquer  I'originalite  de  Bacon 
en  disant  qu'on  ne  saurait  negliger  de  rappeler  son  nom  et 
son  oeuvre  quand  on  parle  du  but  poursuivi  par  les  hommes 

'  Les  recherches  sur  la  theologie  et  I'exegese  de  Roger  Bacon  ont 
ete  faites  a  la  section  des  sciences  religieuses  de  I'ficole  pratique  des 
Hautes-fitudes  {Histoire  des  doctrines  et  des  dogmes).  Voir  Essais, 
ch.  i  et  ch.  xiv. 


88  ROGER  BACON 

de  la  Renaissance  ou  par  les  Reformat eurs,  par  Descartes 
ou  Kepler,  par  la  Societe  royale  et  les  Academies  qui  ont 
groupe  les  chercheurs  de  toute  espece,  par  les  observateurs 
et  les  experimentateurs  qui  ont  realise  tant  d'inventions 
merveilleuses,  par  les  positivistes  qui  ont  proclame  la  correla- 
tion et  la  hierarchie  des  sciences,  comme  la  necessite  d'une 
philosophie  scientifique,  par  les  exegetes  qui  profitent 
des  progres  realises  par  les  sciences  physiques,  les  sciences 
morales  et  historiques  comme  par  I'etude  des  langues. 
S.  Thomas,  par  son  oeuvre  qui  a  triomphe  dans  le  monde 
catholique,  avait  absorbe  dans  la  philosophie  toutes  les 
connaissances  anterieurement  acquises  pour  en  constituer 
I'exegese  et  la  theologie.  Roger  Bacon  a  esquisse  une  oeuvre 
qu'il  n'a  pas  achevee,  mais  dont  les  parties  realisees  nous 
permettent  de  juger  le  but  et  I'ampleur,  La  philosophie 
y  eut  joue  un  role  analogue  a  celui  qu'elle  a  eu  chez 
S.  Thomas  ;  elle  eut  rassemble  tous  les  resultats  obtenus  par 
les  sciences  dans  leur  developpement  successif  et  elle  eut 
avec  elle  constitue  une  exegese  et  une  theologie  qui  nous 
aurait  fait  approcher  de  plus  en  plus  de  la  sagesse  parfaite, 
capable  de  guider  I'homme  dans  ce  monde  et  de  lui  procurer 
la  beatitude  eternelle.  Si  les  savants,  les  philosophes,  les 
reformateurs  religieux  se  reclament  de  preference  de  Roger 
Bacon,  tandis  que  I'Eglise  catholique  s'est  toujours  attachee 
S.  Thomas,  on  ne  peut  s'empecher  de  penser  que  les  nou- 
veaux  thomistes  songent,  apres  Leon  XIII,  a  reunir  les 
avantages  qu'on  peut  retirer  des  deux  methodes,  quand 
ils  veulent  accroitre  les  connaissances  anciennes  par  des 
recherches  nouvelles  —  Vetera  auger e  novis. 


IV 

ROGER  BACON  AND  THE  LATIN  VULGATE 

By  Cardinal  GASQUET 

The  work  of  Roger  Bacon  in  regard  to  the  Vulgate  is  well 
known.  His  opinions  as  to  the  state  of  the  text  in  the 
ordinary  Bibles  of  the  thirteenth  century,  and  his  suggestions 
as  to  the  principles  which  should  regulate  any  revision  have 
been  frequently  set  forth  by  those  interested  in  the  history 
of  the  Latin  Vulgate,  whilst  many  modern  writers,  amongst 
whom  I  may  name  M.  S.  Berger,'  the  Abbe  Martin,^  the 
Franciscan  Father  Theophilus  Witzel,^  and  others,  have 
written  specially  upon  this  subject.  Little  therefore  remains 
to  be  done  but  to  follow  in  their  footsteps. 

From  one  point  of  view  the  whole  of  Roger  Bacon's 
encyclopaedic  works  may  be  regarded  as  leading  up  to  the 
revision  of  the  Latin  Bible,  which  he  considered  so  impor- 
tant. The  necessary  scientific  correction  of  the  text  was 
the  main  reason  impelling  him  to  demand  a  more  accurate 
study  of  languages  and  more  correct  knowledge  of  science. 
Throughout  all  his  various  treatises,  or  parts  of  his  great 
work.  Bacon  constantly  returns  to  the  same  central  idea, 
namely,  that  the  theologians  of  his  day,  and  in  particular 
the  teachers  in  the  great  University  of  Paris,  had  neglected 
to  ground  themselves  sufficiently  in  matters  of  language  and 
science  to  the  great  detriment  of  their  special  studies. 

'  Samuel  Berger,  De  I'histoire  de  la  Vulgate  en  France,  Paris,  1887. 

"  J.  P.  P.  Martin,  La  Vulgate  latine  ait  XI IP  siecle  d'apres  Roger 
Bacon,  Paris,  1888. 

'  Theophilus  Witzel,  O.F.M.,  '  De  Fr.  Rogero  Bacon  eiusque 
sententia  de  rebus  biblicis,'  in  Arch.  Franc.  Hist.,  iii.  3-22,  185-213. 


90  ROGER  BACON 

It  is  clear  that  the  Franciscan  had  expressed  these  views  as 
to  the  decadence  of  theological  studies  to  Pope  Clement  IV, 
before  the  elevation  of  the  latter  to  the  Papacy,  and  as 
a  consequence  that  Pope  in  the  second  year  of  his  pontificate 
communicated  to  the  friar  his  desire  that  he  should  write 
fully  his  criticism  of  the  state  of  ecclesiastical  studies  at 
the  time,  and  make  whatever  suggestions  he  thought  useful 
to  remedy  the  evils  he  perceived.  In  1267,  therefore,  Bacon 
replied  with  his  Opus  Minus,  in  which  the  tract  '  The 
Seven  Capital  Sins  of  Theology '  sets  forth  clearly  the  points 
wherein  he  considers  the  training  then  given  to  ecclesiastics 
was  at  fault. 

The  fourth  of  these  '  Capital  Sins  '  Bacon  declares  to  be 
the  practical  abandonment  of  the  scientific  study  of  the 
sacred  Scriptures  in  favour  of  the  Book  of  the  Sentences  of 
Peter  the  Lombard,  upon  which  in  the  University  of  Paris 
all  theological  training  was  then  based.  He  writes  :  '  When 
any  one  has  read  that  (i.e.  the  Book  of  the  Sentences)  he 
thinks  himself  a  Master  in  Theology,  though  he  has  not 
studied  {non  audiat)  a  thirtieth  part  of  his  Text  (i.  e.  the 
Sacred  Scriptures).'  ^  That  by  the  word  '  Text '  Bacon  means 
the  Bible  is  made  clear  by  what  follows,  for  in  the  context 
he  complains  that  whereas  other  faculties  use  the  text 
proper  to  their  studies  as  the  basis  of  the  teaching  in  the 
schools,  theology  leaves  its  text  practically  on  one  side. 

In  the  forefront  of  his  work,  written  by  direction  of  the 
Pope  and  presented  to  him,  Roger  Bacon  pleaded  for  '  a 
more  thorough  and  scientific  teaching  of  the  Holy  Scripture  '. 
In  his  opinion  there  was  an  imperative  need  for  a  change 
in  this  matter  in  the  schools  of  the  Paris  University.  Some 
readers  of  his  words  may  perhaps  be  inclined  to  regard  his 
expressions  as  not  justified  in  fact,  but  the  whole  passage  is 
worth  quoting  as  giving  the  best  available  evidence.  '  At 
Paris  and  elsewhere ',  he  says, '  the  Bachelor,  who  takes  the 
'  Op.  Minus,  ed.  Brewer,  p.  328. 


THE  LATIN  VULGATE  91 

readings  of  the  Text  (i.e.  the  Bible),  gives  place  to  the  lecturer 
on  the  Sentences.  The  latter  is  always  honoured  and  pre- 
ferred before  the  former.  He  who  gives  lectures  on  the 
Sentences  takes  the  best  hour  according  to  his  pleasure  ;  he 
has  also  a  socius  (or  assistant)  and  his  own  room,  if  he  is 
a  friar.  But  the  one  who  reads  the  Bible  has  not  these 
advantages.  He  has  to  beg  for  whatever  hour  the  lecturer 
on  the  Sentences  may  be  pleased  to  give  him,  &c.  Am  I  not 
right,  therefore,  in  saying  ',  Bacon  concludes,  '  that  the  Text 
of  the  faculty  of  theology  gives  place  to  the  Sentences  ? '  ^ 

But  even  this  evil,  which  he  deplores,  the  learned  Francis- 
can did  not  regard  as  so  serious  as  the  state  of  the  sacred 
text  itself  in  what  he  calls  the  received  Bible,  used  in  the 
University  of  Paris.  In  this,  he  says,  '  the  text  is  for  the 
most  part  horribly  corrupt,^  and  it  is  so  uncertain  that  great 
doubt  must  arise  as  to  the  true  reading.  As  a  consequence, 
those  who  wish  to  correct  the  text  dispute  with  each  other 
as  to  the  real  meaning.  There  are,  in  fact,  almost  as  many 
"  correctors  "  as  readers,  and  they  really  should  more  truly 
be  called  "  corruptors  "  than  "  correctors  ",  since  every  one 
of  them  presumes  to  change  what  he  does  not  understand, 
which  would  not  be  permitted  in  the  case  of  the  works  of 
the  poets.'  ^ 

This  unjustifiable  treatment  of  the  sacred  text,  we  are  told, 
is  made  without  knowledge  or  discretion,  and  in  this  regard 
Bacon  cites  with  approval  the  dictum  of  St.  Augustine  {Cont. 
Faust.,  xxxii.  16),  that  '  when  Latin  codices  disagree,  re- 
course must  be  had  to  many  and  those  the  oldest  MSS.,  since 
ancient  texts  are  to  be  preferred  to  modern,  and  numbers 
to  a  few  '.  In  stating  this  principle  of  criticism,  Bacon 
declares  that  there  is  ample  evidence  to  show  that  in  number- 
less passages  the  Paris  Bible  of  his  day  has  incorporated 
readings  quite  opposed  to  those  to  be  found  in  the  oldest 

'  Ibid.,  pp.  328-9.  ^  Ibid.,  p.  330. 

3  Ibid. 


92  ROGER  BACON 

authentic  manuscripts.  In  these  ancient  codices,  he  says,  may 
be  seen  the  readings  held  as  authentic  by  the  Roman  Church ; 
that  is,  he  adds,  '  the  translation  of  St.  Jerome,  as  St.  Isidore 
declares  in  his  book  De  Officiis  (i.  12) '. 

If,  he  continues,  after  recourse  has  been  had  to  the  ancient 
manuscripts  there  still  remains  a  doubt  as  to  the  proper 
rendering  of  a  passage  in  the  sacred  text,  according  to  the 
teaching  of  St.  Augustine,  St.  Jerome,  and  indeed  of  '  all  the 
doctors  '  of  the  Church, '  recourse  must  be  had  to  the  language 
from  which  the  Latin  text  has  been  translated '  to  determine 
whether  it  has  rendered  the  meaning  of  the  original  exactly 
or  no.  As  an  example  in  point  Bacon  takes  the  words  of 
Mark  viii.  38,  which  in  the  Latin  run  :  '  qui  me  confessus 
fuerit  .  .  .  confitehitur ,'  &c.,  which  should  be  '  confusus  fuerit 
.  .  .  confundehir '  according  to  the  Greek  manuscripts,  which 
have  a  Greek  word  meaning  '  being  ashamed  of '. 

That  this  is  the  true  reading,  Bacon  confirms  by  an 
instructive  use  of  the  Eusebian  Canons.  In  the  second  of 
these  Canons  are  noted  the  passages  in  which  three  of  the 
Evangelists  agree.  Amongst  these  the  passage  in  Mark 
viii.  38  is  seen  to  agree  with  parallel  passages  in  Matthew 
and  Luke.  In  the  former  the  words  used  are,  '  who 
shall  deny  me,'  and  in  the  latter,  '  who  shall  he  ashamed  of 
me  ;  '  thus  confirming  the  opinion  that  the  word  used  in 
the  Latin  version  of  Mark  should  be  confusus  and  not 
confessus. 

Roger  Bacon  does  not  apparently  consider  the  defective 
nature  of  the  Bible  made  use  of  in  the  schools  of  Paris 
as  so  very  extraordinary.  For  forty  years,  he  says,  many 
theologians  and  Paris  booksellers  have  been  copying  and 
selling  the  corrupt  text.  A  great  number  of  careless  scribes 
have  added  to  the  confusion  by  making  changes  of  words, 
&c.,  according  to  their  own  judgement.  Theologians  have 
no  means  of  examining  the  text  critically,  and  so  rely  upon 
it  as  correct.     Later,  when  perhaps  they  became  conscious 


THE  LATIN  VULGATE  93 

that  there  was  something  wrong  or  unsatisfactory,  they 
wished  to  change  what  they  imagined  to  be  wrongly  trans- 
lated. But  '  because  they  had  not  the  ability,  each  one 
made  what  corrections  he  pleased'.  'This',  our  author 
says,  '  is  still  being  done ',  and  as  each  one  has  his  own 
opinion  as  to  what  corrections  should  be  made,  the  result  is 
to  introduce  '  an  almost  endless  diversity  of  readings  '.^  The 
result  is  uncertainty,  and  the  case  is  really  similar  to  that 
described  by  St.  Jerome  writing  to  Pope  Damasus :  '  Where 
there  is  diversity  the  truth  cannot  be  known.' 

The  origin  of  the  difficulty  resulting  in  the  defective  Paris 
text  was,  in  Roger  Bacon's  opinion,  simply  this  :  that  those 
who  did  not  hesitate  to  correct,  made  no  attempt  to  seek  for 
the  readings  to  be  found  in  the  most  ancient  Latin  texts,  and 
were  ignorant  of  the  Greek  and  Hebrew  languages  from 
which  the  Latin  version  was  derived.  Even,  he  says,  a 
good  grammar  would  help  them  and  save  them  from  trying 
to  change  '  the  old  grammar  which  St.  Jerome,  who  trans- 
lated into  Latin,  knew  so  well,  since  he  was  a  pupil  of  the 
great  Donatus  and  the  greater  Priscian '.  Contrary  to 
what  theologians  have  said,  the  text  of  the  Latin  Church 
is  not  a  mixed  one.  It  was  translated  by  St.  Jerome  from 
the  Hebrew,  except  the  Psalms,  which  are  from  the  Septua- 
gint.  The  Psalter,  indeed,  remained  in  the  translation  from 
the  Greek  because  the  Church  was  accustomed  to  its  use  and 
would  not  accept  the  version  made  by  St.  Jerome  from  the 
Hebrew,  which  was  the  only  one  he  himself  thought  to 
be  correct. 

In  this  same  part  of  his  Opus  Minus  Roger  Bacon  gives 
a  full  account  of  the  translations  that  had  been  made  of  the 
Holy  Scripture  before  the  time  of  St.  Jerome.  In  this  he 
manifests  an  extent  of  knowledge  surprising  in  the  thirteenth 
century,  and  which  indeed  could  hardly  be  surpassed  in 

these    days.      His   conclusion   is    that    the   translation    of 

« 
'  Op.  Min.,  p.  333. 


94  ROGER  BACON 

St.  Jerome  was  excellent  in  every  way,  and  that  it  is  the 
only  one  recognized  by  the  Latin  Church,  and  a  return  to 
which  must  be  the  end  of  all  revision. 

He  calls  the  Pope's  attention  to  the  fact  that  the  Septua- 
gint  Greek  is  not  wholly  trustworthy,  as  that  text  too  has 
been  corrupted  by  scribes  and  others.  This  St.  Jerome  had 
noted  in  his  day,  as  for  example  in  Ezekiel  xlii.  2,  where  the 
word  cuhitorum  has  found  its  way  into  the  text,  where  the 
Greek  has  nothing,  and  where  St.  Bede  notes  that  the  word 
should  be  calamorum.  Before  leaving  this  matter,  he  again 
insists  that  the  ancient  Bibles  are  the  only  true  tests  of 
correctness,  and  he  warns  students  against  paying  too  much 
attention  to  the  passages  of  Holy  Scripture  used  in  the 
Divine  Office  and  other  liturgical  services,  since  changes 
have  been  made  for  the  sake  of  greater  clearness  and  for 
aids  to  devotion.' 

The  need  for  possessing  some  knowledge  of  Greek  in  order 
to  make  corrections  safely  is  also  well  illustrated  by  Roger 
Bacon.  He  takes  the  words  of  Matthew  xii.  31,  spiritus 
blasphemiae,  where  the  word  spiritus — usually  understood 
as  meaning  the  Holy  Spirit — is  shown  by  the  Greek  to  be  in 
the  genitive  case  with  blasphemiae  as  blaspheinia.^ 

In  the  Opus  Majus  Bacon  again  insists  upon  the  necessity 
of  examining  the  oldest  Latin  manuscripts  '  existing  in  mon- 
asteries and  not  yet  glossed  or  retouched ',  which  afford  the 
true  version  made  by  the  authority  of  the  Roman  Church. 
'  According  to  the  testimony  of  these  old  Bibles  the  Paris 
edition  should  be  corrected.'  ^  Seeing  the  real  danger  to 
religion  by  the  circulation  of  a  text  of  the  Bible  into  which 
many  errors  had  crept,  the  learned  Franciscan,  in  this  as 

'  Op.  Min.,  p.  347. 

=  A  great  many  manuscripts  have  this  mistake,  as  may  be  seen  in 
the  list  of  authorities  for  this  reading  in  Wordsworth  and  White's 
great  work  on  the  New  Testament. 

^  Opus  Maj.,  ed.  Bridges,  iii.  95. 


THE  LATIN  VULGATE  95 

in  many  other  matters  far  in  advance  of  his  age,  begs  the 
Pope  to  take  seriously  into  consideration  the  question  of 
a  thorough  revision.  Three  centuries  before  the  Council  of 
Trent  Bacon  wrote  to  Clement  IV  :  'I  cry  to  you  against 
this  corruption  of  the  Text,  for  you  alone  can  remedy 
the  evil.' 

The  Franciscan  was  also  seriously  concerned  at  the  private 
attempts  being  made  in  the  thirteenth  century  to  correct 
the  sacred  text.  He  considered  that  the  only  result  of  the 
work  of  these  correctors  will  be  to  make  confusion  worse 
confounded. 

Every  teacher,  he  says,  '  in  the  Order  of  Minorites  corrects 
as  he  pleases  ;  and  the  same  is  the  case  among  the  Friars 
Preachers  and  Seculars.  Each  one  changes  what  he  does 
not  understand.  The  Preachers  have  chiefly  occupied  them- 
selves with  this  kind  of  correction.  Twenty  years  ago  and 
more  they  presumed  to  make  a  correctorium  and  set  it  forth 
in  writing.  But  later  they  made  another  to  supersede  it : 
now  they  hesitate  (as  to  the  corrections)  more  than  others  do, 
not  knowing  where  they  are.  In  this  way  their  corrections 
are  the  worst  kind  of  corruption  and  the  destruction  of 
God's  Text.  It  is  a  much  less  evil  and  indeed  without  any 
comparison  to  make  use  of  the  uncorrected  Paris  Bible  than 
to  accept  their  corrections,  or  those  of  any  others.'  ' 

Bacon's  opinion  was  expressed  strongly  against  the  substi- 
tution of  words  and  phrases  for  the  original  text,  no  matter 
how  much  better  and  clearer  they  might  appear  to  those 
who  used  them.  In  several  places  in  his  works  he  complains 
of  this  tendency  of  the  correctors  of  his  age.  They  never 
do  this  *  when  they  read  the  poets  '  is  his  argument  more 
than  once  repeated,  but  in  the  case  of  Holy  Scripture  *  every 
lector  makes  whatever  changes  he  pleases  '.  ^ 

He  complains  also  of  the  absence  of  unity  and  method  in 
making  corrections,  which  was  manifest  in  all  the  attempts 
made  in  his  time.     The  correctors  were  not  agreed  as  to 

'  Op.  Tertium,  ed.  Brewer,  p.  93. 
-  Op.  Min.,  ed.  Brewer,  p.  330. 


96  ROGER  BACON 

what  text  they  had  to  restore.  Theologians  as  a  body 
seemed  even  to  think  that  the  text  used  by  the  Latin  Church 
was  not  St.  Jerome's  translation  at  all,  but  a  mixed  version 
compiled  from  many  different  sources.  For  this  reason 
with  great  liberty  they  introduce  whatever  words  they  desire 
to  use.  '  But  it  is  certain  that  the  Latin  Church  uses  St. 
Jerome's  translation,  except  in  the  Psalter,  the  translation 
of  which  is  taken  from  the  Septuagint.' '  In  principle, 
therefore.  Bacon  determines  that  every  revision  or  correction 
must  have  for  its  scope  the  restoration  of  St.  Jerome's  text ; 
whereas  the  thirteenth-century  correctors  make  use  of  other 
translations  and  even  take  their  text  from  commentators, 
from  the  ecclesiastical  liturgy,  and  even  from  the  works  of 
Josephus.^ 

For  these  reasons  Roger  Bacon  begs  the  Pope  to  use  his 
supreme  authority  and  prohibit  these  private  attempts  at 
correcting  the  sacred  text,  and  to  commit  this  difficult  and 
laborious  task  to  men  who  possessed  adequate  learning  and 
who  were  skilled  in  the  languages  necessary  for  attempting 
the  important  work.  The  two  things  the  learned  Franciscan 
chiefly  condemns  are :  first,  the  Paris  text ;  and,  secondly,  the 
attempts  at  correction  which  had  been  made,  chiefly  by 
the  Franciscans  and  Dominicans,  in  the  first  half  of  the 
thirteenth  century,  some  forty  years  or  so  before  he  himself 
denounced  these  attempts  to  the  Pope  and  implored  him  to 
put  a  stop  to  them. 

His  condemnation  of  the  majority  of  the  correctors  is  based 
on  several  important  considerations,  amongst  which  are  the 
following  :  they  have  no  adequate  knowledge  of  the  ancient 
Bibles ;  their  knowledge  of  Hebrew  and  Greek  from  which  the 
Latin  is  derived  is  insufficient  ;  they  are  unacquainted  with 
the  best  Latin  grammarians,  and  in  particular  with  the 
works  of  Donatus  and  Priscian,  the  masters  of  St.  Jerome ; 
and  they  were  not  au  courant  with  the  various  versions 
'  Op.  Min.,  ed.  Brewer,  p.  334.  '  Ibid.,  p.  347-8. 


THE  LATIN  VULGATE  97 

which  were  in  existence  in  the  Latin  Church,  nor  had  they 
studied  their  origin  and  history. 

By  the  expression  '  ancient  Bibles  '  Bacon  meant  those 
which  had  come  down  from  the  age  of  St.  Gregory  the 
Great,  St.  Isidore  of  Seville,  and  Alcuin,  '  and  numberless 
other  Bibles  ',  he  writes, '  scattered  in  various  countries,  con- 
temporary with  St.  Isidore  or  before  his  time,  which  are 
free  from  alterations.  They  are  the  same  in  all  things, 
except  for  the  faults  of  copyists,  from  which  no  writing 
is  free.'  ' 

The  account  of  the  origin  of  the  Vulgate  text  given  by 
the  learned  Franciscan  is  of  great  interest  as  showing  not 
only  the  extent  of  his  knowledge  on  this  particular  part 
of  his  subject,  but  his  entire  familiarity  with  the  works  of 
the  Fathers  of  the  Church  and  of  St.  Jerome  in  particular. 

'  St.  Jerome',  he  says,  'found  the  (Latin)  translation  of 
the  Septuagint  disfigured  not  only  by  the  errors  of  the 
scribes,  but  by  having  from  the  first  many  faults  of  omission 
of  necessary  things  and  addition  of  things  superfluous.  He 
(St.  Jerome)  perceived  that  truth  was  in  this  detained  as 
a  captive,  and  for  this  reason  he  resolved  to  give  the  Latin 
Church  a  version  made  from  the  Hebrew.  He  translated 
the  Hebrew  as  well  as  he  could  and  as  exactly  as  he  dared,  for 
he  had  no  wish  to  frighten  his  readers  by  too  great  novelties. 
Denounced,  as  he  was,  as  a  falsifier  and  corruptor  of  the 
Scriptures,  he  did  not  dare  to  translate  everything  exactly 
as  he  wished,  as  may  be  seen  in  what  he  has  written.  Thus 
through  human  frailty  or  the  rapidity  with  which  he  worked 
he  dictated  or  wrote  things  sometimes  inexactly,  as  he 
himself  confesses  in  his  letter  to  Magnus  and  in  his  com- 
mentaries on  Isaias,  where  he  desires  to  correct  what  he  had 
translated  badly.'  - 

Later  in  the  same  part  of  his  work  Bacon  adds  to  this 
account  the  following  : 

'  Knowing  that  his  (St.  Jerome's)  first  translation  (from 
the  Hebrew)  was  not  sufficiently  exact,  wishing  to  set  forth 
the  truth  and  to  satisfy  the  desires  of  students,  he  resolved 

'  Op.  Min.,  ed.  Brewer,  p.  335,  -  Ibid.,  p.  336. 

1689  H 


98  ROGER  BACON 

to  leave  another  translation  in  private  writings.  This  he 
could  do  so  as  not  to  scandalize  the  faithful,  since  this 
second  edition  has  never  been  used  by  the  people  or  by  the 
Church.  At  all  times,  indeed,  very  few  have  used  the 
original  writings  of  St.  Jerome  on  the  Bible.  For  instance, 
Rabanus  (Maurus)  and  Cassiodorus,  two  most  learned  men, 
have  declared  that  they  could  not  find  all  his  works.  Rabanus 
says  this  expressly  in  his  commentary  on  Jeremias.'  ' 

To  enforce  his  conclusion  that  the  only  version  adopted  by 
the  Latin  Church  is  that  which  St.  Jerome  made  under  the 
authority  of  Pope  St,  Damasus,  Roger  Bacon  adds  this 
reflection  : 

*  So  great  a  work  could  not  have  been  accomplished  either 
by  the  doctors  of  Paris  or  by  any  other  person  without 
the  authority  of  the  Holy  See.  It  could  not  have  been  and 
ought  not  have  been  done  without  this  authorization  :  it 
would  have  been  improper.  Can  it  be  said  now  that  this 
work  has  been  concluded  with  this  authorization  either  by  the 
Paris  doctors  or  by  others  or  by  some  sovereign  Pontiff  ? 
But  there  is  no  document,  no  Register  of  any  Pope,  no 
chronicle  or  history  which  says  this.  We  expect  this  in 
matters  of  small  moment  :  and  therefore  with  greater 
reason  must  look  for  it  in  so  grave  a  business,  which  serves 
for  the  foundation  of  all  ecclesiastical  discipline.'  ^ 

It  is  unnecessary  to  examine  more  fully  the  connexion 
of  the  great  Franciscan  doctor,  Roger  Bacon,  with  the 
revision  of  the  Vulgate.  He  shows  in  his  works  that  he  fully 
and  entirely  realizes  the  importance  of  the  critical  examina- 
tion he  advocates,  and  he  lays  down  the  true  principles  on 
which  any  critical  correction  must  proceed.  His  proposal 
to  Pope  Clement  IV  was  to  appoint  a  commission  of  capable 
men  with  the  avowed  object  of  restoring  the  text  of  St. 
Jerome.  The  methods  he  suggests  are  the  scientific  methods 
employed  to-day  in  the  production  of  a  critical  text.  The 
oldest  manuscripts  were  to  be  sought  for,  examined,  weighed, 
and  compared,  and  the  evidence  of  the  be^t  and  oldest  codices 
for  any  reading  was  to  be  taken  as  against  the  less  worthy 
'  Op.  Min.,  ed.  Brewer,  p.  344.  -  Ibid.,  p.  342. 


THE  LATIN  VULGATE  99 

and  the  more  modern.  Finally  the  readings,  even  when 
they  were  almost  certainly  those  of  St.  Jerome,  were  to  be 
controlled  by  the  original  Greek  or  Hebrew,  from  which  this 
version  of  St.  Jerome  has  been  translated. 

What  must  strike  any  reader  of  Roger  Bacon's  works  in 
regard  to  the  Holy  Scripture  is  the  grasp  the  learned  doctor 
had  in  the  thirteenth  century  of  the  whole  subject  of  Biblical 
revision,  and  how  true  and  clear  were  the  critical  principles  he 
laid  down  so  many  centuries  ago. 


H  2 


V 

ROGER  BACON  AND  PHILOLOGY 

By  S.  a.  HIRSCH 

Roger  Bacon  lived  from  the  very  commencement  of 
his  career  in  a  circle  which  was  calculated  to  develop  those 
tendencies  for  research  which  were  innate  in  him.  Robert 
Grosseteste  was  during  the  beginning  of  the  thirteenth 
century  the  champion  of  learning.  His  perseverance  was 
indomitable,  his  attainments  in  science  considerable  for 
the  time  in  which  he  lived,  and  his  endeavours  to  promote 
the  study  of  the  ancient  languages  induced  him  to  invite 
numbers  of  Greek  scholars  into  England  for  the  purpose  of 
initiating  himself  and  his  followers  into  the  mysteries  of 
classical  learning.  He  took  pains  to  collect  as  many  books  as 
could  be  laid  hold  of,  including  treatises  on  Greek  grammar. 

Under  Grosseteste's  direction,  Nicholaus  Graecus  trans- 
lated the  '  Testaments  of  the  Twelve  Patriarchs  '  from  a 
manuscript  which  had  lately  been  brought  from  Athens  by 
his  archdeacon,  John  of  Basingstoke. 

Nicholaus  must  have  been  one  of  those  veri  Graeci,^ 
several  of  whom  lived  in  western  Europe  even  before  Grosse- 
teste ;  one  of  the  very  few  who  were  able  to  impart  a  correct 
knowledge  of  grammar.-  He  became  an  inmate  of  Grosse- 
teste's household. 

John  of  Basingstoke  was  an  excellent  Greek  and  Latin 
scholar.  In  Athens  he  became  cognizant  of  many  things 
the  existence  of  which  was  unknown  to  the  Latins.  He  says 
that,  although  he  had  studied  for  a  long  time  at  Paris,  he 
had  derived  his  real  knowledge  from  the  tuition  of  the 

'  Comp.  Stud.  Phil.,  vi.  434  (Brewer) ;  Greek  Grammar  p.  31. 
'■"  Opus  Tertium,  x.  34  (Brewer). 


102  ROGER  BACON 

learned  Constantina,  who  was  alleged  to  have  been  the 
daughter  of  the  Archbishop  of  Athens.'  He  translated  a 
Greek  grammar,  which  he  called  the  Greek  Donatus.^ 

Bacon  must  also  have  received  a  considerable  stimulus 
towards  the  study  of  the  ancient  languages  from  the  veteran 
scholar,  his  older  contemporary  whose  name  is  unknown  to 
us,  and  who  is  designated  by  him  by  such  a  term  as  homo 
sapientissimus.  Bacon  declares  that  he  was  a  consummate 
Greek  and  Hebrew  scholar  who  had  for  over  thirty  years — 
or,  as  Bacon  says  elsewhere,  for  nearly  forty  years — brought 
his  linguistic  knowledge  to  bear  upon  the  correction  of  the 
Vulgate  and  the  exposition  of  its  literal  meaning ;  that  he 
knew  Latin  grammar  thoroughly  according  to  Priscian,  and 
Greek  and  Hebrew  sufficiently  well  to  understand  the 
principles  and  method  of  correcting,  and  the  way  to  justify 
his  corrections.  Compared  to  him  all  others  were  but 
idiots.^ 

The  intercourse  with  the  circle  of  students  who  were 
gathered  round  Grosseteste,  and  his  acquaintance  with  such 
men  as  Edmund  Rich  and  his  reputed  pupils,  Adam  Marsh, 
Thomas  Wallensis,  and  others,  cannot  but  have  imparted 
a  powerful  impulse  to  a  mind  predisposed  by  nature  to 
immerse  itself  in  the  depths  of  philological  research. 

'  See,  however.  Sir  J.  E.  Sandys,  A  History  of  Classical  Scholarship, 
i.  413. 

~  Another  work  of  his  which  commences  Templum  Domini,  '  in 
quo  particulae  sententiarum  per  distinctiones  dilucidantur  '  (Matthew 
of  Paris,  Chron.  Maj.,  ed.  Luard,  v.  284-7),  ^^^  liave  been  a  work 
on  Syntax,  but  I  rather  believe  that  it  was  a  commentary  on  Peter 
Lombard's  Sentences.  Cf.  Bacon's  Greek  Grammar,  &c.,  Introduc- 
tion, p.  xlviii. 

^  Opus  Tertium,  xxv.  88,  89,  94  (Brewer).  Mr.  A.  G.  Little  has 
communicated  to  me  his  doubts  as  to  Denifie's  identification  of 
homo  sapientissimus  with  William  de  la  Mare,  on  the  ground  that  the 
latter  was  too  young.  These  doubts  are  of  considerable  force  in  view 
of  this  passage  :  Et  adhuc  '  aliqui  senes  perdurant '  qui  sciunt  multum 
ut  homo  sapientissimus,  &c.  The  figures  30  years,  40  years,  in  Bacon's 
writings  must  not  be  taken  too  literally. 


PHILOLOGY  103 

Roger  Bacon  held  that  the  knowledge  of  languages  was 
the  first  gate  that  led  to  the  acquisition  of  wisdom.'  It 
was  particularly  indispensable  to  the  '  Latins  ',  whose  entire 
acquaintance  with  theology  and  philosophy  was  derived 
from  channels  other  than  Latin.  He  did  not  recognize  the 
study  of  languages  to  be  important  for  its  own  sake  ;  it  was 
not  a  scientia  principalis,  like,  for  instance,  mathematics. 
It  was,  like  logic,  only  accidental  to  philosophy.^  But  he 
did  not  for  that  reason  minimize  its  importance.  Recognizing 
as  he  did  that  grammar,  in  the  narrow  sense  of  the  word, 
as  it  was  taught  to  boys,  was  to  music  what  the  work  of  the 
carpenter  was  to  geometry,^  he  yet  demanded  an  independent 
and  scientific  research  into  the  origins  and  the  fundamental 
bases  of  languages. 

It  would  be  idle  to  say  that  Bacon  has  arrived  at  any 
striking  results  in  the  study  of  comparative  philology,  of 
the  structure  of  the  individual  languages  with  which  he 
was  concerned,  or  of  a  comprehensive  knowledge  of  their 
literary  products.  These  subjects,  and  the  topics  connected 
with  them,  form  nowadays  separate  disciplines,  every  one 
of  which  is  treated  on  its  own  merits,  and  is  calculated  to 
engross  the  life-long  attention  of  the  student.  It  would  be 
futile  to  expect  Bacon  to  have  reached  anything  approaching 
the  standard  of  proficiency  in  these  subjects  which  is 
demanded  at  the  present  day  even  of  mediocrities.  But  it 
would  be  an  error  to  imagine  that  many  of  the  questions 
which  have  risen  to  such  prominent  importance  in  recent 
times  did  not  agitate  Bacon's  mind  to  a  large  extent.  They 
had  certainly  attracted  his  attention,  and  it  cannot  be 
denied  that,  given  the  status  which  such  questions  occupied 
at  his  time,  the  scanty  apparatus  at  his  disposal,  and  the 
meagre  attainments  of  his  contemporaries,  he  far  surpassed 

'  Opus  Tertium,  xxviii.  102  (Brewer). 
'  Opus  Majus,  I.  iv.  99  (Bridges). 
^  Opus  Tertium,  lix.  231  (Brewer). 


104  ROGER  BACON 

the  latter  in  his  speculations  upon  the  nature  of  language, 
in  his  insight  into  the  structure  of  the  several  tongues  that 
formed  the  subject  of  his  researches,  and  his  acquaintance 
with  their  literatures,  in  so  far  as  they  were  accessible  to 
him. 

All  such  disciplines  as  are,  in  modern  times,  comprehended 
in  the  term  '  philology  '  were  termed  by  Bacon  '  grammar  '. 
Even  such  topics  as  the  investigation  of  the  origin  of  speech 
are  declared  by  him  to  belong  solely  and  exclusively  to  the 
science  of  grammar.' 

Bacon  holds  =  that  a  systematic  investigation  into  the 
theory  of  '  signs  '  was  indispensable  to  the  knowledge  of  the 
composition  of  languages.  He  voices  his  usual  complaint 
that  this  part  of  grammar  had  not  been  touched  upon  by 
the  Latins,  who  did  not  even  possess  any  translations  of 
more  ancient  works  on  the  subject.  This  was  the  more 
surprising,  seeing  that  it  was  of  the  utmost  utility  in  the 
study  of  all  speculative  truths  of  philosophy  and  theology. 

In  reference  to  the  theory  of  '  signs  ',  Bacon  declares  that 
his  own  investigations  had  led  him  to  the  same  conclusions 
which  his  subsequent  studies  showed  him  to  have  been 
arrived  at  by  Augustine.  A  sign  may  be  either  natural  or 
imposed  by  the  mind.  Signs  imposed  by  the  mind  either 
signify  naturally,  or  are  imposed  at  pleasure  and  voluntarily. 
The  latter  is  the  case  in  human  language :  words  are 
imposed  by  the  mind.  Their  signification  is  arbitrary,  and 
a  word  signifies  nothing  before  imposition.  A  word  can 
be  imposed  upon  itself,  and  thus  become  significant,  e.  g. 
'  white  '  may  be  used  in  the  sense  of  the  word  '  white  ',  or  in 
the  sense  of  a  '  white  '  thing.  When  a  word  is  applied  to 
a  thing  outside  the  mind,  it  signifies  the  thing  itself  and 
nothing  else  (i.  e.  not  the  '  species  '  of  the  thing  in  the  soul). 

'  Opus  Tertium,  xxvii.  loi,  102  (Brewer). 

"  Ibid,,  100 ;  Comp.  Stud.  Theol.,  pp.  38  ff.  ;  Mr.  Rashdall's 
Summary  in  his  Introduction,  pp.  6  ff. 


PHILOLGOY  105 

A  name  imposed  upon  a  thing  outside  the  mind  can  at  the 
same  time  signify  other  things  outside  the  mind  which  can 
then  be  said  to  be  '  co-intellected '  or  '  connoted  '.  The 
name  of  an  '  aggregate  '  or  concrete  thing  signifies  both  the 
formal  cause  of  the  aggregation  (i.  e.  the  meaning  of  the 
concrete  form)  and  the  constituent  elements  of  the  aggrega- 
tion. But  a  distinction  must  be  made.  The  name  signifies 
the  aggregate  primarily  and  principally,  and  the  form  and 
matter  secondarily  or  mediately.  It  signifies  the  aggre- 
gate by  imposition,  and  the  matter  and  form  naturally. 
A  word  cannot  signify  anything  common  to  an  '  ens  '  and 
a  '  non-ens  '.  A  word  imposed  upon  a  thing  can  lose  its 
significance. 

In  coming  to  these  conclusions  on  questions  of  the  philo- 
sophy of  languages  Bacon  has  broken  no  new  ground.  He 
discusses  the  opinions  of  those  who  preceded  him,  but  in 
doing  so  he  shows  himself,  as  everywhere  else,  the  keen 
critic  of  such  speculations,  through  which  he  carefully  steers 
his  own  course.  He  weighs,  and  partly  controverts,  the 
results  arrived  at  by  Aristotle,  Boethius,  Augustine,  and 
Averroes.  He  chastises,  in  his  usual  manner,  Richard  of 
Cornwall,  whom  he  calls  '  famosissimus  apud  stultam  multitu- 
dinem  ' ,  as  the  worst  and  most  stupid  author  of  various 
erroneous  notions.' 

The  question  of  the  origin  of  speech  also  agitated  Bacon's 
mind.  It  is  needless  to  say  that  he  did  not  approach  the 
question  from  the  standpoint  of  anthropology  and  evolution 
in  the  way  modern  science  has  tried  to  obtain  some  under- 
standing about  it,  and,  thus  far,  with  but  scanty  success. 
But  within  the  compass  and  limitations  into  which  his  age 
and  the  state  of  knowledge  accessible  to  him  confined  him, 
he  meditated  on  the  origin  of  languages,  on  the  primitive 
language,  on  the  language  spoken  by  Adam,  and  the  way 
the  latter  found  names  for  the  things.     He  ponders  on  what 

'  Comp.  Stud.  TheoL,  p.  52. 


io6  ROGER  BACON 

would  happen  if  children  were  to  grow  up  in  a  desert — 
whether  they  would  have  intercourse  by  speech,  and  how 
they  would  give  expression  to  their  mutual  feelings  when 
meeting  under  such  circumstances.'  He  was  convinced  that 
this  part  of  '  grammar '  was  indispensable  to  theology, 
philosophy,  and  to  all  wisdom. 

He  was  not  himself  aware,  it  seems,  that  his  philological 
instincts  would  have  led  him  to  the  consideration  of  such 
topics  on  their  own  merit.  He  measured  all  matters  of 
research  that  offer  by  the  uses  to  which  they  could  be  put 
in  the  service  of  philosophy  and  theology.  Like  so  many 
other  scholars  of  that  age,  and  of  subsequent  ages,  he 
acknowledged  only  utilitarian  motives  of  that  kind.  They 
were  certainly  powerful  incentives  to  direct  him  to  the  study 
of  languages.  Whether  '  the  first  authors  of  languages  had 
invented  them  ',  or  whether  the  diversity  of  tongues  was 
'  the  work  of  God,  at  the  division  of  languages  at  the  erection 
of  the  tower  of  Babel  after  the  Flood  ','  or  the  result  of 
'  diversity  of  locality  ',^  the  variety  existed,  and  his  mind 
was  exercised  by  the  desire  of  inquiring  into  those  languages 
in  which  were  couched  the  documents  from  which  theology 
and  philosophy  and  all  wisdom  were  derived. 

Of  these  motives,  the  theological  occupied  to  Bacon  the 
first  and  foremost  rank.     At  the  conclusion  of  his  specula- 

'  Opus  Tertium,  xxvii.  loi  (Brewer).  Mr.  Little  drew  my  atten- 
tion to  a  notice  in  the  Chronicles  of  the  Franciscan  friar,  Salimbene, 
in  regard  to  experiments  with  babies,  undertaken  by  the  Emperor 
Frederick  II.  He  forbade  the  foster-mothers  and  nurses  of  these 
children,  when  feeding  or  bathing  them,  to  prattle  or  talk  to  them. 
Thus  he  thought  he  would  be  able  to  find  out  whether  the  children, 
when  becoming  older,  would  talk  Hebrew  ('  that  being  the  first 
language  '),  or  Greek,  or  Latin,  or  Arabic,  or  the  language  of  their 
parents.  But  the  children  all  died,  not  being  able  to  live  without 
clapping  of  hands,  or  gestures,  or  lullabies.  Mr.  Little  thinks  it 
likely  that  Bacon  may  have  heard  of  these  experiments. 

-  Opus  Tertium,  xxviii.  102  (Brewer). 

^  Ibid.,  xxxvii.  120  (Brewer)  ;  Opus  Majus,  i.  iv.  138  (Bridges). 


PHILOLOGY  107 

tions  on  signs  and  words  in  the  Compendium  Studii  Theologiae 
he  exhorts  the  reader  not  to  lose  sight  of  the  manifold  power 
of  the  word  in  figurative  speech.  The  text  of  the  Bible  was 
full  of  it.  The  word,  he  says,  had,  besides  its  literal  sense, 
three  other  meanings  :  the  allegorical,  the  tropological,  and 
the  more  hidden  meaning  (.  .  .  praeter  sensum  liter alem 
potest  vox  significare  tres  alios  sensus,  scilicet  allegoricum, 
tropologicum,  et  anagogicum)  ;  and  it  was  necessary  to 
consider  the  way  in  which,  in  Holy  Scripture,  the  literal 
sense  concorded  with  the  spiritual.'  Considerations  of  that 
kind  were  strengthened  by  Roger  Bacon's  propensity  to 
mysticism. 

Mysticism  was,  in  Bacon's  time,  closely  mixed  up  with 
religion,  philosophy,  magic,  and  physical  science.  He  also 
believed  in  the  mystical  power  of  words  ;  and,  like  so  many 
others  before  and  after  him,  he  ascribed  a  spiritual  meaning 
over  and  above  the  literal  sense  to  every  word  of  the  Bible. 
Besides  his  philosophical  elucidation  of  the  meaning  and 
application  of  words,  and  their  grammatical  formation,  he 
seriously  ponders  on  their  occult  influence. 

*  For  the  same  knife  cuts  bread  and  wounds  a  man.  In  the 
same  way,  the  wise  man  works  wisely  by  means  of  words,  and 
the  magician  magically.  But  their  mode  of  action  is  different. 
The  former  makes  use  of  a  natural  force ;  the  work  of  the  other 
was  either  nothing  or  else  the  work  of  the  devil.  .  .  .  Since 
the  creation  of  the  world  almost  all  miracles  were  performed 
by  words.  The  word  is  the  principal  product  of  the  rational 
soul,  and  its  greatest  delight.  Words  are  possessed  of 
great  power  when  they  are  the  result  of  profound  thought, 
great  longing,  fixed  intention,  and  strong  confidence.  By 
the  co-operation  of  these  four  functions  the  rational  soul  is 
excited  to  give  its  impress  and  virtue  to  its  own  body,  to 
things  external,  to  its  actions,  and,  above  all,  to  the  words 
which  are  produced  from  within,  and  receive  therefore 
more  of  the  virtue  of  the  soul.  Nature,  says  Avicenna, 
obeys  the  cogitations  of  the  soul,  as  is  shown  by  the  hen  on 
whose  legs  a  spur  grew  by  its  feeling  of  triumph  at  the 

*  Opus  Tertium,  xxvii.  loi  (Brewer). 


io8  ROGER  BACON 

victory  won  by  the  cock.  If  thus  nature  obeys  the  cogita- 
tions of  the  sensitive  soul,  how  much  more  will  it  obey  those 
of  the  intellectual  soul  of  those  who  are  only  one  degree 
below  the  angels  !  Man's  outward  appearance  and  voice 
vary  as  the  greater  or  lesser  sanctity  of  the  soul.  A  con- 
siderable increase  in  the  power  of  either  the  good  or  the  bad 
soul  modifies  the  voice  and  the  air  affected  by  the  latter. 
The  air  thus  formulated  by  the  voice,  and  having  received 
a  strong  impetus  from  the  rational  soul,  can  be  changed 
accordingly,  and  change,  in  its  turn,  the  things  it  contains, 
be  they  agents  or  patients.  It  is  the  same  with  the  body. 
Body  and  soul  forming  a  unit,  the  body  naturally  obeys  the 
cogitations  of  the  soul ;  they  modify  its  outer  appearance. 
It  again  affects,  and  is  affected  by  the  air,  which  was  itself 
affected  by  the  voice.  A  further  change  is  due  to  stellar 
influences.  Whenever  the  voice  is  produced,  the  change 
wrought  by  it  in  the  air  is  complicated  by  the  effect  of  the 
constellations,  and  this  again  acts  upon  the  things  contained 
in  the  air.  Everything  depends,  therefore,  upon  four 
influences  :  the  voice  formulating  the  air,  the  good  or  evil 
condition  of  the  rational  soul,  the  body,  and  the  stars. 
When  cogitating,  intending,  wishing,  and  strongly  hoping 
for  any  change,  a  favourable  condition  of  the  heavenly 
bodies  must  be  chosen  in  conjunction  with  the  other  in- 
fluences ;  in  the  same  way  as  a  skilful  physician  selects 
suitable  stellar  conditions  when  desirous  of  working  a  cure. 
It  was,  as  Avicenna  says,  in  this  way  that  the  prophets  and 
sages  of  old  changed  the  matter  of  the  world  {materiam 
mundi),  and  produced  rain,  or  drought,  or  other  atmospheric 
changes  by  the  power  of  words.  In  this  consists  the  art  of 
alluring  or  repelling  men  and  beasts,  snakes  and  dragons. 
This  is  the  nature  of  every  spell,  and  not  the  mere  utterance 
of  a  word  ;  the  latter  will  have  no  effect  unless  the  devil 
interferes.  The  other  forces  combined  with  the  five  con- 
ditions of  the  soul — strong  thought,  vehement  wish,  firm 
will,  and  either  goodness  or  badness — are  indispensable. 
The  origin  of  songs,  incantations,  and  various  modes  of 
writing  must  be  traced  to  these  influences.' ' 

This  combination  of  the  power  of  words  in  general,  and 

the  spiritual  sense  underlying  the  words  of  the  Bible  in 

particular,  made  it  imperative  for  Bacon  to  devote  himself 

to  the  study  of  Hebrew  and  Greek,  so  as  to  be  able  to  find 

'  Opus  Tertium,  xxvi.  95  ff.  (Brewer). 


PHILOLOGY 


109 


hidden  truths  which  would  elude  the  eyes  of  those  who 
knew  these  writings  only  from  translations.  It  was  only 
by  a  knowledge  of  Hebrew  and  Greek  that  it  was  possible 
to  grasp  the  spiritual  meaning  of  the  '  text  '.  The  *  text  ' 
was  to  Bacon  what  it  was  to  his  predecessors  and  contem- 
poraries, and  what  it  is  to  a  great  many  people  at  the  present 
day — the  Latin  translation.  It  would  be  possible,  he  holds, 
to  study  the  literal  meaning  of  the  '  text ',  but  this  could  be 
of  very  little  avail  for  the  knowledge  of  the  spiritual  sense. 

'Suppose  even  the  "text"  to  be  correct  to  the  letter, 
innumerable  false  and  doubtful  notions  still  remain  on 
account  of  the  ignorance  of  the  languages  from  which  the 
translations  were  made.  But  we  theologians  do  not  know 
even  the  alphabets.  Consequently,  we  understand  neither 
the  text  nor  the  expositions  of  the  saints.'  ' 

Bacon  supported  his  standpoint  with  numerable  examples. 
It  was  impossible  for  any  one  ignorant  of  the  numerical  value 
of  the  Greek  and  Hebrew  letters  to  understand  the  interpreta- 
tions given  by  the  saints,  as,  for  instance,  Bede's  gloss  regard- 
ing the  names  of  the  Beast  in  the  Apocalypse,  the  numerical 
value  of  the  letters  of  each  amounting  to  666  ;  or  another 
passage  of  the  Bible  where  the  numerical  value  both  of  the 
Greek  and  the  Hebrew  letters  coincided  in  revealing  beautiful 
mysteries.^ 

Another  powerful  motive  to  study  languages  was  Bacon's 
disgust  at  the  insufficiency  of  the  existing  translations.  He 
sets  forth  that  philosophy,  religion,  and  science  were  laid 
down  in  documents  which  were  written  in  languages  that  had 
fallen  out  of  the  ken  of  the  majority  of  scholars  of  the  day. 
Of  the  ancient  languages,  there  was  only  one  which  had 
survived  as  the  universal  vehicle  of  thought  and  study  in 
southern  and  western  Europe.     Latin  could  in  Bacon's  time 

'  Opus  Mimts,  p,  349  f.  Cf.  ibid.,  p.  357  ;  Opus  Majus,  i.  iii.  81 
(Bridges) . 

=  Comp.  Stud.  Phil.,  vi.  437  (Brewer)  ;  Greek  Grammar,  p.  194  f., 
and  Introduction,  p.  Ixxv. 


no  ROGER  BACON 

still  rightly  be  called  a  living  language.  But  Bacon  com- 
plained that  the  Latin  world  of  priests  and  students,  the 
'  Latinitas  ',  had  lost  the  knowledge  of  those  very  languages 
that  formed  the  basis  upon  which  everything  that  should 
interest  them  was  reared.  This  would  not  have  been  so  bad 
if  the  Latins  were  possessed  of  original  and  independent 
works  on  all  branches  of  learning.  But  all  wisdom  had  been 
revealed  by  God  to  nations  other  than  Latin.  Philosophy 
was  delivered  on  four  distinct  occasions.  It  was  delivered 
for  the  first  time  in  Hebrew,  complete  in  all  its  details,  by 
Adam  and  Noah  ;  the  second  time,  by  Solomon  ;  but 
Aristotle  and  Avicenna,  who  mark  the  other  two  epochs  in 
the  history  of  philosophy,  were  only  able  to  deliver  it  incom- 
pletely, because  they  were  heathens.  Wisdom  was  delivered 
by  these  only  and  by  none  else ;  it  certainly  had  not  originated 
with  the  Latins.* 

'  The  Latins  never  originated  a  single  text,  either  in 
theology  or  philosophy.  All  texts  were  composed  in  the 
first  and  second  instance  in  Hebrew,  in  the  third  in  Greek, 
and  in  the  fourth  in  Arabic.  .  .  .  Waters  drawn  from  the 
fountains  were  sweeter  than  those  taken  from  turbid 
rivulets,  and  wine  was  purer  and  more  wholesome  when  kept 
in  the  original  cask  than  when  poured  from  vessel  to  vessel. 
If,  therefore,  the  Latins  wished  to  drink  the  pure  and  whole- 
some liquor  from  the  fount  of  wisdom,  they  must  turn  their 
attention  to  the  Hebrew,  Greek,  and  Arabic  languages. 
It  was  impossible  to  recognize  the  proper  form  and  beauty 
and  wisdom  in  all  their  dignity  except  in  the  languages  in 
which  they  were  originally  laid  down.  Oh,  how  delicious 
is  the  taste  of  wisdom  to  those  who  draw  from  the  well  of 
wisdom  in  its  primary  fullness  and  purity  !  All  others  are 
like  those  stricken  with  paralysis,  who  could  not  judge  of 
the  sweetness  of  food  ;  like  those  born  deaf,  who  are  unable 
to  enjoy  the  harmony  of  sound.'  - 

Translations  cannot  possibly  replace  the  original  docu- 
ments. 

'  Opus  Tertium,  x.  32  (Brewer). 

'  Comp.  Stud.  Phil.,  viii.  465 .    Cf .  Opus  Majus,  Part  iii,  for  Bacon's 
opinions  on  these  points. 


PHILOLOGY  III 

'  Jerome  says  that  one  language  cannot  possibly  be 
represented  by  another.  That  which  sounds  well  in  one 
tongue  becomes  ridiculous  when  expressed  in  another. 
Homer  became  ridiculous  when  translated  into  Latin,  and 
that  most  eloquent  poet  could  hardly  be  said  to  speak  at  all.' ' 

The  Latins  derived  their  theology  and  philosophy  merely 
from  translations.  But  translations  were  unsatisfactory. 
Take,  for  instance.  Logic.  The  logician  will  not  find  in  his 
vernacular  terms  by  which  to  express  the  sense  of  the  original. 
He  is  therefore  compelled  to  invent  new  terms.  The  result 
is  that  he  will  only  be  understood  by  himself.  The  same 
obtained  in  all  other  branches  of  knowledge.  The  translator 
must,  consequently,  borrow  words  from  the  language  from 
which  he  translated.  Such  could  neither  be  written,  nor 
pronounced,  nor  understood,  except  by  those  who  under- 
stood the  language  of  the  original.^ 

In  medicine  the  names  of  herbs,  of  spices,  and  other 
things  were,  for  the  most  part,  borrowed  from  the  original 
languages.  The  same  was  the  case  with  the  holy  text  :  all 
names  of  persons,  localities,  and  numerous  other  things  are 
either  Greek  or  Arabic  or  Hebrew.  Numbers  of  words  were 
taken  over  from  Lombardic,  Spanish,  and  other  languages 
that  are  akin  to  Latin.  Bacon  himself,  when  commenting 
in  his  lectures  on  a  word  which  he  took  to  be  Arabic,  was 
laughed  at  by  his  Spanish  hearers,  who  told  him  that  the 
word  was  not  Arabic,  but  Spanish.^  Such  ignorance 
brought  the  Latin  teachers  into  contempt. 

Translations  were  powerless  to  remedy  the  evil.  The 
requirements  necessary  to  procure  a  good  translation — 
a  thorough  knowledge  of  the  languages  from  which  and  into 
which  the  translation  is  made,  and  of  the  subject-matter — 

'  Opus  Teriium,  xxv.  90  (Brewer). 

'  Ibid.    Cf.  Opus  Majus,  1.  iii.  73  (Bridges). 

^  The  cause  was  probably  that  the  Latin  was  a  translation  of 
a  Spanish  translation  of  the  Arabic.  See  Bridges's  note  on  Opus 
Majus,  I.  iii.  68. 


112  ROGER  BACON 

were  possessed  by  very  few  indeed.  All  others  were  frauds. 
Robert  Grosseteste  belonged  to  the  former  class  ;  but  he 
only  acquired  the  capacity  of  translating  when  he  was  an  old 
man  ;  and  the  Greeks  whom  he  had  gathered  around  him 
had  translated  very  little.  The  translations  furnished  by 
Gerard  of  Cremona,  Michael  Scot,  Alfred  the  Englishman, 
Hermann  the  German,  and  William  the  Fleming  (William 
of  Moerbecke)  were  sorry  performances.  The  Bishop 
Hermann  the  German  had  told  Bacon  that  he  did  not  ven- 
ture to  translate  books  on  logic  from  the  Arabic,  because 
he  knew  no  logic.  Not  knowing  logic,  he  could  have  no 
learning.  But  he  did  not  even  know  much  Arabic,  and  he 
was  rather  an  assistant  of  translators  than  a  translator 
himself.  Michael  Scot  palmed  off  as  his  own,  translations 
which  were  for  the  most  part  the  work  of  a  Jew,  Andrew. 
Aristotle,  whose  works  formed  the  foundation  of  all  learning, 
had  suffered  most  at  the  hands  of  these  translators.  Their 
versions  of  his  logic,  natural  philosophy,  and  mathematics 
were  such  that  no  mortal  could  make  head  or  tail  of  them. 
In  consequence,  the  scholars  squabble  among  themselves  as 
to  what  Aristotle  meant.  It  would  have  been  much  better 
if  Aristotle  had  not  been  translated  at  all.  Scholars  laboured 
hard  to  understand  him,  and  the  more  they  laboured  the 
less  they  knew.  For  this  reason  Grosseteste  neglected  the 
works  of  Aristotle,  and  dealt  with  several  topics,  guided  only 
by  his  own  experience  and  research,'  and  certainly  with 
greater  success  than  if  he  had  made  use  of  those  perverse 
translations.  If,  Bacon  says,  he  could  have  his  way,  he 
would  have  all  translations  from  Aristotle  burned.  It  is 
sheer  loss  of  time  to  study  them,  and  it  leads  only  to 
innumerable  errors. 

Ignorance  of  Greek  and  Hebrew,  together  with  some  other 
causes,  were  responsible  for  the  corruption  of  the  text  of  the 

'  But  see  Sir  J.  E.  Sandys,  A  History  of  Classical  Scholarship, 

i-553- 


PHILOLOGY  113 

Vulgate.  The  Paris  text  was  the  worst  of  all.  Everybody, 
however  illiterate  some  of  them  may  be,  and  even  '  married 
people  ',  presumed  to  interfere  with  the  text.  They  knew 
no  grammar,  they  did  not  consult  Priscian,  and  did  not 
know  that,  on  many  points,  Jerome  was  better  informed  even 
than  he.  Nevertheless,  Jerome's  translation  did  not  always 
reproduce  the  true  sense  of  the  originals.  People  inveighed 
against  him  because  he  had  dared  to  deviate  from  the 
Septuagint,  and  he  was  termed  a  falsifier  and  corrupter 
of  the  Scriptures.  He  therefore  adapted  himself  to  the 
previous  versions,  sometimes  to  that  of  Aquila,  sometimes 
to  that  of  Symmachus,  but  chiefly  to  the  Septuagint, 
although  he  knew  that  these  translations  did  not  always 
agree  with  the  originals.  Jerome,  moreover,  admitted  to 
have  occasionally  erred  from  undue  haste.' 

All  these  reasons  combined  caused  Roger  Bacon  to  urge 
upon  his  contemporaries  the  study  of  the  ancient  languages. 
But  he  did  not  stop  at  exhortations.  He  threw  himself 
into  this  pursuit  with  the  same  energy  which  characterized 
his  efforts  in  the  other  fields  of  learning.  It  was  especially 
the  three  languages — Arabic,  Greek,  and  Hebrew,  the  mastery 
of  which  he  considered  to  be  a  conditio  sine  qua  non  for  all 
independent  research  in  theology,  philosophy,  and  science. 

But  Bacon  was  aware  that  no  workman  can  effect  any- 
thing without  proper  tools,  which  were  in  this  case  books 
and  teachers.  He  says  that  it  was  necessary  for  the  Latins 
to  possess  a  short  and  useful  treatise  on  the  languages  other 
than  Latin,  particularly  on  Greek,  Hebrew,  and  Arabic ;  not 
only  because  all  knowledge  they  possessed  was  borrowed 
from  books  written  in  these  idioms,  but  because  their  own 
language  (Latin)  was  based  upon  them.^ 

'  For  the  foregoing  sketch  of  Bacon's  estimate  on  translations 
see  Opus  Majus,  i.  iii.  67  S. ;  ibid.,  iv.  221  (Bridges) ;  Opus  Minus, 
pp.  325,  330-49  ;  Opus  Tertium,  x.  35,  xv.  55,  xxiii.  75-8,  xxv. 
89-95  '    Comp.  Stud.  Phil.,  viii.  465  fE. 

-  Opus  Tertium,  x.  34,  xxv.  88  (Brewer). 

1689  I 


114  ROGER  BACON 

A  treatise  of  that  kind  should  only  contain  the  elements 
of  grammar.  It  would  be  injurious  to  attempt  too  much 
at  first.  The  student  should  not  endeavour  to  master  the 
learned  languages  completely,  so  as  to  know  them  in  the 
same  way  as  he  knew  and  spoke  his  mother  tongue  ;  as  he 
spoke  English,  French,  and  Latin.  Nor  was  it  necessary 
for  the  student  to  be  able  to  translate  scientific  books.  A 
third  and  lower  standard  was  preferable,  and  this  could 
easily  be  attained  under  a  proper  teacher,  and  with  the 
help  of  good  and  concise  manuals.  But  the  student  must 
be  able  to  read  Greek  and  Hebrew,  and  know  the  accidence 
according  to  Donatus.  Once  this  was  acquired,  and  a  proper 
method  followed,  the  construing  and  understanding  of  the 
words  follow  easily.  The  second  degree,  the  capacity  of 
translating,  was  much  more  difficult,  although  not  so  difficult 
as  people  imagined.  But  the  first  degree  was  very  difficult 
indeed  :  it  implied  the  capacity  of  speaking  the  language 
like  the  vernacular,  and  of  using  it  for  teaching  and  preaching 
and  making  speeches.  The  attempt  to  acquire  all  this  would 
only  frustrate  its  object ;  the  student  would  soon  despair, 
and  not  even  reach  the  third  degree. 

'  If  a  person  were  to  apply  himself  from  his  youth  for 
thirty  years,  he  might  attain  all  three  degrees,  or,  at  least, 
the  two  lower  degrees.  It  is  the  first  degree  that  offers  all 
the  difficulty,  as  we  who  have  tried  it  know  from  experience.' ' 

The  problem  of  finding  competent  teachers  of  the  learned 
languages,  although  not  a  difficult  one  to  Bacon  in  one  sense, 
was  far  from  easy  in  another.  Bacon  says  that  the  best 
means  was  to  learn  Greek  from  the  Greeks,  and  Hebrew 
from  the  Jews.  Jews  he  declared  to  be  everywhere,  and 
their  language  was  in  substance  the  same  as  Arabic  and 
Chaldaean.  There  were,  besides,  people  in  Paris,  in  France, 
and  elsewhere  who  knew  sufficient  for  the  purpose.     Greek 

'  Opus  Tertium,  xx.  65  f.  (Brewer) ;  Comp.  Stud.  Phil.,  vi.  433 
(Brewer) . 


PHILOLOGY  115 

accorded  in  most  respects  with  Latin,  and  there  were  persons 
in  England  and  France  who  knew  enough.  In  many  places 
in  Italy  the  clergy  and  population  were  purely  Greek,  and 
it  would  be  worth  the  trouble  to  go  there  for  information. 

And  yet  the  matter  was  not  so  easy  after  all.  Such  of  the 
inhabitants  of  southern  Italy  as  were  veri  Graeci  were  not 
easily  accessible.  Some  of  these  were  still  to  be  found  in 
England,  thanks  to  the  efforts  of  Grosseteste  ;  but  the 
acquisition  of  the  proper  books  and  persons  was  a  task  that 
could  only  be  undertaken  by  prelates  and  wealthy  people.^ 

But  for  educational  purposes  these  Greeks  and  Hebrews 
were,  for  the  most  part,  useless.  They  knew  no  grammar. 
As  there  were  many  laymen  who  spoke  Latin  very  well 
and  yet  had  no  notion  of  the  grammatical  rules  of  that 
language,  in  the  same  way  there  were  only  very  few  Jews 
and  Greeks  who  were  able  to  teach  the  grammar  of  their 
languages  in  a  methodical  and  rational  manner.  Among 
the  Latins  there  were  many  who  could  speak  Greek,  Arabic, 
and  Hebrew,  but  how  many  of  them  knew,  or  could  teach, 
the  grammar  of  these  languages  ?   Not  four. 

Bacon  must  have  early  in  life  conceived  the  idea  of  sup- 
plying the  deficiency,  and  providing  his  contemporaries  and 
a  future  generation  with,  at  least,  elementary  Grammars  of 
the  learned  languages.  He  says  that,  although  he  had  him- 
self studied  for  forty  years,  from  the  time  that  he  first 
learned  the  alphabet,  he  was  yet  convinced  that  within  three 
months  or  half  a  year  he  could  impart  his  own  knowledge  of 
the  sciences  and  languages  by  oral  teaching — provided  he 
had  first  composed  a  text-book,  and  the  student  were  earnest 
and  willing.  Under  such  conditions  he  would  be  able  to 
teach  in  three  days  as  much  Hebrew  as  was  wanted  for 
reading  and  understanding  all  that  was  written  by  the 
saints  and  ancient  sages  in  elucidation  and  correction  of  the 

'  Opus  Tertium,  x.  34 ;  Comp.  Stud.  Phil.,  vi.  434  (Brewer) ;  Greek 
Grammar,  p.  31. 

I  2 


Ii6  ROGER  BACON 

sacred  text.  The  student  would,  however,  have  to  submit 
to  the  prescribed  method.  In  three  more  days  he  would 
teach  sufficient  Greek  for  reading  and  understanding  every- 
thing which  pertains  to  theology,  philosophy,  and  the 
Latin  language.'  Whatever  our  opinion  may  be  as  to  the 
sufficiency  of  three  days  for  the  attainment  of  even  the  most 
elementary  degree,  so  much  is  certain  that  Bacon  himself 
acted  upon  his  suggestion  that  Grammars  should  be 
written. 

There  are  no  traces  in  Bacon's  works  to  show  that  he 
was  interested  in  the  spread  of  a  grammatical  knowledge  of 
modern  languages.  There  can  hardly  be  any  doubt  that  he 
was  an  accomplished  English  and  French  scholar  ;  and  his 
remarks  on  the  dialects  of  several  European  languages,  and 
their  grouping  under  distinct  mother  languages  to  which 
they  are  related,  sufficiently  prove  that  he  had  drawn  them 
within  the  scope  of  his  investigations.  It  is  true  he  anim- 
adverts upon  the  commercial  and  international  advantages 
which  the  commonwealth  of  the  Latins  might  derive  from 
the  study  of  languages,  but  this  fragmentary  notice  seems 
also  to  refer  only  to  the  general  use  which  can  be  made 
of  the  ancient  languages.^  In  another  passage  ■*  he  refers 
to  the  Russians  as  schismatic  Christians,  and  says  that, 
although  they  follow  the  rites  of  the  Greek  Church,  their 
language  is  not  Greek  but  Slavonic.  He  also  makes  some 
remarks  regarding  the  mode  of  writing  in  use  among  the 
Tartars,  and  the  writing  in  pictures  in  vogue  with  the 
Chinese.'^  These  observations,  coupled  with  some  illustra- 
tions in  Norman  French,  and  some  allusions  to  modem 
Greek,  about  which  more  below,  are  all  the  references  we 
find  in  his  works  to  the  languages  spoken  in  his  time. 

Bacon  considered  Latin  his  mother  tongue  by  the  side  of 

'  Opus  Tertium,  xx.  65  (Brewer). 

-  Opus  Majus,  I.  iii.  96  ;  Supplem.  vol.  1 19-120  (Bridges). 

^  Ibid.,  iv.  360,  "  Ibid.  374. 


PHILOLOGY  117 

the  language  of  the  country  in  which  he  was  born.'  The 
Latin  he  employs  in  all  his  writings  is  that  of  the  thirteenth 
century,  and  is  clear,  grammatically  correct,  and  belongs 
to  the  best  specimens  of  mediaeval  Latinity."  He  was 
thoroughly  acquainted  with  a  number  of  Roman  authors, 
of  whose  works  he  makes  ample  use  for  the  purpose  of  illus- 
trating some  rule  of  etymology  or  prosody.^  And  although 
he  complains  that  the  advice  given  by  Boethius  and  Bede 
to  instruct  youths  in  the  writings  of  Seneca  for  the  training 
of  their  morals  was  neglected,  and  that  they  were  taught 
instead  the  fables  and  nonsense  of  Ovid,  which  are  so  full 
of  irreligion  and  immorality  ;  yet  he  himself  did  not  hesi- 
tate to  use  Ovidian  phrases  and  to  cite  his  verses/  Bacon's 
proficiency  in  Latin  grammar  will  again  be  alluded  to.^ 

Bacon's  intention  was  to  compose  grammatical  manuals 
for  the  study  of  Arabic,  Greek,  Hebrew,  and  Chaldaean  ; 
for,  after  having  indicated  the  necessity  for  the  Latins  to 
have  a  sufficient  knowledge  of  the  grammar  of  these  lan- 
guages, he  prefaces  his  Greek  Grammar  ^  and  his  grammatical 

'  Comp.  Stud.  Phil.,  vi.  42,^  {Brev/ev).  Speaking  of  Greek,  Hebrew, 
Arabic,  and  Chaldaean,  he  proceeds  :  Non  tamen  intelligo  ut  quilihei 
sciat  has  linguas  sicut  maternam  in  qua  natus  est,  ut  nos  loquimur 
Anglicum,  Gallicum,  et  Latinum ;  nee  ut  sciamus  tantum  de  his 
Unguis  lit  quilibet  fiat  interpres,  et  transferre  possit  in  linguam 
maternam  Latinam  scientiam  de  Unguis  illis. 

"  Rashdall,  The  Universities  of  the  Middle  Ages,  pp.  595-7  ;  Greek 
Grammar,  Introduction,  p.  Ixxi  f . 

•^  Sir  J.  E.  Sandys,  ut  supra,  p.  573. 

■*  Opus  Tertium,  xv.  55.  Cf.  Sir  J.  E.  Sandys,  ut  supra,  p..  574. 
In  the  Opus  Tertium,  i.  12,  Bacon  quotes  a  verse  as  taken  from 
Ovid's  Tristia,  but  which  is  really  from  Statius.    See  Brewer,  n.  8. 

^  A  grammatical  work  of  considerable  length,  described  as 
Rogeri  Bacon  Summa  de  Grammatica,  exists  in  manuscript  in  Peter- 
house,  Cambridge,  and  in  Worcester  Cathedral.  See  Dr.  M.  R. 
James's  Catalogue  and  Mr.  A.  G.  Little's  Appendix  to  Mr.  Rashdall's 
edition  of  the  Compendium  Studii  Theologiae,  p.  98.  I  could  only 
cursorily  examine  the  Cambridge  MS.,  but  it  requires  a  thorough 
investigation.  Perhaps  I  may  have  an  opportunity  of  dealing  with 
it  on  a  future  occasion.  ^  p.  2. 


Ii8  ROGER  BACON 

treatises  in  the  Compendium  Studii  Philosophiae'  with  the 
remark  that  he  dealt  first  with  Greek  grammar  because  it 
was  the  easiest,  and  more  in  agreement  with  Latin.  This 
imphes  his  intention  of  writing  also  an  Arabic  Grammar. 
There  is  no  indication  in  any  of  Bacon's  acknowledged  works 
that  he  had  accomplished  his  design.  Nor  can  we  at  all  be 
sure  that  his  proficiency  in  Arabic  was  great  enough.  He 
says  that  he  wrote  Greek,  Hebrew,  and  Latin,  but  not 
Arabic.  But  as  he  declares  his  intention  of  dealing  with 
Arabic  on  the  proper  occasion  {locis  s^ns),-  we  may  rest 
assured  that  he  had  acquired  some  knowledge  of  that  lan- 
guage also,  albeit  it  amounted  perhaps  to  no  more  than  what 
he  called  the  third  degree.^ 

With  Greek  it  is  altogether  different.  Here  we  have 
tangible  proofs  of  Bacon's  close  application,  and  ample  data 
by  which  to  estimate  the  standard  of  his  knowledge. 

Let  us  consider  the  judgement  passed  by  Bacon  on  his 
predecessors.  Whenever  he  detects  faults  in  their  works, 
and  attributes  them  to  their  insufficient  knowledge  of 
Greek,  his  remarks  invariably  proceed  from  his  thorough 
mastery  of  the  subject.  On  such  occasions  he  does  not  assail 
the  subject  of  his  criticism  with  kid  gloves  ;  he  shows 
him  the  mailed  fist.  He  never  derides,  he  scourges. 
Bacon  enumerates  the  various  directions  in  which  the  com- 
mon crowd  of  Latin  scholars  wandered  astray.  In  the  first 
place,  they  took  for  Latin,  or  Greek,  or  Hebrew,  or  vice 
versa,  words  which  were  nothing  of  the  kind.  Secondly, 
they  were  at  fault  in  their  derivations,  etymologies,  and 
interpretations.  Thirdly,  their  pronunciation  and  spelling 
were  faulty.     But  it  was  only  partly  their  fault.     They  were 

'  ix.  495  (Brewer). 

-  Opus  Tertimn,  xxv.  88  (Brewer). 

•^  If  Professor  Rieu's  interpretation  of  the  words  quae  vocaniur 
Arabice  Assub  be  correct,  the  appUcation  of  adjectives  in  the  singular 
to  a  plural  noun'j  would  not  show  a  familiar  ^acquaintance  with 
Arabic.    See  Opus  Majus,  ii.  v.  102,  n.  3  (Bridges). 


PHILOLOGY  119 

led  into  error  by  their  foremost  authors,  Papias,  Hugutio, 
and  Brito.  These  were  one  and  all  liars.  Hugutio  was  the 
worst  ;  he  was  at  pains  to  show  that  Latin  texts  were  more 
reliable  than  Greek,  and  Greek  more  reliable  than  Hebrew, 
even  though  the  Greek  be  a  translation  from  the  Hebrew, 
and  the  Latin  translated  from  these  languages.  He  wanted 
to  saddle  Jerome  with  the  same  absurdities  of  which  he 
was  guilty.  He  derived  dogma  from  doceo,  as  if  a  word  in  an 
older  language  could  have  been  derived  from  a  younger ; 
but,  then,  he  thought  dogma  to  be  a  Latin  word.  He  derived 
the  Hebrew  word  Amen  from  the  Greek.  Both  Hugutio 
and  Papias  derived  parasceue  from  the  Latin  paro  and  coena 
=  preparatio  coenae.  Brito  did  not  approve  of  this  etymo- 
logy, but  he  was  no  better  ;  for  he  explained  the  word  Deus  as 
dans  aeternam  vitam  suis.  He  said  that  0e6y  meant  fear. 
Hugutio  and  Papias  said  the  same  ;  and,  Bacon  regrets  to 
say,  Isidore  likewise.  These  people  were  all  Latins,  and 
therefore  ought  either  to  have  adduced  their  authorities 
or  given  the  rationale  of  their  derivations. 

Bacon  himself  assented  to  other  explanations  of  the 
word  6^69.  Either  it  was  derived  from  dico,  '  to  run '  or  '  to 
go  round,'  because  God  comprised  and  protected  the 
universe ;  or  from  aW^iv,  '  to  burn,'  because  God  was 
a  fire,  and  consumed  all  wickedness  {aut  dicitur  ah  '  ethin ' 
quod  est  ardere ;  Deus  enim  est  ignis  consumens  malitiam) ; 
or  from  OedaOai,  '  to  look,'  because  God  considered  and 
perfected  all  things  before  they  were  created.  He  says  that 
these  etymologies  were  correct  and  trustworthy,  because 
they  emanated  from  Johannes  of  Damascus,  himself  a  Greek, 
and  who  was  therefore  able  to  interpret  Greek  words  from 
the  Greek.' 

'  Bacon  had  not  heard  of  the  explanation  given  in  Plato's  Cratylos, 
397  D,  from  dea,  because  God  always  moves,  and  was  first  recog- 
nized, in  the  sun,  moon,  earth,  stars,  and  heaven  ;    nor  that  in 

Herodotus  ii.  52  on  k6(T^(0  deures  to.  navra  npayfiara  koX  ndaas  vofias  eixov. 


120  ROGER  BACON 

Brito,  indignissimus  auctoritate,  derived  the  Hebrew  word 
Gehenna  from  ge,  terra,  and  ennos,  quod  est  profundum,  an 
error  shared  by  Hugutio.  They  both,  with  other  grammati- 
cellae  idiotae,  imagined  the  Hebrew  word  arrabon  (Genesis 
xxxviii.  17)  to  be  arra  bona  [ut  res  quae  datur  pro  coniugio, 
vel  re  bona,  non  pro  mala) .  Other  authors  of  Greek  dictionaries 
also  included  this  word,  as  if  it  were  Greek.  Hugutio  and 
others  showed  what  jackasses  they  were  [et  in  hoc  ostendunt 
se  esse  asinos)  by  averring  that  the  purely  Latin  word  coelum 
was  casa  helios,  and  Brito  gave  an  alternative  derivation 
of  tus,  turis,  from  Oeos."^  Bacon  relates  that  Johannes  de 
Garlandia  had  told  him  that  he  had  blamed  our  trio  for 
spelling  the  word  orichalcum  :  auricalcum,  and  deriving  it 
fancifully  from  aurum  and  calcum.  He  further  takes  these 
authors  to  task  for  their  blunders  in  spelling,  scansion,  and 
etymology,  and  adds  to  them  a  fourth  culprit,  Alexander 
Neckham,  whom  Brito  quoted  as  an  authority  because  he 
was  his  equal  in  making  mistakes.^ 

It   cannot   be   denied  that   Bacon  himself  occasionally 

erred  in  the  same  way.     Thus,  in  the  Opus  Minus,^  when 

describing   Origenes'   sixfold   edition   of   the   Bible,   called 

Hexapia,  he  took  this  word  to  be  a  compound  of  '  hex  ' 

simul  ordine  conscripta,  et '  aplum '  idem  quod  simul.     Later, 

he  must  have  become  aware  that  apla  does  not  mean  simul, 

and   we   find   in   the    Cambridge  fragment   of   his    Greek 

Grammar  :  "*   '  hex '  enim  Graece  idem  est  quod  sex  Latine,  et 

'  aplum '  idem  quod  simplex,  '  six  translations  in  one ',  and 

not    '  six    versions    simultaneously    exhibited '.      But    he 

adheres  to  the  erroneous  derivation  of  the  word.     He  gives 

the  genitive  of  the  word  /3a)^  as  ^cokto9  after  the  analogy 

of  j/y|,  VVKT09,  instead  of  /Sco^oy.^     The  false  quantity  in  the 

'  Bacon  then  quotes  Servius  for  the  derivation  of  tus  from  tundere. 

'  Comp.  Stud.  Phil.,  vii.  446-64,  and  passim  in  his  other  works. 

'  P-  337  (Brewer). 

*  Greek  Grammar ,  pp.  191,  192. 

5  Ibid.,  p.  145. 


PHILOLOGY  121 

word  mathesis  {et  ab  hoc  nomine  mathesis  media  correpta)  he 
corrected  himself.'  But  such  instances  are  extremely  rare, 
and  his  corrections  of  the  errors  of  his  predecessors  display 
his  thorough  acquaintance  with  Greek  forms. 

It  is  not  only  this  intimate  knowledge  of  the  language, 
but  also  his  keen  critical  powers  that  are  proved  by  his 
inexorable  condemnation  of  most  of  the  existing  translations. 
It  would  be  superfluous  to  multiply  examples  ;  a  few 
remarks  will  suffice.  His  horror  of  translations  is  particu- 
larly pronounced  in  reference  to  Aristotle,  and  he  dwells 
upon  one  passage,  which  touches  upon  an  important  point 
of  mediaeval  controversy.  He  says  that  most  of  the 
commentators  of  Aristotle's  De  Anima  (iii.  5)  were  under 
the  impression  that  he  meant  to  convey  that  the  intellectus 
agens  and  the  intellectus  possibilis  were  both  of  them  parts 
of  the  soul.  This,  he  says,  was  an  error  ;  what  Aristotle 
taught  was  that  the  intellectus  agens  came  from  without,  and 
was  not  a  part  of  the  soul.  The  intellectus  agens  was,  in  the 
first  place,  God  ;  and  in  the  second  place,  the  angels.  God's 
relation  to  the  soul  could  be  compared  to  that  of  the  sun  to 
the  eye,  and  that  of  His  angels  to  the  stars.  It  was  a  mistake 
of  omnes  moderni  to  assume  that  the  intellectus  agens  was 
a  part  of  the  soul ;  but  those  who  were  better  informed  did 
not  share  the  error,  such  as  the  venerable  Bishop  of  Paris, 
William  of  Auvergne,  and  Robert  Grosseteste,  and  Adam 
Marsh  ;  and  when  some  presumptuous  Franciscans  asked 
the  latter  what  the  meaning  was  of  intellectus  agens,  he 
answered  that  it  was  Elijah's  raven.  Bacon  sets  forth  that 
the  fault  of  these  moderni  lay  in  a  misinterpretation  of  the 
translation  of  Aristotle's  words.  From  the  phrase  quoniam 
autem  in  omni  natura  est  '  aliquid  quod  agat,  et  aliquid  quod 
patiatur  ',  ita  erit  in  anima,  they  concluded  that  the  agens 
and  the  patiens  were  both  in  the  soul,  and  that  they  formed 
parts  of  it.  But  if  they  had  considered  the  whole  of 
'  Opus  Majus,  I.  iv.  239  n.  i  (Bridges). 


122  ROGER  BACON 

Aristotle's  words  in  their  context  their  tenor  would  have 
shown  them  the  real  meaning.' 

Having  referred  to  a  mistranslation  in  regard  to  the  sur- 
faces of  plane  and  solid  figures,  he  proceeds  to  point  out 
a  ridiculous  mistake  about  the  recurrence  of  a  lunar  rainbow. 
The  words  SioTrep  eu  'ireaiv  virlp  ra  TrevTTqKovra  Sls^  kveTvyp^ev 
fiouov  {Meteor,  iii.  2)  were  translated  so  as  to  convey  the 
meaning  that  a  lunar  rainbow  could  only  occur  twice  in  fifty 
years,  whereas  it  is  clear  that  Aristotle  merely  said  that  for 
upwards  of  fifty  years  the  phenomenon  had  only  been 
observed  twice.-  It  is  unnecessary  to  give  more  examples 
of  mistranslations  from  the  Greek  commented  on  by  Bacon.^ 

Of  the  Grammars  of  the  four  learned  languages  which  it 
was  Bacon's  intention  to  write,  we  possess  only  a  tolerably 
complete  specimen  of  his  Greek  Grammar.  This  may  be 
due  to  the  circumstance  that  he  wrote  it  first  '  because  it 
was  easier,  and  more  in  accordance  with  Latin  '  ,^  and  could 
not  at  a  later  time  give  full  effect  to  his  design.  Or  the 
reason  may  be  that  the  fatality  attaching  to  books  played 
havoc  with  the  others,  and  caused  them  to  disappear.  He 
desired  his  Greek  Grammar  to  be  useful  to  the  Latins  ;  a  com- 
parison of  Greek  and  Latin  grammar  was  therefore  indis- 
pensable ;  and  the  grammar  of  all  languages  was  the  same 
in  substance,  the  divergences  being  merely  accidental. 
Besides,  Latin  grammar  was  modelled  after  that  of  Greek. ^ 

It  is  a  characteristic  peculiar  to  Bacon  that  he  frequently 

'  Opus  Tertium,  xxiii.  74-6  (Brewer)  ;  Opus  Majus,  i.  ii.  38  ff. 
(Bridges).  The  passage  in  De  Anima  which  Bacon  refers  to  runs  : 
fTret  S'  acnrep  iv  andcr]]  ttj  (pvcrfi  eariTi  to  fifv  vXtj  exaoTo)  -yeVei  {tovto  8'  6  navrn 
Bvvdfiei  (Kelva),  erepov  8e  to  oItiov  koi  iroirjTiKov  t(S  iroieiv  vrdvTa,  olov  f)  Te;^!'?; 
Trpos  TTjv  vXrjp  irenovdev,  dvdyKri  koi  ev  ttj  "^vxfj  virapxeiv  ravras  Tas  8ia(f)opds. 

-  Opus  Tertium,  xxiii.  yy  (Brewer)  ;  Opus  Majus,  i.  iv.  212 
(Bridges).  A  lunar  rainbow  was  observed  in  Huntingdonshire  on 
the  8th  of  January  of  this  year. 

^  p.  124  (Brewer). 

"*  Comp.  Stud.  Phil.,  ix.  495  (Brewer)  ;  Greek  Grammar,  p.  3. 

^  Greek  Grammar,  p.  27. 


PHILOLOGY  123 

repeats  in  one  work,  sometimes  in  an  amplified,  sometimes 
in  an  abbreviated  form,  and  at  other  times  even  verbatim, 
that  which  he  has  dealt  with  elsewhere.  This  is  particularly 
the  case  with  Greek  grammar.  He  deals  with  the  subject 
in  the  Opus  Tertium  ;  '  a  fuller  treatment  of  the  whole 
subject  is  preserved  in  part  in  the  Compendium  Studii 
Philosophiae,^  and  a  few  brief  remarks  occur  in  the  third 
part  of  the  Opus  Majus.  The  most  elaborate  treatise  we 
possess  is  his  Greek  Grammar,  a  great  portion  of  which  is 
preserved  in  an  Oxford  manuscript,  while  a  small  fragment 
has  been  discovered  in  the  University  Library  at  Cambridge, 
Thus  a  chapter  on  certain  long  and  short  vowels,  intended 
to  correct  some  vulgar  errors,  is  found  in  exactly  the  same 
form  in  the  Greek  Grammar  ^  and  in  the  Compendium  Studii 
Philosophiae^  Another  section  in  the  Greek  Grammar, 
dealing  with  the  same  matter,  is  nothing  but  an  amplification 
of  the  sixty-third  chapter  of  the  Opus  Tertium.  Some  points  of 
orthography  and  scansion  are  dealt  with  in  the  Compendium  ^ 
and  reproduced  in  the  Greek  Grammar,*^  as  is  also  another 
lengthy  discussion  on  a  similar  topic.  The  lacuna  in  the 
Oxford  manuscript  at  the  end  of  Part  II  contained  probably 
rules  on  punctuation,  and  may  be  filled  in  from  the  sixty- 
second  chapter  of  the  Opus  Tertium.  A  further  number  of 
parallel  passages  will  probably  be  found  when  the  Toulouse 
manuscript,  of  which  Samuel  Berger  has  given  some  extracts, 
will  have  been  published.^  For  whether  some  parts  of  the 
contents  of  that  work  be  ascribed  to  Roger  Bacon,  or  to  one 
of  his  followers,  it  is  certain  that  the  leading  points  originated 
with  Bacon. 

Such  repetitions,  such  overlapping,  are  due  to  his  own 
method  of  working,  to  a  careless  intercourse  with  friends, 

'  Ix.  236-8  (Brewer).  -  vii.  451-519  (Brewer). 

^  pp.  98  ff.  *  pp.  461-4  (Brewer). 

5  pp.  454-9  (Brewer).  ''  pp.  101-4. 

'  Samuel    Berger,    Quam    noiitiam    linguae    Hebraicae    habuerint 
Christiani  medii  aevi  in  Gallia,  Paris,  1893. 


124  ROGER  BACON 

and  to  frauds  of  unscrupulous  copyists.'  He  says  that 
many  copyists  were  required,  and  many  proofs  had  to  be 
prepared,  before  the  final  copy  could  be  completed  in  a 
finished  form.^  He  was  very  careful  in  the  revision  of  the 
proofs,  and  it  was  often  only  the  fourth  or  fifth  that  met 
with  his  final  approval.  But  some  of  the  copyists  were  not 
trustworthy,  and  occasionally  kept  the  copies,  or  gave  them 
away  to  strangers.^  Before  delivering  his  works  to  the  pro- 
fessional copyists,  he  was  in  the  habit  of  composing  several 
drafts  of  what  he  intended  to  publish  ;  they  were  frequently 
disconnected  jottings,  written  for  the  use  of  pupils,  or  at 
the  request  of  friends.  Not  attaching  much  importance 
to  them,  he  neglected  them  and  did  not  retain  them.  But 
worst  of  all  was  the  treachery  of  fraudulent  copyists.'* 

In  the  case  of  Bacon  the  further  distinction  must  be 
made  between  cursory  treatises  on  the  subjects  that  came 
under  his  consideration  and  their  exhaustive  esoteric  treat- 
ment that  was  to  form  his  Scriptum  Principale.  His  inten- 
tion was  to  supply  both  classes  of  writings,  and  a  repetition 
of  the  same  matter  must  needs  follow. 

The  Greek  Grammar  preserved  in  Corpus  Christi  College, 
Oxford,  and  published  in  1902,  is  in  the  main  a  treatise  on 
the  comparative  grammar  of  the  Greek  and  Latin  languages.^ 
Youths,  when  taught  Latin,  are  first  introduced  to  the 
elements  of  writing,  reading,  and  construing  easy  sentences ; 
the  same  method  should  be  followed  in  Greek.  Bacon 
therefore  started  with  the  Greek  alphabet,  classifying 
the  letters,  and  giving  their  shapes,  their  names,  and  their 
numerical  values.  We  must  be  rather  doubtful  as  to  the 
share  the  copyists  bear  in  the  shaping  of  the  letters.     They 

'  Greek  Grammar,  Introduction,  p.  xxxvi  f . 
"  Opus  Tertium,  xvi.  57  (Brewer), 
^  Ibid.,  ii.  13  (Brewer). 

"  F.  A.  Gasquet,  '  An  Unpublished  Fragment  of  a  Work  by  Roger 
Bacon,'  in  the  English  Historical  Review,  xii.  (1897)  500,  501. 
5  Brewer,  Opera  Inedita,  Introduction,  p.  Ixiv. 


PHILOLOGY  125 

differ  in  form  from  those  given  in  the  manuscripts  of  the 
Opus  Majus '  and  in  the  Cambridge  fragment.^  It  is  of 
interest  to  compare  them  with  the  characters  exhibited  in 
his  specimen  of  Greek  palaeography,  at  the  end  of  the 
Compendium  Studii  Philosophiae,  '  the  earUest  in  all  proba- 
bility extant  in  Western  Christendom,'  and  '  an  instance  of 
the  minute  accuracy  with  which  he  prosecuted  these  philo- 
logical studies,  and  the  care  he  had  taken  in  examining 
manuscripts '  ? 

The  alphabet  is  followed  by  the  accents  and  abbreviations 
in  writing  (pp.  9-12) ;  the  article,  some  directions  regarding 
writing  and  reading,  and,  as  reading  lessons,  the  Greek  text 
of  '  Pater  noster,  Ave  Maria,  Credo,  Magnificat,  Nunc  dimittis, 
et  Benedictus,  quae  sunt  fundamenta  fidei ' ,  with  transliteration 
and  translation  (pp.  12-24).  Then  follow  the  letters  of  the 
alphabet  and  their  numerical  values.  The  names  given  to  the 
numerals  are,  roughly,  the  same  as  in  modern  Greek  :  e.  g. 
ena,  dio,  tria,  tessara,  &c.  ;  icossi,  trianda,  salanda,  pindinda, 
&.C.  (pp.  24,  25).  Here  Bacon  takes  the  opportunity  of  com- 
plaining of  the  ignorance  of  bishops  of  even  the  letters  of 
the  Greek  alphabet,  which  tends  to  interfere  with  a  proper 
performance  of  an  important  rite  of  the  Church."*  It  is  the 
duty  of  the  bishop,  when  consecrating  a  church,  to  write 
with  his  pastoral  staff  the  letters  of  the  Greek  alphabet  in 
small  heaps  of  sand  or  ashes.  But,  in  their  ignorance,  they 
perverted  the  shape  of  the  letters,  with  which,  besides,  they 
jumbled  up  the  numerals.^ 

'  For  those  in  the  Vatican  MS.,  see  frontispiece  to  Opus  Majus, 
vol.  iii,  ed.  Bridges  ;  and  those  in  the  Cottonian  MS.,  S.  A.  Hirsch, 
A  Book  of  Essays,  p.  65. 

'-■  Greek  Grammar,  pp.  184,  185. 

^  Brewer,  Opera  Inedita,  p.  Ixiii. 

■*  Bacon  is  much  concerned  about  this.  He  vents  his  dissatis- 
faction three  times  in  this  Grammar  (pp.  25,  81,  83),  and  alludes  to 
this,  and  the  errors  arising  therefrom  quod  esse  non  potest  sine 
injuria  sacramenti,  in  the  Opus  Majus,  i.  iii.  94  (Bridges). 

^  Greek  Grammar,  Introduction,  p.  Ixxiii, 


126  ROGER  BACON 

Before  proceeding  with  the  rules  of  accidence,  Bacon  makes 
some  remarks  on  idioms,  on  the  necessity  of  comparing 
Greek  and  Latin  grammar,  on  distinctions  in  reference  to  the 
'  voice  ',  and  on  the  difference  between  elementum  and  litera. 

An  idiom  is  the  distinct  way  in  which  a  race  of  men  make 
use  of  a  language,  according  to  their  customs  {Idioma  est 
froprietas  linguae  determinata  qua  una  gens  utitur  juxta 
suam  consuetudinem) ,  another  race  using  the  same  language 
in  a  different  way.  Each  language  has  as  many  idioms  as 
there  are  races  that  use  it.  All  languages  spoken  between 
Apulia  and  Spain  are  in  substance  Latin,  and  diversified 
only  as  idioms.'  Chaldaean  and  Hebrew  are  idioms  of  the 
same  language,  in  the  same  way  as  Picardian,  Norman, 
Burgundian,  Parisian,  and  French  are  idioms  of  the  common 
language,  French.^  It  is  the  same  with  the  Greeks  ;  they 
had  one  language  in  substance,  but  various  ways  of  using 
it.  Of  these,  five  idioms  were  especially  famous :  Attic,  Aeolic, 
Doric,  Ionic,  and  the  idiom  in  use  among  the  Boeotians. 
It  was  of  the  utmost  importance  to  know  this,  because  of  its 
utility  to  the  Latins.  For,  after  all,  Latin  grammar  was 
based  upon  that  of  Greek,  and  a  comparison  of  Greek  and 
Latin  grammar  is  imperative  for  the  understanding  both 
of  Greek  and  of  Latin  grammar  ;  and  this  co7tsideration  was 
the  chief  motive  for  writing  the  present  treatise  (p.  27). 

In  regard  to  the  division  of  words.  Bacon  rejects  some  of 
Priscian's  definitions  and  prefers  those  of  Boethius,  who  was 
majoris  auctoritatis  et  in  Unguis  et  in  scientiis.  A  word 
(vox)  is  articulate  when  it  can  be  written  down  in  letters, 
whether  it  convey  a  meaning  or  not.  It  is  then  a  Ae^ty. 
A  letter,  in  writing  and  shape,  is  the  smallest  part  of  an 
articulate  word  ;  but  its  sound  is  an  element.  The  sign  a, 
when  put  down  in  ink,  or  by  means  of  the  style,  is  a  letter, 

'  Opus  Teriium,  xxv.  88  (Brewer). 

'  Cf.  Comp.  Stud.  Phil.,  vi.  438.  Cf.  Opus  Majus,  I.  iii.  66 
(Bridges). 


PHILOLOGY  127 

but  the  sound  with  which  we  express  that  letter  by  the  voice 
is  an  element  (pp.  28,  29).  Of  course  we  must  go  back  for 
such  distinctions  of  Bacon's  to  the  grammatical  disquisitions 
of  the  Stoics.  After  this  Bacon  deals  in  detail  with  both 
Latin  and  Greek  letters,  with  the  classification  of  vowels 
and  consonants,  with  spelling  and  similar  matters  (pp.  29-56). 

The  next  chapter  is  devoted  to  a  critical  examination  of 
a  treatise  on  Greek  grammar,  which  professes  to  be  a  transla- 
tion of  a  work  by  Aristotle.  Bacon  proves  that  it  could  not 
have  been  written  either  by  Aristotle  or  by  any  Greek  ;  it 
was  nothing  but  a  compilation  by  some  Latin  author  out  of 
his  own  head.  He  investigates  the  order  of  sciences,  in  order 
to  arrive  at  grammar.  But  grammar  came  first  in  the 
curriculum  of  instruction  ;  it  was  therefore  impossible  for 
a  pupil  when  learning  grammar  to  understand  the  properties 
of  other  branches  of  learning  which  are  taught  at  a  later 
stage,  and  only  a  fool  would  begin  his  instruction  in  grammar 
with  a  division  of  other  sciences.  Everything  set  forth  by 
that  author.  Bacon  avers,  was  either  false  or  futile  or  absurd  ; 
and  this  could  be  easily  gathered  from  his  (Bacon's)  treatise 
on  Metaphysics,  and  some  other  of  his  dissertations  on  the 
division  of  sciences.  He  would  omit  pointing  out  the  errors 
the  author  committed  in  some  of  his  high-sounding  remarks 
on  the  effects  of  the  celestial  bodies  on  sound  and  voice. 
They  had  been  refuted  elsewhere,  and,  moreover,  did  not 
belong  to  grammar  in  the  narrower  sense  of  the  word.' 

In  a  large  section  of  his  Grammar  (pp.  59-95)  Bacon 
exposes  numbers  of  errors  in  writing  and  speaking  certain 
Greek  words,  particularly  such  as  have  a  y,  although  other 
words  are  also  considered.  The  passage  also  deals  with 
computation  by  means  of  Greek  letters,  and  gives  ample 
rules  about  the  diphthongs.     In  his  remarks  about  words 

'  On  an  apparent  contradiction  between  this  passage  and 
Bacon's  observations  in  Opus  Tertium,  xxvi.  97,  see  Greek  Grammar, 
Introduction,  pp.  xxviii-xxix. 


128  ROGER  BACON 

with  y  he  follows  an  alphabetical  order,  but  in  regard  to  other 
words  he  states  that  he  would  not  continue  alphabetically, 
but  put  down  the  words  as  they  occurred  to  him,  as  he 
intended  to  compose  an  alphabetical  vocabulary  of  all 
Greek  words  that  were  in  use  with  the  Latin  scholars  (p.  68). 

We  cannot  say  whether  he  completed  it,  but  it  is  certain 
that  he  commenced  it,  for  the  grammatical  treatise  inserted 
in  the  Compendium  Studii  Philosophiae  contains  an  alpha- 
betical list  of  Greek  words  in  common  use  with  the  Latins, 
another  list  of  ecclesiastical  terms,  and  a  number  of  gram- 
matical, logical,  mathematical,  and  similar  terms,  without 
alphabetical  order.' 

A  lexicon  in  the  possession  of  the  College  of  Arms  in 
London  (Arundel,  ix)  was  thought  to  be  the  vocabulary 
in  question.^  But  Dr.  M.  R.  James,  in  a  description  and 
analysis  of  this  manuscript,  decides  against  the  assumption.' 
Dr.  James  is  of  opinion  that  there  was  no  evidence  to  show 
that  Roger  Bacon  was  concerned  with  this  lexicon  ;  nor  did 
the  lexicon  show  any  traces  of  borrowing  from  his  works, 
and  more  especially  his  Greek  Grammar.  Dr.  James  sup- 
poses the  author,  or  rather  the  compiler,  to  have  been 
a  member  of  Robert  Grosseteste's  circle  ;  not  Grosseteste 
himself,  but  a  younger  contemporary. 

Another  large  portion  of  the  Greek  Grammar  is  taken  up 
by  Bacon's  treatment  of  accentuation  and  prosody  (pp.  95- 
144),  and  no  wonder !  *  The  subject  was  of  particular  interest 
to  him.  Besides  many  other  authorities  he  particularly 
refers  to  Augustine,'  who  said  that  the  rules  concerning  length 

'  Comp.  Stud.  Phil.,  vi.  441  ff.  (Brewer). 

-  Greek  Grammar,  Introduction,  p.  xxxvi. 

^  '  A  Graeco-Latin  Lexicon  of  the  Thirteenth  Century,'  in  the 
Melanges  offerts  a  M.  ^mile  Chatelain  .  .  .  par  ses  Sldves  et  ses  amis, 
Paris,  1910,  pp.  396  £f. 

*  The  subject  is  also  dealt  with  at  length  in  the  Opus  Tertium, 
Ix-lxiv.  234-8,  and  Comp.  Stud.  Phil.,  vii.  461-4,  Cf,  Opus  Majus, 
I.  iii.  90  (Bridges). 


PHILOLOGY  129 

and  brevity  of  vowels  belonged  rather  to  the  theory  of 
music  than  to  grammar.  The  musician  provided  the  art, 
the  grammarian  was  the  mechanic.^  Not  only  song,  but 
also  metre,  rhythm,  and  accentuation  were  properties  of  the 
human  voice.  Consequently  length  and  brevity  of  the 
vowels,  and  everything  appertaining  to  proper  pronuncia- 
tion, were  parts  of  the  science  of  music.''  But,  Bacon  com- 
plains, it  would  be  much  easier  to  impart  to  the  people  a 
sufficient  knowledge  of  Perspective,  although  it  be  one  of  the 
important  disciplines  of  which  they  knew  nothing,  than  to 
teach  them  this  particular  branch  of  music,  although  every- 
body learned  the  much  slighted  science  of  grammar  from 
his  youth.^ 

Bacon  follows  up  some  definitions  and  rules  with  a  list 
of  errors  commonly  committed  in  metre  in  which  Brito, 
Papias,  and  Hugutio  come  in  for  their  customary  share  of 
vituperation.  He  corrects  erroneous  notions  on  the  quan- 
tities of  a  number  of  words  in  use  among  the  Latins,  on 
quantities  of  vowels  when  followed  by  consonants,  and 
on  aspiration  and  accentuation. 

Of  the  third  part,  which  follows  next,  the  first  and  second 
distinctiones  and  a  portion  of  the  third  are  missing  in  the 
manuscript.  They  must  have  contained  the  rules  about 
the  declension  of  nouns.  What  we  possess  of  it  is  a  continua- 
tion of  the  rules  on  the  genitive.  He  mentions  the  system 
of  declension,  which  is  that  of  the  Kavov^s  da-aycoyLKoi  of 
Theodosius,  i.e.  35  masculine  declensions,  12  feminine,  and 
9  neuter.  He  does  not,  however,  quote  Theodosius  by 
name,  but  only  says  that  the  system  is  in  use  among  the 
Graeci  moderni.  He  himself  prefers  a  simpler  system  of 
three  declensions.     An  account  of  the  synaeresis  follows.'* 

'  Opus  Tertium,  lix.  231  (Brewer). 

^  Opus  Majus,  I.  iv.  237  (Bridges)  ;  Greek  Grammar,  p.  96. 

^  Opus  Tertium,  Ix.  234  (Brewer). 

■*  Which  is  out  of  place  here.    See  Greek  Grammar,  p.  147,  n.  2. 

1689  K 


130  ROGER  BACON 

Compound  nouns,  nine  classes  of  derivative  nouns,  pronouns, 
and  the  verb  are  discussed  at  length  (pp.  158-82). 

In  reference  to  the  verb.  Bacon  assumes,  after  Priscian, 
thirteen  conjugations,  which  he  describes  seriatim,  and  deals 
with  the  voices,  moods,  and  tenses.  He  modifies  his  first 
intention  of  giving  paradigms  of  all  the  classes  of  verbs.  This, 
he  says,  was  undesirable,  first,  on  account  of  their  number, 
and,  secondly,  because  of  the  difficulty  of  understanding 
them  ;  that  this  grammar  was  only  elementary,  and  no 
beginner  would  be  able  to  master  them  all.  He  refers 
students  to  his  larger  treatise,  if  they  should  want  more  in- 
formation. The  present  one  was  written  to  serve  the  require- 
ments of  the  Latins,  so  as  to  enable  them  to  understand  any 
Latin  text,  the  expositions  of  the  saints,  the  grammarians, 
the  poets,  and  the  other  sages  ;  and  such  students  did  not 
want  to  study  all  conjugations.  He  would  therefore  give 
only  one  conjugation  in  Greek  letters,  and  another  in  Latin 
characters.  He  gives  the  forms  of  tvtttco,  following  one  of 
those  manuals  in  which  the  rules  laid  down  by  Dionysius 
Thrax  and  his  immediate  followers  were  rendered  in  the 
form  of  a  catechism  [epcoTiJixaTa).  He  calls  its  author  simply 
Graecus^     No  more  has  been  preserved  in  the  manuscript. 

It  is  unnecessary  to  give  a  description  of  the  Cambridge 
fragment  of  Bacon's  Greek  Grammar.  It  is  evidently  a  draft 
of  some  passages  occurring  in  the  third  part  of  the  Opus 
Majus,  or  of  his  Greek  Grammar.  There  is,  however,  one 
point  of  interest.  In  the  interlineary  reading  lessons  in  the 
Oxford  Grammar,  the  Greek  text  forms  the  lowest  line,  the 
transliteration  in  Latin  characters  the  middle  line,  and 
the  Latin  translation  the  first  line.     Whenever  the  article 

'  Greek  Grammar,  p.  173  :  Sicni  igitiir  Graecus  ante  formationem 
coniugationis  secundum  hoc  verhum,  quaerit  de  hoc  vocabulo,  cuius 
sit  partis  oraiionis,  et  cuius  modi,  et  cuius  significationis,  &c.   .  .  . 

Quaerit  igitur  Graecus  :  tvuto},  iroiov  fiipovs  \6yov  tarl  ;  pr/fiaros'  noias 
€yK\ia(ois',  opuTTiKqs,  &c.,  winding  up  with  the  usual  form  :  Kavovi((Tai. 
Cf.  Greek  Grammar,  Introduction,  pp.  Ixii  ff. 


i 


PHILOLOGY  131 

occurs  in  the  Greek  text  it  is  transliterated  in  the  middle 
line,  but  in  the  first  line  it  is  only  indicated  by  a  blank  space.' 
But  in  the  Cambridge  fragment  the  Greek  article  is  indicated 
by  the  syllable  ar  —  articulus,  e.  g.  In  nomine  ar  Patris,  et  ar 
Filii,  &c.  It  is  noteworthy  that  the  same  method  is  followed 
in  the  Toulouse  manuscript  ;  *  and  in  the  literal  translation 
of  the  Hebrew  Bible,  a  work  of  the  second  half  of  the 
thirteenth  century,  portions  of  which  are  extant  in  Oxford 
and  Cambridge,  this  syllable  is  used  not  only  to  indicate 
the  article  but  also  the  particle  eth  ;  for  instance,  Creavit 
Deus  ar  celum  et  ar  ar  terram. 

It  should  also  be  observed  that  Bacon's  pronunciation  of 
Latin  was  that  common  on  the  Continent.  Both  his  trans- 
literations of  Greek  and  of  Hebrew  show  this.  On  rendering 
the  Latin  equivalents  of  the  Hebrew  vowels,  he  says  that 
they  have  the  sounds  quinque  vocalium  nostrarum  a,  e,  i,  0,  u, 
implying  the  sounds  these  letters  have  abroad.^ 

This  leads  to  the  question  of  Bacon's  pronunciation  of 
Greek.  It  has  already  been  observed  that  the  names  he 
gives  of  the  numerals  are,  on  the  whole,  those  of  the  Greeks 
of  his  day.  The  same  is  the  case  with  his  pronunciation  of 
Greek.  Two  centuries  after  Bacon,  Johann  Reuchlin,  one 
of  the  representatives  of  the  more  successful  renaissance  of 
letters,  introduced  the  style  of  pronouncing  Greek  which 
has  since  received  the  name  of  Itacism,  and  which  was 
commonly  called  the  Reuchlinian  pronunciation,  in  distinc- 
tion from  the  Etacism,  introduced  by  Erasmus.  Both  modes  of 
pronunciation  were  known  to  Bacon,  and  he  gives  the  prefer- 
ence to  the  former,  in  spite  of  the  tradition  of  the  Latins/ 

'  Greek  Grammar,  p.  14  :  Secundum  iamen  quod  ariiculi  non 
construuntur  hie  sicut  reliquae  dictiones,  quoniam  in  Latino  non  sunt, 
et  idea  Latinis  Uteris  tantum  scribuntur  in  seciinda  linea,  sed  in  prima 
nihil  eis  respondet.  ^  Samuel  Berger,  ut  supra. 

^  S.  A.  Hirsch,  A  Book  of  Essays,  pp.  61,  62. 

*  Greek  Grammar,  pp.  31,  32,  Introduction,  p.  xx ;  Bridges, 
Introduction  to  the  Opus  Majus,  p.  i,  n.  i. 

K  2 


132  ROGER  BACON 

Bacon's  indebtedness  to  his  Greek  acquaintances  should 
not  be  overrated.  He  owed  them  much,  but  he  owed  much 
more,  in  the  first  place,  to  the  analytical  powers  of  his  vast 
intellect,  and,  in  the  second  place,  to  his  study  of  books 
on  grammar. 

The  former  enabled  him  to  perceive  the  formation  and 
construction  of  words  and  sentences  when  endeavouring 
by  their  means  to  arrive  at  the  true  meaning  of  the  works 
he  read.  Hence  his  trenchant  criticisms  of  such  mistaken 
interpretations  as  might  have  been  avoided  if  an  adequate 
knowledge  of  the  language  had  guided  the  reader  or  trans- 
lator. His  scrutiny  of  such  Greek  works  as  were  accessible 
to  him  was  carried  on  with  conscientious  care,  both  regarding 
the  letter  and  the  spirit.  He  was  aware  how  limited  a  por- 
tion of  Greek  literature  was  at  his  disposal ;  and  he  never 
ceased  to  appeal  for  the  search  for  and  the  acquisition  of 
new  books.  He  seems  to  have  had  no  copy  of  Homer  in 
the  original ;  many  other  works  he  knew  only  from  transla- 
tions ;  but  he  had  an  intimate  knowledge  of  the  few  Greek 
books  that  were  within  his  reach,  in  particular  some  of  the 
authentic  and  a  few  of  the  spurious  works  of  Aristotle. 
His  Latin  reading  had  a  much  wider  range.'  Hence  it  is  that 
in  his  Grammar  he  demonstrates  his  observations  on  Greek 
orthography  and  prosody  by  quotations  from  Latin  and  not 
from  Greek  authors.^ 

Bacon  gives  a  list  of  the  principal  authorities  on  grammar 
consulted  by  him,  and  of  the  authors  whose  productions  he 
refers  to  as  standard  works. ^  He  names  Bede,  Priscian, 
Donatus,  Servius,  Lucan,  Juvenal,  Statins,  Horace,  Persius, 

'  Sir  J.  E.  Sandys,  ut  supra. 

'  A  verse  of  Callimachus,  quoted  by  Bacon  from  Priscian,  led 
to  a  curious  misunderstanding  [tujs  fiev  6  Mvrja-cipxfios  ((prj  ^tvos,  &§«, 
avvaivo))  .  .  .  Callimachus  poeta  Graecus,  Omnes,  quod  est  nomen 
proprium  viri  in  Graeco,  breviavit,  sicut  docet  Priscianus.  Greek 
Grammar,  p.  40  ;    cf.  p.  95,  and  Introduction,  p.  Ixxiv. 

^  Greek  Grammar,  p.  37. 


PHILOLOGY  133 

Juvencus,  Arator,  Piudentius,  Paulinus,  Prosper,  Sedulius, 
Isidore,  and  Plinius.  This  list  is  not  exhaustive,  but  he 
cites  these  '  as  ancient  and  reHable  authorities,  who  had 
a  thorough  knowledge  of  Greek  grammar,  and,  consequently, 
of  Latin  grammar '.  But  he  refuses  to  acknowledge 
Hugutio,  Papias,  and  Brito  as  authorities.  Priscian's  name 
appears  almost  on  every  page  of  his  Grammar,  but  he  does  not 
blindly  follow  him.  He  declares  him  to  be  more  of  a  compiler 
than  an  author,  saying  that  he  reproduced  the  opinions  of 
others,  from  which  he  selected  what  he  deemed  to  be  correct, 
but  that  he  sometimes,  though  rarely,  made  mistakes,  and 
should  not  be  followed  in  every  case.'  Servius,  whom 
Priscian  frequently  cited,  was  a  greater  authority ;  so  was 
Boethius ;  and  whenever  the  latter  differed  from  Priscian, 
his  view  should  be  adopted.^  But  Bede's  authority  surpassed 
all  of  them.  He  was  most  learned  in  languages  and  gram- 
mar.^ Bacon  thought  him  to  have  been  older  than  Priscian. 
Neither  among  the  '  Latin  '  poets  nor  among  grammarians 
was  there  anybody  greater  than  he  ;  he  was  a  much  greater 
scholar  than  Priscian,  both  in  theological  and  secular 
subjects.'' 

Bacon  also  made  use  of  other  grammatical  works,  which 
he  does  not  quote  by  the  names  of  their  authors,  but  simply 
alludes  to  as  Graeci  audores  in  grammatica  eorum.  But 
whilst  citing  them,  he  deems  it  necessary,  at  the  same  time, 
to  explain  Priscian's  rules,  so  as  to  save  misunderstandings.^ 
Several  of  such  manuals  must  have  been  included  in  those 
which  Grosseteste  had  caused  to  be  imported  from  Greece.*" 
The  knowledge  of  some  of  these  grammarians  must  have 
been  rather  feeble  ;    for,  misled  by  the  similarity  of  the 

*  Opus  Teriium,  Ixi.  245  ;    Greek  Grammar,  p.  131. 

=  Greek  Grammar,  pp.  28,  29.  Cf.  Opus  Teriium,  x.  33  ;  Opus 
Majus,  I.  iii.  67  (Bridges). 

^  Opus  Minus,  p.  332  (Brewer). 

*  Greek  Grammar,  p.  41.  ^  Ibid.,  pp.  165,  169. 
^  Opus  Teriium,  xxv.  91  (Brewer). 


134  ROGER  BACON 

shape  of  some  letters,  they  turned  the  aorist  into  loriston, 
and  6  ai/roy  into  oXlto^^ 

Some  of  the  manuals  that  were  used  by  Bacon  undoubtedly 
followed  the  traditions  of  the  Byzantine  school.  There  are 
some  points  of  likeness  between  his  Grammar  and  those  of 
Constantine  Lascaris  and  Chrysoloras  ;  but  in  other  points 
they  differ.  Professor  Heiberg  ^  urges  that  in  the  reading 
lessons  the  Symholum  particularly  betrayed  the  Byzantine 
origin,  because  it  tallies  almost  verbally  with  Lascaris,  and 
Bacon  reproduced  even  from  his  source  the  phrase  e/c  rov 
Trarpo^  kKiropivofi^vov,  without  adding,  as  Lascaris  did,  the 
words  Kal  rod  vlov,  according  to  the  Latin  dogma.  But 
there  are  also  important  discrepancies ;  as  stands  to  reason, 
considering  Bacon's  critical  scrutiny  of  his  predecessors  ; 
and,  besides,  he  had  probably  access  to  some  of  the  more 
ancient  works  upon  which  the  later  systems  of  grammar  were 
based.  We  have  already  seen  that  Bacon  rejected  the 
Kavovis  ela-aycoyiKoi  of  Theodosius  (c.  the  end  of  the 
fourth  century),  Lascaris  and  Chrysoloras  having  other 
numbers.^  It  is  improbable  that  Bacon  had  any  direct 
knowledge  of  Theodosius  ;  if  he  had,  he  would  have  quoted 
him  instead  of  the  moderni  Graeci.  He  seems,  however,  to 
have  had  some  knowledge  of  Herodian  [c.  i6o).  He  quotes 
him  twice  in  his  Grammar  (pp.  46,  55) ,  and  the  latter  passage 
displays  a  close  acquaintance  with  at  least  a  part  of  his 
works  (.  .  .  sed  necessaria  est  ratio  scrihendi  quam  hie  volo 
inserere  secundum  quod  in  grammatica  Graeca  Herodiani 
diligenter  inter scripsi) . 

The  paradigms  Bacon  uses  were,  for  the  most  part,  the 
same  which  were  in  use  from  the  earliest  times.     The  verb 

'  Greek  Grammar,  pp.  164,  170. 

"  Byzantinische  Zeitschrift,  ix.  479  ;  xii.  343.  Cf.  Greek  Grammar, 
Introduction,  pp.  Ix,  Ixi. 

'  These  canons  were  also  followed  in  the  Graeco-Latin  Lexicon  ; 
Dr.  James,  ut  supra,  p.  407. 


PHILOLOGY  135 

TVTTTco  was  used  probably  since  the  time  of  Dionysius  Thrax 
{c.  100  B.C.)  ;  the  paradigms  for  verba  contracta  and  verbs  in 
-fic,  and  at  least  some  of  the  examples  for  the  declensions, 
have  remained  the  same  ever  since  Theodosius,  and  the 
subjunctive  is  always  given  with  idy.  The  rare  word  /3<£^ 
was  also  a  standard  example  ;  it  was  used  by  Herodian  and 
Theodosius,  and  commented  upon  by  Choeroboscus.^  The 
latter  was  also  quoted  in  the  afore-mentioned  lexicon,  whose 
author  either  had  access  to  a  copy  of  that  author,  or,  as 
Dr.  James  presumes  in  reference  to  his  citations  from 
Pausanius  the  Atticist,  derived  his  knowledge  from  some 
work  in  which  Choeroboscus  had  been  quoted.  It  has 
already  been  mentioned  that  Bacon  had  before  him  a  gram- 
matical catechism,  similar  to  that  of  the  Wolfenbiittel 
Erotemata.  Dr.  James  informs  us  that  a  liher  de  erotematihus 
is  also  quoted  in  the  Graeco-Latin  Lexicon.  It  is  therefore 
evident  that  such  catechisms  were  known  to  the  scholars 
that  belonged  to  Grosseteste's  circle. 

From  the  introductory  sentence  in  Bacon's  Greek  Gram- 
mar, it  appears  that  he  harboured  the  idea  of  including  a 
Chaldaean  Grammar  in  his  Opus  Principale,  but  there  is  no 
sign  that  it  was  written.  He  had  a  thorough  knowledge  of 
Biblical  Aramaic,  and  knew  the  passages  in  the  Bible  written 
in  that  language.  When  reading  the — for  his  age — modern 
expositions  of  more  ancient  commentators,  he  kept  a  critical 
eye  on  such  passages  as  referred  to  Aramaic.  In  this  way 
he  was  able  to  correct  a  gross  misconception.  These  ex- 
positors had  read  in  Jerome's  prologue  to  the  Book  of  Daniel 
that  one  '  pericope  '  of  Jeremiah  was  written  in  Aramaic. 

'  All  theologians  understood  that  "  pericope  "  to  mean  the 
Book  of  Lamentations  ;  that  word  bearing  the  meaning  of 
"small  part",  and  the  Book  of  Lamentations  being  the 
smaller  of  Jeremiah's  books.  These  writers  have  themselves 
to  thank  for  making  such  blunders  ;    they  will  follow  the 

'  See  Greek  Grammar,  Introduction,  p.  Ixii. 


136  ROGER  BACON 

vile  and  imaginary  authority  of  Brito.  Every  Hebraist 
knew  that  the  Book  of  Lamentations  was  written  in  Hebrew. 
Jerome's  remark  appUed  to  one  verse  in  the  tenth  chapter 
of  Jeremiah  (verse  ii).'  ' 

Bacon  reproduces  the  verse  in  the  original  Aramaic,  with 
a  Hebrew  translation,  and  supplies  both  with  an  interhneary 
transHteration  and  a  Latin  translation.^  He  observes  that 
Chaldaean  and  Hebrew  are  merely  different  dialects  of  the 
same  language  ;  where  the  Hebrew  says  Elohim  for  God,  lo 
for  no,  and  Samayim  for  heaven,  the  Chaldaean  says  Elaha 
for  God,  la  for  no,  and  Samaya  for  heaven? 

There  are  more  data  by  which  to  gauge  Bacon's  attain- 
ments in  Hebrew.  We  cannot  tell  whether  he  realized  his 
wish  of  writing  a  Hebrew  Grammar,  but  we  know  that  he 
attempted  it.  The  fragment  discovered  by  the  Reverend 
E.  Nolan  in  the  University  Library  at  Cambridge  is  un- 
doubtedly his  work."*  The  incentives  to  enter  zealously 
upon  the  study  of  Hebrew  were  powerful  for  a  man  of 
Bacon's  frame  of  mind.  He  was  actuated  at  the  same  time 
by  scientific,  religious,  and  mystical  motives.  Science 
directed  him  to  Greek  and  Arabic,  religion  led  him,  more- 
over, to  Hebrew, 

He  was  convinced  that  Hebrew  was  the  language  in  which 
God  had  revealed  to  mankind  His  will  and  His  wisdom. 

'  Opus  Tertium,  vi.  438  (Brewer).  The  passage  occurs  also  in  the 
Opus  Majus,  iii.  That  passage  was  omitted  by  Bridges  in  his  first 
volume,  but  inserted  in  the  supplementary  volume,  pp.  91,  92, 
to  which  a  reduced  facsimile  from  the  Vatican  MS.  forms  the 
frontispiece.  That  manuscript  gives  the  words  correctly  except 
for  the  omission  of  the  n?N.  The  Cottonian  MS.  gives  them  in  an 
irregular  order  ;  a  reduced  facsimile  appeared  in  S.  A.  Hirsch's 
Book  of  Essays,  p.  65. 

-  The  passage  appears  in  the  Toulouse  MS.  See  Berger,  iit  supra, 
P-39. 

^  '  ...  la  pro  non,  et  Samaya  pro  caelo.'  Thus  it  ought  to  read 
in  Comp.  Stud.  Phil.  vi.  439  (Brewer).  Cf.  Opus  Majus,  1.  iii.  72 
(Bridges) . 

*  Printed  after  the  Greek  Grammar,  pp.  198-203. 


PHILOLOGY  137 

'  God  has  revealed  philosophy  to  His  saints,  to  whom  He 
also  gave  the  Law.  He  did  so  because  philosophy  was  indis- 
pensable for  the  understanding,  the  promulgation,  the  adop- 
tion, and  the  defence  of  the  Law,  and  in  many  other  ways  also. 
It  was  for  this  reason  that  it  was  delivered,  complete  in  all 
its  details,  in  the  Hebrew  language.' '  '  The  whole  wisdom 
of  philosophy  was  given  by  God,  who,  after  the  creation  of 
the  world,  delivered  it  to  the  patriarchs  and  the  prophets. 
.  .  .  They  possessed  wisdom  in  its  entirety  before  the  infidel 
sages  obtained  it,  such  as  the  famous  poets,  or  the  Sibyls, 
or  the  seven  wise  men,  or  the  philosophers  after  them.  .  .  . 
All  their  information  about  heavenly  bodies,  about  the 
secrets  of  nature  and  the  superior  sciences,  about  sects,  God, 
Christianity,  the  beauties  of  virtue,  and  the  rectitude  of 
the  Laws,  of  eternal  reward  and  punishment,  resurrection 
of  the  dead,  and  all  other  questions,  were  derived  from  God's 
saints.  The  philosophers  did  not  find  them  out  ;  God  had 
revealed  them  to  His  saints.  .  .  .  Adam,  Solomon,  and  the 
others  testified  to  the  truth  of  the  faith,  not  only  in  holy  writ, 
but  also  in  books  of  philosophy,  long  before  there  were  any 
philosophers  so-called.'  ^  '  Philosophy  was  developed  by 
Noah  and  his  sons,  particularly  by  Shem  ;  and  all  philo- 
sophers and  great  poets  lived  after  them,  and  after  Abraham. 
.  .  .  Zoroaster  invented  the  magic  arts  ;  he  was  the  son  of 
Ham,  the  son  of  Noah.  lo,  who  was  afterwards  called  Isis, 
the  daughter  of  Inachus,  the  first  king  of  the  Argives,  a  con- 
temporary of  Jacob  and  Esau,  taught  the  Egyptians  to 
write.  Minerva,  the  inventress  of  many  things,  lived  about 
the  same  time.  Under  Phoroneus,  Inachus's  son,  moral 
philosophy  was  first  introduced  among  the  heathens. 
Prometheus  was  the  first  teacher  of  philosophy,  and  his 
brother  Atlas  the  first  great  astrologer.  But  he  was 
preceded  by  the  great  astronomers,  the  sons  of  Noah,  and 
by  Abraham.'  ^ 

In  this  way,  Bacon  continues  tracing  the  chain  of 
transmission  of  philosophy,  based  upon  the  writings  of 
his  predecessors,  mixing  up  biblical  and  mythological 
personages,  and  treating  them  after  the  method  first  intro- 
duced by  Euhemerus  of  Crete. 

'  Opus  Tertium,  x.  32  (Brewer). 

^  Ibid.,  xxiv.  79.  Cf.  ibid.,  viii.  24  ;  Comp.  Stud.  ThcoL,  33 
(Rashdall).  '  Op^ts  Majus  (Bridges),  i.  46. 


138  ROGER  BACON 

All  this  wisdom,  Bacon  was  fully  persuaded,  emanated 
primarily  from  the  wisdom  that  was  revealed  by  God  in 
Hebrew.  Besides,  King  Solomon,  who  was  the  second 
promulgator  of  philosophy,  was  possessed  of  great  wealth, 
and  was  thus  enabled  to  complete  his  philosophical 
work  in  Hebrew.  No  wonder,  therefore,  that  Bafon  was 
eager  to  gain  a  more  intimate  knowledge  of  the  divine 
tongue. 

There  was  another  aspect  of  Bacon's  religious  convictions 
which  turned  his  mind  to  Hebrew.  It  was  his  disgust  at  the 
corruptions  that  had  crept  into  the  text  of  the  Bible,  i.  e. 
the  Vulgate,  which  consists  of  the  Latin  translation  of  the 
Septuagint  translation  of  the  Psalms,  and  of  Jerome's 
translation  of  all  other  books.  The  '  text  '  was  overrun 
with  errors,  and  worst  of  all  in  the  Parisian  copy.  The 
eradication  of  errors  from  that  translation  was  considered 
tantamount  to  the  purging  of  '  the  text  of  the  Bible  '. 
Even  at  the  present  day  the  term  '  Biblical  criticism ', 
which  denotes  quite  a  different  procedure,  is  sometimes 
applied  to  the  correction  of  Jerome's  translation.  Before 
Bacon's  time  there  had  been  no  lack  of  Correctoria  which 
attempted  to  restore  the  original  form  of  the  '  text  '.  It 
seems  that  in  Bacon's  time  these  attempts  ran  riot.  He 
complains  that  everybody  interfered  with  the  text  ;  when- 
ever any  one  did  not  understand  it,  he  altered  it.  Both  the 
correction  and  the  understanding  of  the  text  imperatively 
demanded  the  study  of  the  original  languages. 

The  mystical  element  in  Bacon's  nature  also  turned  him 
to  the  study  of  Greek,  and,  much  more  so,  to  that  of  Hebrew, 
important  mysteries  were  concealed  in  the  numerical 
values  of  the  letters  ;  '  the  spiritual  meaning  of  the  text 
was  indissolubly  bound  up  with  the  literal  sense,  and  both 
suffered  equally  if  the  text  was  corrupt  in  most  parts  and 
dubious  in  many  others.^ 

■   Vide  supra,  p.  109.  '  Opus  Minus,  p.  349. 


PHILOLOGY  139 

As  Bacon  had  turned  to  Greeks  for  instruction  in  Greek, 
so  he  consulted  Jews  for  information  on  Hebrew.  In  both 
cases  he  points  out  the  deficiency  in  grammatical  knowledge 
on  the  part  of  most  of  that  class  of  teachers.  His  estimate 
of  the  amount  of  knowledge  attainable  was  the  same  for 
both  languages  ;  as  is  also  his  tripartition  of  the  degrees  of 
proficiency,  his  estimate  of  a  sufficiency  of  three  days  of 
close  application  for  the  acquisition  of  the  lowest  degree, 
provided  a  manual  had  first  been  prepared,  and  the  necessity 
of  earnest  study  for  thirty  years,  if  a  mastery  of  the  highest 
degree  were  desired. 

The  extent  of  Bacon's  knowledge  of  Hebrew  may  be  gauged 
by  those  passages  in  his  works  in  which  he  alludes  to  matters 
Hebrew,  and  by  his  fragmentary  Hebrew  Grammar.  The 
evidence  derived  from  the  former  source  might  induce  us 
to  form  a  low  estimate  of  his  Hebrew  learning,  but  the 
question  is  whether  we  possess  all  the  data  from  which 
to  judge. 

Two  points  offer  themselves  for  consideration  in  this 
respect,  both  based  on  the  fair  assumption  that  Bacon  was 
not  behind  his  contemporaries  in  whatever  knowledge  of 
Hebrew  they  possessed.  There  was,  in  the  first  place, 
Bacon's  elder  contemporary,  the  homo  sapientissimus ,  whom 
he  described  as  a  good  Hebrew  scholar,  '  whose  difficulties 
were  very  great  on  account  of  the  want  of  Greek  and  Hebrew 
Bibles  and  dictionaries,  which,  it  is  true,  existed  in  England 
and  France,  but  were  not  accessible  to  him.'  ^  But  if  Denifle's 
assumption  be  correct,^  that  this  homo  sapientissimus  was  the 
author  of  the  Correctorium  Vaticanum — whether  his  other 
assumption,  that  he  was  identical  with  William  de  la  Mare, 

'  Abbot  Gasquet's  '  Fragment ',  in  English  Historical  Review, 
July  1897,  P-  516. 

-  Denifle,  '  Die  Handschriften  der  Bibel-Correctorien  des  1 3ten 
Jahrhunderts  ',  in  the  Archiv  fiir  die  Literatur-  itnd  Kirchengeschichte 
des  Mittelaliers,  herausgegeben  von  P.  Heinrich  Denifle  und  Franz 
Ehrle,  iv.  (1888)  278. 


140  ROGER  BACON 

be  correct  or  not ' — he  must  have  had  such  books  at  his 
disposal  at  a  later  date,  for  the  Correctorium  displays  an 
intimate  acquaintance  with  works  of  that  kind.  Its  author 
had  read  the  Targum  (the  old  Aramaic  translation)  ;  he 
quotes  the  Perus,  the  '  Commentary  ',  by  which  he  either 
meant  that  of  Rashi,  or  the  commentary  which  existed 
before  him,  and  was  known  under  the  name  of  Perus.  He 
knew  the  Mahberet,  Menahem  ben  Saruk's  Hebrew  lexicon. 
He  had  consulted  the  Hebrew  manuscripts  of  Spain,  and 
distinguished  between  '  modern  '  Hebrew  texts,  '  old  ' 
Hebrew  manuscripts  of  France,  and  '  old  '  Hebrew  manu- 
scripts of  Spain. 

It  is  unthinkable  that  Bacon,  enjoying  the  personal 
acquaintance  of  a  scholar  of  such  eminence,  and  bent  upon 
the  same  pursuits,  should  not  have  benefited  by  the  oppor- 
tunity, and  made  himself  acquainted  with  some  of  the 
sources  which  the  scholar  he  so  much  admired  had  made 
use  of.  It  was  only  intercourse  with  Jews  that  could  have 
brought  such  works  to  the  notice  of  that  author,  and  Bacon 
made  ample  use  of  that  same  medium  of  information. 

This  view  is,  in  the  second  place,  singularly  supported  by  the 
latter  portion  of  the  afore-mentioned  Toulouse  manuscript. 
It  contains  a  collection  of  letters,  in  which  a  questioner,  or 
some  questioners,  ask  for  information  on  Hebrew  subjects, 
and  are  answered  by  the  other  correspondent.  The  questioners 
did  not  know  much  Hebrew,  some  did  not  even  know  the 
Hebrew  letters.  It  was  quite  different  with  the  respondent. 
He  not  only  knew  Hebrew,  but  he  also  quotes  the  Rabbis, 
especially  Rashi.  Berger  does  not  venture  to  say  that  this 
scholar  who  was  consulted  as  an  oracle  was  Roger  Bacon, 
although  there  are  many  almost  verbatim  parallels  in  the 
latter's  acknowledged  writings.  But  if  not  Bacon,  it  was 
some  one  so  closely  connected  with  him  that  he  might  easily 

'  On  William  de  la  Mare,  see  Mr.  Little's  Grey  Friars  in  Oxford, 
p.  215  f. 


PHILOLOGY  141 

be  taken  for  him.  Both  Denifle  and  Berger  came  to  the  con- 
clusion that  the  respondent  was  the  Franciscan  friar,  William 
de  la  Mare,  whom  they  identified  at  the  same  time  with 
Bacon's  homo  sapientissimus ,  and  the  author  of  the  Correc- 
torium  Vaticanum.  If  William  de  la  Mare  was  the  respon- 
dent, it  is  clear  that  Bacon  had  been  the  master  who  was 
mainly  responsible  for  the  learning  displayed  in  the  letters. 
The  concurrence  of  the  responses  with  many  passages  in 
Bacon's  works  is  too  obvious  to  doubt  it.  And  how  can 
we  be  certain  that  the  learned  correspondent  was  not  the 
master  himself  ? 

Roger  Bacon  deals,  in  his  Opus  Majus  (iv),  elaborately 
with  the  subject  of  lunations,  and  explains  that  the  Jews 
used  the  Metonic  cycle  of  19  years,  or  235  lunations,  and  the 
mean  lunation  was  therefore  29  days,  12  hours,  and  -j^^^ 
of  an  hour.  He  added  a  Hebrew  table,  which  has  not  been 
preserved,  and  is  full  of  praise  for  the  Jewish  way  of  fixing 
the  calendar.  In  the  Toulouse  manuscript  it  is  said  that 
the  calendar  and  the  lunations  had  been  more  fully  investi- 
gated by  the  Jews  than  by  the  Greeks  or  the  Arabs.  He, 
the  respondent,  had  had  some  Hebrew  books  sent  him  from 
Germany  by  a  learned  Jew,  who  knew  him  only  by  reputa- 
tion, and  with  whom  he  carried  on  a  regular  correspondence 
in  Hebrew.  If  this  was  written  by  Bacon  himself,  it  would 
corroborate  his  statement  that  he  was  able  to  write  Hebrew. 
The  respondent  proceeds  to  say  that  these  books  were  com- 
posed by  Abraham,  that  they  contained  much  information, 
and  were  provided  with  many  tables.  They  were  more 
useful  on  astronomical  subjects  than  any  which  he  had  seen 
before.  He  had  long  desired  to  possess  such  Jewish  books, 
and  had  written  to  a  certain  Jew  in  Toledo,  in  Spain,  whom 
he  knew,  to  procure  them  for  him,  but  in  that  city  no  com- 
plete copy  could  be  found.  Berger  conjectures  that  the 
book  on  the  new  moon  was  the  Kiddus  Hahodes,  a  treatise 
on  the  calendar,  forming  a  portion  of  one  of  the  larger  works 


142  ROGER  BACON 

of  Maimonides.  The  Abraham  mentioned  here  must  have 
been  Abraham  bar  Hija,  the  author  of  Sefer  Ha-'ibbur. 

All  this  could  very  well  have  been  written  by  Roger 
Bacon,  and  serve  as  evidence  how  hard  he  tried  to  obtain 
books,  and  how  strong  his  desire  was  to  obtain  information 
from  the  Jews.  It  would  show  at  the  same  time  his  acquain- 
tance with  such  Hebrew  works  as  are  nowhere  mentioned 
in  his  known  writings.  But  suppose  the  correspondent  to 
have  been  his  pupil,  the  one  passage  on  the  calendar  suffi- 
ciently indicates  the  source  whence  he  had  drawn  his  infor- 
mation. And  it  was  only  from  Jewish  students  of  Maimo- 
nides' works  that  this  writer  could  have  known  of  the 
division  of  the  Pentateuchal  injunctions  into  '  laws  ',  '  testi- 
monies ',  '  judgements  ',  and  '  precepts '.  It  is  further  note- 
worthy that  these  letters  contain  the  Aramaic  verse  in 
Jeremiah,  transliterated  and  translated  into  Hebrew  and 
Latin  in  the  same  way  as  we  find  it  in  the  Opus  Majus. 
The  description  of  the  Hebrew  final  letters  {men  aperta,  men 
claiisa,  &c.)  is  identical  with  that  in  the  fragment  of  Bacon's 
Hebrew  Grammar,  as  are  also  a  few  other  grammatical  points. 

But  apart  from  such  indirect  evidence,  Bacon's  acknow- 
ledged works  amply  show  that  he  was  competent  to  satisfy 
his  own  demands  on  a  third-rank,  and  even  a  second-rank 
Hebrew  scholar.  Although  he  has  added  nothing  to  the 
stock  of  information,  and  not  a  single  observation  of  his 
can  perhaps  be  called  original,  he  yet  speaks  with  authority, 
and  knowledge  of  the  subject,  when  he  explains  derivations 
of  words  from  the  Hebrew,  or  exposes  blunders  made  by 
some  scholars.  That  he  had  a  good  notion  of  Hebrew 
grammar  is  sufficiently  proved  by  his  remarks  in  the  third 
book  of  the  Opus  Majus,  and  by  the  fragment  of  a  Hebrew 
Grammar  discovered  in  Cambridge.' 

In  the  latter  Bacon  gives  the  names  of  the  letters  of 

'  Greek  Grammar,  pp.  199-208.  Cf.  Hirsch,  A  Book  of  Essays, 
pp.  5a  «. 


PHILOLOGY  143 

the  Hebrew  alphabet  and  their  sounds.  He  describes  the 
ordinary  and  final  letters  in  terms  which  answer  to  those 
used  by  the  Jewish  grammarians.^  True  to  his  doctrine  that 
there  is  only  one  grammar  in  substance,  he  tries  perforce  to 
find  an  analogy  between  Hebrew  and  Greek  in  his  exposition 
of  genders,  cases,  numbers,  the  article,  diphthongs,  and  the 
preposition. 

Accustomed  as  he  was  to  classical  and  occidental  languages, 
where  each  consonant  is  accompanied  by  a  separate  letter, 
which  indicates  the  sound,  he  seems  not  to  have  had  a  clear 
understanding  of  the  system  in  use  in  Hebrew.  In  that 
language  only  the  consonants  are  written  ;  the  sound  is 
only  occasionally  indicated  by  '  vowel  letters  ',  but  usually 
by  some  strokes  or  points  under  or  above  the  consonants, 
except  in  copies  of  the  Bible  designated  for  ritual  use  and 
books  written  for  the  learned,  where  such  signs  of  vocaliza- 
tion are  entirely  absent.  Such  lack  of  understanding 
would  be  all  the  more  strange  if  he  really  had  been  the  Arabic 
expert  he  describes  himself.  He  mentions  the  signs,  and 
at  the  same  time  calls  the  letters  '  aleph,  ain,  he,  heth,  lot, 
vaj'  vowels,  giving  the  word  *  vowel '  the  same  sense  as  in 
Latin  and  Greek  :  a,  e,  i,  0,  u.  Thus,  when  the  occasion 
arises,  he  inserts  one  of  these  letters  where  it  is  quite  inad- 
missible, e.  g.  1^<n  for  *^ii  ;  D^HX^K  for  D*nS« ,  Bacon 
gives  a  fantastic  explanation  of  the  absence  of  vowel  letters 
in  the  Bible.  The  Hebrews,  he  avers,  omitted  them 
because  they  did  not  want  other  nations  to  read  their  books, 
and  when  some  '  wise  philosophers  who  understood  Hebrew ' 
tried  to  translate  the  holy  history,  God  punished  them,  as 
Josephus  teaches  us.= 

'  In  the  Cottonian  MS.  :  uverte,  close,  draite,  torte.  In  the  Vatican 
MS.  :  uverte,  clase,  dreiie,  torte.  In  the  Opus  Minus,  p.  350  (Brewer), 
and  in  the  Cambridge  Grammar,  these  letters  are  simply  designated 
by  the  terms  primum  and  secundum. 

'  Antiq.  xii.  2,  14. 


144  ROGER  BACON 

He  ascribes  to  such  secretiveness  the  circumstance  that 
Babel  is  called  Sesak,  according  to  the  explanation  given 
by  Jerome,  who  had  himself  followed  the  Rabbis.  He  fully 
understood  the  scheme  of  transposition  of  the  letters  of  the 
Hebrew  alphabet  on  which  this  interpretation  rests.' 

As  in  Greek,  so  in  his  transliteration  of  Hebrew  words 
Bacon  gave  the  Latin  vowels  the  sounds  which  they  have 
on  the  Continent.  The  Hebrew  vowels,  he  observes,  have 
the  sounds  quinque  vocalium  nostrarum,  a,  e,  i,  o,  u,  implying 
the  sounds  these  letters  have  abroad. 

In  Hebrew,  there  are  two  principal  styles  of  pronunciation  : 
the  Sephardic,  which  was  in  vogue  in  Spain,  Portugal,  Italy, 
and  the  East,  and  iheAshkenazi,  in  use  in  central,  north-east, 
and  western  Europe.  Bacon  follows,  on  the  whole,  the 
former  mode  of  reading,  which  he  must  have  derived  partly 
from  Jews,  and  partly  from  Jerome's  commentaries.  Might 
he  not,  perhaps,  have  seen  a  copy  of  the  Hexapla,^  of  which 
he  gives  so  accurate  a  description,  and  been  partly  guided 
by.  the  transliteration  found  there  ?  He  transliterates 
3,  5'  5'  ^'  5  ii^to  ba,  be,  bi,  bo,  bu  ;  once  only  H  and  D 
are  rendered  in  the  Cottonian  manuscript  heis  and  teis  ;  in 
all  other  cases  they  are  described  as  cheth  and  teih,  and  we 
always  find  bet  and  tav.  Whatever  pronunciation  the  Jews  of 
England  may  have  used  before  the  Expulsion,  it  is  evident  that 
those  consulted  by  Bacon  had  the  Sephardic  mode  of  reading. 

It  has  already  been  noticed  that  Bacon  considered  it  in 
the  light  of  a  religious  duty  to  utilize  Hebrew  and  Greek 
towards  the  establishment  and  understanding  of  an  authentic 
text  of  the  Vulgate  translation.     He  sets  forth  that  Jerome 

'  Greek  Grammar,  p.  206  ;  Opus  Minus,  pp.  350  ff.    The  scheme  is 
3  *  D  n  T  1  m  i  3  N 

'  Opus  Minus,  p.  337  (Brewer)  :  Origenes  famosissimos  libros 
composuit,  in  qiiibus  .  .  .  opus  interpretis  cujuscunque  descripsit,  ut 
primo  ipsa  Hebraica  Hebraicis  Uteris  poneret,  secundo  loco  per  ordinem 
Graecis  Uteris  Hebraica  verba  describeret,  &c. 


PHILOLOGY  145 

referred  in  his  expositions  to  Hebrew  and  Greek  at  almost 
every  word,  and  was  always  at  pains  to  demonstrate  his 
exegetical  remarks  by  the  languages.'  Bacon  had  adopted 
this  principle,  and  adhered  persistently  to  it.  His  intimate 
acquaintance  with  the  text  of  the  Hebrew  Bible  is  espe- 
cially conspicuous  in  a  passage  of  the  Opus  Majus,^  in 
which  he  rectifies  some  of  the  innumerable  errors  of  the 
Paris  text,  particularly  in  the  matter  of  figures,  e.g.  that 
Arpahsad  lived  after  the  birth  of  Selah  303  years,  instead 
of  403  years  ;  or  that  Re'u  lived  35  years,  instead  of  32 
years,  &c.  The  whole  passage  is,  as  Mr.  Bridges  justly 
remarked,  '  one  of  the  many  proofs  of  the  care  with  which 
Bacon  had  collated  the  Septuagint  and  the  Hebrew  text.' 

Much  in  advance  of  his  age  as  Bacon  was,  he  had  yet  as 
little  idea  of  modern  Bible  criticism  as  he  had  of  modern 
comparative  philology.  He  urged  the  necessity  of  Hebrew 
for  the  correct  understanding  of  the  Bible,  but  he  did  not 
for  a  moment  admit  that  it  was  allowable  to  alter  a  word  of 
the  Vulgate,  even  at  the  instance  of  a  comparison  with  the 
original.  He  could  not  have  approved  of  Stephen  Harding's 
method  of  purifying  the  text.  The  latter  knew  no  Hebrew, 
and  therefore  consulted  the  Rabbis  ;  and  he  erased  from 
the  Latin  text  all  such  passages  and  verses  as  were  not 
found  in  the  original.  The  Correctorium  Parisiense  was  the 
work  of  Hugo  de  S*"  Caro,  a  man  thoroughly  familiar  with 
the  Hebrew  language,  who  all  along  refers  conscientiously 
to  the  Hebrew.  The  Dominicans  continued  his  labours,  in 
which  they  also  displayed  tolerable  knowledge  of  Hebrew. 
But  Bacon  did  not  approve  of  such  methods  ;  to  him  it  was 
not  correcting  the  text,  but  corrupting  it,  and  making  it 
incurable  ;  for  it  was  not  the  question  of  applying  Hebrew  or 
Greek,  but  of  the  restoration  of  Jerome's  text. 

It  was  in  this  spirit  that  the  author  of  the  Correctorium 

'  Opus  Minus,  p.  349  (Brewer), 
=  i.  221  (Bridges). 
1689  L 


146  ROGER  BACON 

Vaticanum — whether  he  was  or  was  not  the  homo  sapientis- 
simus  or  Wilham  de  la  Mare — pronounced  the  warning 
that  'one  must  not  be  unfaithful  to  the  Latin  text  on 
the  testimony  of  the  Hebrew  or  the  Greek  '.  He  opposed 
the  correctors,  especially  Hugo  de  S*°  Caro,  who  altered  the 
Latin  on  the  sole  authority  of  the  Hebrew,  without  the 
support  of  the  manuscripts  ;  and  in  the  same  sense  he  said, 
'  Beware  of  attaching  yourselves  too  much  to  the  Jews.' 

This  principle,  not  to  be  influenced  by  the  Hebrew  to  such 
a  length  as  to  meddle  with  Jerome's  text,  closely  linked 
Bacon  to  the  author  of  that  Correctorium.  In  adherence 
to  this  principle,  Bacon  praises  and  scolds  at  the  same  time 
a  certain  Andrew  {Andreas  quidam),  whom  he  considers  to 
have  sinned  in  that  way.'  I  consider  him  to  be  identical  with 
the  Englishman  Andrew,  an  Augustinian  monk,  who  lived 
about  1150  ;  he  was  a  pupil  of  Hugo  de  S*°  Victore,  and  is 
said  to  have  written  learned  commentaries  on  the  Bible  and 
the  Apocrypha.^  Bacon  discusses  the  ambiguity  of  the 
Latin  translation  of  Genesis  ii.  i,  2.  The  Latin  words  may 
be  forced  to  mean :  '  These  are  the  generations  of  heaven 
and  earth  when  they  were  created,  on  the  day  when  God 
made  heaven  and  earth.  And  all  the  vegetation  of  the  field 
had  not  come  forth  yet,'  &c.  Or  they  may  mean  :  '  These 
are  the  generations,  &c.,  ...  on  the  day  when  God  made 
heaven  and  earth  and  the  vegetation  of  the  field,  before  it 
had  come  forth  on  the  earth,  and  all  the  herbs  of  the  field 
before  they  were  grown.'  Bacon  considers  the  latter  mean- 
ing to  be  more  in  accordance  with  the  Latin,  but  it  would 
contradict  the  narrative  of  the  first  chapter  of  Genesis.  He 
says  that  in  the  phrase  omne  virgultum  agri  antequam  oriretur 
in  terra  the  words  omne  virgultum  were  in  the  nominative, 
and  in  the  sentence  omnemque  herbam  regionis  priusquam 
germinaret  the  word  terra  had  to  be  supplied  or  understood 

'  Comp.  Stud.  Phil,,  viii.  482  f. 

"  Hirsch,  A  Book  of  Essays,  pp.  1 1-15.° 


PHILOLOGY  147 

as  the  subject  to  ger minaret.  Bacon  adopts  this  interpreta- 
tion, not  only  for  the  purpose  of  harmonizing  the  two 
chapters,  but  also  in  order  to  reconcile  the  Latin  translation 
with  the  Hebrew  text,  and  adds  that  the  sense  would  be 
much  clearer  if  we  had  the  word  herha  in  the  nominative. 

Bacon  then  mentions  '  a  certain  Andrew  '  who  had  written 
the  word  herba  in  the  nominative  and  inserted  a  negative 
particle  to  the  verbs  oriretur  and  germinarct  '  quite  in 
accordance  with  the  Hebrew  text '.  How  did  Andrew, 
Bacon  complains,  dare  to  make  his  translation,  which  is 
not  nostra  translatio,  appear  as  if  it  were  ours,  the  authorized 
Latin  text  ?  His  was  neither  a  commentary  nor  a  translation ; 
it  was  nothing  but  a  literal  construing  of  the  Hebrew.  The 
worst  of  it  was  that  many  people  attributed  to  Andrew  an 
authority  which  he  did  not  possess.  Nobody  since  Bede  had 
obtained  the  sanction  of  the  Church  to  expound  Scripture ; 
and  although  Andrew  was  undoubtedly  a  well-read  man, 
and  probably  knew  Hebrew,  yet  for  all  that  he  enjoyed  no 
authority  ;  he  could  not  be  credited,  but  the  Hebrew  text 
must  be  consulted  to  see  whether  he  was  right  or  wrong. 
If  he  were  right,  credence  was  due  to  the  Hebrew,  but  not  to 
him  ;  if  wrong,  he  involved  us  in  the  danger  of  taking  his 
text  for  ours.  Nevertheless,  Bacon  proceeds,  Andrew  had 
the  great  merit  of  inducing  us  to  consult  the  Hebrew,  when- 
ever we  meet  with  some  difficulty  in  our  translation.  Thus, 
in  our  passage,  and  in  many  others,  but  few  people  would  have 
thought  of  the  true  meaning  if  it  had  not  been  for  Andrew, 
We  see  how  Bacon's  love  for  the  investigation  of  the  Hebrew 
original  neutralized  his  orthodoxy  to  a  considerable  extent. 

In  the  same  way  as  Bacon  exposes  misconceptions  in  refer- 
ence to  Greek,  he  also  corrects  false  notions  on  Hebrew 
words.  The  seventh  chapter  of  the  Compendium  Studii 
Philosophiae  contains  a  list  of  words  and  names  which 
were  considered  of  Latin  or  Greek  origin,  but  which  were 
really  derivations  from  the  Hebrew.    He  sometimes  exposes 

L  2 


148  ROGER  BACON 

such  absurdities  in  his  usual  robust  style  ;  for  instance,  as 
has  already  been  remarked,  when  Hugutio  and  Brito  and 
other  idiotic  grammarmongers  explain  arrabon  and  Gehenna 
as  arra  bona  and  ge  ennos.  All  these  instances  exhibit  Bacon 
as  a  thorough  Hebrew  scholar.  The  greater  part  of  them 
refer  to  misunderstood  passages  in  the  writings  of  the 
exegetes,  especially  those  of  Jerome, 

In  one  case,  however,  he  discards  his  usual  bitterness  and 
contumely,  and  is  even  at  pains  to  palliate  the  fault ;  and  no 
wonder!  It  is  this  time  an  error  committed  by  no  less 
a  person  than  Pope  Gregory  the  Great.  Bacon  held  Pope 
Gregory  in  great  veneration,  and  fully  believed  that  the 
latter's  works,  which  were,  after  his  death,  in  danger  of  being 
burned,  were  saved  '  by  a  beautiful  miracle  of  God  '.* 
Pope  Gregory  had  quoted  Job  xlii.  4  thus  :  *  And  he  called 
the  name  of  one  Dies,  and  the  second  Casta,  and  the  third 
Cornustibii.'  These  are  meant  to  be  the  renderings  of 
the  Hebrew  names,  Q'siah,  Yemima,  and  Keren  Happuk 
{nT^p,  na^DV  ^lan  \1p).  Gregory  thought  Cornustibii  = 
Cornus  tibii,  a  compound  of  two  words  denoting  musical 
instruments  (trumpet-fife),  and  observes  that 

'  the  translator  rightly  took  care  not  to  insert  these  names 
as  they  are  found  in  the  Arabic,  but  to  show  their  meaning 
more  plainly  by  translating  them  into  Latin.  For  who  does 
not  know  that  Dies  and  Casta  are  Latin  words  !  But  as  to 
Cornustibii — although  it  is  not  cornus  but  cornu,  and  the 
pipe  of  the  singers  is  called  tibia  and  not  tibium — I  suppose 
he  preferred  to  state  the  thing  as  it  was  without  keeping 
the  gender  of  the  word  in  the  Latin,  and  to  preserve  the 
peculiarity  of  the  language  from  which  he  translated.  Or 
also,  since  he  formed  one  compound  word  out  of  the  two — 
cornu  and  tibia — he  was  at  liberty  to  put  both  words,  which 
are  translated  into  Latin  by  one  part  of  speech,  in  whatever 
gender  he  liked '. 

Bacon  says  ^  that  it  was  clear  to  any  one  able  to  compare 

'  Opus  Majus,  I.  i.  19  (Bridges). 

'  Conip.  Stud.  Phil.,  vi.  I440  (Brewer). 


PHILOLOGY  149 

the  original  Hebrew,  that  the  text  used  by  the  Pope  was 
corrupt ;  that  the  second  part  of  the  compound  word  was 
stibii,  and  not  Hbii ;  that  the  name  was  Cornu  sHbii,  meaning 
a  horn  or  receptacle  for  stibium.  Bacon  correctly  traces 
the  etymology  of  the  name  from  the  Hebrew,  and  adds  that 
the  term  used  here  was  the  same  as  2  Kings  ix.  30,  where 
we  are  told  that  Jezebel  dyed  her  eyes  with  stibium.  Bacon 
finds  excuses  for  the  Pope  ;  the  holy  man's  time  was  fully 
occupied,  and  he  had  not  the  leisure  to  collate  many  copies 
of  the  Bible  to  see  what  the  Greek  and  Hebrew  texts  offered. 
Bacon  reserves  the  indignation  which  he  could  not  vent 
on  the  Pope  for  the  '  crowd  of  modern  theologians  who 
disputed  about  things  they  did  not  understand,  and  persisted 
in  defending  Gregory's  rendering  '. 

Bacon  fell  himself  occasionally,  though  very  rarely,  into 
errors  of  the  same  description.  Thus  he  warns  his  readers  ' 
not  to  confound  Horeb,  the  mountain  of  God,  with  the 
stone  'Oreb  in  R'phidim,  from  which  Moses  had  drawn 
water  ;  the  former  name  being  written  with  a  Heth,  but  not 
the  latter.  As  a  matter  of  fact,  the  latter  name  is  also 
written  with  a  H  (Exod.  xvii.  6),  and  Bacon  evidently 
confused  that  rock  with  the  rock  of  'Oreb,  i'TlS?  '^^X  of 
Judges  vii.  25.^ 

Bacon  nowhere  mentions  the  Hebrew  accents  by  name, 
the  '  tonic  accents  '  as  they  are  called.  As  in  Greek,  he  refers 
also  to  accentuation,  aspiration,  punctuation,  and  prosody 
in  regard  to  Hebrew.  He  says  that  the  Hebrew  text  con- 
tained many  kinds  of  metre,  and  complains  that  the  Latin 

'  Opus  Majus,  I.  iv,  327  (Bridges). 

-  In  the  Compendium  Studii  Philosophiae,  vii.  445,  we  read  : 
Hieremias,  Hievico,  Hierusalem,  Hieronymus  ei  hujusmodi  debent 
aspiravi  in  principio.  This  seems,  at  first  sight,  to  be  an  error,  such 
as  he  always  censures  in  others,  for  how  does  the  name  Hieronymus 
come  to  be  included  in  a  list  of  names  derived  from  the  Hebrew  ? 
But  the  sentence  is  an  abbreviated  reproduction  of  Opus  Teriium, 
Ixi.  247,  and  is  out  of  place  here. 


150  ROGER  BACON 

translators  lacked  that  sense  for  music  which  was  possessed 
by  the  patriarchs  and  the  prophets.  '  The  only  way  in 
which  theologians  could  obtain  a  knowledge  of  Hebrew 
metres  and  rhythms  was  by  recurring  to  the  Hebrew 
original,  and  by  studying  that  branch  of  music'  ' 

But  there  is  evidence  to  show  that  Bacon  knew  the 
accents.     On  mentioning  Jerome's  etymology  of  the  name 
of  Israel,  as  denoting  *  Master  with  God  ',  and  not  as  others 
before  Jerome  had  explained  it  as  '  a  man  who  saw  God  ', 
Bacon  enters  into  the  reasons,  which  prove  the  latter  deriva- 
tion to  be  untenable.     Since  Is  meant '  man  \  Ra'  seeing ', 
El '  God ',  these  commentators  thought  the  patriarch's  name 
to  be  a  compound  of  these  three  words.     Jerome,  Bacon 
says,  rightly  objected  to  this  derivation,  because  the  name 
contained  the  five  letters  lod,  Sin,  Resh,  Aleph,  Lamet, 
making  up  the  name  ^J^ItJ'*, '  Israel.'    The  other  compound 
would  have  to  consist  of  eight  letters  :    Aleph,  lod,  Sin, 
Resh,  Aleph,  He,  Aleph,  Lamet,  forming  the  word  7Xnt<*lK'*K. 
This  would  be  *  Iserael ',  a  word  of  four  syllables , whereas  the 
name  had  only  three,  because  a  dot  under  a  letter  denoted 
the  vowel  i,  two  (horizontal)  dots  e,  and  a  stroke  with  a  dot 
under  it  a  ;    but  the  strongest  argument  was  the  sense  of 
the  word,  which  is  explained  in  the  verse  itself.     Bacon 
illustrates  this  further  by  reproducing  the  whole  verse  in 
Hebrew.     The  Cottonian  manuscript   not  only  gives  the 
vowel  points,  but  also  most  of  the  accents.     Now  it  is  well 
known  that  the  copyists  did  not  much  relish  copying  Greek, 
much  less  copying  Hebrew,  and  supplying  of  their  own  free 
will  a  Hebrew  text  with  accents  must  have  been  the  last 
thing  any  of  them  would  have  dreamed  of  doing.     We  may 
therefore    safely    assume   that   Bacon   himself  had   added 
them.     He  dealt  with  this  point  in  the  Opus  Majus;  and  in 
the  Compendium  Studii  Philosophiae,  where  he  repeats  the 

'  Opus  Majus,  I.  iv.   237   (Bridges)  ;    Opus   Tertium,  Ixiv.   267 
(Brewer)  ;    Hebrew  Grammar,  p.  208. 


PHILOLOGY  151 

discussion/  he  modestly  declares  that  a  fuller  explanation 
of  this  difficulty  would  carry  him  too  far,  and  he  was,  at 
present,  neither  obliged  nor  competent  to  enter  into  all  the 
niceties  of  Hebrew  grammar  connected  with  the  question. 

Philology  was  only  one  of  the  many  branches  of  learning 
that  exercised  Bacon's  mind.  Keeping  this  in  view,  and 
considering  the  scanty  supply  of  books  in  their  original 
languages  which  were  at  his  disposal,  and  the  conditions  of 
linguistic  proficiency  of  his  time,  his  achievements  must 
be  looked  upon  as  truly  wonderful.  He  proved  himself  an 
independent  thinker  in  his  treatment  of  the  philosophy  of 
languages,  but  only  within  the  groove  in  which  the  philo- 
sophers of  his  age  moved  :  starting  from  a  priori  assumptions, 
and  arriving  at  unverifiable  conclusions.  He  showed  himself 
a  keen  critic  in  passing  in  review  the  grammatical  products 
which  his  contemporaries  adopted  as  authorities,  and  on 
questions  of  etymology  none  of  them  was  his  equal. 

His  attainments,  whether  in  classics  or  Semitics  or  com- 
parative philology  or  the  philosophy  of  languages,  do  not 
by  a  long  distance  approach  the  results  of  modern  research 
and  thought.  It  would  be  a  sad  testimonial  to  the  progress 
of  learning  if  they  did ;  if  six  centuries  and  a  half  had  failed  to 
change  the  aspect  of  these  disciplines  beyond  all  recognition. 
It  is  so  with  all  subjects  of  knowledge  ;  given  favourable 
circumstances,  no  one  of  them  will  remain  the  same,  even 
after  the  lapse  of  a  comparatively  short  period.  This  fact, 
instead  of  detracting  from  Bacon's  greatness  as  a  philologist, 
serves  the  more  to  throw  his  efforts  into  stronger  relief 
Forty  years  ago  Huxley  said  that  *  our  "  Mathematick  " 
was  one  which  Newton  would  have  to  go  to  school  to  learn  '. 
Then,  at  what  shall  Isaac  Newton's  '  mathematick '  be 
rated,  when  those  who  come  after  us  shall  be  celebrating  the 
septingentenary  anniversary  of  his  birth  ! 

•  Opus  Majus,  I.  iii.  82  (Bridges)  ;   Comp.  Stud.  Phil.,   vi.   436 
(Brewer) . 


VI 

THE  PLACE  OF  ROGER  BACON  IN  THE 
HISTORY  OF  MATHEMATICS 

By  DAVID  EUGENE  SMITH 

I.  Various  Types  of  Genius  in  the  History  of 
Mathematics 

When  we  consider  the  names  that  stand  out  prominently 
in  the  history  of  mathematics,  we  find  that  the  type  of 
genius  having  place  upon  this  particular  roll  of  honour  is 
very  far  from  being  uniform.  Not  every  man  whose  name 
is  here  recorded  was  a  profound  mathematician,  for  Plato  has 
a  merited  place  only  because  he  laid  deep  the  foundations 
of  the  science.  Not  every  one  was  master  of  his  subject, 
for  Thales  ranks  high,  although  his  knowledge  may  have 
covered  less  than  a  half-dozen  of  the  theorems  of  geometry. 
Some  are  there  because  they  were  great  teachers  and 
inspired  their  pupils  to  high  achievement,  as  was  the  case 
with  Pythagoras  at  Crotona.  Others  are  known  for  compila- 
tions of  the  works  of  their  predecessors,  as  witness  Euclid, 
the  author  of  the  Elements.  One  man  will  be  known  for 
pure  theory,  as  was  Apollonius  of  Perga,  while  another,  like 
Archimedes,  will  be  esteemed  chiefly  because  he  put  the 
theory  of  mathematics  into  practice.  Not  every  one  who 
holds  an  honoured  place  created  a  new  science  as  Newton 
did  when  he  stood  on  the  shoulders  of  giants,  or  Descartes 
when  he  laid  aside  his  work  in  philosophy  to  write  his  little 
classic  on  geometry,  or  the  youthful  Galois  when  he  first 
imagined  the  theory  of  groups. 

It  is  necessary  that  we  keep  this  fact  in  mind  when  asking 
ourselves  whether  Roger  Bacon  deserves  to  rank  among  those 
who  have  made  the  science  of  mathematics  what  it  is  to-day. 


154  ROGER  BACON 

Unless  we  do  this  we  shall  lack  that  judicial  attitude  of 
mind  which  is  necessary  for  a  just  conclusion.  It  is  this 
lack  which  leads  some  writers  to  be  severe  to  the  point  of 
injustice  in  their  judgement  of  the  Middle  Ages,  and  others  to 
be  enthusiastic  to  the  point  of  illusion/  and  that  might  easily 
lead  us  to  dismiss  the  name  of  Bacon  as  unworthy  of  serious 
consideration  in  the  history  of  this  branch  of  knowledge. 

II.  The  Problem  to  be  Considered 

The  problem  suggested  by  the  title  of  this  paper  is  not 
merely  to  find  what  Bacon  knew  of  mathematics,  and  in 
particular  what  he  may  have  discovered.  It  is  quite  as 
much  to  consider  the  mathematics  of  his  time,  the  state  of 
the  science  at  Paris  where  he  studied,  and  at  Oxford  where 
he  imbibed  his  first  knowledge  and  where  he  spent  so  many 
years  in  teaching ;  to  examine  the  works  of  his  contem- 
poraries and  pass  judgement  upon  the  contributions  which 
the  Golden  Era  of  the  Middle  Ages  made  to  the  renaissance 
of  learning.  We  must  consider  the  range  of  Bacon's  know- 
ledge, the  atmosphere  in  which  he  worked,  his  appreciation 
of  mathematics,  and  the  efforts  put  forth  by  him  to  elevate 
the  science,  as  well  as  his  own  contributions  to  its  advance. 
It  is  only  by  taking  such  a  view  of  the  problem  that  we  shall 
be  in  a  position  to  weigh,  for  mathematics,  the  justice  of 
the  title  which  the  world  bestowed  upon  him,  the  title  which 
ranks  him  as  '  Doctor  Mirabilis '  in  the  domain  of  science. 

III.  The  Mathematics  of  Bacon's  Time 

Whatever  may  be  our  judgement  as  to  the  puerility  of  the 
mathematics  of  the  thirteenth  century,  it  is  well  agreed  that 
the  century  itself  represents  the  reawakening  of  the  world 
after  a  long  period  of  intellectual  torpor.  The  universal 
Zeitgeist  was  showing  itself  even  in  the  Far  East  in  a  remark- 
able revival  of  the  study  of  algebra  in  China  ;  it  was  in 
'  A  characteristic  noted  by  M.  Charles  in  his  Life  of  Bacon. 


MATHEMATICS  155 

evidence  in  India,  where  Bhaskara's  works  were  beginning, 
a  generation  or  so  after  his  death,  to  spread  their  influence 
abroad  ;  and  its  power  was  felt  in  even  greater  measure  in 
every  part  of  intellectual  Europe.  The  Arabs,  in  their  poetic 
fashion,  speak  of  an  orange  grove  as  made  up  of  '  lanterns 
of  light  in  a  dark  night  ',  and  one  may  not  inappropriately 
characterize  the  thirteenth  century  by  this  same  phrase.  It 
was  not  a  century  of  great  beacon  lights,  but  it  was  one  in 
which  '  lanterns  of  light  '  were  hung  out  in  all  the  thorough- 
fares of  the  West,  promises  of  the  great  illumination  that 
was  to  come  to  the  world  three  hundred  years  later. 

It  is  naturally  to  Italy  that  we  turn  for  the  first  lighting 
of  these  lanterns  of  the  intellect — to  Italy  which  was  still 
the  world's  centre  of  learning.  And  here  we  find,  in  mathe- 
matics, the  name  of  Leonardo  Fibonacci  {c.  1 175-1250) ; 
Leonardo  Pisano,  the  greatest  genius  in  mathematics  of  all 
the  Middle  Ages — his  epoch-making  Liber  Abbaci  '  appeared 
only  thirteen  years  before  Bacon  was  born,  and  the  youthful 
English  monk  had  already  taken  his  doctor's  degree  at  Paris 
long  before  the  great  Pisan  was  laid  at  rest  in  the  Campo 
Santo  beyond  the  Duomo;  Campanus  {c.  1260),  sometime 
chaplain  to  Urban  IV  and  later  canon  of  the  Sainte  Chapelle 
at  Paris,  was  translating  or  editing  Euclid,  and  writing  on 
the  calendar  and  the  sphaera ;  Guglielmo  de  Lunis  {c.  1250) 
was  helping  to  make  known  to  the  Western  world  the  algebra 
of  the  East ;  Bartolomeo  da  Parma  (c.  1294)  was  soon  to 
take  up  his  teaching  at  Bologna,  and  to  write  the  Tractatus 
de  Sphaera,  which  was  destined  to  be  so  popular  as  a  text- 
book of  the  subject ;  and  in  all  the  important  schools  a 
revival  of  mathematics  was  beginning  to  be  apparent. 

In  France  the  newly-founded  University  of  Paris  was 
making  its  influence  felt.  Alexandre  de  Villedieu  (c.  1250) 
was  teaching  at  the  Sorbonne  about  the  time  that  Bacon 
was  attending  lectures.     It  is  he  who  wrote  the  Carmen  de 

'  As  he  spells  the  title. 


156  ROGER  BACON 

Algorismo,  which  did  so  much  to  popularize  the  new  arith- 
metic, and  his  works  De  Sfhaera  and  De  Computo  Ecclesias- 
tico  were  also  well  known.  Vincent  de  Beauvais,  who  died 
in  1265,  was  working  on  his  Quadruple  Miroir  in  Bacon's 
student  days,  giving,  in  this  humble  forerunner  of  the 
Margarita  Philosophica,  some  popular  knowledge  of  the 
various  branches  of  mathematics.  About  this  period  there 
were  also  written  the  oldest  manuscripts  extant  in  the 
French  language  that  explain  the  Hindu-Arabic  numerals, 
numerals  which  were  already  beginning  to  attract  no  little 
attention  in  Italy.  One  Petrus  de  Maharncuria,'  in  Picardy, 
is  also  mentioned  by  Bacon,  with  the  statement  that  he 
was  one  of  the  two  leading  mathematicians  of  his  time,  but 
no  mathematical  works  of  importance  bear  out  this  tribute, 
and  he  is  now  known  only  for  his  work  on  the  magnet  and  for 
a  few  references  in  one  of  the  books  of  his  English  admirer.'' 

Nor  was  Germany  behind  in  her  encouragement  of 
mathematics  in  the  thirteenth  century.  Jordanus  Nemora- 
rius  ^  appears  to  have  written  his  Algorismus  demonstratus, 
Arithmetica  decern  lihris  demonstrata,  Tractatus  de  Sphaera, 
and  De  Triangulis,  and  his  more  important  Tractatus  de 
Numeris  datis,  while  Bacon  was  yet  a  youth.  Albertus 
Magnus  (1193  or  1205-80),  a  Dominican,  in  his  later  years 
Bishop  of  Regensburg,  taught  mathematics  and  medicine 
at  Padua,  and  metaphysics  in  various  places,  and  was 
lecturing  on  dialectics  at  Paris  in  Bacon's  time.  Hermannus 
Alemannus,  one  of  the  first  of  the  Germans  to  be  interested 

'  Mericourt.  He  was  also  known  as  Petrus  Peregrinus.  There  is 
a  Mericourt-sur-Ancre  (Mericourt-l'Abbe)  and  a  Mericourt-sur-Somme, 
both  in  Picardy,  but  it  is  quite  likely  that  Maharncuria  is  the  modern 
hamlet  of  M^haricourt. 

'  Opus  Tertium,  cap.  xi.  For  manuscripts  of  the  De  Magnets,  see 
Father  E.  Schlund,  O.F.M.,  in  Archiv.  Franc.  Hist.,  v.  22-40. 

^  The  identification  of  him  with  Jordan  of  Saxony,  second  Master- 
General  of  the  Dominican  Order,  though  it  has  the  authority  of  Nic. 
Trivet  {Annates,  ed.  Hog,  p.  211),  is  doubtful.  Cf.  Denifie  in  Hist. 
Jahrbuch  der  Gorres-Gesellschaft,  x.  (1899)  566. 


MATHEMATICS  157 

in  the  Arabic  literature  on  Aristotle,  was  studying  among  the 
Saracens  at  Toledo  about  the  time  that  the  young  English 
scholar  was  in  Paris,  and  doubtless  others  in  the  schools  of 
Germany  were  awakening  to  the  need  for  a  broader  know- 
ledge of  the  science  of  the  Greek  and  Arab  civilizations. 

In  England  the  desire  for  mathematics  had  already  been 
manifest  before  the  thirteenth  century  dawned,  A  well- 
known  couplet,  referring  to  geometry,  relates  that 

Thys  craft  com  ynto  England,  as  y  ghow  say, 
Yn  tyme  of  good  kyng  Adelstones  day. 

This  was  three  centuries  before  Bacon  was  born.  Whether 
it  is  true  or  not,  we  know  that  Adelhard  of  Bath  (c.  1180) 
studied  in  Spain  and  translated  some  parts  of  Euclid's  works 
from  the  Arabic  in  the  twelfth  century,  and  that  Daniel 
Morley,  a  man  with  considerable  taste  for  mathematics,  was 
studying  at  Oxford  in  1180.  In  Bacon's  time  Johannes 
de  Sacrobosco '  (c.  1200-56)  was  teaching  mathematics  and 
astronomy  in  Paris,  writing  the  most  popular  work,  De 
Sphaera  Mundi,  that  had  as  yet  appeared  upon  the  subject, 
and  doing  more,  through  his  Tractatus  de  Arte  numerandi, 
to  make  the  numerals  of  algorism  known  than  any  other 
writer  of  his  time,  not  even  excepting  Alexandre  de  Villedieu. 
John  Peckham  {c.  1230-92),  possibly  a  pupil  of  Bacon's, 
and  later  (1279)  Archbishop  of  Canterbury,  was  no  mean 
scientist.  His  work  entitled  Perspectiva  communis  was 
looked  upon  as  a  classic  for  three  hundred  years,  and  his 
influence  at  Oxford,  where  he  taught  theology  and  philo- 
sophy, must  have  been  a  salutary  one.  Among  the  Oxford 
men  of  about  this  period  mention  should  also  be  made  of 
John  of  Basyngstoke,  not  merely  for  his  general  learning," 

'  John  of  Halifax,  known  also  by  such  variants  of  Sacrobosco  as 
Sacrobusto,  Sacro  Bosco,  and  Sacrobosto. 

-  He  died  in  1252.  Under  this  date  Matthew  Paris  remarks: 
'  Obiit  magister  Johannes  de  Basingestokes,  archidiaconus  Legreces- 
triae,  vir  intrivio  et  quadrivio  ad  plenum  eruditus,'  HisioriaAnglorum, 
in  the  Rolls  Series,  iii.  119. 


158  ROGER  BACON 

but  because  he  acquired  Greek  in  Athens  (1240)  and  took 
back  to  England  some  knowledge  of  the  numeral  system 
and  perhaps  of  the  other  mathematics  of  classical  times. 
A  little  before  this  '  the  wizard  Michael  Scott  '  also  studied 
at  Oxford  and  Paris,  and  went  to  Spain  (c.  1217)  to  acquire 
the  learning  of  the  Saracens.  And  besides  all  of  these  there 
was  still  a  better  scholar  than  any  of  them,  Robert  Great- 
head,  student  at  Paris,  student  and  teacher  at  Oxford,  and 
finally  Bishop  of  Lincoln.  The  influence  of  such  a  man 
upon  the  learning  of  his  day  could  not  have  failed  to  be 
great,  and  although  not  primarily  a  mathematician  he  was 
sympathetic  with  the  advance  of  the  science  and  with  its 
applications  to  the  field  of  physics. 

This  list  contains  the  name  of  no  great  genius  in  mathe- 
matics. Not  one  stands  out  for  having  created  a  new 
theory  or  for  having  improved  in  any  noteworthy  manner 
upon  the  work  of  the  ancient  scholars.  But  when  we  com- 
pare these  men  with  those  of  the  centuries  immediately 
preceding,  we  see  that  theirs  was  a  period  of  activity  and 
of  laying  the  foundations  for  better  things. 

IV.  Personal  Associates  who  may  have  Influenced 

Him 

When  we  consider  the  world  activities  in  mathematics  in 
the  thirteenth  century  we  are  naturally  led  to  inquire  whether 
Bacon  was  in  a  position  to  know  of  them,  and  then  to  take 
account  of  his  knowledge  of  the  science  and  his  appreciation 
of  the  work  of  his  contemporaries.  We  are  so  apt  to  imper- 
sonate the  Middle  Ages  as  a  human  being  looking  with  lack- 
lustre eyes  that  it  requires  some  effort  to  realize  that  the 
twelfth  and  thirteenth  centuries  saw  not  merely  a  revival 
of  peripateticism  in  matters  intellectual,  in  the  study  of 
Aristotle,  but  also  its  revival  in  a  physical  sense,  in  the 
wandering  of  scholars  from  university  to  university.  Books 
could  not  readily  circulate  and  carry  the  world's  learning 


MATHEMATICS  159 

to  scholars,  and  so  the  scholars  circulated  and  disseminated 
the  intellectual  oxygen  throughout  the  body  of  awakening 
Europe.  And  thus,  even  while  Bacon  was  a  student  at 
Oxford,  he  might  easily  have  known  of  the  new  interest  in 
mathematics  in  the  South.  For  about  this  time  there  arrived 
in  this  university  the  first  of  the  Franciscans,  men  from  Pisa, 
Florence,  Treviso,  and  other  Italian  towns,  who  might 
easily  have  given  some  intimation  of  the  work  of  Fibonacci 
and  of  the  commercial  arithmetic  of  which  the  Lombards 
and  Tuscans  were  then  the  masters.  There  was  also  a 
certain  'Thomas  de  Hispania'  who  may  have  told  of  the 
astronomy  of  the  Saracens,  and  there  were  others  whom 
Bacon  might  have  met  at  Oxford,  and  still  more  with  whom 
he  must  have  come  in  contact  in  Paris,  from  whom  he  would 
have  known  of  the  efforts  made  to  revive  the  study  of 
mathematics  in  other  parts  of  Europe.  He  knew  Campanus, 
and  very  likely  learned  from  him  to  appreciate  Euclid's 
works.  He  was  a  friend  of  William  of  Shire  wood,  whom 
he  ranked  much  wiser  than  Albertus  Magnus.  Among  his 
intimates  was  Nicholas,  preceptor  of  Amaury  de  Montfort,' 
from  whom  he  must  have  learned  many  things.  And 
besides  these  men  with  whom  he  came  in  contact  there  were 
others,  such  as  Hermann  the  German  and  John  Peckham, 
both  of  whom  have  already  been  mentioned,  Thomas  de 
Bungay,^  Albertus  Magnus,  a  mysterious  John  of  London,-^ 
and  others  whose  names  will  be  mentioned  later  in  this 
paper. 

■  '  Master  Nicholas,  the  teacher  of  Lord  Amaury  de  Montfort,'  as 
he  describes  him  in  the  Opus  Tertium, 

-  See  Anthony  a  Wood,  p.  73.  '  He  seems  like  Roger  to  have 
attached  a  great  importance  to  mathematics,'  Little,  The  Grey  Friars 
in  Oxford,  p.  153. 

^  See  Montague  Rhodes  James,  The  Ancient  Libraries  of  Canterbury 
and  Dover,  Cambridge,  1903,  p.  Ixxiv  ;  Brewer's  edition  of  the 
Opus  Tertium,  cap.  xi,  xix,  and  xx  ;  Charles,  op.  cit.,  p.  11  ; 
Little,  p.  211,  who  says  that  the  youthful  John  who  was  Bacon's 
favourite  pupil '  was  certainly  not  John  of  London,  or  John  Peckham '. 


i6o  ROGER  BACON 

V.  Knowledge  of  the  Classics  of  Mathematics 
Whether  through  contact  with  such  men  as  these,  or 
from  his  other  teachers  at  Oxford  and  Paris,  in  one  way  or 
another  Bacon  became  famihar  with  several  of  the  great 
classics  of  mathematics.  He  quotes  from  all  the  works  of 
Aristotle,  he  knew  the  Elements  and  Optics  of  Euclid,'  he 
was  familiar  with  the  Almagest  and  Optics  and  two  minor 
works  of  Ptolemy,^  he  had  read  Theodosius  on  the  Sphere,  and 
he  knew  more  or  less  of  the  works  of  Hipparchus,  ApoUonius, 
and  Archimedes,  not  to  speak  of  the  minor  writers  among 
the  Greeks.  He  seems  not  to  have  known  the  works  of 
Heron,  however,  and  his  knowledge  of  Nicomachus  came 
only  from  a  secondary  source. 

The  Roman  civilization  having  contributed  so  little  to  the 
progress  of  mathematics,  it  is  not  strange  that  he  knew  the 
works  of  only  a  few  Latin  authors,  notably  Boethius  and 
such  late  writers  as  Isidorus,  Cassiodorus,  and  Bede,  and  the 
mediaeval  scholar  Jordanus  Nemorarius.^ 

The  Arab  writers  with  whom  he  was  familiar  were  chiefly 
those  whose  major  interest  was  in  astronomy  and  optics. 
His  list  of  these  scholars  includes  the  names  of  Ibn  el-Haitam  * 

In  the  Digby  MS.  of  De  communibus  mathematice,  foL  5 1 ,  b,  i ,  it  is 
difficult  to  determine  whether  it  is  Johannes  Londoniensis  or  Johannes 
Baudoun. 

'  In  De  communibus  mathematice  he  refers  to  a  '  special  edition '  of 
the  Elements  by  Adelhard  of  Bath,  in  addition  to  the  latter's  Elementa : 
'  et  Alardus  Batoniensis  in  sua  edicione  speciali  super  Elementa 
Euclidis  ait.'  This  edition  is  at  present  unknown  and  may  well 
merit  the  attention  of  scholars  who  have  access  to  manuscripts  of 
Adelhard's  works.  He  mentions  this  edition  eight  times,  but 
speaks  of  Adelhard's  Commentum  super  Elementa  Euclidis  only  twice. 

-  He  mentions  him  five  times  in  De  communibus  mathematice. 

^  He  mentions  De  triangulis  twice  and  the  Arithmetica  once  in 
De  communibus  mathematice. 

*  Abu  'All  el-Hasan  ibn  el-Hasan  ibn  el-Haitam,  of  Basra.  The 
transliterations  given  by  Suter  in  vol.  x  of  the  Abhandlungen  zur 
Geschichte  der  Mathematik  (Leipzig,  1900)  are  followed  in  the  writing 
of  all  Arabic  names. 


MATHEMATICS  i6i 

{c.  965-1039),  who  wrote  more  than  a  hundred  works  on 
mathematics,  astronomy,  and  physics  ;  ^  Ibn  Sina  ^  (980- 
1037)  >  0^6  of  the  greatest  physicians  and  philosophers 
among  the  Arabs  ;  el-Kindi  ^  {c.  800-74),  prominent  in 
the  field  of  astronomy ;  Tabit  ibn  Qorra,'*  who  wrote  on  the 
theory  of  numbers  and  geometry,  as  well  as  astronomy, 
and  who  made  numerous  translations  from  the  works  of 
the  Greek  mathematicians ;  Averroes  ^  (c.  1126-98),  the 
celebrated  commentator  on  Aristotle  ;  Al-Fargani,^  one  of 
the  first  of  the  Bagdad  astronomers  of  note  ;  Al-Battani  ^ 
(c.  850-929),  whose  table  of  fixed  stars  (a.d.  911)  was  well 
known ;  besides  numerous  others  of  lesser  importance. 
He  was  not,  however,  acquainted  with  the  works  of  Moham- 
med ben  Musa,^  although  somewhat  familiar  with  algorism,^ 

'  A  partial  list  is  given  in  F.  Woepcke's  translation  of  Omar 
Khayyam's  algebra,  L'Algebre  d'Omav  Alkhayydmi,  Paris,  185 1, 
p.  74,  and  in  Suter,  loc.  cit.,  p.  91. 

-  Commonly  known  as  Avicenna.  His  complete  name  was  El- 
Hosein  ibn  'Abdallah  ibn  el-Hosein  (or  Hasan)  ibn  'Ali,  Abii  'Ali, 
el-Seich  el-Ra'is,  Ibn  Sina.  His  chief  contribution  to  mathematics 
was  in  the  field  of  astronomy. 

^  Abu  JAsuf  Ja'qub  ibn  Ishaq  ibn  el-Sabbah  el-Kindi,  also  called 
Alkindi.     He  was  known  as  '  the  philosopher  of  the  Arabs  '. 

*  Abu'  1-Hasan  Tabit  ibn  Qorra  ibn  MerwS-n,  el-Harr§,ni,  commonly 
known  as  Tabit  ben  Korra. 

^  Muhammed  ibn  Ahmed  ibn  Muhammed  ibn  Rosd,  Abu  Welid. 
He  was  born  in  Cordova.  In  De  communibus  mathematice  the 
name  appears  both  as  Averroys  and  Averrois  (Sloane  MS.,  fol.  76, 
a,  2). 

^  Ahmed  ibn  Muhammed  ibn  Ketir  el-Fargani.     He  died  in  833. 

^  Muhammed  ibn  Gabir  ibn  Sinan,  Abu  'Abdallah,  el-Battani,  also 
known  as  el-Raqqi. 

'^  Muhammed  ibn  Musa  el-Chowarezmi,  Abu  'Abdallih.  He 
taught  in  Bagdad  c.  825,  and  wrote  the  first  work  bearing  the  title 
of  algebra — 'ilm  al-jabr  wa'l  muqabalah.  From  his  name,  el- 
Chowarezmi,  or  al-Khowarazml,  came  the  word  algorism,  meaning 
arithmetic  based  on  the  Hindu-Arabic  numerals,  a  word  appearing 
in  such  varied  forms  as  augrim,  augrym,  and  alghorisme. 

^  '  Vias  algorithmi,  scilicet  quomodo  conjugantur  numeri  et  divi- 
duntur,  secundum  omnem  speciem  algorithmi,'  as  he  says. 
1689  M 


i62  ROGER  BACON 

probably  from  the  works  of  Gerbert  and  Bernelinus,'  nor 
did  he  know  anything  of  the  Persian  algebra  of  Omar 
Khayyam  or  of  the  mathematics  of  India  and  the  Far  East. 
Of  algebra  he  knew  little  beyond  the  name,^  nor  does  he 
mention  a  single  work  on  the  subject ;  but  he  shows  a  worthy 
knowledge  of  the  other  important  lines  of  activity  then 
occupying  the  attention  of  the  Arab  writers. 

We  may  therefore  conclude,  with  respect  to  Bacon's  know- 
ledge of  the  masterpieces  of  mathematics,  that  he  was 
familiar  with  a  considerable  number  of  the  great  classics, 
and  was  in  a  position  to  pass  judgement  upon  the  work  of 
his  contemporaries  and  even  to  add  to  the  stock  of  human 
knowledge  if  his  mental  attainments  permitted  and  his 
tastes  allowed/ 

VI.  Contempt  for  the  Mathematics  then  taught 
With  respect  to  Bacon's  judgement  of  the  mathematics  of 
his  day  it  may  be  said  that  it  was  one  of  profound  and 
vociferous  contempt.  Indeed,  it  is  in  the  expression  of  this 
contempt  that  we  find  one  cause  of  his  failure  to  influence 
the  education  of  his  time  as  much  as  might  have  been 
expected  from  his  learning  and  undoubted  ability.  Instead 
of  soberly  going  about  the  work  of  construction  he  raves 
about  the  shortcomings  of  most  of  his  contemporaries.     For 

'  In  speaking  of  fractions  he  says  :  '  De  hiis  vero  tractatur  in 
sciencia  abbaci.  Abbacus  autem  est  mensa  geometrica  Pithagorica. 
In  qua  Pithagoras  deposuit  omnes  istas  f  ractiones  ut  sciretur  in  quot 
quelibet  res  divideretur  in  istas.  Scripsit  autem  de  hiis  primo  domi- 
nus  Papa  Gebertus  quern  omnes  doctores  sequuntur  et  cum  dictis 
expUcavit  et  explanavit.  Inter  quos  precipue  Bernehus  domino 
Amelio  episcopo  Parisiensi  conscripsit'  (Sloane  MS.,  fol.  91,  a).  He 
goes  on  to  say  that  while  he  knows  of  various  works  he  follows 
Bernelinus  chiefly  :    '  Sequor  autem  Bernellum  principaliter.' 

'  '  Algebra  quae  est  negotiatio,  et  almochabala  quae  est  census,' 
as  he  says  in  the  De  com.  mathem.,  quoted  by  Bridges,  Opus  Majiis, 
I,  p.  Ivii. 

^  In  De  communibus  mathematice  he  mentions  Boethius  twenty-five 
times,  Jordanus  twelve  times  (but  not  liis  De  numeris  datis),  Adelhard 
ten  times,  Euclid  often,  and  other  writers  more  or  less  frequently. 


MATHEMATICS  163 

a  follower  of  the  lovable  St.  Francis  of  Assisi  he  was  filled 
with  a  bitterness  that  is  hard  to  explain,  and  that  militated 
against  his  success,  not  merely  among  his  contemporaries 
but  for  at  least  three  centuries  after  his  death. 

It  must  be  said,  however,  that  this  contempt  was  justified, 
even  if  he  was  undiplomatic  in  its  expression.  He  saw  the 
noble  science  of  mathematics  being  debauched  by  those  who 
merely  sought  to  make  it  immediately  instead  of  potentially 
practical,  and  he  cried  aloud  to  prevent  them.'  He  saw 
even  the  philosophers,  who  should  have  led  the  people  to 
cherish  lofty  ideals,  consenting  to  this  debasement  of  the 
science,  and  he  spoke  out  in  no  uncertain  terms. ^  He  found 
the  teachers  so  poorly  equipped  and  so  unsympathetic  with 
learning  that  a  boy  did  well  who  mastered  the  fifth  proposi- 
tion of  Euclid,  the  fuga  miserorum  which  later  became  the 
pons  asinorum  of  the  schools.^  This  he  asserted  to  be  due 
solely  to  poor  teaching  and  not  to  any  general  lack  of 
capacity  on  the  part  of  the  youth  who  frequented  the  schools. 
Although  he  had  devoted  forty  years  to  a  study  of  the 
sciences  and  the  languages,''  he  asserts  that  the  whole  ground 
could  have  been  covered  in  from  three  to  six  months  had 

'  '  Sed  quia  homines  nesciunt  utilitates  philosophiae  primas,  ideo 
despiciunt  multas  scientias  magnificas  et  pulcherrimas,  et  dicunt, 
"  Quid  valet  haec  scientia,  vel  ilia  ?  "  deridendo,  et  non  ut  addiscant.' 
Opus  Tertium,  cap.  iv  (Brewer). 

"  '  Nam  philosophantes  his  diebus,  quando  dicitur  eis  quod  sciant 
perspectivam,  aut  geometriam,  aut  linguas,  et  alia  multa,  quaerunt 
cum  derisione,  "  Quid  valent  haec  ?  "  asserentes  quod  inutilia  sunt. 
Nee  volunt  audire  sermonem  de  utilitate  ;  et  ideo  negligunt  et 
contemnunt  scientias  quas  ignorant'  (Ibid.).  How  history  repeats 
itself  ! 

^  '  Sic  est  hie  quod  isti  qui  ignorant  utilitatem  alicujus  scientiae, 
ut  sit  geometriae,  statim,  nisi  sint  pueri  qui  coguntur  per  virgam, 
resiliunt  et  tepescunt,  ut  vix  volunt  tres  vel  quatuor  propositiones 
scire.  Unde  ex  hoc  accidit  quod  quinta  propositio  geometriae 
Euclidis  dicitur  Elefuga,  id  est,  fuga  miserorum  ;  elegia  enim  Graece 
dicitur,  Latine  miseria  ;  et  elegi  sunt  miseri.'     Opus  Teriium,  cap.  vi. 

*  Opus  Tertium,  cap.  xx. 

M  2 


i64  ROGER  BACON 

the  conditions  been  wholly  favourable."  He  maintains 
that  the  roots  of  the  difficulty  are  (i)  the  teaching  of  a  large 
amount  of  worthless  matter/  and  (2)  the  fact  that  the  world 
needs  to  have 

'  excellent  mathematicians,  who  should  not  only  know 
what  exists,  original  or  translated,  in  connexion  with 
the  sciences,  but  be  able  to  make  additions  to  them, 
which  is  easy  for  good  mathematicians  to  do.  For  there 
were  only  two  perfect  mathematicians,  Master  John  of 
London,  and  Master  Peter  de  Maharn-Curia,  a  Picard.^ 
There  are  two  other  good  ones,  Master  Campanus  de  Novaria, 

'  '  Et  tamen  certus  sum  quod  infra  quartam  anni,  aut  dimidium 
anni,  ego  docerem  ore  meo  hominem  sollicitum  et  confidentem, 
quicquid  scio  de  potestate  scientiarum  et  linguarum,  dummodo 
composuissem  primo  quiddam  scriptum  sub  compendio.'  Opus 
Tertium,  cap.  xx. 

-  '  Quoniam  autem  libri  et  doctores  mathematice  insistunt 
multiplicacioni  conclusionum  et  demonstracionum,  ideo  nuUus 
potest  pervenire  ad  noticiam  illius  sciencie  secundum  modum 
vulgatum  nisi  cum  ponat  30  vel  40  annos,  ut  planum  est  in  eis  qui 
floruerunt  in  hiis  scienciis,  sicut  Dominus  Robertus  felicis  memorie 
nuper  episcopus  Lincolniensis  ecclesie,  et  Frater  Adam  de  Marisco, 
et  Magister  Johannes  Londoniensis  [Baudoun  ?  The  manuscript  is 
dif&cult  to  read],  et  hujusmodi.  Et  ideo  pauci  student  in  hac 
sciencia,  et  sine  hac  sciri  non  possit  odie,  ut  superius  demonstravi. 
Quapropter  studentes  Latini  habent  maxima  impedimenta  sapiencie 
propter  multiplicacionem  conclusionum  et  demonstracionum  mathe- 
matice, et  precipue  quia  huic  multitudini  est  annexa  crudelis  et 
horrenda  difficultas  in  modo  demonstrandi,  ita  quod  studentes  sper- 
nunt  hanc  scienciam  non  solum  quia  eis  ingeritur  multiplicacio 
conclusionum  et  demonstracionum  inpertransibilis,  set  quia  dif&cultas 
adicitur  infinita. 

'  Superfluunt  igitur  omnes  demonstraciones  conclusionum  super- 
fluarum,  et  hoc  est  respectum  multitudo  (!)  demonstracionum  que 
docetur,  quia  paucitas  conclusionum  utilium  inveniatur.  Et  nisi 
esset  hec  superfluitas  et  difi&cultas  dampnabiles  introducte  in  studio 
mathematice,  quilibet  posset  infra  annum  scire  quantum  modo  ali- 
quis  noverit  infra  20  annos,  et  quantum  eis  sufhceret  in  eternum, 
et  hoc  planum  est  per  experienciam  omni  homini  qui  hunc  tractatum 
mathematice  consideravit  diligenter.'  De  communibus  mathematice, 
Digby  MS.,  fol.  56,  b,  i  and  2. 

^  See  pp.  35,  43,  and  46  of  the  Opus  Tertium. 


MATHEMATICS  165 

and  Master  Nicholas,  the  teacher  of  Amaury  de  Montfort. 
For  without  mathematics  nothing  worth  knowing  in  philo- 
sophy can  be  attained.  And  therefore  it  is  indispensable 
that  good  mathematicians  be  had,  who  are  very  scarce. 
Nor  can  any  one,  except  it  be  the  Pope  or  some  great  prince, 
obtain  their  services,  especially  those  of  the  best  one  of 
them.  For  he  would  hardly  condescend  to  live  with  any 
one,  since  he  wishes  to  be  the  lord  of  his  own  studies,  and 
prosecute  philosophical  investigations  at  his  pleasure.' 

Not  only,  in  his  eyes,  had  most  of  his  contemporaries  no  gift 
for  teaching,  but  few  among  them  even  knew  their  subjects. 
To  him  they  were  mere  charlatans,  posing  as  scholars  but  in 
reality  shams  with  some  happy  power  of  discourse.  Such 
was  the  way  in  which  he  looked  upon  Gerard  of  Cremona, 
who  posed  as  a  translator  of  Euclid  from  the  Arabic,'  and 
upon  Gerard's  friend,  Hermann  the  German,^ 

'  When  I  questioned  him  (Hermann)  about  certain  books  of 
logic,  which  he  had  to  translate  from  the  Arabic,  he  roundly 
told  me  that  he  knew  nothing  of  logic,  and  therefore  did  not 
dare  to  translate  them  ;  ^  and  certainly  if  he  was  unacquainted 
with  logic,  he  could  know  nothing  of  other  sciences  as  he 
ought.  Nor  did  he  understand  Arabic,  as  he  confessed,  .  .  . 
for  he  kept  Saracens  about  him  in  Spain,  who  had  a  principal 
hand  in  his  translations.  In  the  same  way  Michael  the  Scot 
claimed  the  merit -of  numerous  translations.  But  it  is  cer- 
tain that  Andrew,  a  Jew,  laboured  at  them  more  than  he  did. 
And  even  Michael,  as  Hermann  reported,  did  not  understand 
either  the  sciences  or  the  tongues.  And  so  of  the  rest, 
especially  the  notorious  William  Fleming,  who  is  now  in 
such  reputation.     Whereas  it  is  well  known  to  all  the  literati 

^  We  are  quite  uncertain  as  to  the  first  translator  of  Euclid  from 
the  Arabic  into  Latin.  It  is  said  that  Adelhard  of  Bath,  Gerard  of 
Cremona,  and  Campanus  all  made  translations,  but  there  seems 
reason  to  believe  that  they  all  depended  on  some  earlier  translator 
whose  name  is  now  lost. 

^  He  studied  at  Toledo,  as  already  stated,  and  translated  the 
Ethics  of  Aristotle  (1243),  the  Encyclopaedia  of  Muhammed  ibn 
Muhammed  ibn  Tarchan  ibn  Auzlag,  Abu  Nasr,  el  Farabi  (c.  950), 
and  the  Averroes  version  of  the  Poetics. 

^  '  Dixit  ore  rotundo,  quod  nescivit  logicam,  et  ideo  non  ausus 
fuit  transferre.' 


i66  ROGER  BACON 

at  Paris,  that  he  is  ignorant  of  the  sciences  in  the  original 
Greek,  to  which  he  makes  such  pretensions  ;  and  therefore 
he  translates  falsely,  and  corrupts  the  philosophy  of  the 
Latins/  ' 

Although  he  has  a  good  word  to  say  for  his  friend 
Grosseteste,  he  returns  again  to  his  attack  on  the  rest, 
saying  :  '  But  all  the  others  were  ignorant  of  the  languages 
and  the  sciences,  and  above  all  this  William  Fleming,  who 
has  no  satisfactory  knowledge  of  either,  and  yet  has  under- 
taken to  reform  all  our  translations  and  give  us  new  ones. 
But  I  have  seen  [his]  books,  and  I  know  them  to  be  faulty, 
and  that  they  ought  to  be  avoided,'  a  judgement  that  seems 
too  bitter  to  be  taken  as  sound,  especially  in  view  of  the 
work  which  his  rival  seems  to  have  accomplished. 

Of  all  those  who  taught  at  Paris  he  has  only  ill  to  say,  assert- 
ing that  no  one  among  them  could  have  written  such  a  treatise 
as  his  on  perspective,^  and  that  the  works  of  the  greatest 
of  them  (probably  Thomas  Aquinas)  ^  are  characterized  by 
four  glaring  defects — infinite  and  puerile  vanity,  ineffable 
falsity,  voluminous  superfluity,  and  the  omission  of  many 
parts  of  philosophy  of  great  utility  and  beauty/ 

Such  harsh  judgements  characterize  Bacon  himself  rather 

'  The  translation  is  Brewer's.  For  the  original  see  Brewer's 
edition,  p.  47 1,  it  being  part  of  cap.viiiof  the  Compendium  Studii.PhiL 
This  Fleming  was  William  of  Moerbecke,  known  also  as  Guilielmus 
Brabantinus  or  Flemingus.  He  was  chaplain  to  Clement  IV,  at  whose 
instigation  Bacon  wrote  the  Opus  Majus,  and  afterwards  was  also 
chaplain  to  Gregory  X.  He  translated  parts  of  the  works  of  Aristotle 
under  the  direction  of  Thomas  Aquinas,  the  Catoptrics  of  Heron 
of  Alexandria  (ascribing  the  work  to  Ptolemy),  and  the  writings  of 
Archimedes  on  floating  bodies.  It  is  thought  that  Tartaglia  took 
his  translation  of  Archimedes  (1543)  from  WiUiam  of  Moerbecke. 
See  Cantor's  Geschichte  der  Mathematik,  vol.  ii  (2),  p.  514. 

^  *  Assero  igitur  vobis  quod  nullum  invenietis  inter  Latinos,  qui 
sicut  nee  usque  ad  unum  annum  hanc  partem  sapientiae  persolvet, 
sic  nee  usque  ad  decern.'     Opus  Tertium,  cap.  ii. 

^  [Probably  Albertus  Magnus. — A.  G,  L.] 

*  Opus  Tertium,  cap.  ix.  See  also  Brewer's  edition,  p.  lix,  and 
cap.  viii  of  the  Comp.  Studii  Phil. 


MATHEMATICS  167 

than  the  men  of  whom  he  writes.  He  speaks  sUghtingly 
of  Jordanus  Nemorarius,  and  yet  Jordanus  was  unquestion- 
ably his  superior  in  the  details  of  mathematics.  He  has 
little  good  to  say  of  Albertus  Magnus,  and  yet  Albertus  was 
perhaps  a  greater  physicist  than  he.  Disappointment  had 
embittered  him,  a  domineering  and  impatient  nature  had 
warped  his  judgement,  and  he  who  might  have  been  a  great 
beacon  light  was,  by  his  own  manner  of  writing  and  speaking, 
snuffed  out,  for  the  time  being,  like  a  mere  candle  in  the 
gloom. 

VII.   His  Appreciation  of  Mathematics 

Although  Bacon  has  little  of  good  to  say  of  any  of  his 
contemporaries,  his  works  are  full  of  appreciation  for 
mathematics  itself.' 

'  The  neglect  of  it  for  thirty  or  forty  years ',  he  writes,^ 
'  has  nearly  destroyed  the  entire  studies  of  Latin  Christen- 
dom. For  he  who  knows  not  mathematics  cannot  know 
any  other  sciences  ;  what  is  more,  cannot  discover  his  own 
ignorance  or  find  its  proper  remedies.  So  it  is  that  the 
knowledge  of  this  science  prepares  the  mind,  and  elevates 
it  to  a  well-authenticated  knowledge  of  all  things.  For 
without  mathematics  neither  antecedents  nor  consequents 
can  be  known  ;  they  perfect  and  regulate  the  former,  and 
dispose  and  prepare  the  way  for  that  which  succeeds.' 

Again  (p.  64,  Jebb ;  i.  108,  Bridges)  : 

'  These  reasons  are  of  universal  application  ;  to  descend 
to  particulars  would  be  nothing  more  than  to  show  how  all 
parts  of  philosophy  are  learned  by  the  application  of  mathe- 
matics ;  in  other  words,  that  the  sciences  cannot  be  known 
by  logical  and  sophistical  arguments,  as  is  ordinarily  the 
case,  but  by  mathematical  demonstrations  descending  into 
the  truths  and  operations  of  other  sciences,  and  regulating 
them,  for  without  mathematics  they  cannot  be  understood 
or  set  forth,  taught,  or  learned.' 

'  For  example,  see  fol.  73,  b,  i,  of  the  Sloane  MS.  of  De  communihus 
mathematice,  with  quotations  from  Boethius,  Cassiodorus,  and  others. 

-  Opus  Majus,  p.  57  of  the  Jebb  edition  ;  vol.  i,  p.  97  of  Bridges' 
edition  :  translated  by  Brewer,  p.  Ixxiii. 


l68  ROGER  BACON 

And  so  continually  throughout  his  works  we  find  the 
praise  of  mathematics  as  the  key  to  all  the  other  sciences.' 

'  '  Sine  mathematica  non  possunt  sciri  scientiae  istae.'  Opus 
Majus,  cap.  ii,  p.  59  (Jebb)  ;  i.  99  (Bridges). 

'  Sed  constat  praedicamentum  quantitatis  cognosci  non  posse  sine 
mathematica.  Nam  sola  mathematica  constituitur  de  quantitate 
cognoscenda.'     Ibid.,  p.  60  ;   i.  102. 

'  Et  ideo  in  sola  mathematica  sunt  demonstrationes  potissimae 
per  causam  necessariam.  Et  ideo  solum  ibi  potest  homo  ex  potes- 
tate  illius  scientiae  devenire  ad  veritatem.  .  .  .  Et  ideo  in  sola 
mathematica  est  certitudo  sine  dubitatione.'     Ibid.,  p.  63  ;  i.  106. 

'  Quare  patet,  quod  si  in  aliis  scientiis  debemus  venire  in  certitu- 
dinem  sine  dubitatione,  &  ad  veritatem  sine  errore,  oportet  ut 
fundamenta  cognitionis  in  mathematica  ponamus,  quatenus  per 
eam  dispositi  possumus  pertingere  ad  certitudinem  aliarum  scien- 
tiarum,  &  ad  veritatem  per  exclusionem  erroris.'  Ibid.,  p.  63  ; 
i.  106. 

'  Quapropter  manifestum  est,  quod  mathematica  est  omnino 
necessaria  &  utilis  aliis  scientiis.'     Ibid.,  p.  64  ;   i.  108. 

His  Distinctio  Secunda,  of  the  fourth  part  of  the  Opus  Majus  (p.  65  ; 
i.  109),  begins  :  '  In  qua  ostenditur,  quod  res  hujus  mundi  requirunt 
mathematicam.'  He  asserts  :  '  Nam  impossibile  est  res  hujus  mundi 
sciri,  nisi  sciatur  mathematica.' 

Nor  was  he  wide  of  the  mark  when  he  said  :  '  Postquam  manifesta 
est  necessitas  mathematicae  in  rebus  hujus  mundi  &  in  scientiis 
humanis,  nunc  potest  istud  idem  ostendi  in  divina.  Et  hoc  est 
magis  considerandum,  quia  humana  nihil  valent  nisi  applicentur  ad 
divina.  Cum  igitur  ostensum  sit  quod  philosophia  non  potest  sciri, 
nisi  sciatur  mathematica,  &  omnes  sciunt  quod  theologia  non  potest 
sciri  nisi  sciatur  philosophia,  necesse  est  ut  theologus  sciat  mathe- 
maticam.'    Ibid.,  p.  108  ;  i.  175. 

'  Et  ideo  post  linguarum  necessitatem  pono  mathematicam  esse 
in  secundo  loco  necessariam,  ad  hoc  ut  sciamus  quae  scienda  sunt ; 
quae  non  est  nota  nobis  per  naturam  ;  sed  tamen  est  prope  cogni- 
tionem  naturalem  inter  omnes  scientias  quas  scimus  per  inventionem 
et  doctrinam.'     Opus  Teriium,  cap.  xxix ;  Brewer,  p.  105. 

'  Homines  enim  semper  sunt  parati  reprobare  quod  nesciunt,  et 
quae  non  sunt  vulgata,  nee  consueta,  nee  exemplis  declarata.  Et 
maxime  accidit  hie  casus  apud  homines  respectu  mathematicae. 
Et  hoc  procuravit  Diabolus,  quia  nulla  utiUtas  sapientiae,  theologiae, 
et  philosophiae,  nee  istius  mundi,  per  vias  sapientales  procurari 
potest  sine  beneficio  mathematicae,  ut  patet  ex  dictis,  sed  planius  ex 
dicendis.'     Ibid.,  cap.  Ixv;  p.  268. 


MATHEMATICS  169 

He  sought  the  support  of  the  Church  by  showing  the  service 
of  mathematics  in  the  study  of  theology/  and  by  recalUng 
to  memory  the  holy  men  who,  in  earlier  times,  had  con- 
tributed to  the  development  of  the  science.^  And  indeed, 
with  all  the  praise  which  Bacon  gave  to  the  science,  it  must 
be  confessed  that  it  was  not  so  much  mathematics  for  its 
own  sake  which  he  championed,  but  mathematics  as  a  hand- 
maid to  theology  or  the  natural  sciences.  He  represented 
seven  centuries  ago,  as  Aristotle  did  in  the  golden  age  of 
Greece,  and  as  so  many  educators  attempt  to  do  to-day,  the 
field  of  applications  and  the  possibilities  of  correlation,  as 
against  the  science  itself.^  But  with  all  of  his  antagonism 
to  the  ultra-scientific  side,  he  recognized  the  culture  phase 
of  the  subject  to  the  extent  of  asserting  that  the  educated 
man  ought  to  be  familiar  with  the  famous  theorems  of  the 
science.  To  this  end  he  favoured  the  demonstration  of  such 
propositions,  even  though  this  might  lead  to  no  particular 
applications.'* 

Among  the  applications  which  are  related  to  the  affairs 
of  the  Church,  Bacon  calls  attention  to  the  importance  of 
mathematics  in  regulating  the  calendar,  thus  fixing  properly 

'  See  Opus  Tertium,  cap.  liii,  Iviii,  and  Ixvi ;  Brewer,  pp.  199,  226, 
228,  270. 

^  '  Sed  sancti  non  reprobant  mathematicam,  quae  est  pars 
philosoplxiae,  sed  quae  pars  est  artis  magicae,  ut  manifestum  est  per 
sanctos.  Nam  Isidorus  in  tractatu  Astronomiae  dicit,  quod  astro- 
nomia  duplex  est ;  una  est  naturalis,  et  alia  superstitiosa  ;  et 
mathematica  una  derivatur  a  mathesi,  media  correpta,  et  ilia  est  pars 
philosophiae  ;  altera  dicitur  a  fiddrjai,  media  producta,  et  ilia  est  et 
haec  sola  maledicta  imponit  necessitatem  rebus  et  libero  arbitrio.' 
Opus  Tertium,  cap.  ix ;  Brewer,  pp.  25  seq. 

^  '  Nichil  enim  est  necessarium  Christiano  nisi  propter  anime 
salutem,  et  ideo  pauciora  de  partibus  philosophic  eis  concedenda 
sunt  quam  philosophis  infidelibus,  qui  a  veritate  multipliciter 
erraverunt.'     De  communibus  mathematice,  fol.  56,  b,  i, 

■*  '  Unde  est  cum  propter  proposiciones  famosas,  quarum  demon- 
stracionem  ignorare  vile  est  quia  sunt  in  ore  cujuslibet ;  ut  "  Quod 
triangulus  habet  3  angulos  equales  duobus  rectis  ".'   Ibid.,  fol.  56,  b,  2. 


170  ROGER  BACON 

the  great  religious  festivals/  a  subject  to  which,  as  we  shall 
presently  see,  he  devoted  serious  attention. 

Bacon's  repeated  championing  of  the  cause  of  mathe- 
matics would  seem  superfluous  were  we  not  aware  of  the 
opposition  which  it  encountered  as  a  species  of  the  Black  Art. 
To  many  it  was  nothing  more  than  astrology  of  the  lowest 
type,  such  as  we  find  to-day  in  parts  of  India  and  elsewhere 
in  the  Far  East.  It  was  this  antagonism  which  Bacon  sought 
to  remove  by  showing  the  science  in  some  of  its  real  nobility, 
although,  it  must  be  confessed,  without  the  success  which 
a  master  of  the  subject  would  have  met  even  in  the  thirteenth 
century.  In  spite  of  his  defects,  however,  it  must  be  said 
that  mathematics  found  no  more  zealous  champion  in  this 
century  than  Bacon,  and  perhaps  his  influence  in  restoring 
it  to  an  honoured  place  in  the  schools  was  greater  than  we 
have  means  at  the  present  time  of  knowing. 

VIII.  Bacon's  Knowledge  and  Conception  of 

Mathematics 

For  a  long  time  Bacon  was  known  as  '  the  great  mathema- 
tician '.  In  an  edition  of  one  of  his  essays  published  in  1590  ^ 
he  is  spoken  of  as  doctissimus  mathematicus ,  an  appellation 
which  could  have  been  little  more  than  traditional  since 
none  of  his  important  works  had  as  yet  appeared  in  print 
and  his  manuscripts  were  but  little  known.  When  the 
mathematical  part  of  the  Opus  Majus  came  from  the  press,  in 
1614,  there  was  some  basis  for  judgement,  and  the  mathe- 
maticians of  the  seventeenth  century,  if  they  looked  at  the 
work  at  all,  must  have  wondered  that  such  a  title  should 
have  been  given  to  its  author.^     In  the  eighteenth  century, 

'  For  an  appreciation  of  this  position  see  Bridges,  The  Opus  Majus 
of  Roger  Bacon,  preface,  p.  ix. 

-  The  Libellus  de  reiardandis  senectuiis  accidentibus  et  de  sensibus 
conservandis,  Oxford,  1590  ;   English  translation,  Lxjndon,  1683. 

■'  John  Wallis,  following  Vossius  in  the  main,  speaks  of  him  as 
'profundae  eruditionis  vir,  studiisque  hujusmodi  admodum  intentus, 


MATHEMATICS  171 

when  the  history  of  mathematics  began  to  attract  some 
attention,  scholars  set  about  to  examine  the  book  and  to 
weigh  up  the  claims  which  might  be  advanced  to  rank  its 
author  as  a  mathematician  of  power.  Heilbronner  '  was 
one  of  the  pioneers  in  the  making  of  histories  of  this  field 
of  activity,  and  while  he  speaks  of  him  in  general  terms  of 
praise,  and  has  much  to  say  of  his  efforts  to  reform  the 
calendar,  he  recognized,  as  every  student  must,  that  he 
contributed  nothing  to  the  pure  science.^  In  France, 
Montucla,  while  testifying  to  Bacon's  erudition,  did  not 
hesitate  to  express  himself  as  having  little  respect  for  him 
as  a  contributor  to  real  mathematics.^  Bossut,  the  first 
edition  of  whose  history  appeared  in  1802,  speaks  well  of 
his  work  in  optics,  but  has  nothing  whatever  to  say  of  his 
work  in  mathematics  itself.'^  In  Germany,  Kastner  ^  fol- 
lowed the  same  course,  admitting  Bacon's  genius  in  optics, 
but  finding  nothing  worthy  of  commendation  in  his  know- 
in  Arabica  literatura  item  versatus,  virisque  modo  dictis  non  ignotus  ; 
non  putandus  est  hujus  artis  [i.e.  algorismi]  ignarus '.  But  this 
condemns  his  real  ability  in  mathematics  with  very  faint  praise. 
See  De  Algebra  Tractatus,  Oxford,  1693,  pp.  6,  13. 

'  Historia  Matheseos  Universae,  Lipsiae,  1742,  pp.  465-71. 

-  '  Vir  tam  vastae  doctrinae,  ut  Anglia,  imo  orbis,  ea  re  nihil 
haberet  simile,  aut  secundum.' 

^  '  II  n'en  est  point  dans  ce  siecle  qu'on  puisse  comparer  a  Roger 
Bacon.  Ne  avec  un  esprit  avide  de  connoissances,  il  etendit  ses 
vues  sur  toutes  les  sciences,  et  en  particulier  sur  les  mathematiques. 
. .  .  Doue  d'un  genie  digne  d'un  meilleur  temps,  il  sentit  bientot  qu'on 
avoit  entierement  manque  la  vraie  route  pour  faire  quelques  progres 
dans  la  philosophie.  .  .  .  Nous  ne  pouvons  cependant  dissimuler  que 
Roger  Bacon  merite  plus  d'eloges  pour  avoir  senti  I'utilite  des 
mathematiques  dans  la  philosophie  naturelle,  que  pour  avoir  fait 
des  decouvertes  qui  les  aient  etendues.  On  ne  pent  lui  refuser  de 
grandes  vues,  mais  sou  vent  moins  justes  que  gigantesques,  et  plus 
seduisantes  que  solides,  comme  I'examen  de  quelques-unes  de  ses 
inventions    le    montrera.'       Histoire    des    mathematiques,    2*    ed., 

P-  513- 

*  See  the  London  edition,  1803,  p.  189. 

^  Geschichte  der  Mathematik,  1797,  ii.  288-91. 


172  ROGER  BACON 

ledge  of  the  pure  science.  Humboldt,  while  characterizing 
him  as  '  the  greatest  apparition  of  the  Middle  Ages  ',  went 
so  far  as  to  assert  that  Bacon's  chief  defect  was  his  lack  of 
mathematical  knowledge.  And  so  we  may  say  that  writers 
on  the  history  of  mathematics  did  not  hesitate,  during  a 
period  of  two  centuries,  to  take  issue  with  tradition  and  to 
assert  that  Bacon  had  no  claim  whatever  to  recognition  in 
this  field.  New  light  has  been  thrown  upon  the  question 
during  the  past  half-century,  however,  first  by  Brewer's 
publication  of  the  Opus  Minus  and  Opus  Tertium ;  secondly 
by  the  new  edition  of  the  Opus  Majus,  with  notes  by  Bridges, 
in  1897,  and  finally  by  Steele's  work  (not  yet  printed)  on 
De  communihus  mathemaiice/  so  that  we  now  have  at  hand 
the  evidence  upon  which  to  pass  a  more  well-considered 
judgement. 

Perhaps  Bacon's  concept  of  the  range  of  mathematics  can 
best  be  obtained  from  the  last  named  of  these  treatises.  In 
the  Distinctio  tercia  he  discusses  the  nine  parts  into  which 
the  science  is  divided.^  He  also  asserts  that,  besides  these, 
there  are  two  general  divisions,  de  communihus  and  de  pro- 
priis,  a  classification  which  he  tells  us  was  suggested  by 
Alpharabius.^  The  first  of  these  two  divisions,  he  claims, 
should  not  be  classified  as  geometry,  arithmetic,  and  so  on, 
but  as  the  elements,  thus  suggesting  the  breaking  down  of 
the  barriers  between  subjects  in  the  same  spirit  as  that 
which  prompts  many  educators  at  the  present  time  to  follow 

'  Mr.  Steele  kindly  placed  at  my  disposal  his  manuscript  copy  and 
complete  set  of  photographs  of  the  De  communibus  mathematice 
(Sloane  and  Digby  MSS.). 

-  '  Primum  est  de  divisione  mathematice  in  partes  novem  cum 
ordine  earum.'     Sloane  MS.,  fol.  82,  a,  i. 

^  Muhammed  ibn  Muhammed  ibn  Tarchan  ibn  Auzlag,  Abu  Nasr, 
el-Farabi  (c.  870-950),  the  commentator  on  Aristotle  and  Ptolemy, 
and  the  author  of  an  Encyclopaedia.  '  Et  mathematica  habet  duas 
partes  principales,  quarum  quedam  est  de  communibus  et  alia  de 
propriis,  et  hanc  divisionem  ponit  Alpharabius  in  libro  De  Scienciis.' 
Sloane  MS.,  fol.  82,  a,  i. 


MATHEMATICS  173 

a  similar  plan  in  the  earlier  stages  of  instruction.'  Of  the 
second  of  his  two  divisions  he  makes  two  great  subdivisions, 
the  speculative  and  the  practical,  each  of  these  being  further 
divided  into  four  parts — geometry,  arithmetic,  astrology, 
and  music.  In  each  case  he  puts  the  speculative  before  the 
practical  in  order  of  teaching.-  Another  division  is  not  with- 
out interest  because  of  the  terms  employed — that  of  practical 
geometry  into  altimetry,  planimetry,  and  superiometry,  the 
third  of  these  relating  to  the  measure  of  depths  and  solids. 
As  to  the  Opus  Majus,  it  is  evident  that  it  is  not  a  treatise 
on  mathematics.  A  few  references  are  made  to  the  classics 
on  this  subject,  and  much  is  said  in  appreciation  of  the 
science,  but  as  to  any  specific  treatment  of  mathematics 
itself  there  is  none.  Moreover,  in  the  Opus  Tertium,^  Bacon 
shows  clearly  that  mathematics  meant  to  him  little  more 
than  astronomy.  For,  speaking  of  the  difficulty  of  securing 
mathematicians,  and  of  the  cost  of  maintaining  them,  he  says : 

*  And  besides  these  expenses,  other  great  expenses  would 
have  to  be  incurred.  Without  mathematical  instruments 
no  science  can  be  mastered ;  and  these  instruments 
are  not  to  be  found  among  the  Latins,  and  could  not  be 
made  for  two  or  three  hundred  pounds.  And  besides, 
better  tables  are  indispensably  requisite,  for  although  the 
certifying  of  the  tables  is  done  by  instruments,  yet  this 
cannot  be  accomplished  unless  there  be  an  immense  number 
of  instruments,  and  these  are  hard  to  use  and  hard  to 
keep,  because  of  rusting,'^  and  they  cannot  be  moved  from 
place  to  place  without  danger  of  breaking.' 

'  '  Et  hec  pars  mathematice  non  debet  vocari  Geometria  nee 
Arismetica  nee  Astrologia  nee  Astronomia  nee  Musiea  sed  de  elementis 
et  de  radieibus  totius  mathematice  que  debent  premitti  ante  partes 
speciales.'     Sloane  MS.,  fol.  82,  a,  i. 

-  '  Geometria  vero  speculativa  est  prior  quam  sua  practica  quia 
operacionem  addit  supra  nudam  speculationem,  et  universaliter  finis 
speculative  est  practica  et  difficilior  et  nobilior  et  longe  utilior  sicut 
finis  se  habet  ad  ea  que  sunt  ad  finem.'     Sloane  MS.,  fol.  83,  a,  i. 

^  Cap.  xii. 

''  '  Propter  rubiginem.'  This  is  strange,  since  it  suggests  that  brass 
and  bronze  instruments  were  not  common,  the  larger  pieces  being  of 


174  ROGER  BACON 

This  means,  as  already  stated,  that  mathematics  in 
Bacon's  mind  was  Httle  more  than  astronomy  ;  but  it 
tells  us  a  great  deal  more  than  this.  It  gives  us  a  view 
of  the  astronomical  observatory  of  the  thirteenth  century, 
with  its  large  celestial  spheres  and  great  astrolabes,  both 
made  of  iron.  It  shows  us  that,  in  the  massive  instruments 
on  the  walls  of  Peking  and  in  the  observatory  at  Jeypore, 
we  see  to-day  the  outfit  of  the  mathematician  of  Bacon's 
time — instruments  which  are  the  *  contemporary  ancestors  ' 
of  Greenwich  and  Mount  Wilson.  It  shows  us,  too,  that 
science  in  the  period  of  mediaeval  awakening  depended  on 
the  workman  from  the  Orient  for  its  astrolabes  and  spheres, 
since  '  these  instruments  are  not  to  be  found  among  the 
Latins  '.' 

Not  in  the  Opus  Majus  nor  in  the  Opus  Tertium,  then,  do  we 
find  any  evidence  of  a  serious  study  of  mathematics,  nor  any 
appreciation  of  what  the  science  really  is.  We  turn,  then,  to 
the  Compendium  Studii  Philosophiae  which  Bacon  planned, 
and  in  which  the  second  of  the  four  volumes  was  to  be  on 
mathematics.  His  De  laudibus  mathematicae  ^  may  have 
been  intended  as  an  introduction  to  this  part  of  the  work, 
but  at  any  rate  the  first  part  of  the  volume  is  preserved 
and  will  shortly  be  edited  by  Mr.  Steele  from  the  Sloane  MS. 
(No.  2156)  and  the  less  complete  one  in  the  Digby  collection.^ 

iron.  Such  astrolabes  of  the  Middle  Ages  as  we  possess,  however, 
are  of  some  form  of  alloy. 

'  The  reader  will  hardly  need  to  be  reminded  of  the  excellent 
treatise  on  the  astrolabe  written  by  Chaucer  a  century  later,  but  the 
casual  visitor  to  the  British  Museum  may  welcome  the  suggestion 
that  he  should  look  among  the  astrolabes  for  the  very  fine  one  which 
Chaucer  may  have  used  when  he  prepared  it. 

=  The  Opus  Majus  contains  one  version. 

^  The  Sloane  MS.  begins  :  '  Hie  incipit  volumen  vere  mathematice 
habens  sex  libros.  Primus  est  de  communibus  mathematice  et 
habet  tres  partes  principales .  Prima  pars  continet  quedam  communia 
preambula  ad  interiora  mathematice  et  habet  [quinque]  distinctiones. 

'  Prima  distinctio  comparat  mathematicam  ad  metaphysicam  et 


MATHEMATICS  175 

In  this  part  Bacon  begins  with  a  description  of  mathematics 
as  distinguished  from  logic  and  magic.  He  recognizes  the 
necessity  for  the  exact  definition  of  such  terms  as  Hmit, 
continuity,  infinity,  and  dimension.  But  when  he  comes 
to  stating  the  nature  of  geometry  we  see  again  how  Umited 
was  his  grasp  of  the  meaning  of  mathematics.^  There  is, 
to  be  sure,  mention  of  theoretical  geometry,  but  Bacon's 
interest  was  in  minute  questions  concerning  the  definitions 
of  terms,^  sometimes  with  flashes  of  real  genius,^  or  con- 
cerning axioms  and  postulates."*     There  is  little  else  to  his 

separat  earn  a  falsa  mathematica  et  dat  intencionem  ejus  et  libros 
hujus  sciencie  tocius  determinat  et  causas  universales  errorum 
humanorum  in  hac  sciencia  sicut  in  aliis  excludit.  Dat  eciam 
mathematice  laudes  et  utilitates  per  duas  vias,  reservans  secunde 
distinctioni  et  aliis  cetera  que  ad  laudes  et  utilitates  mathematice 
requiruntur.     Et  hec  distinctio  prima  habet  vij  capitula. 

'  In  primo  fiunt  tria  que  in  principio  enumeravi.  Nam  in  primo 
comparo  mathematicam  ad  metaphysicam,  secundo  ad  magicam, 
tercio  replico  numerum  et  ordinem  librorum  que  de  integritate  illius 
sciencie  componuntur.' 

This  quotation  gives  some  idea  of  a  work  that  is  not  mathematics 
but  is  about  mathematics. 

'  In  De  communibus  mathematice  the  only  subjects  of  geometry 
mentioned  are  the  definitions  and  assumptions. 

-  For  example,  consider  his  criticism  of  Euclid's  definition  of  a 
surface  as  bounded  by  lines,  and  therefore  finite,  whereas  '  Superficies 
igitur  in  universali  est  quantitas  continua  habens  duas  posiciones  sine 
profundo,  plana  vero  superficies  non  est  ab  una  linea  ad  aliam  exten- 
sio  in  extremi'tates  suas  eas  accipiens'.     Sloane  MS.,  fol.  78,  b,  i. 

'  As  when  he  accepts  the  definition  oi  angle  as  a  portion  of  space  : 
'  Angulus  autem  in  communi  est  spacium  contentum  inter  plures 
lineas  in  puncto  aliquo  concurrentes  quarum  applicacio  est  indirecta. 
Angulus  vero  superficialis  seu  planus  est  spacium  contentum  inter 
duas  lineas  concurrentes  in  punctum  unum  quarum  applicacio  in  una 
superficie  est  indirecta  quia  cum  directe  opponitur  una  linea  alii  non 
est  angulus  sed  tanquam  linea.'  Sloane  MS.,  fol.  79,  a,  i  and  2. 
The  second  statement  is  as  narrow  as  the  first  is  broad. 

••  Speaking  of  such  an  axiom  as  '  Omne  totum  est  majus  sua  parte 
et  hujusmodi  '  he  says  :  '  Et  hec  dicuntur  concepciones  vel  dignitates 
vel  maxime  proposiciones  vel  auxiomata  secundum  Alardum  super 
Elementa  Euclidis.     Unde  Boetius  dicit  in  Ebdomadibus  quod  con- 


176  ROGER  BACON 

theoretical  geometry,  but  on  the  other  hand  genuine 
sympathy  is  shown  with  the  practical  phase  of  the  work, 
including  architecture  and  both  mechanical  and  civil 
engineering,  and  the  construction  of  astronomical,  optical, 
and  even  surgical  instruments.  All  this  reminds  us  of  a 
passage  in  the  Opus  Tertium  in  which  practical  geometry  is 
described : 

*  Then  there  are  other  instruments  and  tables  of  practical 
geometry,  and  practical  arithmetic,  and  music,  which  are  of 
great  utility  and  are  indispensably  required.  But  more  than 
any  of  these  it  would  be  requisite  to  obtain  men  who  have 
a  good  knowledge  of  optics  (perspectiva)  and  its  instruments. 
For  this  is  the  science  of  true  vision,  and  by  vision  we  know 
all  things.  This  science  certifies  mathematics  and  all  other 
things,  because  astronomical  instruments  do  not  work  except 
by  vision,  in  accordance  with  the  laws  of  that  science.  .  .  . 
But  this  science  has  not  hitherto  been  read  at  Paris  or 
among  the  Latins ;  except  twice  at  Oxford  in  England ;  and 
there  are  not  three  persons  acquainted  with  its  power.'  * 

In  De  communihus  mathematice  Bacon  also  speaks  of 
algorism,^  the  new  arithmetic  based  upon  the  Hindu-Arabic 
numerals  which  were  already  well  known  to  the  astrologers,^ 
and  he  even  mentions  algebra.  While  he  states  the  uses  of 
practical  arithmetic  in  the  construction  of  tables,  mensura- 
tion, alloys  and  coinage,  partnership,  and  other  commercial 

cepcio  est  quam  quis  probat  auditum  et  Alardus  Batoniensis  in  sua 
edicione  special!  super  Elementa  Euclidis  ait :  "  Concepciones  sunt 
que  ultimo  (aliter  primo)  occurrunt  humane  intelligentie  in  quibus 
non  est  exigendum  propter  quid."  '     Sloane  MS.,  fol.  89,  b. 

Similarly  with  respect  to  postulates  he  says  :  '  .  .  .  et  peticiones  et 
supposiciones  in  omnibus  scienciis,  ut  in  Geometria  "  a  puncto  ad 
punctum  rectam  lineam  ducere"et  idem  est  peticio  et  supposicio 
secundum  Anaricura  in  Commentario  Elementorum  Euclidis.  Sed 
quia  magister  petit  a  discipulo  ut  credat  ilia,  vocantur  peticiones  et 
quoniam  discipulus  debet  ilia  credere,  et  hoc  est  supponere,  vocantur 
supposiciones  que  non  potest  in  principio  intelligere  set  credere  donee 
fuerit  excercitatus  in  sciencia  cujus  sunt.'     Ibid. 

'  p.  37  of  the  Opus  Tertium.     See  Brewer,  p.  Ixxvi. 

-  *  Vias  algorithm!. ' 

^  Smith  and  Karpinski,  The  Hindu- Arabic  Numerals,  Boston,  191 1. 


MATHEMATICS  177 

operations,  he  gives  no  evidence  of  his  own  proficiency  in 
calculation,  nor  does  he  show  any  conception  of  the  nature 
of  algebra.  He  distinguishes  between  axioms,  postulates, 
and  definitions,  and  this,  with  some  comments,  makes  up 
most  of  the  geometry  in  De  communibus  mathematice,  but 
he  makes  no  attempt  to  advance  the  science  or  to  prove 
a  single  theorem.  He  gives  some  attention  to  integers  and 
fractions,  and  to  arithmetical,  geometrical,  and  harmonical 
ratio,  and  mentions  the  great  mediaeval  game  of  Rithmo- 
machia,'  but  there  is  nothing  in  any  of  this  that  he  could  not 
have  found  in  Boethius  and  other  writers  with  whose  works 
he  was  evidently  familiar.^  He  shows  that  he  knows  the 
works  of  Apollonius,^  and  he  mentions  the  three  conic  sections, 
stating  that  one  of  them  is  used  in  the  construction  of  burning 
mirrors.  Indeed,  it  is  in  his  optics  that  one  must  look  for 
whatever  of  geometry  Bacon  knew,  beyond  his  numerous 
references  to  Euclid.'* 

IX.  His  Relation  of  Mathematics  to  other  Sciences 

When  we  come  to  consider  Bacon's  real  conception  of 
mathematics,  the  application  of  the  science  to  astronomy 
and  optics,  there  is  cause  for  ranking  him  higher  in  the 
scale.     His  work  on  the  calendar  was,  for  the  time,  note- 

'  '  Hie  ludus  sapiencie  vocatur  Rithmimachia,  id  est,  numerorum 
pugna .  Nam  ad ' '  rithmo ' '  Grece ' '  numerus ' '  est  La  tine,  et ' '  machia ' ' , 
media producta,  "pugna"  dicitur  in  Latina,  et  hec  traduntur  in  libris 
propriis  per  singulas  practicas  nominatis,  ut  in  libro  Rithmimachie 
et  in  Algorismo  complete  in  integris  et  fractionibus,  et  in  Algebra 
que  est  "  negociacio  "  et  in  Alraagabale  que  est  "  census  ",  et  in  libro 
Abaci  [Could  he  have  meant  Leonardo  Fibonacci's  work  ?],  et  in 
aliis  practicis  Arismetice.'     Sloane  MS.,  fol.  85,  a,  i. 

-  In  De  communibus  mathematice  there  is  little  more  of  theoretical 
arithmetic  than  is  found  in  Euclid  and  Boethius. 

■^  In  the  Digby  MS.,  fol.  71,  b,  there  is  a  reference  '  ex  libro  pita- 
midis  ApoUonii  '. 

*  He  mentions  him  thirty  times  in  De  communibus  mathematice. 
See  also  Brewer,  p.  Ixxiv  ;   Vogl,  pp.  67-88  ;  Charles,  p.  291. 
1689  N 


178  ROGER  BACON 

worthy,  as  was  also  his  work  in  optics.  These  topics  are, 
however,  not  the  proper  subject  of  this  paper,  and  may 
therefore  be  dismissed  with  brief  mention.  In  so  far  as 
he  sought  '  per  vias  mathematicae  verificare  omnia  quae  in 
naturahbus  scientiis  sunt  necessaria  ' '  he  is  deserving  of 
great  credit,  for  here  he  enters  upon  territory  that  was 
generally  unknown  in  his  day.^  But  even  here  he  placed 
mathematics  relatively  in  the  background,  insisting  that  its 
conclusions  should  be  verified  by  experiment.  For  it  was 
the  experimental  science  that  was  the  mistress  of  all  the 
rest,  '  domina  est  omnium  scientiarum  praecedentium.' 

His  Optics  is  based  mainly  on  the  Thesaurus  Opticae  of 
el- Hasan  ibn  el-Haitam,^  a  work  made  known  to  European 
scholars  in  the  twelfth  century,  probably  first  through  the 
translation  of  Gerard  of  Cremona.  He  made  an  advance 
on  el- Hasan  ibn  el-Haitam  in  his  study  of  parabolic  mirrors, 
and  his  study  of  the  geometry  of  the  microscope  and  his 
apparent  belief  in  the  possibility  of  the  telescope  are  both 
noteworthy.'' 

In  this  connexion  mention  may  properly  be  made  of  his 
suggestion  of  the  possibility  of  the  aeroplane,  of  high-speed 

'  Opus  Majus,  J  ebb  ed.,  p.  64. 

-  So  in  De  coelestibus,  cap.  i,  or  more  correctly  De  coelestibus, 
part  ii,  cap.  2  (Steele,  p.  342),  quoted  by  Charles  (p.  137,  n.)  from 
the  Mazarine  MS.,  he  says  :  '  Naturales  mundi  [Steele,  nudi]  sciant 
quod  languebunt  in  rebus  naturalibus  [et  cecucient :  Steele],  nisi 
mathematicae  noverunt  [noverint :  Steele]  potestatem,  in  quam 
blasphemant,  ex  infinita  ignorantia,  et  propter  ea  omnium  [rerum 
naturalium]  carent  certitudine.' 

'  See  p.  1 1 . 

*  '  Et  cum  voluerimus  et  longe  posita  videantur  propinqua  et  e 
contrario.  Ita  ut  in  incredibili  distancia  videremus  arenas  et 
litteras  minias  minutas,  et  ut  altissima  videantur  infima  et  e  con- 
trario, et  occulta  viderentur  in  aperto  et  aperta  occultarentur,  et 
quod  unum  videretur  innumerabilia  et  e  contrario,  ita  ut  plures  soles 
et  plures  lune  viderentur  per  artificium  hujusmodi  Geometric.' 
Sloane  MS.,  fol.  84,  a,  2.  Cf.  Opus  Majus  (ed.  Bridges),  ii.  164-6  ; 
opus  Tertium  (ed.  Little),  41. 


MATHEMATICS  179 

engines,  of  self-propelled  ships,  and  of  machines  of  wonderful 
power.'  These  are,  however,  the  ideas  of  the  mathematician 
as  seer  and  poet,  not  of  the  mathematician  as  scholar.  To 
see  in  such  suggestions  any  great  discoveries  is  to  see  in 
Bacon's  belief  in  the  possible  transmutation  of  metals  the 
modern  theory  of  ions  and  electrons,''  and  to  see  in  his 

'  '  Et  quinta  [pars]  est  de  fabricacione  instrumentorum  utilitatis 
mirabiliter  excellentis,  ut  instrumenta  volandi  et  deferendi  in 
curribus  sine  animalibus  in  incomparabili  velocitate  et  navigandi 
sine  remigatoribus  velocius  quam  estimari  possit  per  manus  hominum 
fieri.  Hec  enim  facta  sunt  diebus  nostris  ne  aliquis  subrideat  vel 
stupescat.  Et  hec  pars  docet  formare  instrumenta  per  que  possunt 
incredibilia  pondera  elevari  et  deprimi  sine  difficultate  et  labore,  ut 
homo  per  se  possit  seipsum  et  quicquid  vellet  elevare  et  deprimere, 
et  de  carcere  se  erigere  in  subUme  et  erectum  in  alto  deprimere  sicut 
vellet.'     Sloane  MS.,  fol.  83,  b,  i  and  2. 

To  this  extract  should  be  added  the  following  sentences  from  De 
secvetis  opevihus  artis  et  naturae,  cap.  iv, — De  instrumentis  avtificiosis 
mirabilibus  : 

'  Currus  etiam  possunt  fieri  ut  sine  animali  moveantur  cum 
impetu  inaestimabili,  ut  existimantur  currus  falcati  fuisse  quibus 
antiquitus  pugnabatur.' 

'  Possunt  etiam  fieri  instrumenta  volandi,  et  homo  sedens  in  medio 
instrumenti  revolvens  aliquod  ingenium,  per  quod  alae  artificialiter 
compositae  aerem  verberent,  ad  modum  avis  volantis.' 

'  Possunt  etiam  fieri  instrumenta  ambulandi  in  mari  et  in  fluviis 
ad  fundum  sine  periculo  corporali.  Nam  Alexander  magnus  his 
usus  est,  ut  secreta  maris  videret,  secundum  quod  Ethicus  narrat 
astronomus.'  (Compare  also  Opus  Tevtium,  Little  ed.,  p.  18.  A 
propos  of  this  quotation,  there  is  in  San  Marco,  Venice,  a  mosaic  '  La 
Leggenda  di  Alessandro'  of  which  Bacon  may  have  heard.  It  follows 
closely  the  legend  given  by  the  pseudo  Callisthenes,  with  which 
Bacon  was  familiar,  and  represents  Alexander  as  having  harnessed 
two-winged  griffins,  before  which  two  pieces  of  meat  are  held.) 

'  Et  certum  est,  praeter  instrumentum  volandi  quod  non  vidi  nee 
hominem  qui  vidisset  cognovi,  sed  sapientem  qui  hoc  artificium  ex- 
cogitavit  explicite  cognosco.' 

-  '  Quintomododiciturabstractioatransmutacionibusnaturalibus, 
et  materia  sit  [fit  ?]transmutabili[s],  scilicet  secundum  generacionem, 
concepcionem,  alteracionem,  augmentum,  diminucionem  et  loci 
mutacionem  que  est  causa  dictarum  transmutacionum.'  Sloane 
MS.,  fol.  88,  a,  2. 

N  2 


i8o  ROGER  BACON 

reference  to  the  atomic   theory  some  conception  of  the 
infinitesimal  calculus.^ 

This  is  not  the  place  to  speak  at  any  length  of  Bacon's 
work  as  a  cosmographer.  It  is  proper,  however,  to  mention 
the  fact  that  he  knew  the  earth  to  be  spherical,  and  that 
he  believed  the  radius  to  be  3,245  miles.  He  thereupon 
computed  the  circumference  to  be  20,400  miles,  using  3^ 
for  TT,  and  basing  his  work  upon  that  of  Alfraganus  (el- 
Fargani).^  This  led  him  to  assert  the  possibility  of  voyaging 
westward  from  Spain  to  India,^  in  a  passage  that  was  inserted, 

^  The  reference  is  interesting.  It  shows  Bacon  at  his  worst,  both 
in  breadth  of  mind  and  in  clearness  of  reasoning.  '  Non  sit  mundus 
compositus  ex  infinitis  corporibus  et  indivisibihbus  athomis,  ut  posue- 
runt  Democritus  et  Leucippus  et  Epicurus  et  multi  ahi,  set  erunt 
corpora  mundi  finita  et  divisibilia.  Nam  aUter  sequeretur  quod 
dyametri  essent  commensurabiles  coste,  et  non  solum  commensura- 
biles  set  equales,  quorum  utrumque  est  prius  reprobatum  et  demon- 
stratum  super  septimam  proposicionem  decimi  Elementorum  EucUdis, 
et  Aristoteles  et  omnes  nunc  fatentur  quod  hec  commensuracio  non 
est  possibilis. 

'  Quod  vero  hec  consequencia  sit  vera  planum  est  cuilibet  scienti 
potestatem  geometrie,  et  ideo  ignorans  eam  recurrat  ad  priora  ante- 
quam  ad  postremum  conetur.  Ad  evidenciam  tamen  describatur 
quadratum  cum  dyametro,  et  sint  latera  10  punctorum,  trahantur 
ergo  10  a  singulis  punctis  unius  lateris  ad  singula  puncta  alterius 
lateris  oppositi,  tunc  ille  linee  occupabunt  totum  spacium  quadrati  et 
totam  dyametrum,  et  sic  dyameter  non  habebit  nisi  10  puncta,  et  ita 
non  solum  habebit  communem  mensuram  set  equalem.'  Secundus 
Liber  Communium  naturalium,  qui  est  de  celestibus,  Steele's  edition, 
1913,  p.  317.  ^  See  note  on  p.  161. 

^  '  Dicit  Aristoteles  quod  mare  parvum  est  inter  finem  Hispaniae 
a  parte  occiden talis  et  inter  principium  Indiae  a  parte  orientis.  Et 
Seneca  libro  quinto  dicit  quod  mare  hoc  est  navigabile  in  paucissimis 
diebus,  si  ventus  sit  conveniens.  Et  Plinius  docet  in  Naturalibus 
quod  navigatum  est  a  sinu  Arabico  ad  Gades  :  unde  refert  quendam 
fugisse  a  rege  suo  prae  timore  et  intravit  sinum  maris  Rubri  qui 
vocatur  Arabicus,  qui  circiter  spatium  navigationis  annualis  distat 
a  mari  Indico  secundum  Hieronymum  in  epistola,  ut  inferius  ex- 
ponetur.  Et  ideo  latitudo  terrae  per  quam  decurrit  mare  Rubrum 
est  magna  valde  ;  ex  quo  patet  principium  Indiae  in  oriente  multum 
a  nobis  distare  et  ab  Hispania,  postquam  tantum  distat  a  principio 


MATHEMATICS  i8i 

without  acknowledgement  of  its  source,  in  the  Imago  Mundi 
of  Cardinal  Petrus  Alliacus.'  Humboldt  believed  that  this, 
which  Columbus  quotes  in  a  letter  to  Ferdinand  and  Isabella 
(1498),  had  more  to  do  with  the  discovery  of  America  than 
the  Toscanelli  letters. 

It  is,  however,  in  his  work  upon  the  calendar  that  we  find 
something  tangible  in  Bacon's  mathematics.  Here  he  had 
a  definite  task  to  perform,  one  requiring  not  merely  accuracy 
in  observation,  but  the  verifying  of  old  tables  and  probably 
the  constructing  of  new  ones,  and  a  considerable  amount  of 
computation. 

With  respect  to  his  suggestions  for  the  reform  of  the 
calendar  we  are  not  left  in  the  dark,  since  they  are  set  forth 
in  the  Opus  Majus  ^  and  therefore  have  long  been  known  to 
the  world.  In  this  work  addressed  to  Clement  IV  in  1267,  he 
asserted  that  the  length  of  the  year  of  the  Julian  calendar 
is  too  great  by  one  day  in  125  years. ^  This  was  a  remarkable 
statement  for  the  time,  the  great  Alphonsine  tables,  which 
had  been  completed  only  a  few  years  earlier,  having  asserted 
that  the  error  was  one  day  in  134  years  2  months.  He 
therefore  suggested  dropping  one  day  from  the  Julian  calen- 
dar every  125  years,  stating  that  all  the  learned  world  was 
aware  of  the  error  in  the  Christian  reckoning  and  that  the 
Church  was  thereby  the  subject  of  ridicule  on  the  part  of  the 
Saracens,  Jews,  and  Greeks. 

It  is  hardly  worth  while  to  enter  into  the  details  of  Bacon's 
proposed  reform."*    Suffice  it  to  say  that  he  himself  does 

Arabiae  versus  Indiam.  A  fine  Hispaniae  sub  terra  tarn  parvum 
mare  est  quod  non  potest  cooperire  tres  quartas  terrae.'  From  the 
Bridges  edition  of  the  Opus  Majus,  i.  290. 

'  He  died  in  1425.    His  work  was  first  printed  at  Louvain  in  1480. 

'  As  also  in  the  unpublished  Computus  in  MS.  Royal  7  F.  viii. 

^  He  first  said  130  years. 

*  The  reader  will  find  it  helpful  to  consult  Professor  De  Morgan's 
article  in  the  Companion  to  the  British  Almanac  for  1846,  p.  1 1.  On 
the  question  of  the  authenticity  of  his  calendar,  consult  J.  O.  Halli- 
well,  Rara  Mathematica,  London,  1841,  p.  114. 


i82  ROGER  BACON 

not  tell  how  he  reached  his  conclusion  as  to  the  Julian 
calendar  being  too  long  by  one  day  in  125  years,  a  closer 
approximation  than  any  that  is  known  to  have  been  sug- 
gested before  his  time.  At  any  rate  Clement's  death,  or 
possibly  the  antagonism  generally  aroused  by  Bacon,  put 
an  end  to  any  plans  for  reform,  and  it  was  not  until  Clavius 
was  called  to  Rome,  and  bent  his  energies  to  further  the 
project  of  the  Gregorian  calendar,  that  a  fairly  satisfactory 
system  was  evolved. 

X.  Conclusion 

And  finally,  in  view  of  all  that  has  been  said,  what  is  the 
conclusion  as  to  Bacon's  mathematical  talents  ?  One  is 
liable  to  be  led  away  by  enthusiasm  when  writing  upon  the 
occasion  of  the  seven  hundredth  anniversary  of  any  great 
leader,  to  read  into  his  works  what  is  not  there,  and  to  ascribe 
to  him  abilities  which  he  never  possessed.  Against  this  ten- 
dency it  is  always  necessary  to  be  on  guard.  On  the  other 
hand,  we  who  are  cast  in  Nature's  smaller  moulds  tend  by 
our  own  inferiority  to  depreciate  the  greatness  of  the  world's 
leaders.  To  weigh  in  well-balanced  judicial  scales  the  merits 
of  any  man,  and  particularly  of  any  genius,  is  a  very 
difficult  task. 

If  we  ask  ourselves  the  question  whether  Bacon  was 
doctissimus  mathematicus ,  we  must  first  define  our  terms. 
If  we  mean  to  inquire  if  he  was  justified,  by  his  wide  know- 
ledge of  mathematics  and  by  any  great  discoveries,  in  assum- 
ing the  attitude  of  superiority  which  he  showed  towards 
most  of  his  contemporaries,  there  can  be  but  one  answer, 
and  that  a  negative  one.'  If,  on  the  other  hand,  we  use  the 
terms  relatively,  referring  to  Bacon  as  a  scholar  and  a  leader 
of  scholars  in  the  thirteenth  century,  then  the  answer  is  un- 
questionably an  affirmative  one.     No  one  in  his  generation, 

•  On  the  paucity  of  his  geometry,  consult  also  Steele's  edition  of  the 
opera  hacienus  inedita  Rogeri  Baconi,  Oxford  and  London,  1910-13. 


MATHEMATICS  183 

few  men  in  any  generation,  certainly  no  man  in  mediaeval 
England,  showed  such  sympathy  with  mathematics,  such 
familiarity  with  the  standard  authors  available,  such  clear 
perception  of  the  possible  applications  of  the  science,  and 
such  conviction  of  the  value  of  the  subject  in  a  liberal 
education.  Jordanus  was  his  superior  in  detail,  but  was 
relatively  a  pigmy  in  general  power ;  Albertus  Magnus 
seemed  to  accomplish  more  in  physics  and  chemistry,  but 
Roger  Bacon  gave  a  formula  which  freed  intellect  from 
brute  force — the  formula  for  gunpowder ;  Alexandre  de 
Villedieu  and  Bartolomeo  da  Parma  were  better  known  in 
astronomy,  but  it  was  Bacon's  computations  which  gave  to 
the  Middle  Ages  the  best  calendar  as  yet  devised,  and  which 
led  him  to  set  forth  with  perfect  assurance  the  possibility  of 
circumnavigating  the  globe.  It  is  not  for  his  treatises  nor 
for  his  discoveries  in  the  realm  of  pure  mathematics,  but 
for  his  appreciation  of  the  science,  for  his  knowledge  of  what 
the  world  had  done,  and  for  his  vision  of  what  the  future 
had  in  store,  that  for  seven  centuries  he  has  borne  with  justice 
the  title  of  doctissimus  mathematicus,  a  title  by  which  he  may 
rightly  be  known  even  in  our  own  time  and  in  the  centuries 
to  come. 


VII 

ROGER  BACON  UND  SEINE  VERDIENSTE 
UM  DIE  OPTIK 

Von  EILHARD  WIEDEMANN 

Dreimal  haben  hervorragende  englische  Gelehrte  in 
weitreichender  Weise  das  Wesen  der  in  den  Naturwissen- 
schaften  benutzten  Methoden  eingehend  erortert.  Roger 
Bacon  im  dreizehnten  Jahrhundert  in  verschiedenen  Werken, 
vor  allem  in  dem  Opus  Majus  und  tcrtium,  Bacon  von  Verulam 
am  Ende  des  sechzehnten  und  Anfang  des  siebzehnten 
Jahrhunderts  in  seinem  Novum  Organon,  und  endlich  Whewell 
im  neunzehnten  Jahrhundert  in  seiner  Geschichte  und 
seiner  Philosophie  der  induktiven  Wissenschaften.  AUe 
drei  haben  die  Bedeutung  der  induktiven  Methode  gegeniiber 
und  neben  der  der  deduktiven  betont ;  sie  haben  sie  aber 
nicht  erfunden.  Stets  haben  die  Naturforscher  bewusst 
und  die  Vertreter  der  iibrigen  Wissenschaften  unbewusst  auch 
das  induktive  Verfahren  eingeschlagen,  und  umgekehrt 
geht  man  in  den  Naturwissenschaften  auch  deduktiv  vor,  so 
wenn  nach  Aufstellung  einer  Hypothese  deren  Konsequenzen 
in  einer  Theorie  durchgefiihrt  werden.  Die  induktive 
Methode  geht  in  ihrer  Grundform  philosophisch  auf  Sokrates 
zuriick.  Bei  den  oben  erwahnten  drei  Forschern  treten 
neben  den  methodologischen  und  philosophischen  Unter- 
suchungen  eigene  experimentelle  Arbeiten  zuriick.  Bei 
Roger  Bacon  spielte  hier  sicher  der  von  ihm  selbst  beklagte 
Mangel  an  Hilfsmitteln  eine  grosse  Rolle,  Bacon  von  Veru- 
lams  Zeit  war  mit  ganz  anderen  Aufgaben  erfiillt,  als  dass 
er  sich  langwierigen  Versuchen  hatte  widmen  konnen,  und 


i86  ROGER  BACON 

fiir  Whewell  hatte  wohl,  nachdem  er  sich  einmal  philoso- 
phischen  Problemen  zugewandt  hatte,  die  Kleinarbeit  im 
Laboratorium  einen  Teil  des  Reizes  verloren  ;  eine  Erschei- 
nung,  die  auch  sonst  beobachtet  wird.  Alle  lebten  aber  in 
einer  Zeit,  in  der  eine  Fiille  von  experimentellem  Stoff 
vorlag,  dessen  Bedeutung  von  den  Vertretern  der  sog. 
Geisteswissenschaften  und  vor  allem  von  denen  der  Theologie 
nicht  entsprechend  geschatzt  wurde.  Dies  gait  vor  allem 
von  R.  Bacon,  dessen  gelehrte  Zeitgenossen  als  Scholastiker 
sich  ganz  in  philosophische  Spekulationen  vertieften  und  von 
einem  starken  Autoritatsglauben  erfiillt  vvaren,  wie  wir  dies 
spater  in  dem  Kampf  der  Aristoteliker  gegen  die  Forschungen 
Galileis  wieder  beobachten.  Vor  allem  gegen  diesen  Auto- 
ritatsglauben wandte  sich  R.  Bacon  und  erregte  dadurch 
mannigfachen  Widerspruch  ;  indes  stand  er  darin  nicht 
allein  ;  wie  er,  so  betont  auch  der  um  1300  lebende  Theo- 
doricus  Teutonicus  in  seiner  Schrift  iiber  den  Regenbogen, 
dass  man  dem  Experiment  mehr  als  dem  Aristoteles 
vertrauen  sollte.  Dies  sticht  sonderbar  ab  von  der  Art,  wie 
spater  Scheiners  Entdeckung  der  Sonnenflecken  durch  seine 
Oberen  abgelehnt  wurde. 

Anregungen  zu  der  induktiven  Art  des  Arbeitens  und 
Vorlaufer  in  dieser  Richtung  fand  R.  Bacon  zahlreiche  vor. 
Die  aus  der  Antike  iiberlieferten,  ihm  fast  nur  aus  Ueber- 
setzungen  aus  dem  Arabischen  bekannten,  Werke  boten 
hier  nur  sehr  wenig.  In  der  klassischen,  abgeklarten  Form 
treten  vor  allem  in  der  Optik  des  Euklid,  wie  in  dessen 
Elementen,  die  Wege,  auf  denen  die  Resultate  gewonnen 
waren,  ganz  zuriick  ;  etwas  anderes  liegen  die  Verhaltnisse 
in  der  Optik  des  Ptolemaus.  Dagegen  enthielten  die 
R.  Bacon  bekannten  arabischen  Werke  eine  Fiille  experimen- 
tellen  Materials  und  experimenteller  Methodik,  so  vor  allem 
die  optischen  Schriften  von  Ibn  al  Haitam,  dem  oft  von  ihm 
zitierten  Alhacenus.  Bei  Roger  Bacon  finden  wir,  wie  bei 
zahlreichen    muslimischen    Forschern,    noch    eine    andere 


UEBER  DIE  OPTIK  187 

Methode  ausgebildet,  deren  Bedeutung  auch  R.  Bacon 
betont  und  als  deren  Begriinder  er  oft  angesprochen  wird, 
namlich  die  Anwendung  der  Mathematik  auf  naturwissen- 
schaftliche  Probleme.  In  der  Optik  von  Ibn  al  Haitam,  in 
dessen  Schriften  iiber  den  Brennspiegel,  in  dem  Werk  iiber 
den  Qarastun,  in  Kamal  al  Dins  Schrift  iiber  den  Regen- 
bogen  U.S.W.,  findet  sich  aber  diese  Methode  auf  das  glan- 
zendste  durchgebildet  und  benutzt,  viel  eindringender  als 
bei  R.  Bacon  selbst.  So  wird  auch  das  Urteil  verstandlich, 
das  A.  Gogava  im  Jahre  1548  fallte.  Eine  Schrift  iiber  die 
Eigenschaften  der  Parabel  und  den  Brennspiegel  wurde  neu 
entdeckt  und  nach  deren  Urheber  geforscht.  Man  denkt 
dabei  auch  an  R.  Bacon,  demgegeniiber  bemerkt  Gogava  : 

'  Die  Namen  des  Verfassers  konnen  wir  nicht  angeben,  da 
sie  sich  nicht  in  unserem  Exemplar  finden.  Einige  meinten, 
es  sei  Roger  Bacon,  da  dieser  iiber  diesen  Gegenstand  geschrie- 
ben  hat.  Zu  beachten  ist,  dass  in  alien  Werken  Rogers 
sich  keine  Spur  des  Geistes  der  Geometer  und  des  mathema- 
tischen  Scharfsinnes  zeigt,  die  man  in  diesem  Schrift chen 
erkennen  kann.'' 

Zu  beachten  ist  noch,  dass  Ibn  al  Haitam  zwar  in  den 
Schriften  iiber  den  Brennspiegel  im  wesentlichen  mathema- 
tisch  vorgeht  und  die  Resultate  dann  ohne  eingehende 
experimentelle  Priifung  zur  Konstruktion  der  Spiegel  in 
trefflicher  Weise  verwendet,  dass  er  aber  anderseits  in  seiner 
Schrift  iiber  die  Schatten  die  theoretisch  abgeleiteten 
Resultate  Schritt  fiir  Schritt  durch  den  Versuch  priift. 

Will  man  aber  R.  Bacon  in  seinen  Bestrebungen  die 
Mathematik  zu  verwenden  im  Vergleich  zu  den  Arabern 
gerecht  werden,  so  darf  man  nicht  vergessen,  dass  die  letzte- 
ren  sehr  friih  eine  hoch  entwickelte  Mathematik  besassen, 
dass  Ibn  al  Haitam  freier  iiber  die  Lehre  von  den  Kegel- 
schnitten  verfiigen  konnte  als  R.  Bacon,  wenn  diesem  iiber- 
haupt  die  Uebersetzung  des  ApoUonius  bekannt  war. 

Soweit  die  bisherigen  Forschungen  reichen,  hat  R.  Bacon 
'  [Cf.  Appendix,  nos.  44,  45. — A.G.L.] 


i88  ROGER  BACON 

aber  als  erster  eine  Art  der  Behandlung  benutzt,  die  in 
seiner  Schrift  de  SpecuHs  uns  entgegentritt.  Nach  einer 
geometrischen  Konstruktion  Euklids  sollte  der  Brennpunkt 
im  Mittelpunkt  des  spharischen  Hohlspiegels,  nach  R.  Bacon 
selbst  aber  weiter  nach  dem  Spiegel  zu  liegen.  Unter  nur 
geringer  Benutzung  mathematischer  Schliisse  werden  aus 
Betrachtungen  allgemeiner  Art  die  beiden  Resultate,  die 
zunachst  beide  richtig  zu  sein  scheinen,  eingehend  diskutiert 
und  die  tatsachhche  Lage  des  Brennpunktes  gefunden.  Wir 
haben  hier  ein  allgemeineres  Verfahren  als  das  von  den 
Vorgangern  R,  Bacons  geiibte  ;  es  tragt,  wie  mir  scheint, 
einen  Charakter,  der  sich  dann  bei  abendlandischen  Gelehrten 
immer  wieder  findet/ 

Der  Stoff,  an  den  die  Gelehrten  in  der  Zeit  R.  Bacons 
und  dieser  selbst  ankniipfen  konnten,  war  einmal  aus  dem 
Altertum  gekommen  und  teils  durch  direkte  Tradition  iiber- 
mittelt,  teils  aus  den  arabischen  und  hebraischen  Uebersetzun- 
gen,  die  selbst  wieder  in  das  Lateinische  iibertragenwurden, 
zuganglich  geworden.  Vor  allem  waren  es  aber  die  Ergeb- 
nisse  der  muslimischen  Gelehrten,  die  fiir  R.  Bacon  von 
Bedeutung  waren  ;  er  zitiert  selbst  deren  eine  ganze  Reihe. 
Von  anderen  hat  er  sicher  gehort.  Zeigt  sich  doch,  je  mehr 
wir  Kenntnis  von  den  Leistungen  der  arabisch  sprechenden 
Nationen  erhalten,  wie  weit  diese  fortgeschritten  waren,  und 
wie  viel  von  ihnen  an  das  christliche  Abendland  mitgeteilt 
wurde.  So  fusst  ja  Papst  Sylvester  in  seinen  geodatischen 
Arbeiten  auf  allgemein  im  Orient  verbreiteten  Methoden,  so 
lasst  sich  Friedrich  II.  von  agyptischen  Gelehrten  belehren, 
Alphons  von  Castilien  entnimmt  ihnen  seine  Weisheit,  weiter 
lassen  sich  viele  Notizen  in  Leonardos  Werken  auf  Ueber- 
setzungen  aus  dem  Arabischen  zuriickfiihren.  Gross  ist 
die  uns  bekannte  Zahl  von  solchen ;  vieles  spricht  aber 
dafiir,  dass  daneben  noch  zahlreiche  andere,  z.  B.  in  das 
Italienische,  vorhanden  waren.     Neben  den  theoretischen 

'  Vgl.  die  Arbeit  von  J.  Wiirschmidt  in  diesem  Bande. 


UEBER  DIE  OPTIK  189 

Ergebnissen  sind  aber  auch  teils  durch  Geschenk,  teils  als 
Beute,  Proben  der  Wunderwerke  der  Technik,  wie  sie  die 
Orientalen  schufen,  so  die  Automaten  und  die  kunstvollen 
Uhren,  in  das  Abendland  gebracht  worden,  von  anderen 
haben  Kaufleute  und  Kreuzfahrer  berichtet.  Von  solchen 
Werken  hat  auch  R.  Bacon gehort  oder  sie  gesehen,  so  erklaren 
sich  manche  seiner  mechanischen  Konstruktionen  und 
seiner  Plane  nach  dieser  Richtung,  die  der  Zeit  entsprechend 
iiber  das  mogliche  hinaus  weiter  gesponnen  werden. 

Um  die  Leistungen  R.  Bacons  neben  denen  gleichzeitiger 
und  friiherer  Gelehrten  in  der  muslimischen  Welt  richtig  zu 
wiirdigen,  muss  man  die  ganz  verschiedenen  Verhaltnisse, 
unter  denen  sie  wirkten,  beachten.  In  der  muslimischen 
Welt  hatte  eine  Schar  von  Gelehrten  zunachst  unter  dem 
Schutz  der  Chalifen  das  Erbe  der  Antike  aufgenommen 
und  weiter  entwickelt.  An  den  verschiedensten  Orten 
entstanden  Schulen,  die  einzelnen  Forscher  traten  in  den 
regsten  Wechselverkehr,  und  ganz  abgesehen  von  dem 
intellektuellen  Interesse  an  Mathematik  und  Astronomie 
wiesen  die  praktischen  Bediirfnisse,  die  Bestimmung  der 
Gebetszeiten,  die  Aufgaben  der  Architekten  auf  sie  hin. 
Mochte  auch  in  spateren  Zeiten  die  Orthodoxie  sich  zu  den 
exakten  Wissenschaften  wie  zu  gewissen  philosophischen 
Richtungen  feindlich  stellen,  ja  deren  Werke  verbrennen, 
so  war  das  doch  nie  in  dem  ganzen  Reich  der  Fall.  Gerade 
in  solchen  Zeiten  wurde  die  grosse  Sternwarte  in  Maraga 
gegriindet,  Nasir  al  Din  al  Tusi  leitet  sie,  und  neben  ihm 
wirkten  andere.  Selbst  ein  durch  seine  sufischen  Bestre- 
bungen  theologisch  so  gefahrdeter  Mann,  wie  Omar  al  Chaj- 
jami,  konnte  Werke  ersten  Ranges  schaffen.  Ueberwog  etwa 
in  einem  Sultanat  die  orthodoxe  Richtung  zu  sehr,  so  boten 
andere  Hofe  den  Gelehrten  eine  willkommene  Zufluchtsstelle. 
Dadurch  waren  alle  Bedingungen  fiir  eine  emsige  wissen- 
schaftliche  Tatigkeit  des  einzelnen  gegeben.  Ganz  anders 
lag  dies  bei  R.  Bacon.     Er  war  unter  seinen  Zeitgenossen 


igo  ROGER  BACON 

fast  der  einzige,  der  sich  naturwissenschaftlichen  Problemen 
zuwandte;  statt  der  sorgfaltigen  vielfach  kommentierten 
arabischen  Uebersetzungen  aus  den  alten  Sprachen  standen 
ihm  nur  die  durch  eine  doppeltc  Uebertragung  oft  sehr  ver- 
derbten  Texte  zur  Verfiigung.  Als  Franziskaner  stand  er 
imter  der  strengen  Aufsicht  des  Ordens,  und  wenn  dieser 
etwas  fiir  irrig  oder  verwerflich  erklart  hatte,  so  war  ein 
Arbeit  en  in  der  gleichen  Richtung  sehr  erschwert,  ja,  wenn 
der  Papst  sich  dessen  Anschauungen  anschloss,  unmoglich 
gemacht.  Gerade  diese  Umstande  haben  R.  Bacon  stets 
und  stets  gehindert.  Nur  im  aussersten  Siiden,  in  Sizilien, 
hatte  er  freier  arbeiten  konnen.  Wir  miissen  daher  doppelt 
anerkennen,  dass  er  trotz  alledem  so  viel  geleistet  hat. 

Gegeniiber  den  friiheren  Gelehrten  und  auch  einem  Teil 
der  spateren  hat  R.  Bacon  aber  das  grosse  Verdienst,  in 
systematischer  Weise  auf  die  Bedeutung  der  Erfahrung 
hingewiesen  und  gezeigt  zu  haben,  dass  wir  auf  zwei  Arten 
erkennen,  durch  den  Schluss  [argumentum)  und  durch  den 
Versuch  {experimentum) .  Dabei  betont  er,  dass  man  ohne 
den  Versuch  oder,  was  oft  an  dessen  Stelle  tritt,  die  Beobach- 
tung  [experientia)  bezw.  Erfahrung,  in  vielen  Fallen  zu 
keinem  sicheren  Resultat  gelangen  kann.  Bel  dem  dama- 
ligen  Stand  der  Wissenschaft  ist  es  natiirlich,  dass  besonders 
zahlreiche  Beispiele  der  Optik  entnommen  sind.  Ein  wei- 
teres  typisches  Beispiel  aus  einem  anderen  Gebiet  sei  wenig- 
stens  erwahnt.  Es  wird  berichtet,  dass  der  Diamant  nur 
unter  Zuhilfenahme  von  Bocksblut  zerkleinert  werden  kann  ; 
ein  Versuch  lehrt  R.  Bacon,  dass  das  nicht  der  Fall  ist,  son- 
dern  der  Diamant  nur  durch  den  Diamant  zerkleinert  wird. 

Im  folgenden  sollen  die  physikalischen  Kenntnisse  und 
Leistungen  R,  Bacons  auf  einem  von  ihm  besonders  gepflegten 
Gebiete,  namlich  dem  der  Optik,  etwas  eingehender  gewiirdigt 
werden. 

Von  alien  Zweigen  der  Naturwissenschaften  konnen,  wenn 
wir  von  der  Astronomie  absehen,  im  Mittelalter  als  Wissen- 


UEBER  DIE  OPTIK  191 

schaften  im  modernen  Sinn  nur  zwei  angesehen  werden: 
einmal  die  Mechanik,  als  die  Lehre  von  dem  Schwerpunkt, 
dem  Hebel  und  den  einfachen  Maschinen  einschliesslich  der 
verschiedenen  Formen  der  Wage,  als  Schnellwage  und  als 
gleicharmige  Wage ;  hier  schliesst  sich  die  Lehre  vom  Schwim- 
men  und  von  spez.  Gewicht  an.  Das  zweite  Gebiet  ist  die 
Optik  ;  hier  liessen  sich  die  relativ  einfachen  Gesetze  leicht 
scharf  fassen,  oder  doch  wenigstens  wie  bei  der  Brechung 
die  numerischen  Grundlagen  in  Tabellen  zusammenstellen. 
Die  Probleme  auf  den  anderen  Gebiet  en  waren  zu  kompliziert, 
die  Erscheinungen  zu  zahlreich,  als  dass  man  damals  schon 
hatte  einfache  Gesetze  oder  Gesetzmassigkeiten  aufstellen 
konnen,  trotzdem  vielfach  die  Forschung  in  wissenschaft- 
licher  Weise  gefiihrt  wurde  und  zahlreiche  bedeutungsvolle 
Einzelheiten  gewonnen  wurden.  Ein  typisches  Beispiel 
hierf iir  ist  die  Chemie,  der  schon  ein  grosses  Tatsachenmaterial 
zur  Verfiigung  stand,  in  der  schon  Ansatze  zu  einer  quanti- 
tativen  Untersuchung  der  Korper  vorhanden  waren  ;  wis- 
senschaftlich  wurde  sie  aber  erst,  als  Lavoisier  die  Wage  zu 
dem  Instrument  der  Chemiker  machte  und  die  Erkenntnis 
allgemein  wurde,  dass  alle  Substanzen  sich  aus  einer  be- 
schrankten  Anzahl  wohl  definierter  Korper,  den  Elementen, 
nach  bestimmten  Verhaltnissen  zusammensetzen.  Gegeniiber 
der  Mechanik,  die  nur  in  einer  Zweigwissenschaft,  der  Pneu- 
matik,  eine  grossere  Mannigfaltigkeit  darbot,  hat  die  Optik 
den  grossen  Vorzug,  in  der  strengen  Gesetzmassigkeit  des 
Strahlenganges  den  Verstand  zu  befriedigen  und  in  der 
grossen  Fiille  der  Erscheinungen,  so  wohl  auf  der  Erde  wie 
am  Himmel,  die  Phantasie  und  den  Forschertrieb  immer 
von  neuem  anzuregen. 

Durch  ihre  Doppelstellung  als  mathematische  und  physi- 
kalische  Wissenschaft  erregte  die  Optik  schon  im  Altertum 
weitgehendes  Interesse,  das  noch  durch  die  zu  ihr  gehorigen 
optischen  Tauschungen  gesteigert  wurde.  Ihre  Bedeutung 
charakterisiert  Kamal  al  Din  dadurch,  dass  er  von  ihr  sagt, 


192  ROGER  BACON 

dass  sie  nicht  nur  einen  Zweig  der  Mathematik,  sondern 
ihren  Gipfel  bildet.  Bacon  selbst  schildert  sie  nach  der 
Ausgabe  von  Combach  in  der  Einleitung  zur  PerspecHva 
etwa  folgendermassen  : 

'  Ich  mochte  Dich  und  andcre  der  Wissenschaft  wiirdige 
Manner  fiir  die  Wissenschaft  der  PerspecHva  begeistern.  So 
wisse  denn,  dass  zahlreiche  Manner  iiber  diese  Wissenschaft 
geschrieben  haben,  einige  wie  EukUd  und  Jacobus  Alkindi 
haben  nur  allzuwenig  geschrieben,  andere  haben  Abhand- 
lungen  iiber  einzelne  Teile  der  Perspektiva  verfasst,  wie  das 
Buch  iiber  das  Sehen,  dasjenige  iiber  die  Spiegel  und  noch 
andere.  Alhazen  (Ibn  al  Haitam)  war  sowohl  dem  Stoff 
wie  der  DarstcUung  nach  gar  zu  weitschweifig,  wahrend 
Ptolemaus  recht  mittelmassig  verfuhr.  Auf  Deinen  Wunsch 
hin  will  ich  nun  das  Wesentliche  aus  alien  Schriftstellern 
zusammenfassend  darstellen.  Dabei  muss  man  aber  mein 
Werk  iiber  die  Spezies  stets  zu  Handen  haben,  da  man  sonst 
nicht  das  Wertvolle  der  Perspektiva  verstehen  kann. 

'  Diese  Wissenschaft  ist  weit  schoner  und  niitzlicher  als 
andere  und  auch  ergotzlich,  da  unser  Ergotzen  hauptsachlich 
auf  dem  Sehen  beruht.  Licht  und  Farbe  sind  im  Verhaltnis 
zu  den  anderen  Dingen,  die  uns  durch  die  Sinne  zugetragen 
werden,  von  besonderer  Schonheit  ;  aber  nicht  nur  um 
Schonheit  handelt  es  sich  dabei,  sondern  auch  um  den 
Nutzen  und  die  Erfiillung  von  Bediirfnissen.  Aristoteles 
sagt  ja  im  ersten  Buch  der  Metaphysik,  dass  der  Blick 
allein  uns  die  Unterschiede  in  den  Dingen  aufweist  ;  denn 
durch  ihn  gewinnen  wir  sichere  Erfahrungen  iiber  alle  Dinge, 
die  im  Himmel  und  auf  der  Erde  sich  finden.  Durch  zum 
Sehen  eingerichtete  Instrumente  betrachtet  man  die  Erschei- 
nungen  am  Himmel,  wie  Ptolemaus  und  die  anderen 
Astronomen  lehren  ;  ebenso  ist  dies  bei  den  Dingen  der  Fall, 
die  in  der  Luft  erzeugt  werden,  so  den  Kometen,  dem 
Regenbogen  und  ahnlichen  Erscheinungen.  Denn  deren 
Erhebung  iiber  den  Horizont,  ihre  Grosse,  Gestalt,  Menge 
und  alle  ihre  Eigenschaften  werden  durch  die  Betrachtung 
mit  dem  Auge  unter  Zuhilfenahme  von  Instrumenten  sicher 
gestellt.  Was  sich  aber  auf  der  Erde  findet,  das  lernen  wir 
durch  den  Gesichtssinn  kennen,  denn  der  Blinde  kann  iiber 
diese  Welt  keine  wertvoUen  Erfahrungen  sammeln.' 

(Hieran   schliesst    sich   ein  Vergleich   mit    dem    Horen, 
Riechen,  Fiihlen,  dann  wird  fortgefahren.) 


UEBER  DIE  OPTIK  193 

'  Nur  das,  was  niitzlich  ist,  und  zahlreiche  und  herrliche 
Wahrheiten  umfasst,  kann  eine  Wissenschaft  fiir  sich  bilden, 
sonst  geniigt  es,  den  Gegenstand  als  einen  Teil  einer  anderen 
Wissenschaft  zu  behandeln.  Nun  haben  die  Philosophen  von 
alien  Sinnen  nur  fiir  das  Sehen  eine  besondere  Wissenschaft 
geschaffen,  die  Perspectiva;  daher  muss  die  Erkenntniss 
durch  diesen  Sinn  einen  weit  hoheren  Nutzen  als  durcli 
einen  anderen  Sinn  bringen.  Was  ich  soeben  im  Allgemeinen 
ausgefiihrt  habe,  soil  im  folgenden  im  Einzelnen  betrachtet 
werden,  indem  ich  die  Wurzeln  dieser  schonsten  Wissenschaft 
aufdecke.  Eine  andere  Wissenschaft  mag  hoher  stehen,  keine 
bietet  aber  so  viel  an  lieblichem  und  schonem  Nutzen  dar.' 

Die  Ergebnisse  seiner  optischen  Forschungen  hat  R.  Bacon 
an  verschiedenen  Stellen  unter  verschiedenen  Gesichts- 
punkten  zusammengestellt.  Eine  Einzeluntersuchung  iiber 
die  Hohlspiegel  gibt  der  Tractatus  de  speculis,  dann  behandelt 
Bacon  die  Optik  zweimal  im  Opus  majus.  In  der  Perspectiva 
lieferte  er  eine  knappe,  geistvolle  Uebersicht  iiber  den  dama- 
ligen  Stand  dieser  Wissenschaft,  die  im  Herausheben  der 
wesentlichen  Punkte,  im  Zuriickdrangen  des  rein  Mathema- 
tischen  und  in  der  Ersetzung  langatmiger  Beweise  durch 
anschauliche  Betrachtungen  uns  einen  wertvollen  Einblick 
in  die  grosse  Klarheit  des  Denkens  unseres  Gelehrten  liefert. 
Im  Grossen  und  Ganzen  folgt  Bacon  der  Disposition  des 
Stoffes  wie  sie  Ibn  al  Haitam  in  seiner  Optik  gegeben.  Mag 
auch  fast  AUes  alteren,  vor  allem  arabischen,  Quellen  ent- 
nommen  sein,  Form  und  Auffassung  sind  modern,  nicht  mehr 
scholastisch. 

Die  Lehre  von  den  Spezies,  vor  allem  diejenige  von  deren 
Multipiicatio,  wird  hochst  charakteristisch  nicht  in  abstrakter 
Weise  behandelt,  sondern  vielfach  unter  Anschluss  an 
optische  Erscheinungen.  Endlich  zieht  Bacon,  um  den 
Wert  der  Mathematik  nachzuweisen,  vielfach  Beispiele  aus 
der  Optik  heran.  In  dem  Abschnitt  iiber  die  Scientia 
Experimentalis  dient  endlich  der  Regenbogen  zur  Erlauterung 
der  experimentellen  auf  die  Anschauung  gegriindeten 
Methodik. 

1689  o 


194  ROGER  BACON 

Wenden  wir  uns  nun  zur  Optik  selbst  !  Sie  wird  von 
R.  Bacon,  wie  von  seinen  Vorgangern,  wesentlich  als  eine 
Lehre  vom  Sehen  behandelt,  d.  h.  die  Probleme  werden  vom 
physiologischen  bezw.  psychologischen  Standpunkt  aus 
erortert.  Nicht  der  Gang  der  Strahlen  ist  das,  was  in  der 
Perspectiva  zunachst  untersucht  wird,  sondern  es  wird 
gefragt,  welche  Eindriicke,  Tauschungen,  Bilder  erhalt  das 
Auge  bei  geradlinig  fortschreitenden,  reflektierten  iind 
gebrochenen  Strahlen.  Die  Strahlung  selbst  und  ihre 
Zerlegung  bei  Reflexion  und  Brechung  dienen  als  Beispiel 
flir  die  Lehre  von  der  muUiplicatio  specierum,  hier  freilich  in 
so  ausgiebiger  Weise,  dass  dieser  Abschnitt  bei  R.  Bacon 
eine  Optik  in  unserem  Sinn  darstellt  ;  er  ist  zu  erganzen 
durch  den  Traktat  iiber  die  Spiegel  oder  richtiger  iiber  die 
Hohlspiegel.  Diese  Art  der  Behandlung  diirfte  noch  einen 
besonderen  Grund  haben  ;  in  den  meisten  Fallen  sind  die 
von  uns  wahrgenommenen  Bilder  nicht  reelle,  die  durch  das 
Schneiden  wirklich  vorhandener  beobachtbarer  Strahlen 
entstanden  sind,  sondern  es  sind  virtuelle  Bilder,  also  im 
Sinne  der  alteren  Optiker  optische  Tauschungen  ;  in  anderen 
Fallen  handelt  es  sich,  z.  B.  bei  dem  Betrachten  der  Gegen- 
stande  in  gerader  Richtung,  gar  nicht  um  Bilder,  sondern 
um  die  Beurteilung  der  Grosse,  Gestalt  und  Bewegung  von 
Objekten. 

Daneben  wird  auch  der  Strahlengang  selbst  beobachtet 
und  betrachtet,  wenn  er  sich  durch  besondere  Erscheinungen 
kenntlich  macht,  zunachst  bei  der  geradlinigen  Fortpflanzung. 
Diese  beweist,  wie  R.  Bacon  erwahnt,  al  Kind!  durch  die 
Schattenhnien  der  Korper  und  Alhazen  durch  die  sichtbaren 
Linien,  die  entstehen,  wenn  Licht  in  ein  Zimmer  eindringt, 
in  dem  sich  staubige  Luft  befindet.  Weiter  werden  die 
Lichtstrahlen  eingehend  verfolgt  bei  den  Brennspiegeln, 
sowohl  den  spharischen,  wie  den  parabolischen  in  ihren 
verschiedenen  Formen,  und  endlich  bei  der  Brechung,  sei 
es  dass  die  Abhangigkeit  von  Einfallswinkel  und  Ablenkungs- 


UEBER  DIE  OPTIK  195 

winkel  beim  Uebergang  aus  einem  diinneren  in  ein  dichteres 
Medium  und  umgekehrt  festgelegt  wird,  sei  es  dass  der 
Strahlengang  in  brechenden  Medien  und  die  Brennwirkung 
einer  Kugel  untersucht  wird. 

Das  sich  geradlinig  fortpflanzende  Licht  braucht  dazu  cine, 
wenn  auch  fiir  die  Sinne  nicht  wahrnehmbare,  Zeit ;  ein 
Schluss,  der  aus  allgemeinen  Betrachtungen  abgeleitet 
wird.  Die  Strahlen  konnen  sich  kreuzen  und  gehen  dann 
in  gerader  Richtung  weiter,  wie  dies  durch  einen  Versuch 
nachgewiesen  wird. 

Von  den  bei  dem  geradlinigen  Sehen  auftretenden  Tau- 
schungen  erwahnt  R.  Bacon  unter  anderen  die  folgenden  : 
Schnell  bewegte  Korper  erscheinen  grosser,  als  sie  wirklich 
sind.  Sieht  man  grelle  Farben  und  wendet  dann  das  Auge 
nach  einem  hellen  Ort,  so  wirken  die  Farben  nach.  Wird 
ein  Gegenstand  durch  ein  feines  gefarbtes  Tuch  mit  kleinen 
Oeffnungen  betrachtet,  so  erscheint  die  Farbe  des  Gegen- 
standes  mit  denen  des  Tuches  gemischt.  Die  Farbenspezies 
von  Objekt  und  Faden  nahern  sich  hier  in  diesem  Fall  im 
Auge  auf  einen  nicht  mehr  zu  unterscheidenden  Abstand. 
Der  Abstand  zwischen  Auge  und  Objekt  wird,  falls  sich 
zwischen  beiden  keine  Gegenstande  befinden,  oft  falsch 
geschatzt.  Eine  auch  sonst  besprochene  Erscheinung  ist 
die,  dass  eckige  Gegenstande  in  grosser  Entfernung  rund 
erscheinen.  Weiter  erortert  R.  Bacon  die  Falle,  wo  Gegen- 
stande sich  scheinbar  bewegen,  wahrend  sie  eigentlich  ruhen 
und  nur  Gegenstande  in  ihrer  Nahe  sich  bewegen.  Auch 
die  von  Ptolemaus  erwahnte  Erscheinung  des  Zusammen- 
fiiessens  der  Farben  zu  einer  einzigen  beim  Farbenkreisel 
wird  erwahnt. 

Bei  der  Lehre  von  der  Reflexion  wird  zunachst  das  Re- 
flexionsgesetz  aufgestellt,  nach  dem  der  Winkel  des  ein- 
fallenden  Strahles  gleich  dem  Winkel  des  zuriickgeworfenen 
ist ;  die  beiden  Winkel  sind  diejenigen  zwischen  den  Strahlen 
und  der  reflektierenden  Flache.     Die  genauere  von  Ibn  al 

o  2 


196  ROGER  BACON 

Haitam  angegebene  Bestimmung,  dass  einfallender  Strahl, 
reflektierter  Strahl  und  Einfallslot  in  einer  Ebene  liegen 
miissen,  fehlt.  Zugleich  wird  nach  Alhazen  ein  Apparat 
beschrieben,  um  das  Reflexionsgesetz  zu  priifen. 

Das  Bild  liegt  da,  wo  die  Sehstrahlen,  die  nachher  nach 
dem  Objekt  reflektiert  werden,  bei  ihrer  Verlangerung  sich 
mit  der  Kathete,  d.  h.  dem  vom  Objekt  auf  die  spiegelnde 
Flache  gefallten  Lot  schneiden.  Daraus  folgt,  dass  bei 
ebenen  Spiegeln  das  Bild  ebenso  weit  hinter  diesem  liegt, 
wie  der  Gegenstand  vor  ihnen. 

Als  Spiegel  benutzt  R.  Bacon  solche  aus  Erz,  gutem  Stahl, 
Silber  und  mit  Blei  hinterlegtem  Glas. 

Spiegelarten  gibt  es  nach  R.  Bacon  und  den  Gelehrten, 
die  sich  mit  der  Perspektiva  befasst  haben,  sieben  :  Den 
ebenen,  den  spharischen,  den  pyramidenformigen  (kegel- 
formigen)  und  den  zylinderformigen,  die  jeweilig  innen  oder 
aussen  poliert  sind,  also  von  der  Innen-  oder  Aussenflache 
das  Licht  zuriickwerfen.  Dazu  kommt  dann  der  para- 
bolische  Spiegel,  den  Ibn  al  Haitam  ebenso  wie  Roger  Bacon 
fiir  sich  behandelt. 

Bei  den  ebenen  Spiegeln  werden  die  auftretenden  Grossen 
sehr  scharf  definiert.  Bei  ihnen  ist  der  Irrtum  im  Verhaltnis 
zu  anderen  Spiegeln  am  kleinsten,  da  die  Dinge  in  entspre- 
chender  Form  und  Grosse  auftreten,  Nur  die  relative  Lage 
ist  geandert,  das  rechte  wird  zum  linken  (im  senkrechten 
Spiegel),  das  obere  zum  unteren  (im  horizontalen).  Mit 
alien  Spiegelarten  haben  die  ebenen  das  gemeinsam,  dass 
weder  die  Dinge  selbst  an  ihrer  wahren  Stelle  erscheinen 
noch  dass  der  Ort  der  Bilder  dort  liegt.  Hier  betont  nun 
R.  Bacon,  dass  der  Ort  der  Bilder  ein  nicht  wirklicher  ist ; 
er  sagt :  '  Wenn  wir  vom  Ort  des  Bildes  sprechen,  verstehen 
wir  darunter  nur  die  Erscheinung  des  Dinges  und  nichts 
anderes.' 

Nachdem  die  Gesetze  der  Reflexion  festgelegt  sind,  konnen 
die    an    Spiegeln    auftretenden    Erscheinungen    eingehend 


UEBER  DIE  OPTIK  197 

behandelt  werden.  Durch  passende  Anordnung  von  solchen 
kann  ein  Gegenstand  mehrfach  erscheinen,  also  in  Winkel- 
spiegeln.  Hierbei  weist  unser  Gelehrter  auf  die  mannig- 
fachen  Kunststiicke,  die  man  mit  solchen  Spiegeln  ausfiihren 
kann,  hin  :  dass  Gegenstande  da  erscheinen,  wo  sie  nicht  sind 
u.s.w.  Hier  mischen  sich  aberglaubische  Vorstellungen  ein. 
Die  Damonen  sollen  durch  Spiegel  den  Menschen  wunder- 
bare  Dinge  zeigen  und  verborgene  Dinge  an  das  Tageslicht 
bringen. 

Weiter  wird  aus  dem  Reflexionsgesetz  geschlossen,  dass 
das  Mond-  und  Sternenlicht  nicht  reflektiertes  Sonnenlicht 
sein  kann,  da  dieses  bei  den  als  vollkommen  glatt  vorausge- 
setzten  kugelformigen  Gestirnen  nur  nach  einer  Richtung 
reflektiert  werden  wiirde.  Die  Kraft  der  Sonne  wirkt 
vielmehr  auf  die  Gestirne  und  erzeugt  das  Leuchten. 

Die  Tatsache,  dass,  wenn  man  einen  belegten  Glasspiegel 
unter  Wasser  legt,  man  zwei  Bilder  von  der  Sonne  und  dem 
Mond  sieht,  wird  im  Unterschied  von  anderen  richtig  erklart. 

Aus  der  Angabe,  dass,  wenn  man  auf  hohen  Bergen  gegen- 
iiber  von  feindlichen  Staaten  und  Heeren  Spiegel  aufstellt, 
man  alles,  was  in  beliebiger  Entfernung  geschieht,  erkennen 
kann,  ist  auf  die  Entdeckung  des  Spiegelteleskopes  von 
R.  Bacon  geschlossen  worden,  was  natiirlich  ganz  ausgeschlos- 
sen  ist. 

Bei  den  spharischen  Spiegeln  tritt  an  Stelle  der  '  Kathete  ' 
der  durch  den  Gegenstand  gelegte  Kugeldurchmesser ;  das 
Bild  entsteht  da,  wo  der  Sehstrahl,  der  als  eine  von  einem 
punktformigen  Auge  ausgehende  Linie  gedacht  ist,  und  der 
am  Spiegel  reflektiert  wird,  diesen  Durchmesser  schneidet. 
So  ergeben  sich  ohne  weiteres  die  Lagen  der  Bilder,  wenn 
eine  spiegelnde  Hohlkugel  gegeben  ist.  Ist  in  der  Figur  a 
das  Auge  und  das  Objekt  auf  dem  Durchmesser  lo  gelegen, 
so  liegt  das  Bild  auf  dem  Schnittpunkt  der  riickwartigen 
Verlangerung  der  nach  a  refiektierten  Strahlen  mit  lo.  Im 
speziellen  Fall,  wo  der  reflektierte  Strahl  ae  parallel  zu  lo 


igS 


ROGER  BACON 


verlauft,  also  diesen  erst  in  der  Unendlichkeit  schneiden 
wiirde,  verlegt  R.  Bacon  das  Bild  nach  e  selbst.  Sonst 
entsprechen  den  Lagen  des  Objektes  w,  ^,  ^  die  Bildpunkte 


/,  s,  0.     Liegt  der  Gegenstand  im  Mittelpunkt,  so  liegt  das 
Bild  auch  dort. 

Bei  der  Lehre  von  der  Lage  des  Bildes  in  spharischen 
Spiegeln  ist  aber  von  R.  Bacon  wie  auch  von  anderen 
alteren  Gelehrten  der   Nachweis   nicht    geliefert,  dass   alle 


UEBER  DIE  OPTIK  199 

Strahlen,  die  von  einem  Punkt  ausgehen,  sich  wiederum  in 
einem  Punkt  schneiden. 

Anschliessend  an  diese  Betrachtungen  und  an  Ibn  al 
Haitam  wird  bemerkt,  dass  man  je  nach  der  Lage  des  Auges 
von  einem  Gegenstand  im  Hohlspiegel  vier,  drei,  zwei  oder 
auch  nur  ein  Bild  erhalten  wird  ;  dabei  weist  R.  Bacon 
darauf  hin,  dass  wir  beim  Sehen  mit  zwei  Augen  eigentlich 
zwei  Bilder  sehen  miissten  ;  da  diese  aber  sehr  nahe  anein- 
ander  liegen,  so  sieht  man  doch  nur  eines.  Von  Interesse 
ist  endlich  die  Bemerkung,  dass  je  nach  dem  Abstand  der 
Gegenstande  in  Hohlspiegeln  verschiedene  Bilder  entstehen  ; 
dabei  betont  R.  Bacon,  dass  er  hier  eine  Ableitung  in  der 
Katoptrik  verbessert  habe.  Die  Zylinder-  und  Kugelspiegel 
werden  nur  ganz  kurz  erwahnt. 

Die  bekannte  Aufgabe  von  Ibn  al  Haitam,  den  Reflexions- 
punkt  bei  einem  der  obigen  Spiegel  zu  finden,  wenn  Auge  und 
Objekt  gegeben  sind,  behandelt  R.  Bacon  nicht.  Auf  die 
wichtigen  Ausfiihrungen  iiber  die  parabolischen  Hohlspiegel 
wird  Herr  Dr.  Wiirschmidt  eingehen. 

Auch  die  Frage,  ob  die  Farben  am  Schweif  des  Pfaues  und 
am  Hals  der  Taube  wirkliche  Farben  sind,  oder  ob  sie  nur 
von  verschiedenen  Einfallswinkeln  u.s.w.  herriihren,  wird 
behandelt. 

Im  Anschluss  an  Ptolemaus  erortert  R.  Bacon  die 
Brechung  des  Lichtes,  und  zwar  sowohl  an  Kugelflachen,  als 
auch  an  einer  ebenen.  Zunachst  wird  der  allgemeine  Satz 
aufgestellt,  dass  beim  Uebergang  aus  einem  diinneren  in 
ein  dichteres  Medium  der  gebrochene  Strahl  zwischen  die 
geraden  Strahlen  und  das  Lot  im  Brechungspunkte  fallt, 
beim  Uebergang  aus  einem  dichteren  in  ein  diinneres  Medium 
aber  der  gerade  Strahl  zwischen  Lot  und  gebrochenen  Strahl 
fallt. 

Messungen  iiber  die  Abhangigkeit  des  Ablenkungswinkels 
—  dieser  war  es  der  den  alten  Optikern  zuerst  entgegentrat  — 
von  dem  Einfallswinkel  teilt  R.  Bacon  nicht  mit  ;    direkt 


200  ROGER  BACON 

erwahnt  er  auch  den  Apparat  von  Ptolemaus  und  Ibn  al 
Haitam  nicht,  deutet  aber  vielleicht  in  Op.  majus,  i,  S.  113 
(Ausgabe  von  Bridges),  auf  ihn  bin, 

Weiter  wird  das  Bild  eines  Punktes,  der  sich  in  einem 
anderen  Medium  als  dem  Auge  befindet,  dorthin  verlegt, 
wo  der  zum  Auge  gelangende  Strahl  bei  seiner  Verlangerung 
die  Kathete,  d.  h.  das  von  dem  Objekt  auf  die  Grenzflache 
gezeichnete  Lot,  schneidet.  Bei  spharischen  Spiegeln  ist 
diese  Kathete  der  durch  den  betreffenden  Punkt  gehende 
Radius. 

Wie  andere,  so  beschaftigt  auch  R.  Bacon  die  Frage  nach 
dem  Grund,  warum  ein  Stab  im  Wasser  geknickt  und  eine 
Miinze  im  Wasser  gehoben  erscheint ;  er  geht  im  Anschluss 
an  seine  Vorganger  richtig  vor  und  verlegt  das  Bild  eines 
Punktes  des  Objektes  in  den  Schnittpunkt  der  Kathete  mit 
der  Verlangerung  des  Sehstrahles,  der  zum  Objekt  hin  ge- 
brochen  wird. 

Fast  zu  derselben  Zeit  hat  Friedrich  II.  dies  Problem 
aufgeworfen  und  sich  an  agyptische  Gelehrte  um  Auskunft 
gewendet.  Diese  haben  ihm  aber  eine  ganz  ungeniigende, 
rein  spekulative  Antwort  gegeben.  So  sehen  wir,  wie  in 
Aegypten  die  Kenntnis  der  bedeutenden  Leistungen  von 
Ibn  al  Haitam  verloren  gegangen  war,  wahrend  sie  im 
christlichen  Abendland  durch  Uebersetzungen  bekannt  waren 
und  von  R.  Bacon  benutzt  wurden. 

Bei  spharischen  Flachen  zwischen  zwei  Medien  wird  bei 
der  Untersuchung  angenommen,  dass  sich  Auge  und  Mittel- 
punkt  auf  einem  Radius  befinden.  Durch  Zeichnungen 
werden  die  Falle  erlautert,  dass  die  dem  Auge  zugekehrte 
Flache  konvex  oder  konkav  ist,  und  dass  das  Auge  zwischen 
Mittelpunkt  und  Kugelflache  oder  auf  der  anderen  Seite 
des  Mittelpunktes  gelegen  ist. 

Bei  der  Untersuchung  der  Brechung  im  Auge  werden,  was 
wichtig  ist,  nicht  nur  die  von  einem  Objekt  senkrecht  auf  die 
Hornhaut  und  Linse  fallenden  Strahlen  untersucht,  sondern 


UEBER  DIE  OPTIK  201 

auch  die  schrag  auftreffenden  ;  so  wird  gezeigt,  dass  von 
einem  Punkt  nicht  nur  ein  Strahl  zu  der  Linse,  die  als  das 
eigentliche  perzipierende  Organ  betrachtet  wird,  gelangt, 
sondern  eine  ganze  Schar,  die  beim  Auftreffen  auf  die 
Hornhaut  entsprechend  abgelenkt  werden. 

Die  Brennkugel  behandelt  R.  Bacon  zweimal  in  Opus 
Majus,  Bd.  i,  S.  113,  und  ii,  S.  471.  Da  es  sich  um  einen 
Versuch  von  R.  Bacon  selbst  handelt,  so  soil  die  Stelle  mitge- 
teilt  werden : 

Wir  nehmen  einen  spharischen  Kristall  oder  ein  rundes 
Glasgefass,  fiillen  es  mit  Wasser  und  lassen  die  Sonnenstrahlen 
hindurchfallen  ;   dann  ergibt  sich  auf  der  Seite,  welche  der 


Soit/ne 


Fig.  2. 

Sonne  abgewendet  ist,  ein  Brennpunkt,  der  leicht  entziind- 
liche  Stoffe  zum  Brennen  bringt.  Dies  ware  nicht  moglich, 
wenn  nicht  beim  Uebergange  des  Strahles  in  verschiedene 
Mittel  Brechung  eintrate.  Der  durch  den  Mittelpunkt  des 
Gef asses  gehende  Strahl  wird  nicht  gebrochen,  da  er  lotrecht 
zum  Glase,  zum  Wasser  und  zur  umgebenden  Luft  ist. 
Dabei  gilt  das  Zentrum  der  Kugel  zugleich  als  Mittelpunkt 
fiir  die  inneren  und  ausseren  Medien.  Alle  anderen  Strahlen, 
die  nicht  durch  das  Zentrum  gehen,  fallen  schief  auf  und 
werden  beim  Eintritt  in  die  Kugel  zum  Einfallslot  und  beim 
Austritt  aus  derselben  iiber  den  geraden  Gang  hinaus 
gebrochen,  so  dass  der  gebrochene  Strahl  den  durch  das 
Zentrum  gehenden  Achsenstrahl  schneidet.  In  denselben 
Schnittpunkt  fallen  dann  auch  noch  unzahlige  andere 
Strahlen,  so  dass  ein  Brennpunkt  entsteht. 

Zu  beachten  ist,  dass  die  von  R.  Bacon  gegebene  Figur 
nicht  richtig  ist  ;  der  Irrtum  kommt  daher,  dass  in  ihr  die 
Divergenz  der  Strahlen,  die  von  der  Sonne  kommen,  eine 


202  ROGER  BACON 

viel  zu  grosse  ist ;  daher  werden  die  Strahlen  in  der  Kugel 
untereinander  parallel.  Die  ganze  Ableitung  und  Behandlung 
steht  hier  weit  hinter  derjenigen  zuriick,  die  Ibn  al  Haitam 
in  seiner  Schrift  iiber  die  Brennkugel  gegeben  hat ;  diese  hat 
R.  Bacon  offenbar  nicht  gekannt. 

Im  Anschluss  an  die  Brechung  an  spharischen  Flachen 
hat  R.  Bacon  audi  die  vergrossernde  Wirkung  von  Kugel- 
segmenten  genau  erkannt  und  sich  von  ihrer  Ursache 
Rechenschaft  zu  geben  gesucht.     Er  sagt : 

Nimmt  man  ein  Kugelsegment  aus  Kristall  oder  Glas  und 
ist  die  Hohe  des  Segments  kleiner  als  der  Radius,  so  sieht 
man  Buchstaben  und  kleine  Gegenstande  grosser,  wenn  man 
die  konvexe  Seite  dem  Auge  zukehrt.  Denn  das  Auge  ist 
dann  gleichsam  im  diinneren,  das  Objekt  im  dichteren 
Medium  und  zwischen  Zentrum  und  Auge.  Also  ist  der 
Sehwinkel  grosser  und  auch  das  Bild  ist  grosser  und  naher. 
Deshalb  gibt  dieses  ein  vorziigliches  Instrument  fiir  alte 
Leute  und  solche,  die  schwache  Augen  haben,  denn  sie 
konnen  damit  noch  so  kleine  Buchstaben  in  hinlanglicher 
Grosse  sehen.  —  Ist  aber  die  Hohe  des  Segments  grosser  als 
der  Radius,  oder  haben  wir  eine  Halbkugel,  so  entsteht  der 
Fall,  dass  das  Objekt  ausserhalb  des  Zentrums  des  Mediums 
zu  liegen  kommt.  Das  Bild  riickt  in  die  Feme  und  wird 
ebenfalls  grosser.  Nimmt  man  Kristallkorper  mit  ebener 
Flache,  so  treten  ahnliche  Erscheinungen  zu  tage,  doch  ist 
die  konvexe  Form  besser. 

Weiter  sagt  R.  Bacon  : 

Durch  das  Sehen  nach  gebrochenen  Strahlen  konnen  sich 
auch  sehr  grosse  Dinge  als  sehr  klein  darstellen.  Ebenso 
kann,  was  sehr  weit  entfernt  ist,  ganz  nahe  gesehen  werden 
und  umgekehrt.  Denn  es  konnen  durchsichtige  Medien 
{perspicua  ;  hier  nicht  Spiegel)  so  fiir  das  Auge  und  das 
Objekt  angeordnet  werden,  dass  die  Strahlen  dorthin  ge- 
brochen  werden,  wo  und  unter  welchem  Winkel  wir  wollen,  so 
dass  wir  ein  Ding  in  der  Nahe  und  in  der  Feme  sehen  konnen. 
Und  so  konnen  wir  aus  unglaublicher  Entfernung  die  klein- 
sten  Buchstaben  lesen.  Und  da  wir  den  Sehwinkel  beliebig 
vergrossern  konnen,  so  muss  ein  Knabe  wie  ein  Riese,  ein 
Mann  wie  ein  Berg  erscheinen  und  ein  Heer  als  riesig  gross 
erscheinen  und  ebenso,  was  weit  entfernt  ist,  ganz  nahe  und 


UEBER  DIE  OPTIK  203 

umgekehrt.  Ja,  wir  wiirden  Sonne  und  Mond  gleichsam 
vom  Himmel  herabziehen  und  damit  die  Feinde  schrecken 
konnen, 

Neben  den  Erscheinungen  der  physiologischen  und  physi- 
kalischen  Optik  hat  R.  Bacon  sich  auch  eingehend  mit  der 
Lehre  vom  Regenhogen  befasst  und  bilden  diese  Untersuch- 
ungen  einen  wesentlichen  Teil  der  scientia  experimentalis. 
Wir  heben  nur  heraus,  dass  er  den  Regenbogen  auf  eine 
Reflexion  von  Strahlen  zuriickfiihrt,  aber  nicht  auf  eine 
solche  von  ebenen  Spiegeln,  sondern  von  Konvexspiegeln, 
die  von  den  Wassertropfen  geliefert  werden. 

Die  interessanten  Angaben  iiber  die  Lochkamera  werden 
in  dem  Aufsatz  von  Dr.  Wiirschmidt  besprochen  werden. 

Ich  hoffe,  durch  die  obigen  Ausfiihrungen  ein,  wenn  auch 
nur  unvoUstandiges,  Bild  von  den  Werken  eines  derjenigen 
Gelehrten  gegeben  zu  haben,  die,  je  mehr  man  sich  mit 
ihnen  befasst,  um  so  bedeutender  erscheinen. 


VIII 

ROGER   BACONS   LEHRE  VON   DER 

SINNLICHEN  SPEZIES  UND  VOM 

SEHVORGANGE 

Von   SEBASTIAN  VOGL 

I.  Die  Spezieslehre 

Seit  dem  hochsten  Altertum  gait  in  einigen  philosophi- 
schen  Schulen  der  Grundsatz  :  Nichts  ist  im  Verstande, 
was  nicht  vorher  im  Sinn  war  :  nihil  est  in  intellectu,  quod 
prius  non  fuerit  in  sensu. 

Im  Mittelalter  nahmen  ihn  die  Scholastiker  an,  unter 
denen  ganz  besonders  Roger  Bacon  mit  seiner  eingehenden 
Erorterung  iiber  die  Fortpflanzung  der  Spezies  und  ihre 
Wahrnehmung  im  Sinnesorgane  hervorragt. 

Auch  in  der  Neuzeit  hat  es  nicht  an  Verteidigern  obigen 
Satzes  gefehlt.  Insbesondere  haben  sich  die  gelehrten 
Landsleute  Roger  Bacons,  namlich  Bacon  von  Verulam, 
Hobbes  und  Locke,  der  Erforschung  dieses  Prinzipes  ge- 
widmet  und  gerade  letzterer  ihm  eine  besondere  Erklarung 
gegeben,  nach  der  man  ihn  als  den  Vater  des  neueren 
Sensualismus  betrachtet. 

Da  Locke  wie  seine  Vorganger  noch  in  den  Theorien  der 
Scholastik  gebildet  war,  von  denen  aus  sie  sich  zu  ihrer 
selbstandigen  Auffassung  durchrangen,  so  mag  es  nicht 
ohne  Interesse  sein,  Spezieslehre  und  Sehvorgang,  diese 
wichtigen  Momente  fiir  die  Erkenntnislehre,  nach  dem 
beriihmten  Franziskanermonch  Roger  Bacon  kennen  zu 
lernen. 

Wir  wollen  zunachst  einen  kurzen  Ueberblick  iiber  die 
Spezieslehre  bei  den  Scholastikern  iiberhaupt  geben  und 
dann  Roger  Bacons  Theorie  in  den  Hauptziigen  auffiihren. 


2o6  ROGER  BACON 

Zur  Zeit  der  Hochscholastik  bildete  Aristoteles  die 
Grundlage  fiir  die  Erkenntnistheorie.  Genau  wie  bei 
ihm  ist  es  Grundlehre,  dass  jeder  Begriff  nur  mit  Hilfe 
sinnlicher  Vorstellungen  von  den  ausseren  Dingen  gewonnen 
werden  kann.  Beim  Gesichtssinn  ware  der  das  Auge 
treffende  Reiz  eines  Baumes,  die  Fortleitung  dieses  Reizes 
zum  Gehirn  und  weiterhin  die  Umwandlung  desselben  in 
den  psychischen  Akt  der  Wahrnehmung  des  Baumes,  die 
Vorbedingung  fiir  das  Entstehen  des  Begriff  es  Baum, 
Die  vom  Gegenstand  ausgewirkten  Formen,  die  sich  im 
psychischen  Akte  zum  Bilde  gestalten  und  auch  spater 
wieder  Nachbild  und  auch  ohne  unmittelbare  Wahrneh- 
mung nur  durch  das  Vorstellungsvermogen  wieder  erneuert 
werden  konnen,  nennen  die  Scholastiker  species  sensihilis : 
Spezies,  weil  es  gleichsam  das  Bild  des  Baumes  ist ;  sensibel, 
weil  es  mittels  des  Sinnesorganes  gewonnen  resp.  festge- 
halten  oder  erneuert  wird.  Species  sensihilis  ist  also  eine 
anschauliche  Bezeichnung  des  Eindruckes,  der  vom  Reize 
auf  das  Sinnesorgan  ausgeiibt,  und  vom  Organe,  das  beseelt 
ist,  aufgefasst  wird.  Wir  konnen  species  sensihilis  mit  Bild 
oder  Erkenntnisbild  iibersetzen ;  dies  ist  aber  nicht  so  gemeint, 
dass  das  Ding  draussen  und  ein  Bild  von  ihm  drinnen  in 
der  Seele  ist,  sondern  so,  dass  das  Bild  draussen  und  drinnen 
zugleich  ist,  draussen  in  seinem  ganzen  Dasein,  drinnen  als 
Bild,  gleichsam  durch  eine  ideale  Repriisentation.  Das- 
jenige,  wodurch  das  Ding  Bild  wird,  ist  sein  eigentlicher 
Wesenskern,  den  es  bei  Abstreifung  der  Materialitat  und 
beim  Einzuge  in  unser  Inneres  beibehalt. 

Fiir  die  Art  und  Weise,  wie  sich  das  Denken  der  sensi- 
blen  Spezies  bemachtigt,  sei  nur  kurz  darauf  verwiesen,  dass 
die  sensible  Spezies  selbst  etwas,  wenn  auch  nicht  gerade 
Korperliches,  so  doch  Korperhaftes  ist,  das  im  korperlichen 
Organ  als  seiner  Bedingung  fiir  die  Wahrnehmung  haftet. 
Das  Denken  aber  ist  eine  rein  geistige  Tatigkeit.  Da 
helfen  sich  die  Scholastiker  dem  Aristoteles  folgend  dadurch 
aus  der  Schwierigkeit,  dass  sie  an  dieser  Stelle  des  Ueber- 


LEHRE  VON  DER  SINNLICHEN  SPEZIES      207 

ganges  nicht  den  Korper  auf  den  Geist,  sondern  umgekehrt 
den  Geist  auf  den  Korper  wirken  lassen.  Das  Sinnliche 
muss  seiner  rohen  Formen  entkleidet  werden  und  gleichsam 
durch  den  Schmelztiegel  des  tatigen  Verstandes  {infellectus 
agens)  hindurchgehen  ;  hier  erst,  durch  dieses  Licht,  wie 
sie  es  nannten,  gewinnen  die  sensiblen  Spezies  den  Charakter 
der  Intelligibilitat. 

Wenden  wir  uns  nun  der  Spezieslehre  bei  Roger  Bacon  zu. 
Derselbe  widmet  ihr  einen  ausfiihrlichen  Traktat  :  De  multi- 
plicatione  specierum  ;  ausserdem  nimmt  auch  die  Perspec- 
tiva  vielfach  Bezug  darauf. 

I.    Name  und  Begriff  der  Spezies^ 

Jedes  Wirksame,  so  fiihrt  Bacon  aus,  sei  es  eine  Sub- 
stanz  oder  ein  Akzidens,  eine  korperliche  wie  eine  geistige 
Substanz,  betatigt  sich  durch  seine  Kraft,  die  es  auf  die  ihr 
unterstellte  Materie  ausiibt,  und  zwar  die  Substanz  mehr 
als  das  Akzidens,  die  geistige  Substanz  mehr  als  die  korper- 
liche.    So  wirkt  das  SonnenUcht  {lux)  seine  Kraft  in  der 
Luft  als  Licht  {lumen),  das  sich  iiber  die  ganze  Welt  hin 
ergiesst.     Und  diese  Kraft  hat  verschiedene  Namen.     Sie 
heisst    Aehnlichkeit    {similitudo)    und    Bild    {imago)    mit 
Riicksicht  auf  das,  wo  von  sie  ausgeht,  dem  sie  ahnlich  ist 
und  das  sie  nachahmt  ;    species  mit  Riicksicht  auf  die  Sinne 
und  den  Intellekt,  wie  auch  Aristoteles  und  die  Naturkun- 
digen  sie  gebrauchen  ;    idolum  in  Bezug  auf  die  Spiegel  ; 
phantasma  und  simulacrum  bei  den  Traumerscheinungen, 
weil  diese  Spezies  die  Sinne  durchdringen  und  bis  zu  der 
inneren  Seele  gelangen  und  in  den  Traumen  wie  die  Dinge 
selbst  erscheinen,  von  denen  sie  stammen  und  denen  sie 
ahnlich  sind  ;   fonna  heisst  die  Spezies  im  Sprachgebrauch 
des  Alhacen  (Ihn  al  Haitam),  des  Autors  der  Optik  ;  intentio 
im  gewohnlichen  Sinn  der  Naturkundigen,  indem  sie  sagen 
will,  dass   sie   nicht  das  Ding  selbst  ist,  sondern  nur  eine 

'  Bridges,  Opus  Majus,  i.    109  ff.;    ii.  409  £f.  (De  multiplicatione 
specierum) :  Brewer,  Opus  Tert.,  cap.  316. 


2o8  ROGER  BACON 

Beziehung  zu  dem  Dinge,  d.  i.  die  Aehnlichkeit  ;  umbra 
philosophorum :  umbra,  well  die  Spezies  nur  in  einem 
zweifachen  Falle  gut  wahrnehmbar  ist,  namlich  an  einem 
Strahl,  der  durch  eine  Oeffnung  in  einen  dunklen  Raum 
fallt,  und  wenn  die  Spezies  stark  gefarbt  ist,  d.  h.  wenn  Licht 
durch  ein  stark  gefarbtes  Glas  fallt,  so  sieht  man  im  abge- 
kehrten,  schattigen  Raum  die  Farbe  des  Glases  —  philoso- 
phorum, well  nur  die  tiichtigen  Philosophen  ihre  Natur  und 
Wirkung  erkennen.  Sie  heisst  ferner  Kraft  [virtus)  mit 
Riicksicht  auf  Entstehen  und  Vergehen,  Wie  die  Sonne 
ihre  Kraft  auf  die  Dinge  der  Welt  erstreckt,  um  Entstehen 
und  Vergehen  zu  bewirken,  so  sagen  wir  von  jedem  Agens, 
dass  es  seine  Kraft  auf  ein  Patiens  auswirkt.  Eindruck 
[impressio]  heisst  die  Spezies,  weil  sie  den  Eindriicken 
ahnlich  ist,  weshalb  Aristoteles  ihre  Entstehung  mit  dem 
Eindrucke  vergleicht,  den  ein  Siegelring  auf  Wachs  macht, 
wenn  dies  auch  nicht  iiberall  zutrifft.  Passio  endlich  wird 
sie  genannt,  weil  das  Medium  und  der  Sinn  bei  Aufnahme 
der  Spezies  eine  Veranderung  in  ihrer  Substanz  erleiden. 
Spezies  ist  aber  hier  nicht  als  eines  der  Aristotelischen 
Pradikabilien  zu  fassen,  welche  die  Scholastiker  Universalien 
nennen,  sondern  als  der  erste  Effekt  eines  natiirlichen  Agens. 
Unter  Spezies  versteht  demnach  Bacon  das  von  einer 
wirkenden  Ursache  Ausgewirkte,  und  zwar  zunachst  das- 
jenige,  was  von  der  wirkenden  Ursache  kraft  ihrer  eigenen 
Natur  ausgewirkt  wird  und  somit  eine  Aehnlichkeit  mit 
ihr  hat.  Es  ist  also  nicht  mehr  lediglich  die  Bedeutung,  die 
Species  sensibilis  in  der  Scholastik  sonst  hat,  obwohl  diese 
der  Ausgangspunkt  ist,  sondern  iiberhaupt  jede  Wirkung. 

2.  Das  Wesen  der  Spezies^ 

Hinsichtlich  des  Wesens  der  Spezies  ist  zu  sagen,  dass 

sie  dem  Agens  ahnlich  ist  in  der  spezifischen  Wesenheit,  in 

der  Wirkung  und  in  der  Begriffsbestimmung.     Denn  das 

Agens  hat  das  Bestreben,  sich  das  Patiens  zu  assimilieren. 

'  Bridges,  ii.  4ioff. ;  i.  119. 


LEHRE  VON  DER  SINNLICHEN  SPEZIES       209 

1st  das  Agens  Feuer,  so  macht  es  das  Patiens  zu  Feuer,  ist 
das  Agens  Warme,  so  macht  es  das  Patiens  zu  Warme, 
ist  es  Licht,  so  zu  Licht  u.s.w.^  Daraus,  sowie  aus  dem  Bei- 
spiele,  bei  dem  das  Licht  durch  eine  Oeffnung  fallt,  und  dem 
anderen,  bei  dem  das  Licht  durch  ein  stark  gefarbtes  Glas 
hindurchgeht,  ersieht  man,  dass  die  Spezies  des  Lichtes 
wieder  Licht  ist,  die  Spezies  der  Farbe  wiederum  Farbe, 
die  Spezies  der  Warme  wiederum  Warme.  Aber  die  Spezies, 
die  der  Mensch  wirkt,  ist  nicht  Mensch  ;  denn  ist  auch 
die  Spezies  von  derselben  spezifischen  Natur,  so  ist  sie  es 
doch  auf  einer  unvollstandigen  Seinsstufe,  die  im  letzteren 
Falle  gar  nicht  vollstandig  werden  kann.  Farbe,  Licht  und 
Warme  konnen  aber  ihrer  Natur  nach  eine  starkere  Spezies 
wirken  als  alle  anderen  Dinge. 

Daraus  ergibt  sich  eine  weitere  Wahrheit,  namUch  dass 
der  Effekt,  der  dem  Agens  im  Wesen  ahnlich  ist,  nur  einer 
sein  kann.  Dieser  heisst  der  effectus  univocus  und  seine 
Entstehung  generatio  univoca.  Es  gibt  aber  noch  andere 
Effekte,  die  effectus  aequivoci,  und  deren  Entstehen  generatio 
aequivoca,  heissen.  So  ist  das  Licht  in  der  Luft  oder  an 
einem  Stern,  das  von  der  Sonne  kommt,  ein  effectus  univocus, 
Verwesung  und  Tod,  die  aus  dem  SonnenHchte  folgen,  sind 
effectus  aequivoci.'^  Aber  am  Anfange,  solange  der  Effekt 
unvollstandig  ist,  spricht  man  nur  von  Spezies,  Kraft  u. 
dgl.,  und  das  so  lange,  als  das  Patiens  in  seiner  spezifischen 
Natur  verbleibt ;  assimiUert  sich  aber  das  Patiens  dem 
Agens  mit  Hilfe  jener  Spezies  und  Kraft,  wie  wir  beim  Holze 
sehen,  das  durch  Aufnahme  der  Feuerspezies  Feuer  fangt, 
so  wird  die  spezifische  Natur  des  Patiens  aufgehoben  und 
der  komplette  Effekt  hervorgerufen  ;  dann  spricht  man 
nicht  mehr  von  Spezies,  sondern  bezeichnet  es  mit  dem 
Namen  des  Agens  selbst.  Das  Holz  wird  dann  Feuer, 
Flamme,  Kohle.  Die  Spezies  von  Feuer  und  das  Feuer 
selbst  unterscheiden  sich  nur  wie  komplett  und  inkomplett. 

'  Bridges,  ii.  411.  -  Ibid.  413-4. 

1689  p 


210  ROGER  BACON 

Dies  gilt  aber  nur  bei  den  irdischen  Dingen,  die  der 
Zerstorung  unterliegen.  Bei  den  (nach  scholastischer  Auf- 
f assung)  unzerstorbaren  Himmelskorpern  kann  ganz  wohl  die 
Spezies  zu  einem  kompletten  Effekt  vervollstandigt  werden, 
ohne  dass  das  Agens  selbst  dort  entsteht.  Sonne  und  Mond 
sind  geschaffen,  ein  vollkommenes  Licht  zu  haben.'  Bei  der 
Mondfinsternis,  bei  welcher  der  Mond  im  Schatten  ist, 
bemerkt  man  noch  ein  rotliches  Licht  ;  das  ist  eine  schwache 
Spezies  des  Lichtes,  die  von  dem  Lichte  kommt,  das  an  den 
Schattengrenzen  voriibergeht.  Nachher  wird  das  Licht 
auf  dem  Monde  wieder  komplett  und  klar.  Es  wird  aber 
der  Mond  nicht  zur  Sonne.  Das  Licht  kann  sich  vervoll- 
standigen,  aber  nicht  die  Spezies  der  Sonnensubstanz. 

Bacon  erortert  ferner  eingehend  die  Frage,  was  denn 
alles  eine  Spezies  wirkt.^  Es  sind  dies  in  erster  Linie  die 
eigentUchen  sensiblen  Quahtaten  wie  Licht,  Farbe,  Ton, 
Kalte,  Warme.  Sie  iiben  einen  Reiz  auf  die  Sinnesorgane 
aus  und  ganz  allgemein  nimmt  der  Sinn  die  Spezies  der- 
selben  auf.  Eigenartig  ist  es  beim  Schall,  was  hier  nicht 
eingehender  erortert  werden  soil.  Andere  Pradikamente 
wie  Grosse,  Lage,  Bewegungszustand,  Relation  (Zusammen- 
ordnung  mit  anderen  Dingen)  u.s.w.,  die  durch  den  sensus 
communis  (das  Zentrum,  welches  alle  Sensationen  empfangt, 
die  Einheit  des  sensitiven  Bewusstseins  ermoglicht  und  die 
Sensationen  miteinander  vergleichen  kann)  wahrgenommen 
werden,  wirken  keine  Spezies.  Grosse  und  Gestalt  folgen 
aus  den  Spezies  von  Licht  und  Farbe,  die  von  den  Objekten 
ausgehen.  Auch  die  Materie  ohne  Form  wirkt  keine  Spezies, 
weil  sie  nur  leidend  ist. 

Um  das  Wesen  der  Spezies  genauer  zu  bestimmen,  muss 
man  die  potentia  activa  eines  Dinges  von  seiner  potentia 
receptiva  unterscheiden.  Letztere  kommt  hier  nicht  in 
Frage,  denn  sie  ist  dasjenige,  vermoge  dessen  die  Materie 
die  Form  vom  Schopfer  aufnehmen  konnte.  Wiirde  in  der 
Materie  nur  eine  potentia  receptiva  fiir  die  Spezies  angenom- 

'  Bridges,  ii.  415  ;  i.  128.  "^  Ibid.,  ii.  418  f. ;  vgl.  ii.  56,  72  f. 


LEHRE  VON  DER  SINNLICHEN  SPEZIES       211 

men,  so  miissten  wir  die  wirkende  Ursache  als  Geberin  der 
Form,  die  Spezies  als  Form  ansehen,  was  sie  nicht  ist.  Sie 
ist  auch  nicht  anzusehen  wie  etwa  der  Abdruck  eines 
Siegels  im  Wachse,  sondern  sie  entsteht  im  Patiens  per 
naturalem  impressionem  et  eductionem  de  potentia  materiae 
patientis  und  zwar  per  eductionem  de  potentia  activa  materiae 
patientis,  wobei  die  actio  naturalis  bis  in  die  Tiefe  des  Patiens 
vordringt,  wie  aus  dem  Kapitel  iiber  die  Art  und  Weise  der 
Fortpflanzung  der  Spezies  noch  klarer  ersichtlich  sein  wird. 

Die  Spezies  einer  Substanz  ist  Substanz,  die  eines  Akzidens 
ist  Akzidens,  die  eines  Kompositums  ist  Kompositum,  die 
Spezies  eines  Einfachen  ist  einfach,  die  Spezies  der  Materie 
ist  Materie,  die  einer  Form  ist  eine  Form,  die  eines  Univer- 
sale ist  universal  und  die  eines  Singulare  singular. 

Von  grossem  Interesse  ist  das  Kapitel,  das  Roger  Bacon 
der  Substanz  widmet.'  Nach  ihm  wirken  auch  die  Sub- 
stanzen  eine  Spezies.  Diese  Lehre  ist  den  iibrigen  Scholasti- 
kern  fremd.  Auch  Aristoteles  scheint  die  Ansicht  zu 
vertreten,  dass  die  Substanzen  nicht  aus  sich  selbst  heraus 
wirken,  sondern  durch  ihre  Grundqualitaten. 

Es  kann  ja,  wie  Bacon  ausfiihrt,  ein  Akzidens  nicht 
erzeugt  werden,  ehe  nicht  sein  Subjekt  erzeugt  ist.  Also 
muss  immer  zuerst  die  Substanz  ihre  Spezies  erzeugt  haben, 
ehe  das  Akzidens  daran  seine  Spezies  heften  kann.  Die 
Spezies  der  Substanz  kann  allerdings  nicht  von  den  Sinnen 
und  auch  nicht  vom  sensus  communis  erkannt  werden,  aber 
sie  wird  durch  einen  gewissen  geistigen  Vorgang  erfasst, 
welcher  demjenigen  verwandt  ist,  vermoge  dessen  das 
Lamm  im  Wolfe  seinen  natiirlichen  Feind  erkennt  und  vor 
ihm  flieht.  Das  Lamm,  sagt  Bacon,  nimmt  die  Spezies  der 
Komplexion  des  Wolfes  wahr,  die  das  Organ  des  Wahrneh- 
mungsvermogens  {aestimativa)  infiziert  und  verletzt ;  deshalb 
flieht  es  den  Wolf  beim  ersten  Anblick,  wenn  es  ihn  auch 
friiher  nie  gesehen  hat.  Das  ist  die  Spezies  der  Substanz,  die 
'  Ibid.,  ii.  419  ff.  ;  vgl.  ii.  75. 
P  2 


212  ROGER  BACON 

dem  Lamme  selbst  schadlich  und  feindlich  ist.  Dagegen 
bestarkt  die  Spezies  einer  freundlichen  und  ansprechenden 
Substanz  von  Seiten  eines  anderen  Lammes  das  Organ  der 
facuUas  aestimativa  und  darum  flieht  ein  Lamm  das  andere 
nicht.  Deshalb  kann  die  sensitive  Seele  ganz  gut  die 
Substanz  durch  deren  Spezies  wahrnehmen,  wenn  auch 
nur  wenige  dies  einsehen  und  der  gewohnliche  Haufe  der 
Naturkundigen  behauptet,  dass  die  substantielle  Form 
keinen  Einfluss  auf  den  Sinn  ausiibt.  Es  wird  diese  Spezies 
nicht  von  den  fiinf  ausseren  Sinnen  und  auch  nicht  vom 
sensus  communis  aufgenommen,  sondern  nur  von  der  vis 
cogitativa  und  aestimativa  als  den  Teilen  der  sensitiven 
Seele.  Von  den  fiinf  Sinnen  und  vom  sensus  communis 
werden  nur  die  Akzidentien  erfasst,  obgleich  die  Spezies 
der  substantiellen  Formen  durch  sie  hindurchgehen.  Und 
da  jede  geschaffene  Substanz  aus  Materie  und  Form  zusam- 
mengesetzt  ist,  muss  die  Spezies  der  Substanz  von  der 
ganzen  Zusammensetzung  ausgehen,  also  von  der  Materie 
und  der  Form,  nicht  von  der  Form  allein. 

Nach  Thomas  von  Aquin  nimmt  das  Tier  in  den  sinnlichen 
Objekten  etwas  wahr,  was  keiner  besonderen  Sensation 
entspricht .  Das  Lamm  flieht  den  Wolf,  nicht  seiner  Hasslichkeit 
wegen,  sondern  well  es  ihn  als  gef ahrlich  erkennt ;  der  Vogel 
sucht  das  Reisig  nicht  um  seiner  Schonheit  willen,  sondern 
well  es  ihm  zum  Bauen  des  Nestes  dient.  Die  Fahigkeit, 
diese  Beziehungen  {intentiones)  wahrzunehmen,  heisst  facultas 
aestimativa.  Sie  ist  bei  den  Tieren  von  rein  instinktartigem 
Charakter,  im  Menschen  aber  von  psychologischer  Art  und 
hat  den  Namen  vis  cogitativa  oder  ratio  (Vernunft  )particu- 
laris  (weil  sie  sich  nicht  auf  das  Allgemeine  wie  der  Verstand 
bezieht) . 

Bacon  entgegen  lehrte  spater  Locke  die  Unerkennbarkeit 
der  Substanz,  ahnlich  wie  die  der  Kraft.  Sie  sind  nach  ihm 
nur  Hilfsbegriffe  unseres  Verstandes,  wodurch  wir  uns 
die  bei  den  Naturerscheinungen  beobachtete  Gesetzlichkeit 


LEHRE  VON  DER  SINNLICHEN  SPEZIES       213 

verstandlich  zu  machen  suchen.  Wir  konnen  weder  die 
Substanz  fiir  sich,  ausserhalb  ihrer  Eigenschaften  oder  von 
diesen  gesondert  erkennen,  noch  konnen  wir  eine  Kraft 
direkt  und  von  ihren  Wirkungen  getrennt  wahrnehmen. 
Gleichwohl  wiirde  aber  ohne  die  Idee  von  Substanz  und 
Kraft  die  objektive  Welt  unseres  Bewusstseins  sozusagen 
in  Staub  zerf alien  (Schultze). 

Wichtig  fiir  die  Sehtheorie  Bacons  ist  die  Annahme,  dass 
auch  die  Sinnesorgane  eine  Spezies  wirken.  Jede  korperliche 
Substanz,  sagt  er,  kann  eine  Spezies  wirken,  also  auch  die 
Sinnesorgane.  Beim  Auge  ist  dies  an  sich  klar.'  Wir  sehen 
das  Auge  eines  anderen  und  unser  eigenes  im  Spiegel.  Viele 
leugneten,  dass  vom  Auge  etwas  ausgehe,  auf  die  Annahme 
hin,  dass  das  Sehen  nur  durch  Aufnahme  nach  innen  sich  voll- 
ziehe  und  nicht  durch  Aussenden,  iiberhaupt  nicht  dadurch, 
dass  irgend  etwas  vom  Auge  entstehe,  das  wirke  und  zum 
Sehakte  beitrage.  Dass  das  aber  falsch  ist,  erhellt  aus  der 
Metaphysik  des  Aristoteles  (!)  ausdriicklich,  dann  aus 
Tideus  de  Aspectihus  ganz  klar  und  aus  der  ganzen  Optik 
des  Ptolemaeus,  und  dies  halt  gegen  alles  stand,  was  Alhacen, 
Avicenna  und  Averroes  dagegen  lehren  wollen.  Wie  die 
leblosen  Dinge  eine  leblose  Spezies  wirken,  so  wirkt  das 
Belebte  eine  Spezies,  die  gewissermassen  eine  Kraft  der 
Seele  hat.  Denn  wie  sich  ein  lebloser  Gegenstand  zu  seiner 
Spezies  verhalt,  die  ihm  ahnlich  ist,  so  das  beseelte  Wesen 
zu  der  ihm  ahnlichen  Spezies.  Daraus  folgt  nicht,  dass 
das  Medium  (Luft  oder  sonst  etwas  Durchsichtiges)  beseelt 
wird,  sondern  es  wird  nur  dem  beseelten  Wesen  durch  die 
aufgenommene  Spezies  assimiliert. 

3.    Art  und  Weise  der  Fortpflanzung  der  Spezies "" 

Die  Physik  der  Scholastik  war  wesentlich  antiatomistisch. 
Nichts  erklarte  sie  durch  rein  mechanische  Mittel,  auf  alles 
dehnte  sie  die  Begriffe  des  Aktes,  der  Form  und  der  Kraft 

'  Bridges,  ii,  65  f.  '  Cf.  Bridges,  ii.  429  ff. ;  vgl.  ii.  14. 


214  ROGER  BACON 

aus.  Die  Araber  hingegen  huldigten  mehr  der  atomisti- 
schen  Welterklarung.  Diese  leuchtet  auch  bei  Bacon  durch, 
indem  er  die  Art  und  Weise  der  Fortpflanzung  der  Spezies 
nach  dem  Muster  des  Arabers  Alhacen  erklart. 

Die  Lehre  Alhacens  liber  die  Fortpflanzung  der  Spezies 
kommt  unserer  Auffassung  von  einem  Netzhautbilde  aus- 
serst  nahe.  Alhacen  nimmt  namlich  an,  dass  die  Gegenstande 
punkt weise  auf  das  Auge  wirken,  so  dass  jeder  Punkt  von 
Licht  und  Farbe  des  Objektes  auf  der  Netzhaut  sich  abbildet 
und  dort  wahrgenommen  wird  durch  das  ultimum  sentiens, 
wobei  die  Sehkraft  iiber  die  ganze  Retina  wirksam  gedacht 
ist.  Er  sagt  :  Hat  der  Gegenstand  eine  einzige  Farbe,  so 
wird  jener  Teil  des  hohlen  Nervs  (Netzhaut),  als  eines  emp- 
findenden  Korpers,  auch  nur  eine  Farbe  haben.  Sind  aber 
die  Teile  des  Sehobjektes  von  verschiedener  Farbe,  so  wer- 
den  auch  die  Teile  jener  empfindenden  Stelle  der  Netzhaut 
von  verschiedener  Farbe  sein  und  das  ultimum  sentiens 
nimmt  die  Farbe  des  Objektes  aus  der  Farbung  wahr,  die 
es  an  jenem  Teile  vorfindet. 

Horen  wir  nun  Bacon  :  Alhacen,  schreibt  er,  lehrt  im 
zweiten  Buche  seiner  Optik,  dass  in  der  Hohlung  des  nervus 
communis  (nach  der  Perspectiva  ist  damit  die  Retina 
gemeint)  der  beiden  Augen  und  ebenso  auf  dem  Teile  des 
empfindenden  Organs,  namlich  der  anterior  glacialis,  welche 
der  vordere  Teil  der  Pupille  ist,  die  Umrisse  des  Objektes 
abgebildet  werden.  Diese  Umrisse  gehoren  zu  dem  all- 
gemein  Wahrnehmbaren,  wie  aus  demselben  Buche  her- 
vorgeht,  weshalb  Quantitat  und  Gestalt  u.s.w.  einen  Ein- 
druck  und  eine  Spezies  im  Organe  zu  wirken  scheinen,  und 
zwar  vorher  schon  in  der  Luft.  Dies  findet  aber  nach 
Alhacen  nicht  deshalb  statt,  well  die  Grosse  eine  Spezies 
wirkt,  sondern  weil  von  der  ganzen  Oberflache  des  Dinges  die 
Spezies  der  Farbe  und  des  Lichtes  kommt.  Dabei  werden 
die  Spezies  von  Farbe  und  Licht,  die  von  den  einzelnen 
Teilen  des  Dinges  kommen,  nicht  in  einem  Teile  der  Pupille 
vermischt,  sondern  werden  auf  der  Oberflache  der  Pupille 
unterscheidbar  angeordnet  in  wahrnehmbarer  Quantitat 
und  nach  der  Zahl  der  Teile  des  Objektes,  damit  das  Auge 
unterschiedlich  die  ganze  Farbe  oder  das  ganze  Licht  des- 


LEHRE  VON  DER  SINNLICHEN  SPEZIES       215 

selben  erfasse.  So  also  wird  in  der  Pupille  die  Grosse  des 
Objektes  abgebildet,  d.  h.  die  Farbe  der  ganzen  Grosse  oder 
das  Licht  in  der  Weise,  dass  dort  nur  die  Spezies  der  Farbe 
oder  des  Lichtes  auf  der  Pupille  angeordnet  ist  und  nicht 
die  Spezies.  der  Grosse  selbst.  Ganz  ahnlich  findet  die 
Abbildung  der  Umrisse  des  Gegenstandes  und  ihre  Ab- 
zeichnung  auf  dem  empfindenden  Gebiet  (Linse)  und  dem 
nervus  communis  (Netzhaut)  in  der  Weise  statt,  dass  Farbe 
oder  Licht  der  Umrisse  ihre  Spezies  wirken,  die  sich  abbildet 
und  im  Organ  und  Medium  anordnet,  aber  nicht  die  Umrisse 
selbst.    So  namlich  will  der  Autor  verstanden  sein. 

Auf  Grund  dieser  Annahme  finden  wir  es  nur  folgerichtig, 
wenn  Bacon  weiterhin'  die  Fortpflanzung  der  Spezies  wie 
eine  Strahlung  auffasst,  die  nach  alien  Linien,  Winkeln 
und  Figuren  stattfinden  kann,  je  nachdem  die  Naturgesetze 
es  verlangen.  Als  Grundlage  hierfiir  dient  ihm  ein  Traktat 
'  iiber  die  physikalischen  Linien,  Winkel  und  Figuren,  nach 
welchen  alle  Wirkungen  der  Natur  sich  voUziehen,'  von 
seinem  Lehrer  Robert  Grosseteste,  dem  nachmaligen  Bischof 
von  Lincoln.  Und  zwar  findet  die  Strahlung  von  jedem 
Punkte  oder  kleinsten  Telle  eines  Dinges  statt  und  dazu 
nach  alien  Richtungen  hin,  so  dass  jeder  Lichtpunkt  gleich- 
sam  unzahlige  Strahlen  nach  alien  Richtungen  hin  ent- 
sendet,  nach  oben  und  nach  unten,  nach  vorne  und  nach 
riickwarts.  Wo  also  auch  das  Auge  sich  befinden  mag, 
iiberall  wird  es  von  einem  Strahle  getroffen,  wenn  nicht  ein 
Hindernis  dazwischen  liegt.  Das  Auge  sieht  aber  nur  durch 
die  Spezies,  die  herankommt ;  also  muss  zu  ein  und  demselben 
Punkte  eine  strahlenf  ormige  Spezies  {species  radiosa)  kommen. 

Die  Fortpflanzung  findet  ferner  nach  geraden  Linien  statt. 
So  verlangt  es  die  Natur  und  durch  Versuche  lasst  sich  dies 
augenfallig  zeigen.  Bacon  beruft  sich  dabei  auf  Alkindi, 
der  in  seiner  Optik  den  geradlinigen  Strahlengang  an  dem 
Schatten  nachweist,  den  die  Korper  werfen,  und  an  den 
Strahlen,  die  durch  ein  Fenster  einfallen. 

Die  geradlinige  Fortpflanzung  findet  indes  nur  so  lange 

'  Bridges,  ii.  458  ;  vgl,  i.  117. 


2i6  ROGER  BACON 

statt,  als  sie  in  einem  gleichmassig  dichten  Medium  ver- 
lauft.  Aendert  sich  die  Dichte,  so  werden  die  Strahlen 
von  ihrer  Richtung  abgelenkt  oder  ganz  geknickt,  d.  h.  sie 
folgen  den  Gesetzen  der  Refraktion  und  Reflexion. 

Wie  aber  findet  die  Fortpflanzung  des  Strahles  im  Medium 
selbst  statt  ?  Sind  es  vielleicht  kleinste  Teilchen,  die  sich 
ablosen  und  fortgeschleudert  werden  ?  Letzteres  kann  nicht 
sein  ;  die  Fortpflanzung  findet  nicht  durch  Emission  statt, 
sondern,  wie  schon  gesagt,  durch  Eduktion  aus  der  aktiven 
Potenz  der  Materie.  Die  Aktion  der  Korper  aufeinander  iibt 
sich  nach  der  Lehre  der  Scholastiker  nicht  durch  die  blosse 
lokale  Bewegung  aus,  sondern  vielmehr  durch  die  Eduktion 
der  Potenz  in  den  Akt.  Die  vorherrschende  Idee  in  dieser 
Theorie  ist,  dass  die  physische  Welt  nicht  durch  die  blosse 
Ausdehnung  erklart  wird,  sondern  dass  die  Natur  der 
Korper  die  Annahme  von  Aktualitaten  und  Kraften  fordert, 
die  nicht  durch  blosse  geometrische  Grossen  gemessen  werden 
konnen.  Durch  die  Geometrie  erklart  man  die  Phanomene 
nur  bis  zu  einem  gewissen  Grade ;  viele  Dinge  aber  bleiben 
iibrig,  von  denen  man  nur  Rechenschaft  geben  kann,  wenn 
man  sich  auf  den  Dynamismus  oder  die  Theorie  der  Aktivi- 
taten  beruft.  Bacon  lehnt  die  Emanationstheorie  der  alten 
Philosophen  Epikur  und  Lukretius  ab,  die  spater  Newton 
in  verfeinerter  Form  wieder  zur  Erklarung  der  Fortpflan- 
zung des  Lichtes  annahm.  Seine  Ansicht  ist  somit  naher 
verwandt  mit  der  von  Young. 

Horen  wir  nun  seine  Erklarung  selbst  :^ 

Wenn  ofters  Ausdriicke  gebraucht  werden  wie  '  eine 
Spezies  entsenden '  u.  dgl.,  so  darf  man  sich  das  nicht  so 
vorstellen,  als  ob  vom  Agens  sich  etwas  ablose,  das  weiter 
geht.  Beim  Agens  haben  wir  nur  Substanz  und  Akzidens, 
etwas  Mittleres  gibt  es  nicht.  Nun  kann  aber  kein  Akzidens 
seinen  Trager  verandern  und  kein  substantieller  Teil  wird 
verandert,  ohne  dass  die  ganze  Substanz  korrumpiert  wird. 
Wiirde  vom  Agens  etwas  herausgehen,  so  miisste  eine  Zer- 
storung  und  Auflosung  erfolgen,  wie  es  bei  den  riechenden 

'  Bridges,  ii.  431-43  ;  vgl.  457. 


LEHRE  VON  DER  SINNLICHEN  SPEZIES       217 

Substanzen,  z.  B.  beim  Moschus  oder  Weihrauch,  der  Fall 
ist,  wo  beim  Auflosen  oder  Verbrennen  Teilchen  frei  werden 
und  ausstromen.  Anders  ist  es  beim  Licht.  Die  Himmels- 
korper,  die  am  meisten  Licht  verbreiten,  sind  nicht  kor- 
ruptibel  (nach  mittelalterlicher  Ansicht).  Also  kann  die 
Spezies  nicht  etwas  sein,  das  vom  Agens  fortgeht,  und  das 
Patiens  kann  nicht  etwas  aus  dem  Agens  aufnehmen. 

Das  Agens  erzeugt  aber  die  Spezies  auch  nicht  aus  dem 
Nichts,  ebensowenig  bekommt  es  die  Spezies  irgendwoher 
ausserhalb  seiner  und  ausserhalb  des  Patiens,  um  sie  in  das 
Patiens  zu  ergiessen.  Sie  muss  also  entweder  durch  Im- 
pressio  entstehen,  ahnlich  wie  Aristoteles  nach  dem  Vor- 
bilde  des  Siegelabdruckes  in  Wachs  annahm,  oder  durch 
natiirliche  Veranderung  und  Eduktion  aus  der  Potenz  der 
Materie  des  Patiens.  Nun  reicht  aber  die  Impressio  auch 
nicht  zur  Erklarung  hin,  denn  diese  findet  nur  auf  der  Ober- 
flache  des  Patiens  statt,  wo  durch  Aufdriicken  sich  die  einen 
Telle  heben,  die  anderen  senken,  wahrend  doch  die  Wirkung 
bis  auf  den  Grund  des  Patiens  gehen  muss.  Uebrigens 
wiirden  wir  ja  die  eindriickenden  Dinge  selbst  nicht  sehen, 
wahrend  durch  die  Spezies  die  Dinge  selbst  sichtbar  werden. 

Es  bleibt  also  nur  iibrig,  die  Entstehung  der  Spezies  durch 
Veranderung  [inimutatio)  oder  Eduktion  aus  der  aktiven 
Potenz  der  Materie  des  Patiens  zu  erklaren.  Das  Agens 
wirkt  seinen  Effekt  nicht  durch  Vereinigung  seiner  Sub- 
stanz  mit  dem  Patiens,  sondern  durch  Reizwirkung  auf  die 
verborgene  Aktivitat  der  Materie  des  Mediums,  die  mit 
dem  Agens  verbunden  ist.  Dabei  wirkt  das  Agens  als 
Ganzes  nach  der  Tiefe  des  Patiens  und  nicht  bloss  derjenige 
Teil  des  Agens,  der  das  Patiens  beriihrt.  Sonst  miisste  ja 
ein  kleiner  Korper  die  gleiche  Wirkung  aussern  wie  ein 
grosser  und  es  ware  gleich,  wenn  man  die  Halfte  der  Sonne 
hinwegnahme.  Es  kann  aber  das  Agens  nicht  im  Grunde 
des  Patiens  sein  hinsichtlich  der  Substanz,  wohl  aber  der 
Kraft  nach,  um  aus  der  Potenz  des  untersten  Teiles  des 
Patiens  etwas  zu  erzeugen.  Wir  haben  uns  demnach  den 
Verlauf  der  Fortpflanzung  in  der  Weise  zu  denken,  dass 
sich  die  Oberflachen  von  Agens  und  Patiens  beriihren. 
Dadurch  entsteht  Aktivitat  auf  dem  ersten  Teil  des  Patiens 
und  diese  pflanzt  sich  fort  bis  auf  den  Grund  dieses  Teil- 
chens,  das  ein  Korper  ist,  so  klein  wir  ihn  auch  nehmen 
woUen.  Ist  das  erste  Teilchen  in  Bewegung  gesetzt,  so  hat 
es  die  Spezies  aktuell  und  iibt  seine  Wirkung  auf  das 
zweite  Teilchen  aus,  dieses  wieder  auf  das  dritte  und  so  fort 
bis  zum  Schlusse.    Und  so  muss  es  sein,  well  das  Agens  sich 


2i8  ROGER  BACON 

nicht   mit  dem   zweiten  und  den  nachfolgenden  Teilchen 
in  Verbindung  setzt  und  sie  nur  mittelbar  anregt. 

Mit  dieser  Auffassung  hangt  auch  die  weitere  zusammen, 
dass  die  Spezies  zwar  materieller  Natur,  aber  doch  kein 
eigentlicher  Korper  ist,  dennoch  aber  drei  Dimensionen 
hat.' 

Alhacen  und  Alkindi  schreiben  der  Spezies  Lange, 
Breite  und  Tiefe  zu,  woraus  man  entnehmen  mochte,  dass 
sie  ein  Korper  sei.  Dem  ist  aber  nicht  so.  Denn  die  Spezies 
zerteilt  nicht  die  Wande  des  Mediums,  in  dem  die  Fort- 
pflanzung  stattfindet.  Auch  konnen  nicht  zwei  Korper  an 
ein  und  demselben  Ort  sein.  Da  die  Spezies  aus  der  Potenz 
des  Mediums,  also  aus  einem  materiellen  Prinzip  erzeugt 
wird,  so  kann  sie  keine  andere  Natur  haben  als  die  des 
Mediums  selbst  und  wir  miissen  annehmen,  dass  sie  dieselbe 
Natur  mit  dem  Medium  gemeinsam  hat.  EndHch  existiert 
die  Spezies  nicht  fiir  sich,  sondern  in  einem  anderen  Ding, 
das  seine  spezifische  korperhche  Natur  beibehalt  sowie 
seinen  Ort.  Nur  dort,  wo  das  Medium  die  Spezies  empfangt 
tritt  eine  Alteration  ein.  Der  Strahl  ist  also  eigentlich 
nichts,  sondern  nur  ein  momentan  durch  das  Agens  modifi- 
zierter  Teil  des  Mediums  und  hat  keine  andere  Dimension 
als  diejenige,  die  dieser  modifizierte  Teil  besitzt. 

Nun  entsteht  eine  Schwierigkeit.  Nehmen  wir  an,  das 
Medium  sei  in  Ruhe  und  eine  Spezies  schreite  im  Medium 
fort  und  nehme  verschiedene  Orte  ein.  Dann  mochte  man 
meinen,  die  Spezies  miisse  ein  Korper  sein,  da  nur  ein  Korper 
in  einem  anderen  ruhenden  Korper  eine  Ortsveranderung 
hervorbringen  kann.  Darauf  ist  zu  sagen  :  Weder  das,  was 
am  ersten  Teil  sich  befindet,  verlasst  diesen  Teil,  noch  geht 
das,  was  am  zweiten  ist,  auf  den  dritten  iiber,  sondern  jeder 
Teil  bleibt  an  seinem  Platze.  Es  bewegt  sich  also  nicht 
etwas  von  Ort  zu  Ort,  sondern  es  findet  vielmehr  eine 
ununterbrochene  Erneuerung  statt,  ahnlich  wie  beim 
Schatten,  der  stets  neu  und  neu  hinsichtlich  des  Ortes  ent- 
steht. Es  findet  keine  eigentliche  Ortsveranderung  desselben 
Subjektes  statt,  sondern  eine  Erneuerung  des  Subjektes 
selbst  ;  denn  die  Spezies  ist  eine  passio  medii  und  hat 
keinen  bestimmten  Platz,  wo  sie  gerade  ware. 

Nehmen  wir  weiter  an,  das  Agens  sei  andauernd  in  einem 
durchsichtigen  Medium.    Bleibt  dann  auch  die  erste  Spezies, 

'  Bridges,  ii.  459,  502. 


LEHRE  VON  DER  SINNLICHEN  SPEZIES       219 

solange  das  Agens  gegenwartig  ist,  oder  vergeht  sie  und 
wird  immer  wieder  durch  eine  neue  ersetzt  ?  Nach  Alhacen 
vergeht  sie  und  entsteht  immer  wieder  neu,  und  zwar  sehr 
schnell.  Sonst  miisste  die  Brennstelle  bei  einem  Spiegel  noch 
viel  intensiver  sein,  als  wir  sie  wahrnehmen.  Es  gewinnt 
also  die  Natur  des  Mediums  die  Oberhand  iiber  die  Spezies 
und  vernichtet  sie  jedesmal  sofort,  wenn  sie  entstanden  ist, 
und  zwar  in  einem  unmerklichen  Zeitmoment.  Uebrigens 
ist  diese  Zeit  grosser  bei  einem  dichteren,  als  bei  einem 
diinneren  Medium  infolge  des  grosseren  Widerstandes. 

Wenn  die  Spezies  kein  eigener  Korper  ist,  ist  sie  dann 
vielleicht  geistiger  Natur,  wie  manche  glaubten?'  Sie  ist 
materiell,  denn  sie  entsteht  aus  einem  Korper,  befindet 
sich  in  einem  korperlichen  und  materiellen  Medium  und 
hat  auch  materielle  Wirkungen,  wie  Warme,  Faulnis  u.s.w. 
Sie  ist  von  derselben  Wesenheit  wie  der  komplette  Effekt, 
in  den  sie  schliesslich  iibergeht.  Der  komplette  Effekt 
aber  ist  materiell  und  folglich  auch  der  inkomplette,  die 
Spezies. 

Da  nun  die  Spezies  materieller  Natur  und  in  den  Dimen- 
sionen  eins  mit  dem  Medium  ist,  so  mochte  man  meinen, 
sie  miisste  durch  Luftbewegung^  hin-  undherschwanken,  was 
beim  Strahl  durchaus  nicht  der  Fall  ist.  Er  bleibt  ganz 
und  gar  an  seinem  Platze.  Dies  erklart  sich  dadurch,  dass 
jedes  Luftteilchen,  in  dem  sich  die  Spezies  befindet,  zwar 
fortwahrend  durch  ein  anderes  erneuert  wird,  dass  aber 
auch  die  Spezies  sich  auf  dem  Gange  von  Teilchen  zu  Teil- 
chen  erneuert.  Diese  Erneuerung  fande  auch  statt,  wenn 
die  Luft  in  Ruhe  ware.  Wechseln  die  Luftteilchen  an  der- 
selben Stelle,  so  vergeht  die  Spezies  sobald  das  Teilchen  aus 
der  Richtung  des  Strahles  gekommen  ist,  und  entsteht  erst 
wieder  wenn  ein  anderes  an  diese  Stelle  tritt. 


4.    Kreuzung  und  Vermischung  der  Spezies^ 

Da  die  Spezies  materieller  Natur  sind,  so  miissen  sich  die 
gleichartigen,  falls  sie  sich  schneiden,  vermischen  und  ver- 
einigen  konnen.  Dabei  gewinnt  entweder  die  eine  iiber  die 
andere  die  Oberhand,  wie  beispielsweise  ein  starkes  Licht 
ein  schwaches  iiberstrahlt,  oder  es  wird  ein  mittleres  daraus, 
wie  es  bei  den  Farben  zu  sein  pflegt,  oder  sie  wir  ken  in 

'  Bridges,  ii.  43  £f. ;  50  ff. ;  507  S-  vgl.  i.  43- 

^  Ibid.,  ii.  504.  ^  Ibid.,  ii.  39-46.  511  ff. 


220  ROGER  BACON 

gleicher  Weise  und  verstarken  sich,  wie  annahernd  gleich 
Starke  Lichter  ihren  Effekt  vergrossern  konnen. 

Treffen  zwei  oder  mehrere  Spezies  zusammen,  so  haben 
sie  im  allgemeinen  im  Vereinigungspunkte  verschiedene  Rich- 
tung.  Von  diesen  verschiedenen  Richtungen  sei  nun  eine 
lotrecht  zum  Auge,  die  anderen  schief,  dann  kommt  der 
lotrechte  Strahl  als  Hauptstrahl,  die  schiefen  aber  nur 
durch  die  akzidentellen  Strahlen,  die  sie  verbreiten,  zum 
Auge.  Der  Hauptstrahl  iibertrifft  jedoch  alle  akzidentellen, 
so  dass  in  Wirklichkeit  kein  gemischter  Strahl  wahrgenom- 
men  wird,  wenn  auch  eine  gemischte  Spezies  zum  Auge 
gelangt,  weil  letztere  nur  akzidenteller  Art  ist. 

Stellen  wir,  wie  es  Alhacen  getan,  vor  eine  kleine  Oeffnung 
drei  Lichter,  und  zwar  so,  dass  die  Strahlen  von  verschie- 
dener  Seite  her  sich  in  der  Oeffnung  vereinigen  miissen,  so 
konnen  wir  beobachten,  dass  die  Strahlen  nach  der  Vereini- 
gung  von  einander  unterschieden  in  der  gleichen  Richtung 
wie  vorher  weitergehen.  Von  einer  Vermischung  gewahren 
wir  nichts.  Trotzdem  findet  in  der  Oeffnung  eine  wahre 
Vermischung  statt  ;  da  aber  das  Licht  sich  geradlinig 
fortpflanzt,  so  geht  es  auch  jenseits  des  Loches  in  der- 
selben  Richtung  weiter.  Die  Nebenstrahlen,  die  von  den 
drei  Hauptstrahlen  ausgehen,  werden  von  letzteren  ver- 
dunkelt. 

Bacon  rollt  hier  das  Problem  auf,  das  erst  Bernoulli 
(1738)  richtig  deutete,  namlich  wie  es  moglich  sei,  dass 
Licht-,  Warme-,  und  Schallwellen  ohne  gegenseitige  Storung 
auf  unsere  Sinne  wirken  konnen.  Er  glaubt  dies  dadurch 
erklaren  zu  konnen,  dass  stets  die  lotrechte  Wirkung  wahr- 
genommen  werde,  die  alle  anderen  iibertreffe. 

Die  lotrechte  Wirkung  besitzt  nach  Bacon '  iiberhaupt  die 
grosste  Kraft.  Ein  Stein,  der  lotrecht  zur  Erde  fallt,  habe 
eine  viel  grossere  Wucht,  als  wenn  er  auf  der  schiefen 
Ebene  hinabrollt,  wobei  ihn  freilich  der  Augenschein  tauscht. 

Bridges,  i.  120-4;  ii.  468,  539  f. :  vgl.  ii.41 :  OpusTevt.  (Brewer),  1 14. 


LEHRE  VON  DER  SINNLICHEN  SPEZIES       221 

Welters  wirkt  dann  ein  gerader  Strahl  starker  als  ein 
gebrochener,  da  der  gebrochene  an  der  Brechungsstelle  ein 
Hindernis  erfahrt,  das  ihn  schwacht.  Der  gebrochene  ist 
wieder  starker  als  der  reflektierte,  well  bei  letzterem  das 
Hindernis  grosser  ist  als  bei  ersterem.  Gehen  wir  vom 
Punkte  zum  Korper  iiber,  so  miissen  wir  annehmen,  dass 
sich  bei  diesem  die  Wirkung  nach  einer  Strahlenpyramide' 
vqllzieht,  deren  Basis  die  Oberflache  des  Objektes  und  deren 
Spitze  in  einem  Punkte  des  Auges  liegt.  Die  Achse  der 
Pyramide  (Kegel)  ist  dann  der  lotrechte  Strahl,  nach  wel- 
chem  die  Wirkung  am  starksten  ist.  Dabei  wirkt  ein 
kiirzerer  Kegel  starker  als  ein  langerer,  da  der  Abstand  des 
ersteren  vom  Auge  kiirzer  ist  und  deshalb  die  Kraft  nicht 
so  geschwacht  wird.  Dieser  Grund  iiberwiegt  auch  den,  dass 
ein  spitzer  Kegel  sich  mehr  der  senkrechten  Richtung  nahert 
als  ein  stumpier. 

5.    Der  Gang  des  Lichtes  erfordert  Zeit"^ 

Empedokles  hatte  gelehrt,  dass  das  Licht  Zeit  braucht 
zur  Fortpflanzung.  Aristoteles  widersprach  ihm,  indem  er 
sich  vom  Scheine  tauschen  liess.  Ihm  folgten  die  meisten 
anderen,  darunter  Seneca  und  Heron,  die  Araber  Alkindi, 
Averroes,  spater  auch  Leonardo  da  Vinci  und  sogar  noch 
Bacon  von  Verulam  und  Descartes.  Eine  Ausnahme 
machten  besonders  der  Araber  Ihn  al  Haitam  (Alhacen) 
und  Roger  Bacon.  Aber  erst  O.  Romer  (1673)  erbrachte 
den  sicheren  Beweis,  dass  das  Licht  zur  Fortpflanzung  Zeit 
braucht. 

Bacon  kennt,  was  seine  Vorganger  lehren.  Alkindi  z.  B. 
argumentiere  :  Wenn  ein  gewisser  Raum  in  einer  unmerk- 
lichen  Zeit  durcheilt  wird,  so  muss  ein  doppelter  Weg  in 
einer  doppelt  so  langen  Zeit  zuriickgelegt  werden  u.s.f. 
Deshalb  miisste  doch  die  Zeit,  die  zum  Wege  von  Osten 
nach  Westen  notig  ist,  wahrnehmbar  sein.  Wir  merken 
'  Bridges,  ii.  39.  ^  Ibid.,  ii.  67-74,  525-9. 


222  ROGER  BACON 

aber  nichts  daran,  also  muss  das  Licht  in  einem  einzigen 
unteilbaren  Moment  entstehen. 

Demgegeniiber  sei  jedoch  zu  bemerken  dass  das  Entstehen 
der  Spezies  zwar  schnell  und  in  unmerklicher  Zeit  vor  sich 
gehe,  aber  zwischen  den  einzelnen  Momenten  noch  ganz 
unmerkliche  Abstufungen  moglich  seien.  Dass  auch  die 
ganze  Zeit,  die  das  Licht  von  Osten  nach  Westen  braucht, 
unter  der  Schwelle  der  Sinneswahrnehmung  bleiben  konne, 
wie  das  erste  Zeitteilchen,  erklare  sich  daraus,  dass  unser 
Auge  iiberhaupt  eine  merkHche  Zeit  braucht,  um  einen 
Eindruck  wahrzunehmen.  Auch  Alhacen  lehre,  dass  jede 
natiirhche  Veranderung,  also  auch  die  Lichtfortpflanzung, 
in  der  Zeit  vor  sich  gehe.  Denn  wenn  das  Licht  in  einem 
bestimmten  Momente  am  Anfange  eines  Raumes  ist,  so 
konne  es  in  demselben  Momente  nicht  auch  am  Ende 
desselben  sein.  Das  Licht  lege  in  einem  Augenblicke 
einen  Punkt  zuriick,  eine  Strecke  aber  in  der  Zeit. 

Die  Fortpflanzung  der  Spezies  in  der  Zeit  folgert  Bacon 

auch  aus  dem  Widerstande  im  Medium,  den  sie  auf  dem 

Gange  zu  iiberwinden  hat.    Er  schreibt  : 

Nach  Alhacen  entsteht  im  Medium  immer  Verdiinnung 
und  Verdichtung,  wobei  das  Diinne  dem  Verdichten  wider- 
strebt.  Dadurch  wird  die  Spezies  immer  schwacher  und 
schwacher,  die  Kraft  vom  Agens  her  wird  mit  der  Ent- 
fernung  immer  geringer  und  das  durchlaufene  Medium 
manchmal  dichter,  wie  z.  B.  die  Luftschichten  gegen  die 
Erdoberflache  zu  immer  dichter  werden.  Das  Medium  kann 
sogar  so  dicht  werden,  dass  der  Strahl  reflektiert  wird.  Aber 
nie  ist  es  so  dicht,  dass  nicht  doch  irgendwie  eine  Spezies 
hindurchginge,  wenn  wir  es  auch  mit  den  Sinnen  nicht 
wahrnehmen.  Selbst  durch  dicke  Klumpen  von  Gold  und 
Erz  gehen  noch  die  Spezies  von  Schall  und  Warme  hindurch. 
Was  aber  die  Schnelligkeit  der  Fortpflanzung  anlangt,  so 
wird  sie  auch  durch  die  Widerstande  nicht  so  weit  verzogert, 
dass  wir  die  Zeit  wahrnehmen  konnten.  Und  so  miissen 
wir  denn  sagen,  dass  diese  Bewegung  die  schnellste  ist, 
die  wir  kennen,  so  schnell,  dass  sie  mit  keiner  anderen  ver- 
glichen  werden  kann. 


LEHRE  VON  DER  SINNLICHEN  SPEZIES       223 


II.  Der  Sehvorgang* 

Bacon  selbst  berichtet,  dass  hinsichtlich  des  Sehvorganges 
bei  den  Alten  und  Arabern  zwei  Hauptansichten  herrschten. 
Die  einen  lehrten  nach  Plato,  dass  beim  Sehen  das  Auge  in 
der  Weise  aktiv  sei,  dass  es  einen  gewissen  Ausfluss  entsende 
um  die  Gegenstande  zu  erfassen,  wie  z.  B.  dass  das  Auge 
einen  Fiihlstrahl  zu  den  Sternen  schickt,  der  sie  erfasst 
und  dem  Auge  das  Bild  zuriickgibt.  Die  anderen  nehmen 
mit  den  Stoikern  (eigentlich  sind  es  die  Aristoteliker)  an, 
dass  das  Sehen  sich  dadurch  vollziehe,  dass  das  Auge  etwas 
nach  innen  aufnimmt  und  nicht  etwas  nach  aussen  ent- 
sendet. 

Diese  Unterscheidung  ist  freilich  nur  im  allgemeinen  rich- 
tig,  desgleichen  bei  Albertus  Magnus,  der  diese  beiden 
Theorien  ausfiihrlich  in  seinem  Commentar  zum  Buche 
de  Sensu  et  Sensato  erortert  und  dann  die  der  Platoniker 
nachdriicklichst  bekampft. 

Im  grossen  und  ganzen  konnen  wir  als  Vertreter  dieser 
hier  genannten  Platon'schen  Richtung  bezeichnen :  Pytha- 
goras, Parmenides,  Empedokles,  Demokrit,  Epikur,  Lukre- 
tius  ;  vielfach  nahmen  diese  an,  dass  durch  die  Fiihlstrahlen 
sich  Bilder  und  Formen,  Hautchen  oder  Plattchen  von  den 
Dingen  ablosen,  die  nach  Farbe  und  Anordnung  der  Teile 
den  Gegenstanden  selbst  gleichen.  Ferner  sind  nach 
dieser  Richtung  zu  nennen  Apulejus  aus  Madaura,  Hipparch, 
Euklid,  Ptolemaeus,  Theon,  Tideus,  Augustinus,  von  den 
Arabern  hauptsachlich  Alkindi,  auf  den  sich  Bacon  neben 
Euklid  und  Ptolemaeus  besonders  beruft. 

Zu  den  Aristotelikern  im  Sinne  Bacons  gehoren  vor  allem 

die  Araber  Avicenna,  Averroes,  Alhacen,  wir  konnten  noch 

die  getreuen  Briider  Rhazes  und  andere  nennen.     Aristo- 

teles    selbst,    den   Bacon    fiir   seine    Sehtheorie    anspricht, 

'  Bridges,  ii.  30  ff.,  51  ff. ;  i.  1 19  ff. 


224  ROGER  BACON 

erwahnt  im  5.  Buche  de  Generatione  Animalium  beide 
Theorien,  Strahlen  zum  und  vom  Auge,  ohne  einer  derselben 
einen  bestimmten  Vorzug  zu  geben.  An  einer  anderen 
Stelle  aber,  namlich  im  Traktate  de  Sensu,  verurteilt  er 
entschieden  die  Strahlung  vom  Auge. 

Nach  diesen  allgemeinen  Bemerkungen  wollen  wir  nun 
die  eigenartige  Sehtheorie  Roger  Bacons  selbst  betrachten. 

Beim  Sehen,  so  fiihrt  er  aus,  handelt  es  sich  vor  allem  um 
die  Spezies  von  Licht  und  Farbe.  Ohne  Licht  sieht  man 
nichts  und  zu  starkes  Licht  verdunkelt  alles  schwache  Licht, 
schwacht  das  Sehen  und  schadet  dem  Auge.  Dass  ganz 
besonders  die  Farben  auf  das  Sehen  Einfluss  haben,  ergibt 
sich  daraus,  dass  das  Auge,  wenn  es  beispielsweise  auf  hell 
beleuchtetem  dichteren  Griin  geruht  hat  und  sich  dann  auf 
einen  dunklen  Ort  hinwendet,  den  Eindruck  des  Griinen  noch 
eine  Zeitlang  beibehalt,  oder,  wenn  man  es  auf  einen  massig 
beleuchteten  weissen  Gegenstand  richtet,  den  Eindruck 
von  weiss  und  griin  gemischt  empfindet.  Das  Licht  modi- 
fiziert  auch  die  Farbenempfindung,  wie  wir  es  bei  den 
Farben  der  Taube,  an  der  Pfaufeder,  an  den  Schuppen  der 
Fische  und  am  faulen  Eichenholz  deutlich  sehen,  die  durch 
den  Wechsel  der  einfallenden  Lichtstrahlen  (!)  entstehen. 

Ausser  Licht  und  Farbe  gehoren  sodann  zum  Sehen  noch 
ein  gewisser  Abstand  des  Gegenstandes  vom  Auge,  Lage  des 
Gegenstandes  im  Gesichtsfeld  und  eine  entsprechende 
Grosse  des  Gegenstandes.  Weitere  Bedingungen  sind,  dass 
das  Objekt  dichter  als  die  Luft  und  der  Himmel  sei,  sowie 
eine  entsprechende  Diinnheit  und  Durchsichtigkeit  des 
Mediums. 

Das  Sehen  selbst  vollzieht  sich  zunachst  mittels  der  Strah- 
len eines  Strahlenkegels,  der  seine  Spitze  im  Zentrum  des 
Auges  hat  und  dessen  Basis  auf  dem  Sehobjekte  liegt.  Die 
einzelnen  Strahlen  des  Kegels  stehen  auf  den  Kugelflachen 
der  Augenteile  senkrecht  und  projizieren  auf  der  Linse 
gleichsam  die  Punkte  des  Objektes  in  verkleinertem  Mass- 


LEHRE  VON  DER  SINNLICHEN  SPEZIES       225 

stabe,  aber  in  derselben  Anordnung  wie  am  Objekte  selbst. 
Ausser  diesen  von  den  Punkten  des  Objektes  her  senkrecht 
einfallenden  Strahlen  gelangen  aber  von  ihnen  auch  noch 
schiefe  Strahlen  und  schiefe  Kegel  zum  Auge,  die  das  Bild 
nicht  storen,  da  sie  ja  durch  ihre  Richtung  und  durch  die 
Brechung,  die  sie  im  Auge  erleiden,  schwacher  sind.  Ja 
die  Brechung  kann  sie  sogar  zum  namlichen  Punkte  im  Auge 
fiihren,  wohin  auch  die  lotrechten  gelangen,  wodurch 
die  Wirkung,  die  von  ein  und  demselben  Punkte  ausgeht, 
verstarkt  wird.  Der  lotrechte  Kegel  heisst  der  eigentliche  Seh- 
oder  Strahlenkegel.  Seine  Basis  ist  mit  Riicksicht  auf  das 
Deutlichsehen  beschrankt.  Was  ausserhalb  dieser  Grenze 
liegt,  wird  schlecht  oder  gar  nicht,  die  Stelle,  auf  welche  die 
Achse  gerichtet  ist,  am  deutlichsten  gesehen. 

Ausser  den  Spezies,  die  vom  Objekt  ausgehen  und  auf 
das  Auge  wirken,  nimmt  Bacon  merkwiirdigerweise  entgegen 
der  klaren  Lehre  Alhacens  und  anderer  mit  Berufung  auf 
Tideus,  Ptolemaeus  und  besonders  Alkindi  und  falschlich 
auf  Aristoteles  einen  Ausfiuss  aus  dem  Auge  an,  zwar  nicht 
einen  rein  materiellen  wie  einige  der  Alten,  sondern  einen 
beseelten,  der  aber  doch  der  Spezies  von  leblosen  Dingen 
sehr  ahnlich  ist. 

Horen  wir  seine  Ausfiihrungen  : 

Wie  ein  unbeseelter  Gegenstand  eine  unbeseelte  Spezies 
wirkt,  so  das  beseelte  Organ  eine  beseelte,  die  gleichsam  an 
der  Kraft  der  Seele  teil  hat.  Man  darf  also  nicht  annehmen, 
dass  diese  Spezies  sich  wie  ein  Korper  vom  Auge  zum 
Objekte  hin  erstrecke ;  auch  nicht,  dass  die  Augenspezies 
die  des  Gegenstandes  an  sich  reisse  und  zum  Auge  fiihre  ; 
wir  miissen  die  Ansicht  des  Aristoteles,  dass  das  Sehen  aktiver 
und  passiver  Natur  sei,  so  verstehen,  dass  das  Auge  die 
Spezies  des  Objektes  auf  nimmt  und  zugleich  seine  Kraft  auf 
das  Medium  bis  zum  Objekte  in  unmerklich  kurzer  Zeit 
ausiibt.  Wie  jedes  Naturding  seine  Wirkung  durch  eigene 
Kraft  vollbringt,  so  erkennt  auch  das  Auge  durch  seine 
eigene  Kraft  ein  Ding,  das  ausserhalb  seiner  liegt.  Die 
Spezies  der  Dinge  bediirfen  iiberhaupt  der  Anregung  von 

1689  Q 


226  ROGER  BACON 

Seiten  des  Auges,  wodurch  sie  prapariert  und  dem  beseelten 
Organ  angepasst  werden. 

Aehnlich  wie  bei  den  Spezies  der  Objekte  haben  wir  uns 
also  von  der  Linse  des  Auges  aus  unzahlige  Kegel  zu  denken, 
die  alle  dieselbe  Basis  haben  und  deren  Spitzen  sich  auf  die 
einzelnen  Punkte  des  Objektes  erstrecken.  Unter  alien 
diesen  ist  einer  der  Hauptkegel,  dessen  Achse  durch  alle 
Zentren  des  Auges  geht.  Wir  haben  uns  also  zwei  Kegel 
zu  denken,  einen  vom  Objekt  und  einen  vom  Auge.  Sie 
treffen  an  einem  bestimmten  Orte  zusammen,  wobei  keine 
Verwirrung  entsteht,  da  sie  nicht  von  derselben  Art  sind 
und  die  Kraft  der  Seele  den  unbeseelten  Strahlenkegel 
iiberwiegt.  Die  Natur  bietet  uns  dafiir  ein  Beispiel.  Die 
Luft  konnen  wir  nicht  sehen,  solange  sie  in  unserer  Nahe 
ist  ;  erst  in  grosser  Entfernung  nehmen  wir  sie  wahr.  Der 
Grund  liegt  nicht  bloss  darin,  dass  sich  viele  Schichten 
angehauft  haben  (wie  ja  auch  ein  tiefes  Wasser  dunkler 
erscheint),  sondern  weil  die  Sehkraft  nicht  mehr  hinreicht, 
sie  zu  durchdringen.  Ein  weiteres  Beispiel  liefert  Licht  und 
Farbe  des  Himmels  in  einem  Wasserspiegel  betrachtet. 
Da  mochte  man  meinen,  es  miisse  die  entfernte  Luft  eine 
sichtbare  Spezies  haben,  die  zum  Auge  vom  Wasserspiegel 
refiektiert  wird.  Dem  ist  aber  nicht  so.  Es  existiert  nur 
die  Spezies  des  Auges,  die  sich  ohne  Wasserspiegel  in  unge- 
brochener  Linie  bis  zum  Firmamente  fortpflanzt,  hier  aber 
reflexiv  vermittelst  des  Spiegels  in  jene  Feme  gelangt/ 


Roger  Bacon  gehort  zu  den  wenigen  Mannern,  die  im  13. 
Jahrhundert,  als  die  scholastische  Philosophie  alles  be- 
herrschte,  sich  dem  Studium  der  Natur  widmeten.  Er  war 
ein  originaler  Denker.  Wir  haben  seine  Spezieslehre  in  den 
Hauptziigen  kennen  gelernt  und  im  Anschluss  daran  seine 
Sehtheorie  betrachtet.  Aus  allem  tritt  uns  der  reale,  auf 
das  Einzelne  und  Praktische  gerichtete  Sinn  des  Englanders 
entgegen.  Die  Spezieslehre  bildet  aber  iiberhaupt  den 
Schliissel  zum  Verstandnis  seiner  Physik,  namentlich  der 
Optik.  Sie  bewegt  sich  zwar  noch  ganz  auf  dem  Boden  der 
Scholastik,  aber  es  leuchtet  doch  ein  tieferes  Verstandnis 
^  Bridges,  ii.  7%,  92. 


LEHRE  VON  DER  SINNLICHEN  SPEZIES       227 

und  ein  klareres  naturwissenschaftliches  Urteil  hindurch, 
als  bei  seinen  Zeitgenossen  im  Abendlande.  In  mancher 
Hinsicht  ist  durch  ihn  der  Weg,  den  der  beriihmte  englische 
Kanzler  desselben  Namens,  Bacon  von  Verulam,  drei 
Jahrhunderte  spater  einschlug,  vorgezeichnet.  Die  Zeit,  in 
der  Bacon  lebte,  war  noch  nicht  die  der  Renaissance  der 
Wissenschaften.  Gleichwohl  waren  seine  Ideen  und  Ver- 
suche  nicht  unfruchtbar,  denn  sie  legten  in  den  Schoss 
des  Abendlandes  einen  Keim  wissenschaftlicher  Erneue- 
rung  nieder,  der  sich  dann  in  den  spateren  Jahrhunderten 
entwickelte. 


Q  2 


IX 

ROGER  BACONS  ART  DES  WISSENSCHAFT- 
LICHEN  ARBEITENS,  DARGESTELLT 
NACH  SEINER   SCHRIFT  DE  SPECULIS 

Von  J.  WURSCHMIDT 

Wenn  wir  versuchen  wollen,  uns  von  der  Art  des  wissen- 
schaftlichen  Arbeitens  eines  grossen  Mannes  eine  Vorstellung 
zu  machen,  so  werden  wir  nicht  solche  Werke  betrachten, 
in  denen  er  die  Summe  seiner  Erfahrungen  und  Kenntnisse 
niedergelegt  hat,  sondern  ein  Spezialwerk  untersuchen,  in 
welchem  er  ein  wissenschaftliches  Problem  sich  stellt  und 
nach  alien  Richtungen  diskutiert.  Eine  solche  Einzelunter- 
suchung  Roger  Bacons  bezieht  sich  auf  die  Brennspiegel 
und  ist  niedergelegt  in  seiner  Schrift  De  speculis.  Wahrend 
Herr  E.  Wiedemann '  in  einer  Arbeit  iiber  die  Geschichte 
des  Brennspiegels  untersucht  hat,  wie  sich  die  Ergebnisse 
R.  Bacons  historisch  einreihen,  sollen  die  folgenden  Aus- 
fiihrungen  lehren,  welches  die  Arbeitsmethode  dieses  *  Be- 
griinders  der  mathematischen  Physik ',  wie  ihn  S.  Vogl " 
bezeichnet,  gewesen  ist.  Zur  allgemeinen  Charakterisierung 
des  Mannes  und  seiner  bedeutsamen  Leistungen  auf  dem 
Gebiete  der  Naturwissenschaften  sei  auf  die  Ausfiihrungen 
S.  Vogls  hingewiesen. 

Der  Traktat  De  speculis  von  R.  Bacon  wurde  gemeinsam 

mit  seiner  Perspectiva,  einem  Telle  seines  Opus  mains,  von 

Johannes  Combach  1614  in  Frankfurt  herausgegeben  und 

beschaftigt  sich,  wie  der  Name  sagt,  mit  der  Theorie  der 

Spiegel,  jedoch  wird  nur  die  Lehre  von  den  spharischen  und 

*  E.  Wiedemann,  Wied.  Ann.,  Nr.  39,  S.  no,  1890. 
=  S.  Vogl,  Die  Physik  R.  Bacos,  In.-Diss.,  Erlangen,  1906. 


230  ROGER  BACON 

parabolischen  Hohlspiegeln,  die  wegen  ihrer  seit  alters 
bekannten  Eigenschaft  als  Brennspiegel  das  Interesse  am 
meisten  beanspruchen,  behandelt. 

Ein  Blick  auf  die  der  Schrift  beigegebenen  Zeichnungen 
zeigt  zunachst,  dass  in  dem  Werk  scheinbar  ganz  verschie- 
dene  Probleme  behandelt  werden  ;  nur  die  ersten  Figuren 
zeigen  den  spharischen  Hohlspiegel  und  die  von  der  Sonne 
ausgehenden  und  an  dem  Spiegel  reflektierten  Strahlen, 
daran  schliessen  sich  Abbildungen,  die  sich  auf  die  Schatten- 
bildung  leuchtender  Korper  und  den  Durchgang  des  Lichtes 
durch  Oeffnungen  beziehen.  Erst  die  letzten  Seiten  des 
Werkes  beschaftigen  sich  wieder  mit  dem  Spiegel,  und  zwar 
mit  dem  parabolischen  Hohlspiegel  und  seiner  Konstruktion, 
ebenso  befassen  sich  die  dem  Traktat  angefiigten  '  Notulae 
despeculo''  mit  dem  Hohlspiegel.  Vogl  behandelt  dement- 
sprechend  die  einzelnen  Telle  in  verschiedenen  Abschnitten 
seiner  Arbeit,  teils  in  den  Kapiteln  iiber  spharische  bezw. 
parabolische  Hohlspiegel,  hier  im  Zusammenhang  mit  den 
im  opus  maius  iiber  dieses  Gebiet  niedergelegten  Ansichten, 
teils  in  dem  Kapitel '  iiber  die  durch  eine  Oeffnung  erzeugten 
Bilder  '. 

Eine  eingehendere  Priifung  des  Werkes  wird  jedoch  zeigen, 

in  welcher  Weise  R.  Bacon  die  scheinbar  ganz  verschiedenen 

Gebiet  en  der  Optik  angehorigen  Gegenstande  zur  Losung 

eines  bestimmten  Problemes  benutzt  hat.     So  erhalten  wir 

einen  Einblick  in  die  wissenschaftliche  Arbeitsmethode  des 

Mannes,  zugleich  geht  hieraus  hervor,  inwieweit  R.  Bacon 

von   friiheren  Gelehrten,    die   sich   mit   diesen   Problemen 

beschaftigten,  beeinflusst  ist,  und  wo  er  selbstandig  vor- 

gegangen  ist. 

'  Wie  ich  einer  brieflichen  Mitteilung  von  Professor  Clifton  an 
Geheimrat  Wiedemann  entnehme,  ist  das  Oxforder  Manuskript 
der  '  Notulae  '  (Bodley  874)  von  der  gleichen  Hand  wie  die  des 
Werkes  selbst,  stammt  also  wie  dieses  aus  der  Zeit  zwischen  1400 
und  1425.  Ob  R.  Bacon  selbst  der  Verfasser  der  'Notulae '  ist  oder 
nicht,  steht  nicht  fest. 


DE  SPECULIS  231 

Im  ersten  Abschnitt  seiner  Schrift  untersucht  R.  Bacon 
die  von  einem  Punkt  der  Sonne  ausgehenden  und  an  einem 
spharischen  Hohlspiegel  reflektierten  Strahlen  ;  hiebei  wird 
derjenige  Punkt  der  im  Endlichen  gedachten  Sonne  gewahlt, 
der  auf  der  durch  den  Sonnenmittelpunkt  gehenden  Achse 
des  Spiegels  liegt,  und  gezeigt,  dass  ein  mit  der  Achse  nicht 
zusammenfallender  Strahl  nach  der  Reflexion  diese  in 
einem  Punkt  schneidet,  der  zwischen  dem  Mittelpunkt  des 
Hohlspiegels  (Kugelmittelpunkt)  und  dem  Spiegel  selbst 
(Pol)  gelegen  ist  (vgl.  Fig.  i).     Ferner  wird  bewiesen,  dass 


Fig.  I. 

alle  Strahlen,  die  in  gleichem  Bogenabstand  von  der  Spie- 
gelachse  auffallen,  nach  dem  gleichen  Punkt  der  Achse 
reflektiert  werden.  Hiebei  beruft  sich  R.  Bacon  auf  einen 
friiheren  Autor,  der  iiber  Brennspiegel  geschrieben  hat. 
Da  aber  von  demselben  Autor  eine  von  der  ersten  ganz 
abweichende  Ansicht  aufgestellt  wurde,  namlich  dass  die 
reflektierten  Strahlen  sich  im  Mittelpunkt  der  Kugel  schnei- 
den,  so  diskutiert  er  auch  diese  eingehend.  Es  werden 
hiezu  die  Strahlen  betrachtet,  die  von  verschiedenen  Punkten 
der  Sonnenoberflache  ausgehen  und  durch  den  Mittelpunkt 
hindurchgehen  ;  diese  fallen  senkrecht  auf  den  Spiegel  und 
werden  in  sich  selbst  reflektiert,  wodurch  im  Mittelpunkt  ein 
Brennpunkt  entsteht.  Der  Autor,  auf  den  sich  R.  Bacon 
beruft,   ist   Euklid,  in  dessen  Katoptrik  sich  die  beiden 


232  ROGER  BACON 

Ansichten  finden.  Und  zwar  sind  hier  genau  die  gleichen 
Zeichnungen  des  Strahlenganges  gegeben,  wie  wir  sie  bei 
R.  Bacon  (vgl.  Fig.  i  u.  2)  finden.  Von  der  uns  gelaufigen 
Betrachtungsweise,  die  parallele  von  der  Sonne  ausgehende 
Strahlen  zurKonstruktion  desBrennpunktes  des  Hohlspiegels 
benutzt,  findet  sich  hier  noch  keine  Andeutung  ;  die  Sonne 
wird  nicht  in  praktisch  unendlicher,  sondern  in  endlicher 
Entfernung  vom  Spiegel  gedacht,  und  es  werden,  wie  gezeigt, 
im  ersten  Falle  Strahlen  von  einem  Punkt,  im  zweiten  von 
verschiedenen  Punkten  der  Sonnenoberflache  betrachtet. 


Fig.  2. 

R.  Bacon  stellt  sich  nun  die  Aufgabe,  zwischen  diesen 
beiden  zunachst  scheinbar  gleich  berechtigten  Ansichten 
zu  entscheiden  ;  hier  nimmt  er  in  hohem  Masse  die  Erfahrung 
{expenentia)  bezw,  das  Experiment  zu  Hilfe. 

Dass  von  dem  im  ersten  Falle  betrachteten  Punkt  der 
Sonne  Licht  nach  alien  Punkten  des  Spiegels  gelangen  kann, 
ist  an  sich  klar,  da  sich  das  Licht  geradlinig  fortpflanzt, 
und  somit  zu  alien  Punkten  gelangen  kann,  die  vor  der  in 
jenem  Punkt  an  die  Sonne  gezogenen  Tangente  liegen. 
Zugleich  aber  folgt,  dass  nicht  nur  von  diesem  einen  Punkt 
der  Sonne,  sondern  von  alien  Punkten  des  sichtbaren  Teiles 
der  Sonne  (der  durch  die  Tangenten  vom  Auge  an  die 
Sonnenkugel  begrenzt  ist)  nach  dem  im  Pol  befindlichen 
Auge   Lichtstrahlen  gelangen  konnen.     Von   alien  diesen 


DE  SPECULIS  233 

Strahlen  ist  aber  nach  einer  von  R.  Bacon  mehrfach  geaus- 
serten  Ansicht  der  Zentralstrahl,  d.  h.  der  in  der  Achse 
verlaufende,  der  kiirzeste  und  hat  infolgedessen  die  starkste 
Wirkung.  R.  Bacon  geht  also  hier  von  der  Erfahrungstat- 
sache  aus,  dass  die  Intensitat  des  Lichtes  mit  der  Entfernung 
abnimmt,  freilich  wendet  er  sie  hier  in  einem  Fall  an,  bei 
dem  infolge  der  grossen  Entfernungen  die  Verschiedenheit 
des  Lichtweges  tatsachlich  nicht  in  Betracht  kommt.  Der 
zweite  Grund  dafiir,  dass  dieser  Zentralstrahl  die  starkste 
Wirkung  hat,  ist  nach  unserem  Autor  darin  zu  suchen,  dass 
er  senkrecht  aus  der  leuchtenden  Flache  austritt,  wahrend 
alle  anderen  Strahlen  einen  schiefen  Winkel  mit  dieser 
bilden.  Auch  diese  Ansicht  R.  Bacons  beruht  wohl  auf 
einem  Erfahrungssatz,  namlich  der  Tatsache,  dass  von  alien 
unter  irgendeinem  Winkel  auf  eine  Flache  auffallenden 
Strahlen  der  senkrechte  die  starkste  Wirkung  hat ;  dieser 
Fall  wird  hier  auf  die  aus  einer  leuchtenden  Oberflache 
austretenden  Strahlen  iibertragen. 

Aus  dem  Satz  von  der  geradlinigen  Fortpfianzung  des 
Lichtes  folgt  ferner,  dass  nicht  nur  nach  dem  Achsenpunkt 
(Pol)  des  Spiegels,  sondern  nach  jedem  Punkt  von  alien  Punk- 
ten  der  Sonnenoberflache,  wenigstens  von  alien  durch  den 
Tangentialkegel  von  jenem  Punkt  begrenzten,  Strahlen  gehen. 
Auch  in  diesen  Strahlenkegeln  sind  aus  den  beiden  oben 
angefiihrten  Griinden  die  Zentralstrahlen  die  wirksamsten. 

R.  Bacon  ist  somit  zu  der  richtigen  Erkenntnis  gekommen, 
dass  auf  jeden  Punkt  des  Hohlspiegels  von  alien  Punkten 
der  Sonnenoberflache  Strahlen  kommen,  also  ein  Strahlen- 
kegel  trifft ;  die  unendlich  vielen  Strahlen  all  dieser  unend- 
lich  vielen  Strahlenkegel  vereinigen  sich  dann  in  einem 
Punkt  oder,  wie  er  ganz  treffend  bemerkt,  auf  einer  kleinen 
Stelle,  '  die  nicht  so  breit  ist  wie  ein  Denar.' 

Die  Schwierigkeit,  die  noch  darin  liegt,  dass  ja  in  Wirk- 
lichkeit  nicht  alle  Strahlenkegel  nach  dem  einen  Punkt 
reflektiert  werden,  kann  er  noch  nicht  iiberwinden  ;  jedoch 


234  ROGER  BACON 

miissen  wir  bedenken,  dass  ja  auch  wir  iiber  diese  Schwierig- 
keiten  bei  der  elementaren  Darstellung  der  Theorie  des 
Hohlspiegels  noch  fliichtiger  hinweggehen,  wenn  wir  nur 
parallele  von  der  Sonne  ausgehende  Strahlen  zur  Konstruk- 
tion  benutzen. 

Die  zweite  von  Euklid  gemachte  Annahme,  namlich  dass 
der  Brennpunkt  mit  dem  Mittelpunkt  des  Spiegels  zusam- 
menfalle,  ist  aber  durch  die  bisherigen  Ausfiihrungen  erledigt, 
denn  durch  diesen  Mittelpunkt  gehen  von  der  Sonne  zwar 
unendlich  viele,  aber  eben  nur  einfach  unendlich  viele 
Strahlen,  wahrend  durch  den  wirklichen  Brennpunkt,  wie 
die  obige  Darstellung  zeigt,  eine  grossere  Mannigfaltigkeit 
von  Strahlen,  namlich  unendlich  viele  Strahlen  unendlich 
vieler  Strahlenkegel  gehen. 

Wichtig  ist  nun  zu  sehen,  wie  diese  Grundtatsache,  dass 
nicht  ein  Punkt  der  Sonnenoberflache,  sondern  alle  innerhalb 
des  Tangentialkegels  gelegenen  Punkte  Licht  aussenden, 
von  R,  Bacon  unter  Zuhilfenahme  von  Erfahrung  und 
Experiment  nachgepriift  wird. 

Dass  tatsachlich  alle  Punkte  Licht  aussenden,  lehrt  uns 
zunachst  die  Erfahrung.  Dies  sehen  wir  an  den  Schatten, 
die  bei  alien  Gegenstanden,  die  kleiner  als  die  Sonne  sind, 
konvergieren,  im  speziellen  am  Erdschatten,  dessen  Beobach- 
tung  bei  einer  Mondfinsternis  moglich  ist.  In  sinnreicher 
Weise  untersucht  R.  Bacon  wohl  im  Anschluss  an  andere 
Gelehrte  an  diesem  Beispiele  die  verschiedenen  anderen 
moglichen  Falle,  namlich  dass  der  Schatten  durch  Parallele 
begrenzt  oder  divergent  ist,  indem  er  nachweist,  dass  in 
diesen  beiden  Fallen  die  Dauer  der  Mondfinsternis  viel 
grosser  sein  miisste,  als  wir  tatsachlich  beobachten.  So 
bleibt  nur  die  Moglichkeit  eines  konvergenten  Schattens. 
Ein  einziger  Licht  aussendender  Punkt  wiirde  einen  divergen- 
ten  Schatten  liefern,  ebenso  auch  ein  leuchtender  Korper  von 
kleineren  Dimensionen  als  der  schattengebende,  wie  der 
Autor   ausfiihrlich   an   den   entsprechenden  geometrischen 


DE  SPECULIS  235 

Konstruktionen  beweist ;  also  ist  zur  Erzeugung  eines 
konvergenten  Schattens  ein  leuchtender  Korper  erforderlich, 
dessen  Dimensionen  grosser  sind  als  die  des  schattengeben- 
den,  wie  dies  ja  bei  der  Sonne  der  Fall  ist. 

Einen  weiteren  Nachweis  fiir  seinen  Satz  sucht  R.  Bacon 
durch  den  Versuch  zu  erbringen,  namlich  mittels  des  Durch- 
ganges  des  Sonnenlichtes  durch  eine  enge  Oeffnung.  Die 
hiebei  auftretenden  Erscheinungen  hat  er  im  allgemeinen 
richtig  beobachtet,  namlich  dass  das  Bild  in  kleinem  Abstand 
von  der  Oeffnung  dieser  ahnlich  ist,  dagegen  bei  grosserer 
Entfernung  dem  leuchtenden  Objekt,  also  der  Sonne ; 
auch  der  Spezialfall  der  teilweise  verfinsterten  Sonne  ist 
ihm  bekannt.  Die  Erklarung  der  Erscheinungen  durch 
R.  Bacon  ist  eine  ahnliche,  wie  sie  auch  Vitello  und  sein  jiin- 
gerer  Zeitgenosse  Johannes  Pecham  geben.  Sie  bereitet 
ihm,  wie  nicht  anders  zu  erwarten,  Schwierigkeiten,  da 
er  nicht  achtlos  an  den  moglichen  Einwanden  voriibergeht. 
Auf  Einzelheiten  sei  hiebei  nicht  eingegangen,  da  die  Ein- 
wande  und  Schwierigkeiten  ausfiihrlich  bei  Vogl  besprochen 
werden,  nur  darauf  sei  hingewiesen,  dass  fiir  R.  Bacon  das 
Experiment,  die  beobachtete  Erscheinung,  so  massgebend 
ist,  dass  er  bei  einem  Widerspruch  mit  der  Theorie  sich 
sofort  entschliesst,  diese  fiir  ungeniigend  zu  erklaren.  Er 
macht  darauf  aufmerksam,  dass  er  seinen  nun  folgenden 
Erklarungsversuch  nicht  fiir  absolut  richtig  halt  ;  es 
handelt  sich  bei  ihm  eben  nur  darum,  die  Theorie  so  umzuge- 
stalten,  dass  sie  mit  den  Erfahrungstatsachen  iibereinstimmt, 
und  er  bemerkt  mit  Recht :  '  wenn  die  wahre  und  voll- 
standige  Ursache  dieses  Durchganges  des  Lichtes  durch 
eine  Oeffnung  bekannt  ware,  so  wiirde  sie  in  eine  bedeutende 
Kenntnis  der  multiplicatio  des  Sonnenlichtes  und  ihrer 
Folgen,  der  Licht-  und  Warmewirkung,  einfiihren.'  Der 
freilich  nicht  gelungene  Erklarungsversuch  beruht  darauf, 
dass  er  sowohl  den  auf  den  Mittelpunkt  der  Oeffnung  treff en- 
den  Strahlenkegel  als  auch  eine  von  der  Sonne  ausgehende 


236  ROGER  BACON 

Strahlenpyramide  untersucht,  deren  gleichfalls  in  der  Sonne 
liegende  Basis  ahnlich  der  Oeffnung  ist.  (Diese  wird  im 
speziellen  Fall  als  Dreieck  gewahlt.)  Auch  hier  kniipft  er 
wieder  an  eine  experimentelle  Tatsache,  an  eine  Beobach- 
tung  an,  namlich  dass  das  Licht  der  Sterne  durch  das  viel 
wirksamere  Sonnenlicht  fiir  uns  am  Tage  ausgeloscht  wird, 
nur  vom  Boden  eines  Brunnens  konne  man  auch  am  Tage  die 
Sterne  sehen.  So  werde  auch  die  Wirkung  gewisser  Strahlen 
des  Kegels  durch  die  der  Pyramide  iibertont  und  verdunkelt. 
Hiemit  hat  R.  Bacon  die  Untersuchung  soweit  fortgefiihrt, 
dass  er  zu  seinem  eigentlichen  Thema,  der  Theorie  des 
Hohlspiegels,  zuriickkehren  kann.  Wir  wissen  nun,  dass 
fiir  den  Hohlspiegel  alle  von  der  Sonne  kommenden  Strahlen, 
also  Strahlenkegel,  in  Betracht  kommen  und  miissen  den 
weiteren  Verlauf  dieser  Strahlenkegel  untersuchen.  R.  Bacon 
geht  von  den  einfachsten  Fallen  der  Reflexion  aus,  behandelt 
sie  aber  nicht  fiir  einzelne  Strahlen,  sondern  gleich  fiir  die 
einzelnen  Strahlenkegel,  die  von  der  Sonne  ausgehen.  Er 
zeigt,  dass  bei  einem  ebenen  Spiegel  ein  derartiger  konver- 
genter  Strahlenkegel  entweder  in  sich  selbst  bei  senkrechter 
Achse  zum  Spiegel,  oder  in  einen  anderen  Kegel  bei  schiefer 
Achse  reflektiert  wird,  indem  er  das  Reflexionsgesetz  auf 
die  einzelnen  Strahlen  der  Kegel  anwendet.  (Die  reflek- 
tierten  Strahlenkegel  sind  natiirlich  divergent  geworden; 
vgl.  Fig.  3.)  Dann  wendet  er  diese  Resultate  auf  die  ge- 
kriimmten  Spiegel  an,  die  saulen-  oder  pyramidenformigen 
Konkav-  oder  Konvexspiegel,  die  spharischen  oder  para- 
bolischen  Hohlspiegel,  fiir  die  er  sich  auf  die  '  Verfasser  der 
Perspektive  '  und  auf  '  die  Verfasser  der  Biicher  iiber  die 
gewohnlichen  und  Brennspiegel '  beruft.  (Hiezu  sei  auf  die 
Arbeit  von  E,  Wiedemann  iiber  die  Geschichte  der  Brenn- 
spiegel, sowie  auf  die  Ausfiihrungen  S.  Vogls  verwiesen.) 
R.  Bacon  schliesst  sich  aber  nicht  an  diese  ihm  bekannten 
Darstellungen  der  Lehre  vom  Hohlspiegel  an,  sondern  setzt 
seine  Betrachtungen  ganz  selbstandig  fort.     Er  bemerkt. 


DE  SPECULIS 


237 


dass  bei  der  Reflexion  der  obigen  Strahlenkegel  ihre  Oeff- 
nungswinkel  erhalten  bleiben  ;  er  weist  darauf  hin,  dass 
dieser  fiir  die  Sonnenstrahlen  32'  (gleich  dem  scheinbaren 
Sonnendurchmesser)  ist,  und  zeigt,  dass  ein  derartiges  kon- 
vergentes  Strahlenbiindel  nach  der  Reflexion  an  einem 
Punkte  eines  Spiegels  ein  divergentes  wird.  So  ist  auch  beim 
Hohlspiegel  die  '  Sammlung  '  der  Strahlen  in  einem  Punkte, 
dem  Brennpunkte,  nur  eine  scheinbare,  denn,  wenigstens 
fiir  die  Strahlen  jedes  einzelnen  Kegels,  bewirkt  die  Reflexion 
eine,  wenn  auch  geringe,  Zerstreuung.     Nun  erst  macht  der 


Fig.  3. 


Fig.  4. 


Autor  den  Uebergang,  der  uns  heutzutage  so  gelaufig  ist 
bei  der  Behandlung  der  Probleme  der  geometrischen  Optik  : 
an  Stelle  der  Kegel  betrachtet  er  deren  A  chsen,  die  man  dann 
in  abkiirzender  Bezeichnungsweise '  Strahlen '  nennen  konne ; 
vereinigen  sich  diese  genau  im  Brennpunkt,  so  werde  das  fiir 
die  anderen  Strahlen  der  Kegel  in  der  Nahe  des  Brennpunktes 
der  Fall  sein.  Nachdem  so  die  Strahlenkegel  durch  die 
Zentralstrahlen  ersetzt  sind,  entsteht  noch  die  Frage,  ob 
man  diese  von  einem  Punkt,  dem  Sonnenmittelpunkt, 
ausgehenden  Zentralstrahlen  durch  parallele  Strahlen  erset- 
zen  darf.  Zur  Entscheidung  betrachtet  der  Autor  wieder 
die  Verhaltnisse  beim  ebenen  Spiegel.  Hier  fallt  streng 
genommen  nur  ein  einziger  Zentralstrahl  unter  90°  auf,  die 


238  ROGER  BACON 

anderen  unter  spitzen  Winkeln  ;  sie  werden  also  nach  dem 
Reflexionsgesetz  nach  aussen,  nicht  in  sich  selbst  reflektiert 
(vgl.  Fig.  4).  Da  aber  die  Winkel  sehr  wenig  von  einem 
Rechten  verschieden  sind,  so  ist  diese  Abweichung  unmerk- 
lich.  Wir  beobachten  also,  dass  die  Strahlen  in  sich  selbst 
reflektiert  werden,  und  konnen  somit  auch  die  einfallenden 
Strahlen  als  praktisch  parallel  betrachten,  Jetzt  erst  ist 
R.  Bacon  auf  dem  Punkt  angelangt,  von  dem  die  Betrach- 
tungen  eines  Ibn  al  Haitam  ihren  Ausgangspunkt  genommen 
haben.  Die  verschiedenen  Formen  der  Konkav-  und 
Konvexspiegel  werden  nun  in  aller  Kiirze  behandelt,  ohne 
dass  auf  Einzelheiten  eingegangen  wird  ;  so  wird  der  Satz, 
dass  der  Brennpunkt  hochstens  um  den  halben  Durchmesser 
des  Spiegels  vom  Achsenpunkt  entfernt  ist,  nur  erwahnt, 
aber  nicht  bewiesen.  Ausfiihrlicher  will  sich  der  Autor  mit 
dem  Spiegel  beschaftigen,  der  nicht  wie  der  spharische  nur 
alle  auf  einen  Kreis  fallenden  Strahlen,  sondern  alle  iiber- 
haupt  auf  ihn  treffenden  in  einem  einzigen  Punkte  sammelt, 
mit  dem  parabolischen  Hohlspiegel.  Die  Konstruktion  der 
Parabel  interessiert  ihn  zunachst ;  sie  wird  aus  einem 
Kreiskegel,  der  zunachst  halbiert  wird,  durch  einen  Schnitt 
parallel  einer  Mantellinie  gewonnen.  Mit  Hilfe  dieser 
(halben)  Parabel  wird  dann  der  Spiegel  selbst  hergestellt, 
ganz  ebenso,  wie  dies  bei  Ibn  al  Haitam  beschrieben 
ist,  und  zwar  entweder  ein  '  eiformiger  '  oder  ein  '  ring- 
formiger  '  Spiegel.  Die  beiden  Darstellungen  stimmen  teil- 
weise  fast  wortlich  iiberein,  nur  ist  die  des  Arabers  weit 
ausfiihrlicher.  Ueber  die  Lage  des  Brennpunktes  bei  der 
Parabel  macht  R.  Bacon  keine  Angaben  ;  er  bemerkt,  dass 
er  hieriiber  nichts  sicheres  wisse.  Hieraus  geht  hervor,  dass 
er  die  Abhandlung  Alhacens  zu  der  Zeit,  als  er  sein  Werk 
schrieb,  wohl  nur  teilweise  gekannt  hat,  namlich  nur  den 
Abschnitt,  der  sich  auf  die  Konstruktion  des  Spiegels  bezieht.' 

'  In  den  dem  Werke  angefugten  '  Notulae  de  speculo  '  werden 
einige  spezielle  Aufgaben  der  Theorie  der  Brennspiegel  behandelt. 


DE  SPECULIS  239 

Aus  der  vorliegenden  Darstellung  geht  hervor,  in  welcher 
Weise  R.  Bacon  auf  dem  Gebiete  der  Naturwissenschaften 
gearbeitet  hat.  Er  hat  hier  versucht,  ein  spezielles  Problem 
nach  alien  Richtungen  zu  diskutieren,  und  zwar  geht  er  von 
den  iiberlieferten  Theorien  aus,  priift  diese  an  Erfahrung 
und  Experiment,  um  bei  einem  etwaigen  Widerspruch 
zwischen  Theorie  und  Erfahrung  nach  einer  widerspruchs- 
freien  Theorie  zu  suchen.  Die  mathematischen  Hilfsmittel 
verwendet  er,  soweit  es  ihm  der  Stand  seines  Wissens  erlaubt, 
indem  er  sie  zur  Erklarung  der  beobachteten  Tatsachen 
anwendet ;  er  macht  die  mathematische  Untersuchung  aber 
niemals  zum  Ausgangspunkt  seiner  Betrachtungen,  wie  das 
bei  den  arabischen  Gelehrten  vielfach  der  Fall  ist.  Hiedurch 
unterscheidet  sich  seine  Arbeitsmethode  ganz  wesentlich 
von  der  mehr  das  rein  Mathematische  betonenden  der  Araber; 
von  seinen  christlichen  Zeitgenossen  hebt  er  sich  ab  durch 
die  stete  Betonung  der  Wichtigkeit  der  Erfahrung  und  des 
Experimentes  gegeniiber  den  Ueberlieferungen  der  friiheren 
Gelehrten,  dem  Autoritatsglauben  der  Scholastiker. 

Wir  fassen  das  Resultat  unserer  Untersuchung  nochmals 
zusammen : 

R.  Bacon  hat  in  dem  vorliegenden  Werk  De  speculis 
geradezu  ein  Muster  fiir  die  griindliche  Behandlung  eines 
naturwissenschaftlichen  Problemes  geschaffen,  das  wertvoll 
bleibt,  wenn  auch  manche  Irrtiimer  sich  in  ihm  finden,  die 
durch  die  Weiterentwicklung  der  Wissenschaft  iiberwunden 
worden  sind. 


Zunachst  wird  der  Beweis  des  Satzes  nachgeholt,  dass  beim  sphari- 
schen  Hohlspiegel  der  Brennpunkt  hochstens  um  ein  Viertel  des 
Durchmessers  vom  Achsenpunkt  entfernt  ist,  dann  wird  die  Kon- 
struktion  der  Parabel  mittels  ihres  Parameters  L,  des  latus  rectum, 
endlich  werden  einige  sich  hieraus  ergebende  Folgerungenbesprochen. 
Die  Darstellung  schliesst  sich  ziemlich  genau  an  die  Ibn  al  Haitams 
an,  so  dass  man  schliessen  kann,  dass  R.  Bacon,  bezw.  der  nicht 
naher  bekannte  Autor  der  '  Notulae',  zur  Zeit  der  Abfassung  dieses 
Anhanges  dessenWerke  iiber  spharische  und  parabolische  Hohlspiegel 
gekannt  hat. 


X 

ROGER  BACON  ET  L'HORREUR  DU  VIDE 

Par  PIERRE  DUHEM 

On  a  peu  remarque  rinfluence  exercee  par  renseignement 
de  Roger  Bacon  sur  les  doctrines  physiques  de  la  Scolastique ; 
parfois,  cependant,  cette  influence  a  ete  tres  profonde; 
nous  voudrions  en  donner  un  exemple;  nous  le  ferons  en 
disant  comment  Bacon,  au  sujet  de  la  non-existence  du 
vide,  a  developpe  des  idees  a  peine  soup9onnees  avant  lui, 
et  comment  la  theorie  qu'il  avait  proposee  a  ete  adoptee 
dans  les  Universites  de  Paris  et  d'Oxford. 

I.  L'Impossibilite  du  Vide  et  l'Experience.  —  Les 

Arabes 

Ni  Aristote,  ni  ses  commentateurs  grecs  n'avaient  soUicite 
I'experience  d'apporter  son  concours  a  I'argumentation  de- 
veloppee  par  le  Philosophe  '  contre  la  possibilite  du  vide  ; 
ce  concours,  les  physiciens  arabes,  au  contraire,  n'ont  pas 
manque  de  I'invoquer. 

Al  Gazali,  par  exemple,  cite  ^  '  divers  signes  naturels  par 

'  C'est  ce  que  nous  avons  etabli  dans  :  Le  Systeme  du  Monde: 
Histoire  des  doctrines  cosmologiques  de  Platon  a  Copernic,  premiere 
partie,  ch.  V,  §  xiv,  t.  i,  pp.  323-32.  —  Le  lecteur  trouvera  en  cet 
endroit  1' expose  des  opinions  de  Philon  de  Byzance,  de  Heron 
d'Alexandrie,  d'Alexandre  d'Aphrodisias,  de  Themistius  et  de  Sim- 
plicius,  auxquelles  nous  ferons  allusion  dans  ce  qui  va  suivre. 

-  Philosophia  Algazelis,  lib.  II,  tract,  i,  cap.  vi :  Ex  tribus 
signis  probatur  non  dari  vacuum  ;  ed.  Venetiis,  1506,  fol.  sign,  g  2, 
coll.  b  et  c. 

1689  R 


242  ROGER  BACON 

lesquels  est  detruite  la  science  du  vide.'     Parmi  ces  signes,  il 
mentionne  ceux  que  manifestent  les  ventouses  : 

'  Par  la  succion,  I'air  est  attire  et,  avec  I'air,  se  trouve 
attiree  la  peau  de  rhomme  auquel  on  veut  appliquer  la 
ventouse  ;  en  effet,  si  elle  n'etait  pas  attiree,  le  vide  intcr- 
viendrait,  ce  qui  n'a  pas  lieu.  II  en  est  de  mdme,  et  pour 
la  meme  raison,  dans  le  vase  oil  I'eau  se  trouve  retenue  bien 
que  le  vase  soit  retourne,  I'orifice  en  bas  ;  en  effet,  si  I'eau 
sortait,  il  ne  resterait  plus  rien  au  fond  du  vase  ...  II  est 
done  impossible  que  le  vide  soit  et  que  les  surfaces  de  deux 
corps  se  separent  a  moins  que  quelque  chose  ne  vienne  s'inter- 
poser  ...  II  en  est  de  meme  en  une  foule  d'inventions 
ingenieuses  qui  prouvent  I'impossibilite  du  vide.' 

Moise  Maimonide  ecrivait  de  m^me  '  : 

'  Sache  aussi  que  \e celehre Livre  des  Artifices,  compose  par 
les  Beni-Schakir,  renferme  au  dela  de  cent  artifices  qui,  tous, 
sont  appuyes  de  demonstrations  et  ont  ete  mis  en  pratique  ; 
or  si  le  vide  pouvait  exister,  pas  un  seul  de  ces  procedes  ne 
pourrait  s'effectuer,  et  bien  des  operations  hydrauliques  ne 
pourraient  avoir  lieu.  Cependant,  on  a  passe  la  vie  a  argu- 
menter  pour  confirmer  ces  propositions  et  d'autres  sem- 
blables.' 

Ces  Beni-Schakir  dont  Maimonide  nous  parle  ici,  ce  sont 
les  trois  fils  de  Mousa-ben-Schakir,  nommes  Mohammed, 
Ahmed  et  Al-Hasan  ;  ils  florissaient  au  ix®  siecle,  et  avaient 
acquis  une  grande  reputation  de  mathematiciens  et  de 
mecaniciens ;  le  traite  de  Mathematiques  qu'ils  avaient 
compose  en  collaboration  est  demeure  celebre  sous  le  titre 
de  Livre  des  Trois  Freres.^ 

Le  Livre  des  Artifices,  ou  les  Trois  Freres,  prenant  I'impos- 
sibilite du  vide  comme  axiome,  en  deduisaient  I'explication 
d'une  foule  d'appareils  hydrauliques  plus  ou  moins  ingenieux, 

'  MoisE  BEN  Maimoun,  dit  Ma'imonide,  Le  guide  des  egares, 
premiere  partie,  ch.  Ixxiii,  iii,  trad.  S.  Munk,  t.  i,  pp.  384-5. 

-  Le  texte  arabe  du  traite  de  Mecanique  des  Fils  de  Mousa  est 
conserve  en  manuscrit  a  la  Bibliotheque  du  Vatican.  [Le  livre  des 
Appareils  pnemnatiques  et  des  machines  hydrauliques  par  Philon  de 
Byzance,  edite  et  traduit  en  Frangais  par  le  Baron  Carra  de  Vaux 
{Notices  et  extraits  des  manuscrits  de  la  Bibliotheque  Nationale  et 
d'autres  bibliotheque s,  t.  xxxviii,  premiere  partie,  p.  40.    m  dcccc  ii.)] 


L'HORREUR  DU  VIDE  243 

avait,  sans  doute,  le  meme  degre  d'originalite  que  la  plupart 
de  traites  scientifiques  des  Arabes  ;  il  n'etait  qu'une  com- 
pilation ou  une  adaptation  des  reliques  de  la  Science  grecque. 

Les  traites  de  Philon  de  Byzance  et  de  Heron  d'Alexandrie 
ont  ete,  de  bonne  heure,  traduits  en  arabe  ;  ils  ont  fourni  la 
matiere  de  compilations  telles  que  celle  des  Trois  Freres  ; 
ils  ont  fourni  aussi  des  arguments  aux  philosophes  peripate- 
ticiens.  Ceux-ci  ont  rejete  les  considerations  par  lesquelles 
Philon  et  Heron  croyaient  etablir  I'existence  de  pores  tres 
delies,  d'interstices  vides  entre  les  molecules  qui  composent 
les  corps  ;  mais  ils  ont  conserve  les  experiences  par  lesquelles 
ces  auteurs  montraient  I'impossibilite  de  realiser  un  espace 
vide  de  dimensions  notables  ;  ces  experiences,  ils  les  ont 
donnees  comme  la  confirmation  de  la  doctrine  du  Stagirite. 

Averroes  n'a  pas  pu  ignorer  les  divers  ouvrages  ou  les 
auteurs  arabes  s'efforgaient  de  demontrer  par  I'experience 
I'impossibilite  du  vide  ;  mais  il  n'en  a  que  tres  peu  subi 
I'influence.  II  a  surtout  lu  les  commentateurs  grecs 
d'Aristote,  et  nous  avons  dit  comment  ces  commentateurs 
faisaient  complete  abstraction  de  ce  genre  de  demonstrations. 
Toutefois,  malgre  le  desir  qu'il  avait,  sans  doute,  d'imiter 
leur  abstention,  Averroes  n'a  pu  se  garder  de  toute  allusion 
aux  preuves  experimentales  qui  avaient  cours  chez  ses 
compatriotes. 

Aristote,  puis  Simplicius,  avaient  parle  de  I'experience  de 
la  clepsydre  comme  propre  a  demontrer  que  I'air  est  un 
corps  ;  ils  n' avaient  fait,  en  la  rapport  ant,  aucune  allusion 
a  I'impossibilite  du  vide.  Dans  ce  qu'Averroes  dit  de  la 
m^me  experience,'  nous  trouvons  une  telle  allusion,  encore 
que  bien  fugitive  : 

■  lis  pressaient,  dit-il,  des  outres  gonflees,  au  point  de 
sentir  au  toucher  le  jet  de  I'air  qui  en  sort,  et  ils  manifestaient 
par  la  que  I'air  n'est  pas  le  vide,  mais  bien  un  corps.     Ils  en 

'  AvERROis  CoRDUBENSis  lit  Uhvos  Aristotelis  de  physico  auditu 
commentaria  magna,  lib.  IV,  summa  11,  cap.  i,  comm.  51. 

R  2 


244  ROGER  BACON 

laisaient  autant  a  I'aide  de  I'entree  de  I'air  dans  les  chante- 
pleures  {in  cantaploris) .'  En  effet,  tant  que  cet  instrument 
demeure  clos  par  le  haut,  I'eau  ne  coule  pas  par  le  bas  ;  elle 
s'ecoule  des  qu'on  en  debouche  le  haut.  Cela  provient 
necessairement  de  I'entree  de  I'air  dans  I'instrument  ; 
lorsque  I'eau  en  sort,  il  ne  demeure  pas  vide,  mais  I'air 
succede  a  I'eau.' 

Averroes  a  lu  le  commentaire  de  Themistius  au  Traite  du 
del ;  son  attention  a  ete  vivement  attiree  par  la  discussion 
entre  I'auteur  et  Alexandre  d'Aphrodisias  au  sujet  de  la 
succion  de  I'eau  par  les  ventouses  et  les  vases  echauffes  ; 
a  son  tour,  il  a  repris  en  grand  detail  cette  discussion. - 

En  exposant  I'une  des  experiences  dont  parle  Themistius, 
Averroes  y  introduit  une  modification  ;  il  suppose  que  Ton 
mette  une  chandelle  dans  un  vase,  qu'on  en  bouche  aussitot 
1 'orifice,  et  qu'on  enleve  le  couvercle  apres  avoir  plonge 
dans  I'eau  le  col  du  vase.  Cette  modification  ne  s'expli- 
querait-elle  pas  par  ceci  qu'Averroes  a  sous  les  yeux  le 
traite  de  Philon  de  Byzance  et  que,  des  experiences  qui  y 
sont  decrites,  il  confond  la  seconde  avec  la  premiere  ? 

Averroes  prend  parti  pour  Alexandre  contre  Themistius 
qui,  dit-il,  '  a  detruit  les  raisons  d'Alexandre  sans  rien  dire 
qui  ait  trait  a  la  question  [et  nihil  dicit  in  hoc) . . .  Pour  nous, 
nous  dirons  que  la  cause  est  ici  manifeste  et  toute  prochaine 
a  qui  prend  la  peine  de  reflechir  ;  et  Ton  s'etonne  de  I'igno- 
rance  de  ces  hommes  profonds  a  ce  sujet. 

'  En  effet,  une  partie  de  I'air,  ayant  ete  changee  en  la 
nature  du  feu,  se  meut  vers  le  haut  ;  alors,  elle  est  suivie  par 
le  corps  qui  se  trouve  au-dessous,  que  ce  soit  de  I'air  ou  de 
I'eau . . .  Au  moment  ou  Ton  met  dans  I'eau  I'orifice  du  vase, 

'  '  Chantepleure,  nous  dit  le  dictionnaire  de  Littre,  sorte  d'enton- 
noir  qui  a  un  long  tuyau  perce  de  trous  pour  faire  couler  les  liquides 
dans  un  tonneau  sans  les  troubler.'  II  est  clair  que,  par  ce  nom,  on 
a  voulu  designer  ici  un  instrument  propre  a  repeter  I'experience  que 
Philon  realisait  avec  un  ceuf  metallique  pourvu  d'un  goulet  et 
perce,  dans  le  fond,  de  petits  trous. 

=  AvERROis  CoRDUBENSis  In  lihtos  Aristotelis  de  Caelo  comm^ntaria 
magna,  lib.  IV,  summa  iii,  cap.  v,  comm.  39,  digressio. 


L'HORREUR  DU  VIDE  245 

cette  partie  ignee  s'eleve  vers  la  partie  superieure  du  vase  . . . ; 
le  vase  n'est  plus  rempli ;  c'est  pourquoi  I'eau  suit  dans 
I'espace  vide.  Un  jour,  j'ai  brise  un  vase  que  j'avais 
ainsi  place  sur  I'eau,  et  j'ai  trouve  de  I'eau  attachee  aux 
parois  du  vase.  C'est  aussi  la  cause  de  ce  qui  advient  dans 
les  ventouses  oil  Ton  met  du  feu  ;  et  c'est  la  premiere  cause 
de  I'ascension  de  I'eau. 

'  II  y  a  une  seconde  cause  que  donne  Alexandre.  Apres 
que  la  partie  ignee  de  I'air  aura  ete  eteinte,  I'air  se  refroidira, 
il  occupera  moins  de  place,  et  il  attirera  I'eau  par  la  necessite 
qu'il  n'y  ait  pas  de  vide  [de  necessitate  vacui).' 

II  semble  que  cette  explication  donnee  par  Averroes  doive 
beaucoup  a  Philon. 

II.  L'Impossibilite    du    Vide    et   l'Experience    [suite). 
L'Influence  du   Traite  De  inani  et   vacuo  sur  la 

SCOLASTIQUE  CHRETIENNE 

Instruite  par  les  Arabes  des  experiences  propresademontrer 
I'impossibilite  du  vide,  la  Scolastique  latine  s'est  vivement 
interessee  a  ce  genre  de  preuves.  Nous  nous  proposons 
d'examiner  sommairement  comment  elle  les  a  connues  et 
par  quelles  reflexions  elle  en  a  feconde  I'enseignement. 

II  y  aura  interet,  comme  on  le  verra  tout  a  I'heure,  a  ne 
pas  suivre  I'ordre  chronologique  pour  exposer  I'histoire  de 
ce  chapitre  de  Physique  experimentale.  Nous  pla9ant 
d'emblee  au  milieu  du  xiv*  siecle,  nous  allons  rapporter,  tout 
d'abord,  ce  qu'en  ont  dit  Jean  Buridan  et  son  disciple 
Marsile  d'Inghen. 

Jean  Buridan  affirme  la  valeur  de  ces  demonstrations 
experimentales  : 

'  En  Physique  {In  scientia  naturali),  dit-il,'  il  faut  accor- 
der  comme  un  principe  toute  proposition  universelle  qui 
pent  ^tre  prouvee  par  induction  experimentale,  et  cela 
de  la  maniere  suivante  :  En  plusieurs  cas  particuliers  de 
cette  proposition,  on  trouve  manifestement  qu'il  en  est 
ainsi,  et    jamais,  en  aucun   cas    particulier,  il   n'apparait 

'  JOHANNis  BuRiDANi  SubttHssime  quesiiones  super  octo  physicorum 
Hbros,  lib.  IV,  quaest.  vii,  fol.  Ixxiii,  col.  c. 


246  ROGER  BACON 

d'objection.  D'ailleurs  Aristote  dit  fort  bien  que  beau- 
coup  de  principes  doivent  etre  re9us  et  connus  par  le 
sens,  la  memoire  et  Texperience  ;  jamais  il  ne  nous  a  ete 
possible  de  savoir  que  tout  feu  est  chaud. 

*  Or,  par  une  semblable  induction  experimentale,  il  nous 
apparait  qu'aucun  lieu  n'est  vide.  Partout,  en  effet,  nous 
rencontrons  quelque  corps  naturel,  soit  I'air,  soit  I'eau,  soit 
quelqu'autre  substance.  En  outre,  nous  constatons  par 
I'experience  que  nous  ne  pouvons  separer  un  corps  d'un 
autre  a  moins  qu'un  troisieme  corps  n'intervienne.  Aussi, 
si  tous  les  trous  d'un  soufflet  etaient  si  parfaitement  bouches 
que  I'air  n'y  put  penetrer,  nous  ne  pourrions  jamais  separer 
Tune  de  I'autre  les  deux  parois  du  soufflet  ;  et  vingt  chevaux, 
dont  dix  tireraient  d'un  cote  et  dix  de  I'autre  ne  le  pourraient 
faire  davantage  ;  jamais  les  deux  parois  du  soufflet  ne  se 
separeraient  I'une  de  I'autre  a  moins  qu'une  rupture  ou  une 
perforation  ne  permit  a  quelque  corps  de  se  glisser  entre 
elles.  Avec  un  chalumeau  dont  vous  mettez  une  pointe 
dans  du  vin  et  I'autre  dans  votre  bouche,  en  aspirant  I'air 
que  contient  le  chalumeau,  vous  attirez  le  vin,  vous  le  forcez 
a  monter,  encore  qu'il  soit  grave ;  il  faut,  en  effet,  que  cet 
air  que  vous  aspirez  soit  immediatement  suivi  de  quel- 
qu'autre corps,  afin  qu'il  n'y  ait  pas  de  vide.  II  y  a  ainsi 
une  foule  d'autres  experiences  mathematiques. 

'  Nous  devons  done  accorder  que  le  vide  ne  peut  naturelle- 
ment  exister  a  titre  de  verite  connue  par  ce  moyen  qui 
suffit  a  poser  et  conceder  les  principes  en  Physique.  Par 
cette  induction,  il  est  acquis  qu'il  n'y  a  pas  de  vide  .  .  . 
Tou jours,  en  effet,  nous  voyons  les  corps  naturels  se  suivre 
en  demeurant  contigus  les  uns  aux  autres  ;  entre  eux,  il  ne 
se  forme  aucun  espace  depourvu  de  tout  corps  naturel,  d'air 
ou  d'eau  ou  de  quelqu'autre  substance  de  ce  genre.' 

Dans  son  Abrege  de  Physique,  Marsile  d'Inghen  nous  fait 
entendre  un  echo  fidele  de  I'enseignement  de  Buridan. 

'  Le  vide,  dit-il,'  ne  peut  exister  naturellement  ;  on  le 
prouve  :  En  Physique  {in  philosophia  nattirali),  on  doit 
accorder  comme  un  principe  ce  qui  peut  etre  prouve  par 
induction  experimentale  ;  or,  de  cette  maniere  on  peut 
prouver  par  induction  experimentale  que  le  vide  n'existe 
pas  ;  done  etc.  La  majeure  est  connue,  car  la  Physique 
est  fondee  sur  I'experience  {Philosophia  naturalis  fundatur 

'  Marsilii  Inguex  Ahhreviationes  lihri  physicorimi,  fol.  sign.  e. 
col.  d. 


L'HORREUR  DU  VIDE  247 

super  experientiam) .  La  mineure  est  evidente,  car  I'expe- 
rience  nous  enseigne  que  personne  ne  pourrait  separer  un 
corps  d'un  autre  si  un  troisieme  corps  ne  s'interposait.  Si 
les  trous  d'un  soufflet  etaient  bien  clos,  de  telle  fa9on  qu'au- 
cun  corps  ne  put  penetrer  a  I'interieur,  I'experience  montre 
que  cent  chevaux  ne  pourraient  separer  I'une  de  I'autre  les 
parois  du  soufflet,  a  moins  que  Tune  d'elle  ne  se  rompit  ou 
qu'il  ne  se  fit  par  ailleurs  quelque  ouverture  par  laquelle 
un  corps  put  entrer.' 

Dans  ses  Questions,  Marsile  d'Inghen  prouve  egalement 
I'impossibilite  du  vide  : 

*  En  second  lieu,  dit-il,'  cela  se  prouve  par  les  experiences 
qui  se  trouvent  au  Traite  du  vide  {per  experientias  quae 
ponuntur  in  Tractatu  de  inani  et  vacuo).  Les  corps  naturels, 
en  effet,  se  meuvent  contrairement  a  leurs  inclinations  pro- 
pres,  afin  que  le  vide  ne  se  produise  pas. 

*  La  premiere  experience  est  celle  de  I'eau  qui  monte  pour 
eteindre  une  cbandelle  recouverte  d'un  vase. 

'  La  seconde  experience  est  la  suivante  :  Que  Ton  fasse 
un  vase  ayant  deux  jambes,  I'une  plus  longue  que  I'autre  ; 
si  Ton  plonge  le  plus  petit  bras  dans  I'eau  et  qu'on  aspire 
I'air  par  le  bras  le  plus  long,  I'eau  montera  par  le  bras  le  plus 
court,  ce  qu'elle  ne  ferait  point  si  ce  n'est  pour  empecher 
qu'il  n'y  eut  de  vide. 

'  La  troisieme  experience  montre  qu'un  grave  souleve,  et 
que  rien  ne  retient,  ne  tombe  pas,  afin  que  le  vide  ne  se 
produise  pas  ;  ainsi,  dans  les  choses  d'ici-bas,  le  vide  ne  pent 
gtre  produit  par  un  agent  naturel.  La  premisse  se  prouve 
ainsi :  Soit  un  vase  qui  a,  en  bas,  un  grand  nombre  de  petits 
trous  et,  en  haut,  un  grand  orifice  ;  on  le  remplit  d'eau,  et 
on  bouche  I'orifice  superieur  ;  alors,  I'eau  ne  tombe  pas 
par  les  orifices  inferieurs  ;  cela  ne  saurait  etre,  sinon  pour 
empecher  le  vide.' 

Marsile  d'Inghen  nous  rapporte  done  trois  experiences  de 
Philon  de  Byzance,  dont  une  est  fort  singuliere  et  caracteris- 
tique  ;  il  nous  les  rapporte  dans  I'ordre  meme  ou  Philon  les 
presente  ;  il  ajoute  qu'elles  sont  racontees,  avec  beaucoup 
d'autres,  dans  un  certain  Tractatus  de  inani  et  vacuo.     II 

'  Quaestiones  Johannis  Marcilii  Inguen  super  octo  physicorum 
tibros,  lib.  IV,  quaest.  xiii. 


248  ROGER  BACON 

n'en  faut  pas  davantage  pour  nous  amener  a  penser  que  ce 
trait  e  etait  une  traduction  ou  une  adaptation  du  livre  de 
Philon. 

L'existence  d'une  traduction  latine,  faite  d'apres  un  texte 
arabe,  des  Pneumatiques  de  Philon  n'a,  d'ailleurs,  rien 
d'hypothetique.  En  1870,  Valentin  Rose  a  decouvert  et 
publie '  une  telle  traduction,  intitulee  Liber  Philonis  de 
ingeniis  spiritualibus  ;  c'est  meme  de  la  sorte  que  les  his- 
toriens  modernes  ont,  tout  d'abord,  connu  I'oeuvre  de 
Philon. 

II  se  pourrait,  d'ailleurs,  que  le  Tractatus  de  inani  et  vacuo 
dont  Marsile  d'Inghen  nous  a  parle  ne  fut  pas  cette  traduc- 
tion m^me  de  Philon  de  Byzance,  mais  quelque  traite  com- 
pose, sous  I'inspiration  du  livre  de  Philon,  par  un  auteur 
arabe.  Certain  texte  nous  donnera  occasion,  plus  loin, 
de  reprendre  cette  question  et  de  lui  donner  une  reponse 
probable. 

Maintenant  que  nous  avons  constate  aux  mains  des 
Scolastiques  parisiens,  durant  la  seconde  moitie  du  xrv® 
siecle,  I'existence  d'un  Tractatus  de  inani  et  vacuo,  directe- 
ment  ou  indirectement  emprunte  a  Philon  de  Byzance,  nous 
sommes  conduits  a  rechercher  le  temps  ou  ces  demonstra- 
tions experimentales  de  Timpossibilite  du  vide  furent,  tout 
d'abord,  connues  par  les  physiciens  de  la  Chretiente  latine. 

Qu'elles  Taient  ete  pendant  toute  la  duree  du  xrv^  siecle, 
nous  n'en  saurions  douter. 

Nous  verrons  en  effet,  que,  bien  avant  Marsile  d'Inghen, 
on  invoquait  les  experiences  que  cet  auteur  declare  em- 
pruntees  au  Tractatus  de  inani  et  vacuo.  Dans  un  moment, 
nous  entendrons  Jean  de  Jandun  decrire  quelques-unes  de 
ces  experiences.  Jean  le  Chanoine  en  fera  autant  et,  en 
particulier,    n'omettra    pas    I'experience    de    la    chandelle. 

'  Valentin  Rose,  Anecdota  graeca  et  graeco-latina,  vol.  ii,  pp.  299- 
313.  Berolini,  1870.  Reimprime  dans  Heronis  Alexandrini  Opera 
quae  supersunt  omnia,  ed.  W.  Schmidt,  vol.  i,  pp.  458-89. 


L'HORREUR  DU  VIDE  249 

A  celle-ci,  on  peut  reconnaitre  une  allusion  dans  le  passage 
suivant  de  Nicolas  Bonet  : ' 

'  Voici  encore  un  siijet  de  doute  :  Peut-on  avoir  le  vide 
naturellement  ?  La  production  du  vide  par  la  nature  est- 
elle  impossible  ?  On  dit  communement  qu'elle  est  impossible, 
si  bien  que,  pour  qu'il  n'y  ait  pas  de  vide  dans  la  nature,  un 
grave  monte,  et  un  corps  leger  descend  ;  on  le  voit  par  I'eau 
qui  monte  dans  un  vase  apres  que  Fair  y  a  ete  transforme 
{aerc  corrupto)  et  aussi  par  I'eau  qui  monte  dans  la  clepsydre 
et  dans  la  chantepleure  [in  defsedra  et  cantaplora).' 

Comme  Nicolas  Bonet,  Walter  Burley  rapproche  la 
clepsydre  de  la  chantepleure  ;  il  nous  donne,  en  outre,  la 
description  de  ces  instruments  : 

'  Le  second  signe  par  lequel  on  prouvait  que  I'air  est 
quelque  chose,  c'est,  dit-il,-  le  suivant  :  On  prenait  un 
certain  instrument  ou  vase  que  Ton  appelait  clepsydre  ou 
chantepleure  ;  ^  ce  vase  a  plusieurs  trous  ;  I'un  de  ces  trous 
est  en  haut  et  I'autre  en  bas.  Si  ce  vase  est  rempli  d'eau 
et  si  I'orifice  superieur  est  bouche,  de  telle  sorte  que  I'air  ne 
puisse  entrer  d'aucune  maniere,  on  peut  ouvrir  I'orifice 
inferieur  sans  que  I'eau  s'ecoule  par  cet  orifice  ouvert  au 
bas  du  vase.  Mais  si  Ton  ouvre  I'orifice  superieur,  I'eau 
s'ecoule  par  le  trou  ou  par  les  trous  inferieurs  ;  et  Ton  voit 
alors  que  I'air  entre  par  I'orifice  superieur.  Par  suite,  done, 
de  la  rentree  de  I'air,  I'eau  s'ecoule  ;  auparavant,  elle  ne 
pouvait  s'ecouler,  parce  que  I'air  ne  pouvait  entrer ;  il 
apparait,  par  la,  que  I'air  est  quelque  chose,  car  il  faut  que  la 
cause  de  cet  ecoulement  soit  quelque  chose.' 

Burley  connait  done  deux  instruments  propres  a  faire 
I'experience  dont  il  parle  ;  I'un  presente,  dans  le  bas,  un 
seul  orifice  et  I'autre  en  porte  plusieurs.  Or  Philon  emploie 
successivement  ces  deux  sortes  de  vases  ;  le  premier  lui  sert 
a  montrer  que  I'air  est  un  corps,  le  second  a  realiser  I'ex- 
perience que  Burley  vient  de  decrire. 

'  NicoLAi  BoNETi  Physica,  lib.  V,  cap.  iv  ;  Bibliotheque  Nationale, 
fonds  latin,  MS.  n"  6678,  fol.  151   r°  ;  MS.  n°  16132,  fol.  118,  col.  d. 

-  BuRLEUs  super  octo  Hbros  physicovum  ;  lib.  IV,  tract.  11,  cap.  i, 
ed.  Venetiis,  1491,  fol.  sign,  n  2,  col.  a. 

^  L'edition  citee  porte  :    tantaphova,  au  lieu  de  :    cantaplora. 


250  ROGER  BACON 

Burley  pouvait  bien  emprunter  an  commentaire  d'Aver- 
roes  les  mots  clepsydre  et  chantepleure  ;  mais  la  description 
de  ces  instruments  ne  s'y  trouvait  pas  ;  il  est  probable  que, 
directement  ou  indirectement,  Burley  la  tenait  du  Tractatus 
de  inani  et  vacuo. 

Les  physiciens  de  la  premiere  moitie  du  xiv^  siecle  ont  done 
connu  le  Tractatus  de  inani  et  vacuo.  Remontons  plus  haut 
dans  le  passe ;  nous  pourrons,  croyons-nous,  decelev  la 
presence  de  ce  livre  aux  mains  d' Albert  le  Grand. 

Voici  un  passage  '  de  la  Physique  d'Albert  : 

'  On  prouve  que  I'air  est  un  corps  et  non  point  rien  du  tout, 
en  se  servant  d'outres  pour  le  demontrer.  On  montre  aussi 
la  force  de  I'air  dans  les  clepsydres  qui  sont  des  instruments 
qui  ravissent  (furantia)  I'eau  ;  car  cleps  est  un  mot  grec 
qui  signifie  larcin  et  ydros  signifie  eau.  Get  instrument  est 
etroit  par  le  haut  ;  il  porte  un  col  termine  par  un  petit  orifice 
que  Ton  pent  boucher  avec  le  doigt  ;  par  le  bas,  il  est  large, 
et  le  fond  en  est  perce  de  beaucoup  de  trous.  Apres  qu'on 
I'a  plonge  dans  I'eau,  si  Ton  bouche  I'orifice  superieur,  I'eau 
ne  coule  pas  par  le  bas.  Ces  gens  disaient  que  cela  provient 
de  la  force  de  I'air  qui  retient  I'eau.  Mais  ils  se  trompaient. 
S'il  est  vrai  de  dire,  en  effet,  que  Fair  est  quelque  chose,  ce 
n'est  pas,  cependant,  a  cause  de  la  force  de  I'air  que  I'eau 
demeure  immobile  dans  le  vase  ;  c'est  parce  que  rien  n'est 
vide.  II  faut  done  que  les  surfaces  des  corps  soient  conjoint es 
les  unes  aux  autres  ;  partant,  I'eau  ne  se  separe  aucunement 
de  la  surface  de  I'air  [qui  reste  a  la  partie  superieure  du  vase], 
a  moins  que  cet  air  ne  la  puisse  suivre  dans  sa  chute  et  qu'un 
autre  air  ne  puisse  succeder  a  celui-la  ;  c'est  ce  qui  a  lieu 
lorsque  I'orifice  superieur  est  debouche.  C'est  I'un  des 
principes  dont  se  servent  les  ingenieurs  ;  par  ce  principe,  en 
effet,  on  combine  une  multitude  de  vases  et  de  siphons  [Et 
hoc  est  unum  principiorum  quo  utuntur  qui  /admit  ingenia  ; 
fiiint  enim  multa  vasa  et  sy phones  per  illud  principium) .  Aussi, 
ceux  qui  veulent  lever  un  grand  poids  avec  un  petit  instru- 
ment rendent-ils,  tout  d'abord,  inseparables  les  surfaces  du 

'  Alberti  Magni  Liber physicorum ,  lib.  IV,  tract.  1 1,  cap.  i :  Quod 
physici  est  tractate  de  vacuo  et  quibus  rationibus  probatur  vacuum 
esse,  et  quibus  non  esse,  ab  antiquis ;  et  illi  qui  dicebant  vacuum 
non  esse  contradicebant  ad  problemata. 


L'HORREUR  DU  VIDE  251 

corps  qu'ils  veulent  soulever  et  de  rinstrument  ;   alors,  par 
celui-ci,  ils  levent  celui-la.' 

II  n'est  pas  douteux  qu'Albert  le  Grand  n'ait  sous  les 
yeux,  lorsqu'il  ecrit  ce  passage,  le  Tractatus  de  inani  et  vacuo 
traduit  ou  imite  de  Philon  de  Byzance  ;  non  seulement  il 
lui  emprunte  la  description  de  I'instrument  propre  a  I'ex- 
perience  dont  il  parle,  mais  il  le  suit  encore  en  affirmant  que 
I'eau  et  I'air  doivent  demeurer  conjoints  sans  qu'il  y  ait, 
entre  leurs  surfaces,  aucun  intervalle  vide.  De  ce  principe, 
il  indique,  d'ailleurs,  une  application  qui  ne  se  trouvait  pas 
au  livre  de  Philon  ;  il  avait,  sans  doute,  vu  des  enfants  qui 
s'amusaient  a  soulever  un  pave  a  I'aide  d'une  laniere  de  cuir, 
mouillee  et  fortement  appliquee  a  la  surface  de  la  pierre.' 

Saint  Thomas  d'Aquin  avait  lu  le  commentaire  d' Albert 
le  Grand  ;  nous  reconnaissons,  en  effet,  un  souvenir  tres  net 
de  ce  commentaire  dans  le  passage  que  voici :  ^ 

'  lis  demontrent  encore  que  I'air  est  done  de  force  en  pom- 
pant  I'eau  dans  des  clepsydres,  c'est-a-dire  dans  des  vases 
qui  ravissent  [furantibus]  I'eau  ;  en  effet,  dans  ces  vases,  en 
meme  temps  que  I'air  est  attire,  I'eau  est  egalement  attiree. 
En  outre,  I'entree  de  I'eau  y  est  empechee  a  moins  que  I'air 
n'en  sorte.' 

Si  Saint  Thomas  d'Aquin  a  lu  Albert  le  Grand,  il  ne  parait 
pas,  en  revanche,  qu'il  ait  lu  le  Traite  De  inani  et  vacuo.  De 
ce  que  son  maitre  avait  emprunte  a  ce  traite  il  n'a  rien  garde. 

Au  contraire,  dans  I'oeuvre  d'un  disciple  immediat  du 
Doctor  communis,  nous  allons  reconnaitre  un  emprunt  pro- 
bable a  ce  traite. 

Saint  Thomas  d'Aquin  n'avait  pas  acheve  son  commen- 

'  Dans  son  Traite  du  Ciel,  Albert  le  Grand  parle  de  I'ascension  de 
I'eau  dans  les  vases  echauffes  et  du  sang  dans  les  ventouses  ;  mais 
il  ne  fait  que  paraphraser  le  commentaire  d'Averroes  sans  y  rien 
ajouter  (Alberti  Magni  De  Caelo  et  Mundo,  lib.  IV,  tract.  1 1 ,  cap.  viii : 
In  quo  probatur  quod  media  elementa  sunt  in  locis  suis  magis  gravia 
quam  levia) . 

-  Sancti  Thomae  Aquinatis  Expositio  in  libros  physicorum 
Aristotelis,  lib.  IV,  lect.  ix. 


252  ROGER  BACON 

taire  au  TraiU  du  del  d'Aristote  ;  apres  la  viii®  le^on  du 
troisieme  livre,  il  avail  laisse  tomber  la  plume.  Son  fidele 
eleve  Pierre  d' Auvergne  termina  ce  commentaire.  Cast  dans 
I'addition  de  Pierre  d' Auvergne  que  nous  trouvons  ce  qui  suit : ' 

'  Que  Ton  prenne  un  vase  creux  dont  I'orifice  soil  plus 
etroit  que  le  fond  ;  qu'on  y  introduise  une  chandelle  allumee 
ou  bien  encore  qu'on  en  chauffe  fortement  le  fond  ;  puis  qu'on 
le  renverse  de  telle  fa9on  que  I'orifice  en  soit  plonge  dans 
I'eau  ;  I'eau  est  attiree  vers  le  haut,  hors  de  son  lieu  naturel. 
Au  contraire,  si  le  vase  etait  applique  de  la  mdme  maniere 
a  de  la  terre,  la  terre  ne  s'eleverait  pas. 

'  La  cause  du  premier  effet  pent  etre  la  suivante :  Par  la 
chaleur  de  la  chandelle  ou  encore  la  chaleur  du  vase  embrase, 
I'air  qui  se  trouve  dans  ce  vase  est  rarefie  et  transforme  en 
feu  ;  transforme  en  feu  et  mu  vers  le  fond  du  vase,  il  se 
contracte  en  un  moindre  volume,  et  cela  pour  deux  raisons,' 

dont  nous  passerons  le  tres  illogique  detail. 

'  Un  signe  de  cette  condensation  de  I'air  pent  etre  le 
suivant  :  Si  Ton  brise  le  vase  dispose  comme  il  vient  d'etre 
dit,  on  trouvera  de  I'eau  au  fond  ;  Averroes  dit  qu'il  en  a 
parfois  trouve. 

'  Or  I'air  etant  comprime  dans  un  moindre  volume,  I'eau 
se  meut  en  meme  temps  vers  le  haut,  en  suivant  la  surface 
de  I'air,  qui  a  avec  I'eau  une  ressemblance  naturelle  ;  et  afin 
qu'il  ne  s'interpose  aucun  vide,  il  monte  un  volume  d'eau 
egal  au  volume  dont  I'air  est  comprime. 

'  Si  alors,  par  I'exterieur,  on  echauffe  le  fond  du  vase, 
I'eau  redescend  a  son  lieu  naturel ;  par  la  chaleur,  en  effet, 
I'air  qui  avait  ete  condense  dans  le  fond  du  vase  se  rarefie 
et  revient  a  sa  disposition  premiere.' 

Remarquons  que  cette  experience,  telle  que  Pierre 
d' Auvergne  la  complete,  est  textuellement  celle  qui,  au 
XVII®  siecle,  devait  donner  le  premier  thermometre.  Or  ce 
complement,  rien  de  ce  qu'ont  ecrit  les  commentateurs  d'Aris- 

'  Lihri  de  celo  et  mundo  Aristotelis  cwn  expositione  Sancti 
Thome  de  Aquino,  et  cum  additione  Petri  de  Alvernia.  Colophon : 
Uenetijs  mandato  et  sumptibus  Nobilis  viri  domini  Octaviani  Scoti 
Civis  modoetiensis.  Per  Bonetum  Locatellum  Bergomensem.  Anno 
a  salutifero  partu  virginal!  nonagesimoquinto  supra  millesimum  et 
quadringentesimum.     Lib.  IV,  text.  comm.  39,  fol.  74,  coll.  c  et  d. 


L'HORREUR  DU  VIDE  253 

tote  ne  Fa  pu  suggerer ;   Philon,  au  contraire,  a  sa  premiere 
experience,  adjoint  une  contre-epreiive  toute  semblable. 
Pierre  d'Auvergne  poursuit  en  ces  termes  : 

*  Quant  a  la  cause  pour  laquelle  la  terre  ne  serait  pas 
soulevee  si  Ton  disposait  le  vase  a  son  egard  comme  on  I'a 
fait  pour  I'eau,  c'est  que  ses  diverses  parties  ont  peu  de 
continuite  entre  elles,  en  sorte  qu'elle  n'est  pas  bien  contigue 
a  la  surface  de  Fair  ;  aussi,  grace  a  la  porosite  de  ses  parties, 
ne  peut-elle  pas  bien  empecher  I'entree  de  I'air  exterieur. 
Mais  s'il  arrivait  que  la  terre  a  laquelle  le  vase  est  applique 
fut  bien  continue  en  ses  diverses  parties  et  qu'elle  ne  permit 
pas  I'entree  de  I'air  exterieur,  il  serait  necessaire  ou  bien 
que  le  feu  n'eut  pas  d'action  pour  rarefier  Fair,  par  exemple 
parce  qu'il  s'eteindrait,  ou  bien  que  le  vase  se  brisat,  ou  bien 
que  Ton  admit  I'existence  du  vide,  ou  bien  que  la  terre  fut 
soulevee ;  et  le  plus  raisonnable,  c'est  de  penser  que  ce  dernier 
effet  se  produirait,  car  c'est  celui  qui  correspond  a  la  moindre 
inclination  en  sens  contraire.' 

Albert  le  Grand  avait  fait  une  simple  allusion  a  cette 
pensee  :  Les  corps,  dans  la  nature,  se  suivent  toujours  de 
telle  sorte  qu'il  n'y  ait  aucun  vide  entre  eux.  Cette  pensee  se 
retrouve  dans  I'exposition  de  Pierre  d'Auvergne,  et  sous 
une  forme  oil  nous  reconnaissons  les  idees  que  professait 
Philon  de  Byzance  touchant  I'affinite  entre  I'air  et  I'eau. 
Cette  pensee,  simplement  developpee,  va  devenir  une  des 
doctrines  favorites  de  Roger  Bacon. 

III.  La  Nature  universelle  et  la  Fuite  du  Vide 
SELON  Roger  Bacon 

Appliquons-nous  a  suivre  le  developpement  de  cette  pensee 
au  cours  des  divers  ouvrages  que  Roger  Bacon  a  composes. 

Des  deux  series  de  questions  sur  la  Physique  que  conserve  le 
manuscrit  d'Amiens,  examinons,  d'abord,  la  premiere.  Des 
la  premiere  question  relative  au  vide,^  Bacon  va  poser  le 
principe  dont  il  fera,  par  la  suite,  un  frequent  usage. 

*  RoGERi  Bacon  Questiones  naturales  et  primo  quesHones  Hbri  phy- 
sicorum,  lib.  iv.  Queritur  de  vacuo  ;  est  igitur  questio  utrum 
vacuum  sit.     Bibl.  municipale  d'Amiens,  ms.  n°  406,  fol.  22,  col.  b. 


254  ROGER  BACON 

II  se  demande  si  le  vide  existe.  Selon  la  methode  des  sic 
et  non,  il  commence  par  presenter  quelques  raisons  en 
faveur  de  la  reponse  qu'il  a  I'intention  de  rejeter,  c'est-a-dire 
de  I'affirmative.  Puis  vient  une  arp;iimentation  qui  conclut 
en  sens  contraire  : 

*  Rien  de  ce  qui,  pour  les  choses  naturelles,  est  privation 
et  desordre  {inordinatio)  n'est  necessaire  en  la  nature ;  or  le 
vide  est  cela  ;   done  etc. 

'  En  second  lieu,  on  reconnait  qu'il  n'existe  pas  dans  la 
nature,  car  dans  la  nature  il  n'est  rien  d'oiseux,  rien  qui 
soit  en  vain  ;   done  etc. 

'  La  majeure  [de  la  premiere  raison  est  evident e].  La 
nature,  en  effet,  desire  toujours  ce  qui  est  le  meilleur  ; 
partant,  elle  desire  I'ordre  qui  est  meilleur  que  le  desordre 
parce  qu'il  est  fini  et  a  une  cause.  La  mineure  est  aussi 
evidente,  car  il  est  ecrit  dans  le  texte  que  le  vide  serait  infini 
s'il  existait  ;  il  manquerait  done  le  premier  terme  et  le 
dernier  terme  et,  par  consequent,  serait  sans  ordre  {inor- 
dinatum).' 

L'appetit  d'ordre  qu'eprouve  la  nature  universelle  con- 
traindra  done  les  corps  a  se  mouvoir  de  telle  maniere  qu'aucun 
espace  vide  ne  se  produise  entre  eux. 

Ce  principe,  nous  allons  voir  Bacon  I'appliquer  des  sa 
seconde  question,  qui  traite  '  de  la  clepsydre  '.'  II  va,  dit-il, 
chercher  '  le  sens  de  ce  qu'on  lit  dans  le  texte  :  D'une 
maniere  semblable  ils  demontraient,  a  I'aide  des  clepsydres, 
que  le  vide  n'existe  pas  '.  Evidemment  Bacon  a  mal  lu 
le  texte  d'Aristote  ;  il  I'a  interprete  par  I'intermediaire  de 
quelque  commentaire ;  a  I'aide  des  clepsydres  on  demontrait, 
selon  Aristote,  que  I'air  etait  un  corps,  non  que  le  vide 
n' existait  pas. 

'  II  faut  d'abord  remarquer,  ajoute-t-il,  que  le  mot  cleps- 
ydre a  comme  deux  significations, 

'  Dans  un  sens,  on  appelle  clepsydre  un  petit  trou  qu'on 
perce,  dans  un  tonneau,  a  cote  du  grand  trou  (la  bonde)  par 
lequel  on  verse  le  vin  ;   on  le  perce  afin  que  les  vapeurs  qui 

'  Roger  Bacon,  Op.  laud.,  lib.  iv:  Queritur  de  clepsedra  ;  MS. 
cit.,  fol.  22,  col.  c. 


L'HORREUR  DU  VIDE  255 

s'elevent  de  rhumidite  du  vin,  par  I'effet  de  la  clialeur 
naturelle,  tandis  que  la  fermentation  s'accomplit,  puissent 
sortir  et  ne  brisent  pas  le  tonneau  . .  .  On  appelle  aiissi  cleps- 
ydre  ce  qui  sert  a  boucher  ce  trou. 

'  En  un  autre  sens,  la  clepsydre  est  un  vase  qui,  dans  sa 
partie  superieure,  a  un  trou  ou  orifice  unique  et  qui,  dans 
sa  partie  inferieure,  a  sept  trous  plus  petits  que  I'orifice  supe- 
rieur.  C'est  de  la  clepsydre  prise  avec  cette  signification 
que  nous  entendons  a  present  parler.' 

II  est  clair  que  Bacon,  lorsqu'il  ecrivait  ces  lignes,  ignorait 
le  sens  du  mot  clepsydre  ;  mais  il  avait  sans  doute  remarque 
qu'au  commentaire  d'Averroes  ce  mot  est  traduit  par  le  mot 
chantepleure  ;  aussi  s'empresse-t-il  de  lui  assigner  toutes 
les  significations  que  chantepleure  prend  en  francais,  y  com- 
pris  celles  qui  ne  sauraient  aucunement  convenir  a  clepsydre. 
Ce  lui  sera,  d'ailleurs,  une  occasion  de  consacrer  une  bonne 
partie  de  la  question  de  la  clepsydre  a  exposer  ses  idees  sur 
la  fermentation  du  vin.  Mais  bornons-nous  a  ce  qu'il  dit 
de  la  clepsydre  entendue  au  second  sens. 

'  La  premiere  question  est  relative  a  ceci,  qui  est  connu 
par  I'experience  :  Si  Ton  pose  le  doigt  sur  I'orifice  superieur  de 
la  clepsydre,  I'eau  qui  s'y  trouve  ne  s'ecoule  pas  par  les  petits 
trous,  mais  si  Ton  enleve  le  doigt,  tout  aussitot  I'eau  en 
descend  et  tombe  en  pluie.' 

Que  cet  equilibre  de  I'eau  retenue  dans  la  clepsydre  soit 
contraire  aux  principes  de  la  Physique  d'Aristote,  Bacon  le 
montre  avec  insistance  et  par  divers  raisonnements.  De 
la  la  difficulte  qu'il  voulait  examiner  et  dont  il  propose  la 
solution  suivante  :  ' 

'  De  I'immobilite  ou  equilibre  de  I'eau  dans  la  clepsydre 
pendant  que  le  doigt  est  applique  [a  I'orifice  superieur],  il  y 
a  trois  causes. 

'  La  premiere  est  la  petitesse  ou  I'etroitesse  des  trous 
inferieurs  ;  si  ces  trous  etaient  plus  grands,  I'eau  tomberait 
au  travers. 

'  La  seconde  cause  est  I'air  qui  entre  ou  penetre  par  ces 
petits  trous  ;    a  cause  de  sa  fluidite,  il  soutient,  porte  et 

'  Roger  Bacon,  loc.  cit.,  fol.  22,  coll.  c  et  d. 


256  ROGER  BACON 

retient  I'eau  {secunda  causa  est  aer  ingrediens  vel  suhintrans 
hujusmodi  foramina  parva  qui,  propter  sui  humidum,  hujus- 
modi  aquam  defert,  portat  et  retinet). 

'  Ce  sont  la  les  causes  efficient es.  La  troisieme  est  une 
cause  finale  ;  c'est  I'ordre  des  corps  de  I'Univers  et  la  con- 
venance  de  la  Machine  du  Monde  (prdinatio  corporum 
universi  et  mundi  machine  convenientia) ,  savoir  :  Qu'il  n'y 
ait  pas  de  vide,  qui  est,  pour  les  choses,  une  cause  de  desordre 
et  de  destruction,  comme  nous  le  verrons  plus  bas. 

'  II  est  evident  par  la  que  ces  trois  causes  se  reunissent  en 
une  cause  unique,  qu'elles  ne  font  qu'une  seule  cause,  savoir  : 
Qu'il  n'y  ait  pas  de  vide  {ne  sit  vacuum)  .  .  . 

'  Tout  grave  tend  vers  le  bas  et  se  meut  vers  le  bas  s'il 
n'est  empeche  et  retenu  ;  a  ce  mouvement  vers  le  bas,  il  est, 
cependant,  des  conditions  accessoires.  La  nature,  en  effet, 
desire  toujours  le  meilleur  ;  or  qu'un  grave  demeure  immo- 
bile en  haut,  supporte  et  retenu  par  I'air,  il  y  a,  a  cela,  moins 
d'inconvenient  qu'a  I'existence  du  vide  qui  detruirait  tout 
I'ordre  de  la  nature  .  .  . 

'  De  I'air  et  des  autres  corps,  il  y  a  lieu  de  parler  de  deux 
manidres  differentes.  D'une  premiere  maniere,  en  tant 
qu'ils  sont  en  leurs  lieux  naturels ;  en  ce  cas,  I'air  ne  porte 
pas  I'eau.  D'une  seconde  maniere,  en  tant  qu'ils  se  trouvent 
en  des  lieux  etrangers  a  leur  nature  ;  en  ce  cas  I'air  pent 
soutenir  I'eau  qui  se  trouve  en  un  lieu  etranger  a  sa  nature, 
et  cela  afin  qu'un  plus  grand  inconvenient  soit  evite.' 

II  sera  de  mode,  a  partir  du  xvii^  siecle,  de  plaisanter  cette 
cause  finale  invoquee  par  Bacon  a  cote  des  causes  efficientes  ; 
mais  Bacon  se  conformait  ici  aux  principes  essentiels  du 
Peripatetisme  qui,  dans  la  cause  finale,  voit  toujours  la 
veritable  cause. 

II  prend,  d'ailleurs,  ses  precautions  pour  qu'on  n'aille  pas 
raccuser  de  faire  du  vide  une  cause  efficiente,  d'attribuer  au 
vide  un  pouvoir  d'attirer  I'eau  dans  la  clepsydre.  A  cette 
question  :  ^  '  Le  vide  est-il  une  cause  ? '  il  repond :  '  Le  vide 
n'est  rien,  il  n'est  pas  une  nature  ;  or  ce  qui  est  cause  est 
une  certaine  nature  ;  le  vide  n'est  done  pas  une  cause.' 

A  cette  objection  :    '  La  ventouse  vide  attire  le  sang  et, 

'  RoGERi  Bacon  Op.  laud.,  lib.  iv  :  Queritur  septimo  utrum 
vacuum  sit  causa  aliqua  ;  MS.  cit.,  fol.  23,  col.  c. 


L'HORREUR  DU  VIDE  257 

si  elle  n'etait  pas  vide,  elle  ne  I'attirerait  pas,'  il  repond  en 
distinguant  diverses  sortes  d'attractions.  La  premiere  qu'il 
mentionne  est  celle  par  laquelle  Taimant  attire  le  fer . . .  La 
derniere  '  est  une  attraction  qui  se  fait  par  le  vide,  grace 
a  I'excitation  et  a  la  disposition  produite  par  la  chaleur.  C'est 
de  cette  maniere  que  la  ventouse  attire  le  sang  ;  voila 
pourquoi  on  met  dans  les  ventouses  des  etoupes  ardentes 
qui  y  engendrent  de  la  chaleur  ;  cette  chaleur  echauffe  I'air 
et  attire  le  liquide  pour  se  conserver  ;  car  le  liquide  est 
I'aliment  de  la  chaleur. 

*  II  est  done  evident  qu'une  attraction  ne  se  produit  jamais 
par  le  vide  seul  et  en  tant  que  tel,  mais  par  quelqu'autre 
cause.  Si  I'eau  est  attiree  et  retenue  dans  la  clepsydre 
tandis  que  le  doigt  est  pose  sur  I'orifice,  cela  ne  se  fait  pas  par 
le  vide  mais  par  la  nature  meme  et  I'ordre  des  corps,  c'est-a- 
dire  de  I'eau  et  de  I'air,  afin  que  le  vide  ne  survienne  pas,  car 
si  ce  vide  se  produisait,  il  serait  pour  eux  une  cause  de 
desordre  et  de  destruction.' 

Dans  ce  phenomene,  done,  le  vide  n'est  pas  cause  efficiente  ; 
les  causes  efiicientes,  ce  sont  les  corps  en  presence,  I'air  et 
I'eau.  II  n'est  pas  davantage  cause  finale  ;  la  cause  finale, 
c'est  I'ordre  et  la  conservation  des  corps  naturels  ;  c'est 
a  cet  ordre  que  tend  la  nature  ;  et  les  corps  se  meuvent  ou 
demeurent  immobiles  de  telle  maniere  que  cet  ordre  soit 
sauvegarde,  dussent-ils,  pour  cela,  aller  a  I'encontre  des  lois 
qui  reglent  leurs  mouvements  et  repos  naturels. 

Telle  est  la  doctrine  que  Bacon  formule  avec  une  enti^re 
nettete  des  la  premiere  serie  de  ses  questions  sur  la  Physique. 

Cette  doctrine,  nous  I'allons  retrouver  dans  la  seconde 
serie  des  questions  sur  la  Physique  ;  nous  I'y  retrouverons 
plus  developpee,  mais  aussi  plus  confuse. 

Dans  ces  nouvelles  questions,  en  effet.  Bacon  expose 
I'etude  experimentale  du  vide  suivant  un  ordre  qui  est 
conforme  a  la  methode  au  sic  et  non  et  aux  precedes  de 
discussions  chicanieres  de  la  Scolastique,  mais  qui  deroute 
singulierement  nos  habitudes. 

1689  s 


258  ROGER  BACON 

II  s'agit  de  presenter  une  experience  oii  le  mouvement 
naturel,  annonce  par  la  Physique  d'Aristote,  ne  se  produit 
pas,  et  oil,  par  ce  repos  imprevu,  la  formation  du  vide  est 
empechee.     Voici,  a  pen  pres,  comment  procede  Bacon  : 

II  annonce  I'experience  comme  un  moyen  de  faire  le  vide  ; 
il  la  decrit  comme  si  le  mouvement  naturel,  annonce  par  la 
Physique  peripateticienne,  se  produisait  en  realite,  en- 
trainant  la  formation  d'un  espace  vide. 

Puis  il  enumere  les  diverses  autres  manieres  dont  on 
pourrait  imaginer  que  les  choses  se  passassent  et  il  argumente 
pour  ou  contre  ces  diverses  manieres,  toujours  sans  jeter  le 
moindre  regard  sur  la  realite. 

Alors  seulement  il  presente,  a  titre  de  solution  du  debat, 
I'experience  telle  qu'elle  se  manifeste  aux  sens,  et  il  I'explique 
par  Taction  que  la  nature  universelle  exerce  afin  qu'il  n'y 
ait  pas  de  vide. 

C'est  done  au  travers  de  ces  demarches  compliquees  qu'il 
nous  faut  suivre  la  pensee  de  Bacon. 

L'etrangete  de  ces  demarches  se  manifeste  de  prime  abord. 
Notre  auteur,  adversaire  determine  du  vide,  annonce  son 
etude  experimentale  en  ces  termes,'  peu  propres,  assurement, 
a  nous  en  faire  deviner  la  conclusion  :  '  Apres  avoir  demontre 
par  des  raisonnements  qu'il  faut  admettre  le  vide,  on  montre 
€galement,  par  des  exemples  et  des  experiences,  qu'il  faut 
admettre  le  vide.' 

Bacon  presente  successivement  cinq  experiences  ;  allons 
d'abord  a  la  cinquieme  ;  c'est  celle  qui  a  ete  decrite  et 
etudiee  dans  la  premiere  serie  des  questions  sur  la  Physique. 

'La cinquieme  experience^  est  celle  qu'Aristote  indiquedans 
le  texte.  Que  Ton  prenne  un  vase  plein  d'eau  qui  a  plusieurs 
trous  dans  le  bas  et,  dans  le  haut,  un  orifice  bouche.     Tout 

'  Questiones  supra  lihrum  physicorum  a  magistro  dicto  Bacuun: 
Ostenso  per  rationes  quod  sit  ponere  vacuum,  item  per  exempla  et 
experimenta  ostenditur  quod  sit  ponere  vacuum.  MS.  cit.,  fol.  47» 
col.  d. 

MS.  cit.,  fol.  48,  coll.  c  et  d. 


L'HORREUR  DU  VIDE  259 

ce  qui  est  hors  de  son  lieu  propre  tend  a  ce  lieu,  pourvu  qu'il 
n'en  soit  pas  empeche  et  qu'il  soit  hors  de  ce  lieu.  L'eau 
qui  est  la  tend  done  en  bas.  Des  lors,  il  se  produirait  un 
vide  en  haut,  pres  de  rorifice  bouche,  et  l'eau  ne  demeurerait 
pas  en  repos,  comme  il  parait,  afin  d'empecher  que  le  vide 
ne  se  fasse.  Car  Aristote  dit  cela,  que  l'eau  demeurerait  en 
repos  afin  que  le  vide  ne  se  fit  pas  ;  et  il  ne  parait  pas  que 
cela  soit  vrai,  car  l'eau  qui  est  la,  etant  hors  de  son  lieu 
naturel,  tend  naturellement  en  bas.' 

On  avait  bien  fort  accoutume  de  presenter  I'experience 
de  Philon  de  Byzance  pour  commenter  la  phrase  ou  Aristote 
fait  mention  des  clepsydres,  car  Bacon  en  vient  a  s'imaginer 
que  I'experience  et  le  raisonnement  de  Philon  sont  dans  le 
texte  d'Aristote. 

Apres  avoir  ainsi  mis  sur  le  compte  de  I'experience  le 
contraire  de  ce  qu'elle  nous  enseigne  en  realite,  Bacon  nous 
presente  des  arguments  contre  ce  que  nous  manifestera  tout 
a  I'heure  le  temoignage  des  sens  : 

'  Ce  que  vous  objectez,  que  l'eau  ne  descendrait  pas 
afin  qu'il  ne  se  fit  pas  de  vide,  est  sans  valeur.  C'est  une 
petition  de  principe  ;   il  faudrait  le  prouver. 

'  En  outre,  une  negation  ne  peut  etre  la  cause  d'une  affir- 
mation ;  or  cette  proposition  :  l'eau  demeurerait  en  repos, 
est  une  proposition  affirmative  ;  la  cause  n'en  peut  etre 
cette  proposition  negative  :   afin  que  le  vide  ne  se  fit  point. 

'  De  meme  encore,  la  descente  de  l'eau  est  naturelle.  Le 
concours  des  parois  du  vase  est  contre  nature.  II  vaut  done 
mieux  admettre  la  descente  de  l'eau,  puisqu'elle  est  naturelle, 
que  le  concours  des  parois  ou  le  repos  de  l'eau,  puisque  ces 
deux  choses  sont  contre  nature.' 

A  la  supposition  erronee  que  l'eau  descendrait,  une  nouvelle 
supposition  erronee  est  venue  s'aj outer  d'une  maniere  impli- 
cite  :  Pour  empecher  la  production  du  vide,  les  parois  du 
vase  pourraient  se  rejoindre.  Au  moment  ou  Bacon  nous 
annonce  la  solution  du  debat,  il  va  tout  d'abord  parler 
comme  s'il  penchait  en  faveur  de  cette  supposition  erronee. 
C'est  seulement  apres  avoir  fait  ce  nouveau  detour  qu'il  nous 
proposera  enfin  I'opinion  qu'il  regarde  comme  correcte. 

s  2 


26o  ROGER  BACON 

'  Solution.  Je  dis  qu'en  vertu  de  I'ordre  de  la  nature 
universelle  les  parois  se  rejoindraient,  afin  que  le  vide  ne  se 
fit  point  {ex  ordinatione  naturae  universalis  .  .  .  ne  fieret 
vacuum).  Je  dis  que  ce  n'est  pas,  pour  cela,  une  petition  de 
principe  ;  car  dans  les  demonstrations  necessaires  il  faut 
postuler  le  principe  ;  cela  n'est  pas  absurde  [inconveniens) , 
car  c'est  toujours  ainsi  qu'Aristote  argumente  contre  Platon. 

*  A  I'autre  argument,  je  reponds  qu'il  n'y  a  pas  seulement 
la  une  negation,  mais  qu'une  chose  affirmative  y  est  jointe, 
savoir  la  distance  des  parois  et  le  salut  de  la  nature.  Des 
lors,  il  est  necessaire  d'admettre  que  I'eau  demeure  en  repos  ; 
il  vaut  mieux  admettre  cela  que  de  supposer  le  vide.  Afin 
done  que  le  vide  ne  se  fasse  pas,  afin  de  sauver  la  disposition 
du  vase  et  I'ordre  de  la  nature  universelle,  I'eau  demeure 
en  repos  ;  et  ce  n'est  pas  seulement  afin  que  le  vide  ne  se 
fasse  pas  ;  ce  n'est  done  pas  une  pure  negation. 

*  A  I'autre  argument,  je  reponds  :  Bien  que  le  vase  soit  un 
corps  continu  en  toutes  ses  parties,  il  est  contraire  a  sa 
nature  particuliere  que  ses  parois  se  rejoignent.  Partant,  il 
ne  faut  pas  que  I'eau  tombe  ;  alors,  en  effet,  la  figure 
naturelle  du  vase  serait  detruite  ou  bien  le  vide  se  produirait, 
et  cela  serait  contraire  a  la  nature  universelle  ;  il  faut  done 
que  I'eau  demeure  en  repos. 

'  Que  I'eau  ne  descende  pas  c'est  un  accident  contraire  a 
la  nature.  Ce  repos  vaut  done  mieux  que  la  destruction  de 
la  nature  ou  d'une  disposition  naturelle  ;  cela  vaut  mieux 
que  d'admettre  le  vide  ou  la  reunion  des  parois,  car  ces  deux 
choses  sont,  par  essence,  contraires  a  la  nature  ;  ce  serait 
absolument  contraire  a  la  disposition  essentielle  du  vase  ;  il 
peut  y  avoir  deux  sortes  de  reunions  des  parois,  une  reunion 
naturelle  et  une  reunion  contre  nature  ;  or  cette  derniere 
reunion  de  deux  parois  est  essentiellement  contre  nature. 
II  vaut  done  mieux  que  I'eau  demeure  en  repos,  ce  qui  n'est 
qu'un  accident  contraire  a  la  nature,  que  s'il  se  produisait 
une  chose  contre  nature  qui  fut  essentielle.' 

Nous  avons  reproduit  en  entier  la  discussion  de  cette 
cinquieme  experience  ;  non  seulement,  en  effet,  le  principe 
de  Physique  que  Bacon  entend  etablir  y  est  tres  clairement 
expose,  mais,  en  outre,  nous  y  trouvons  un  exemple  tres 
caracteristique  de  la  methode  que  notre  auteur  a  coutume 
de  suivre.  Nous  pourrons  maintenant  parler  d'une  maniere 
un  peu  plus  sommaire  des  quatre  premieres  experiences. 


L'HORREUR  DU  VIDE  261 

La  premiere  de  ces  experiences  est  celle-ci :  Que  deux 
disques  plans  soient  exactement  appliques  I'un  sur  I'autre 
et  que  Ton  souleve  brusquement  le  disque  superieur  ;  I'air 
ne  pourra  penetrer  instantanement  au  centre  de  I'espace 
compris  entre  les  deux  disques  ;  le  vide  s'y  produira  done 
pendant  un  moment. 

Faisons  grace  au  lecteur  des  multiples  chicanes  auxquelles 
cette  proposition  donne  lieu.  Retenons-en  cependant  cette 
phrase  :  ^ 

'  Comme  si  la  paume  de  ma  main  touchait  la  Seine,  ut  si 
palma  mea  tangat  Secanam.'' 

EUe  nous  apprend,  en  effet,  que  la  question  fut  discutee  a 
Paris.  Retenons-en  egalement  ce  passage,  qui  prepare  la 
solution : 

'  D'autres  disent  que  les  disques  ne  pourront  etre  souleves 
s'ils  gardent  leur  configuration,  de  telle  maniere  que  chaque 
partie  [du  disque  superieur]  soit  soulevee  egalement.  Au 
fur  et  a  mesure  que  les  diverses  parties  sont  soulevees, 
I'air  penetre  d'une  maniere  successive  ;  a  Tinstant  mdme 
ou  une  partie  est  soulevee.  Fair  penetre  au-dessous,  afin 
qu'il  ne  se  fasse  point  de  vide.' 

Voici  maintenant  la  solution  que  propose  Bacon  : 

*  Si  les  deux  disques  etaient  superposes  I'un  a  I'autre,  on 
ne  pourrait  jamais  soulever  le  disque  superieur  a  moins  d'en 
incliner  quelque  partie.  II  faut  done  que  quelque  inclinaison 
se  fasse  avant  qu'on  puisse  le  soulever  ;  sinon  le  vide  se 
produirait ;  et  cela  provient  de  la  nature  universelle.  lis 
repondent  done  bien  ceux  qui  repondent  que  le  disque  ne 
peut  etre  souleve  de  la  sorte. 

'  Cela  se  voit,  dans  I'eau,  d'une  maniere  evidente.  Que 
Ton  pose  sur  I'eau  un  verre  {cyphus)  [retourne],  et  qu'on  le 
souleve  en  gardant  la  meme  configuration,  sans  1 'incliner 
d'un  cote  plus  que  de  I'autre  ;  il  n'y  a  pas  d'homme  au 
monde  qui  le  pourrait  lever  ;  aussi,  comme  il  est  mani- 
feste  au  sens,  faut-il,  pour  le  lever,  I'incliner  d'abord  d'un 
certain  cote.     II  en  est  de  meme  dans  I'air,  bien  qu'avec 

^  MS.  cit.,  fol.  47,  col.  a. 


262  ROGER  BACON 

les  deux  disques  ce  ne  soit  pas  aussi  manifeste  au  sens 
qu'avec  le  verre.  C'est  pourquoi,  done,  il  ne  faut  pas 
admettre  le  vide.' 

On  aime  a  faire  de  Roger  Bacon  un  adepte  precoce  de  la 
methode  experimentale  ;  des  pages  comme  celles-ci  nous 
montrent  assez  qu'il  experimentait  seulement  en  imagina- 
tion. Chacun  sait  qu'un  verre  plonge  dans  I'eau  se  laisse 
soulever  sans  grand  effort  ;  au  contraire,  I'adherence  de  deux 
disques  plans  se  pent  observer  sans  aucune  difficulte.  II  est 
clair  que  notre  auteur  n'avait  tente  ni  Tune  ni  I'autre  des  deux 
epreuves. 

La  troisieme  experience  ^  se  fait  au  moyen  d'un  vase 
pansu  que  Bacon  appelle  une  marmite  [olla)  ;  mais  il  ajoute 
que  I'orifice  en  est  de  petite  dimension  {modicum  orificium). 
Que  Ton  remplisse  d'eau  ce  vase,  et  qu'on  le  ren verse  ;  si 
I'eau  s'ecoule,  I'espace  contenu  dans  la  pause  demeurera  vide. 

Que  se  passe-t-il  en  realite  ?  *  L'eau  doit  plutot  demeurer 
immobile,  comme  I'experience  le  montre.' 

Cette  experience  fait  double  emploi  avec  celle  que  Bacon 
avait  decrite  en  sa  premiere  serie  de  questions  et  a  laquelle  il 
va  donner  ici  le  cinquieme  rang  ;  il  ne  I'ignore  pas,  puisque, 
pour  preparer  la  reponse  que  nous  venons  de  citer,  il  ecrit : 

'  Prenons  un  vase  perfore  dont  le  fond  porte  une  foule  de 
petits  trous  ;  emplissons-le  et  bouchons  I'orifice  superieur  ; 
rien  ne  sortira  par  les  trous  inferieurs  bien  qu'ils  ne  soient 
pas  bouches,  car  le  vide  se  ferait  a  la  partie  superieure  du 
vase  ;  part  ant,  l'eau  demeure  en  repos  ;  elle  ne  descend 
point  ni  ne  se  rarefie  ;  l'eau  done  demeurera  purement  et 
simplement  en  repos  ;  elle  ne  se  repandra  pas,  afin  que  le 
vide  ne  se  produise  pas  en  ce  lieu.' 

La  presence,  dans  la  discussion  de  Bacon,  de  ces  deux 
experiences  qui  sont,  au  fond,  identiques,  semble  pouvoir 
s'expliquer  par  la  lecture  du  traite  de  Philon  de  Byzance  ; 
I'experience  *  de  la  marmite '  serait  suggeree  par  celle  au 
moyen  de  laquelle  Philon  demontre  que  I'air  est  un  corps. 
1  MS.  cit.,  fol.  48,  col.  a. 


L'HORREUR  DU  VIDE  263 

Nous  n'insisterons  pas  sur  ce  que  Bacon  dit  de  la  troisieme 
experience  et  de  la  quatrieme  :  ces  experiences,  en  effet, 
telles  qu'elles  sont  decrites,  sont  denuees  de  toute  significa- 
tion reelle.  Par  exemple/  *  la  troisieme  experience  est 
celle  du  tonneau  de  bronze  plein  d'eau  et  bien  clos.  Si  on 
le  garde  pendant  un  an,  on  trouve  qu'il  contient,  a  la  fin, 
moins  d'eau  qu'au  commencement.  Cependant  rien  n'a  pu 
en  sortir  ni  y  entrer.     La,  done,  il  y  a  le  vide.' 

Dans  le  traite  de  Philon  de  Byzance,  il  ne  se  trouve  rien 
qui  ait  pu  sugg^rer  semblable  affirmation.  Mais  on  n'en 
pent  dire  autant  du  traite  de  Heron  d'Alexandrie  ;  la,  en 
effet,  nous  lisons  :  ^  'Si  Ton  enferme  cette  eau  dans  un 
recipient  de  verre,  de  bronze  ou  d'une  autre  matiere  solide, 
et  si  on  la  place  longtemps  au  soleil,  cette  eau  ne  diminue 
point,  si  ce  n'est  d'une  toute  petite  fraction  (ovk  eXaTTovrai, 
ii  fir)  jrapa  fiLKpov  jiopiov  TravraTraa-iy  avTov).'  Serait-ce  la 
la  source  de  la  fausse  experience  affirmee  par  Bacon  ?  En  ce 
cas,  le  Tractatus  de  inani  et  vacuo  auquel  Bacon,  comme  la 
plupart  des  Scolastiques,  parait  avoir  emprunte  ses  connais- 
sances  experimentales  ne  serait  pas  simplement  cette  traduc- 
tion du  traite  de  Philon  de  Byzance  que  Valentin  Rose  a 
exhumee  ;  ce  serait  une  compilation,  d'origine  arabe,  oil 
les  souvenirs  de  Heron  d'Alexandrie  se  meleraient  a  ceux 
de  Philon.  De  cette  supposition,  nous  trouverons  bientot 
une  confirmation. 

Ce  que  Bacon  a  dit  des  experiences  relatives  au  vide, 
dans  ses  deux  series  de  Questions  sur  la  Physique,  fournit 
la  matiere  des  considerations  qu'il  reprend  dans  ses  divers 
ouvrages. 

Voici,  d'abord,  dans  VOpus  majus,^  I'experience  des  deux 

1  MS.  cit.,  fol.  48,  col.  a. 

-  Heronis  Alexandrini  Spiritualium  liber  a  Federico  Com- 
mandino  translaius.  Urbini,  mdlxxv,  fol.  5, 2°. — Heronis  Alexan- 
drini Opera  quae  supersunt  omnia,  ed.  W.  Schmidt,  vol.  i,  pp.  14-15. 

^  Fratris  Rogeri  Bacon  Opus  majus,  ed.  Jebb,  pars  IV, 
dist.  iv,  cap.  ix  :  An  corpora  se  tangant  in  puncto  ;  p.  93. 


264  ROGER  BACON 

disques  appliques  Tun  a  I'autre  et  qu'on  ne  peut  separer. 
Nous  retrouvons,  presque  dans  les  mSmes  termes,  les  con- 
siderations que  nous  avions  deja  lues  dans  la  seconde  serie 
des  Questions,  y  compris  celle-ci  : 

'  II  faut  dire  que  Ton  ne  peut  elever  I'un  des  disques 
au-dessus  de  I'autre  en  leur  gardant  meme  configuration ; 
pour  que  I'un  d'eux  puisse  etre  souleve  au-dessus  de  I'autre, 
il  faut  qu'on  I'incline  ;  I'air  entre  ainsi  peu  a  peu.  Cela  se 
peut  fort  aisement  eprouver  au  moyen  d'un  verre  plonge 
dans  I'eau  ;  car  pour  rien  au  monde  {pro  mundo)  il  ne  peut 
etre  lev6  si  Ton  garde  meme  configuration  a  ses  parties  ;  la 
cause  en  est  que  I'eau  doit  venir  peu  a  peu  en  occuper  le 
lieu.  C'est  la  la  cause  positive  {afjirmativa)  en  consequence 
de  laquelle  le  vide  se  trouve  exclu.' 

Dans  YOpus  majus,  Bacon  n'avait  parle  du  vide  que  d'une 
maniere  incidente ;  il  en  traite  ex  professo  au  cours  de 
YOpus  tertium.  La,  nous  retrouvons  '  I'experience  du  vase 
dont  le  fond  est  crible  de  petits  trous  ;  la  aussi  I'auteur 
rappelle  qu'il  a  parle,  dans  VOpus  majus,  de  I'adherence  de 
deux  disques  exactement  appliques  I'un  contre  I'autre. 

La  raison  de  cette  adherence,  c'est  que,^  de  la  separation 
des  deux  plaques,  '  resulterait  une  discontinuity  {discon- 
tinuatio)  de  la  nature  et  entre  les  parties  de  I'Univers,  dis- 
continuite  a  laquelle  le  vide  se  trouve  attache  [annexum)  .  .  . 
Aussi,  qu'un  homme  essay e  de  soulever  le  disque  superieur 
en  le  maintenant  parallele  a  I'autre  [aequaliter),  il  n'y 
parviendra  jamais  .  .  .  Dans  I'eau,  cela  apparait  bien.  Si 
quelqu'un  pose  sur  I'eau  la  concavite  d'un  verre,  en  tenant 
ce  verre  par  le  pied,  il  peut  experimenter  qu'en  maintenant 
la  figure  bien  egale  de  tous  cotes  il  ne  parviendra  par  aucune 
violence  a  le  tirer  de  I'eau.' 

L'experience  du  vase  perfore  donne  a  Bacon  I'occasion 
d'exposer  ses  idees  sur  la  fuite  du  vide  avec  une  precision 
et  une  ampleur  qu'il  ne  leur  avait  pas  encore  accordees. 

'  RoGERi  Bacoxis  Opus  tertium,  ed.  Brewer,  cap.  xliii,  pp.  155-6. 
"  RoGERi  Baconis  Op.  laud.,  cap.  xlv,  p.  166. 


L'HORREUR  DU  VIDE  265 

'  Rien,  dit-il,'  n'empeche  I'eau  de  couler  ni  ne  le  lui 
defend  ;  c'est  par  sa  propre  nature  qu'elle  demeure  en  repos 
bien  que  soulevee,  en  vue  de  la  continuite  de  la  nature 
commune  a  tous  les  corps,  continuite  qui  doit  etre  conservee  - 
entre  les  diverses  parties  de  I'Univers.  L'eau,  en  effet,  est 
une  certaine  nature  qui  a  deux  sortes  de  rapports.  L'un 
est  le  rapport  qu'elle  a  a  son  lieu  propre.  L'autre  est  le 
rapport  qu'elle  a  en  vertu  de  la  continuite  du  milieu  {medii) 
naturel,  afin  de  garder  cette  continuite  avec  les  autres  corps 
naturels.  Cela,  elle  ne  le  ferait  pas  si  elle  tombait,  car  I'air 
ne  pent  entrer  par  I'orifice  bouche.  Or  le  rapport  qu'a  l'eau 
a  cette  continuite  qu'il  s'agit  de  sauver,  prime  le  rapport 
qu'elle  a  a  I'egard  de  son  lieu  propre  ;  le  premier  de  ces 
rapports,  en  effet,  lui  est  du  en  tant  qu'elle  est  une  partie  de 
rUnivers  ;  le  second,  celui  qui  concerne  son  mouvement  de 
descente,  lui  est  seulement  du  en  tant  qu'elle  est  apte  a  etre 
logee,  qu'elle  pent  etre  entouree  par  un  lieu  qui  lui  convient 
mieux  qu'un  autre  lieu.  Mais  etre  une  partie  de  I'Univers, 
c'est  une  propriete  qui,  pour  l'eau,  passe  avant  la  propriete 
d'etre  logee  et  entouree  par  quelque  chose  qui  lui  convienne, 
ime  propriete  qui  lui  est  plus  essentielle  ;  elle  pent,  en  effet, 
continuer  d'etre  de  l'eau  lors  meme  qu'elle  ne  serait  pas 
entouree  par  un  tel  lieu  qui  lui  convint  ;  mais  elle  ne  pourrait 
continuer  d'etre  de  l'eau  si  elle  n'etait  plus  une  partie  de 
I'Univers.  Si  done  l'eau  demeure  immobile  en  I'air,  ce  n'est 
pas,  d'une  fa^on  premiere  et  proprement  dite,  afin  que  le 
vide  ne  soit  pas  [propter  negationem  vacui)  ;  c'est  afin  de 
sauver  la  continuite  de  la  nature  dans  le  Monde  ;  et  de  cette 
continuite,  la  privation  du  vide  decoule  a  titre  secondaire. 
Ainsi  ce  n'est  pas  une  negation  qui  est,  ici,  cause  d'une 
affirmation,  mais  une  affirmation.  Qu'a  cette  affirmation 
une  negation  soit  annexee,  cela  n'a  pas  d'inconvenient,  car 
toute  affirmation  entraine  avec  elle  une  infinite  de  negations 
qui  lui  sont  adjointes  .  .  .  jNIais  une  negation  ne  saurait,  d'une 
fa9on  premiere  et  principale,  importer  une  affirmation  ;  elle 
n'en  pent  etre  la  cause  ;  elle  en  peut  seulement  accompagner 
la  cause,  comme  il  arrive  ici.' 

Apres  avoir  assiste,  en  lisant  les  deux  series  de  Questions  sur 
la  Physique  et  YOpus  Majus,  aux  tatonnements  et  aux  essais 
de  la  theorie  baconienne,  nous  la  contemplons,  maintenant, 

'  Ibid.,  pp.  165-6. 

'  Le  texte  public  par  Brewer  porte  :  salvatae  \  un  ms.  porte  : 
salvande  ;   il  faut,  croyons-nous  :   salvandam. 


266  ROGER  BACON 

en  son  plein  ach^vement  ;  Bacon,  en  effet,  ne  la  perfection- 
nera  pas  da  vantage ;  aux  Communia  Naturalium,  il  formulera 
encore  quelques  propositions  utiles  a  recueillir,  mais  il  ne 
donnera  plus  de  son  syst^me  I'expose  dogmatique  qu'il  a 
presente  dans  VOpus  tertium. 

Nous  retrouvons,  aux  Communia  Naturalium,  I'experience 
des  deux  disques  adherents,'  enfin  debarrass6e  de  la  fausse 
experience  du  verre  renverse  sur  I'eau  ;  nous  y  retrouvons 
aussi '  I'experience  que  Philon  de  Byzance  faisait  avec  un 
vase  au  fond  crible  de  petits  trous. 

C'est  a  propos  de  cette  derniere  experience  que  sont  emises 
les  reflexions  suivantes  : 

'  Ce  n'est  pas  d'elle-meme  que  la  nature  particuliere  de 
I'eau  demeure  en  I'air,  mais  par  la  force  de  la  nature  univer- 
selle  qui,  sans  cesse,  requiert  et  conserve  la  continuite  des 
corps  naturels,  continuite  que  le  vide  dissout.  On  voit 
done  quelle  est  ici  la  cause  efficiente  :  C'est  la  nature  univer- 
selle  a  laquelle  obeit  la  nature  particuliere.  On  voit  aussi 
quelle  est  la  cause  finale  :  C'est  la  continuite  naturelle  des 
corps  de  ce  Monde.  Voila  I'affirmation  dont  resulte  la 
negation  du  vide.  Nous  ne  posons  done  pas  une  negation 
comme  cause  d'une  aflirmation,  mais  au  contraire  .  .  .' 

'  Si  Ton  disait  que  I'eau  ne  descend  pas  afin  que  le  vide  ne 
se  produise  pas,  ce  ne  serait  pas  une  solution,  car  une  nega- 
tion ne  peut  etre  la  cause  d'une  affirmation.  II  faut  dire 
que  I'eau  est  retenue  en  I'air  par  la  loi  de  la  nature  universelle, 
afin  qu'il  y  ait  coiltinuite  entre  les  corps  de  la  nature  ;  de 
cette  continuite,  I'exclusion  du  vide  decoule  a  titre  secondaire. 
C'est  done  une  affirmation,  savoir  la  continuite,  qui  est  cause 
d'une  affirmation,  savoir  le  repos  de  I'eau  dans  le  vase.' 

La  doctrine  dont  nous  avons  suivi  le  developpement  au 
travers  des  ecrits  de  Roger  Bacon  semble  bien  lui  appartenir 
en  propre.  A  peine,  croyons-nous,  en  avait-il  trouve  chez 
ses  predecesseurs  un  germe  presque  infime.  Albert  le  Grand, 
repetant  le  propos  de  Philon  de  Byzance,  s'etait  borne  a  dire, 

'  Opera  hacteniis  inedita  Rogeri  Baconi,  fasc.  iii.  Liber  primus 
communium  naturalium  Fratris  Rogeri,  pars  III,  dist.  ii,  cap.  \i, 
ed.  Steele,  pp.  221-3. 

-  Roger  Bacon,  loc.  cit.,  pp.  219-20  et  p.  224. 


L'HORREUR  DU  VIDE  267 

au  sujet  de  rimmobilite  de  I'eau  dans  la  clepsydre  :  '  C'est 
parce  que  rien  n'est  vide.  II  faut  done  que  les  surfaces  des 
corps  soient  conjointes  les  unes  aux  autres.  Quia  nihil  est 
vacuum  ;  et  ideo  oportet  superficies  corporum  esse  conjunctas.' 

A  partir  de  cette  minime  indication,  Roger  Bacon  a 
developpe  toute  une  theorie  ;  et,  de  cette  theorie,  il  convient 
de  marquer  I'importance. 

Aristote  avait  explique  tous  les  mouvements  des  corps 
inanimes  que  contient  I'orbe  de  la  Lune,  a  partir  de  la  suppo- 
sition du  lieu  naturel.  A  chaque  corps  correspond  un  lieu 
propre  oil  sa  forme  substantielle  atteint  la  perfection  ;  ce 
lieu  est  le  centre  du  Monde  pour  les  corps  graves,  la  region 
contigue  a  I'orbe  de  la  Lune  pour  les  corps  legers.  Place 
dans  son  lieu  naturel,  un  corps  y  demeure  en  repos.  Mis 
liors  de  son  lieu,  il  tend  a  s'y  rendre  ;  s'il  n'est  retenu,  il  se 
meut  vers  lui. 

Or  les  experiences  que  decrivent  Philon  de  Byzance  ou 
Heron  d'Alexandrie  mettent  constamment  cette  Mecanique 
en  defaut  ;  on  y  voit  des  corps  que  rien  ne  retient  et  qui 
demeurent  immobiles,  bien  qu'ils  ne  se  trouvent  pas  en  leur 
lieu  naturel ;  on  y  voit  monter  des  corps  graves  et  descendre 
des  corps  legers.  La  Mecanique  d'Aristote  reclame  done 
une  modification  ou  un  complement. 

Avant  d'etre  corps  de  telle  nature,  corps  celeste,  corps 
grave  ou  corps  leger,  un  corps  est,  tout  simplement,  une 
partie  de  I'Univers  corporel ;  avant  la  nature  particuliere 
que  lui  confere  sa  forme  substantielle,  il  a  une  nature  univer- 
selle  qui,  selon  la  doctrine  d'Avicebron,  chere  a  Bacon,  lui 
est  donnee  par  la  corporeite.  En  vertu  de  sa  nature  particu- 
liere, le  corps  tend  a  son  lieu  propre  ;  mais  en  vertu  de  la 
nature  universelle  qu'il  possede  il  a  une  autre  tendance  ; 
il  tend  a  demeurer  sonde  aux  corps  qui  lui  sont  immediats, 
afin  que  toutes  les  parties  de  I'Univers  demeurent  unies  et 
contigues.  Comme  la  nature  universelle  surpasse,  en  excel- 
lence, la  nature  particuliere,  la  seconde  tendance  est  plus 


268  ROGER  BACON 

puissante  que  la  premiere.  On  peut  done  observer  des 
repos  et  des  mouvements  qui  contredisent  aux  lois  de  la 
gravite  et  de  la  leg^ret^  ;  ces  repos  ont  pour  cause  la  tendance 
de  la  nature  universelle,  qui  assure  la  parfaite  et  perp^tuelle 
continuity  entre  les  divers  corps  du  Monde. 

La  theorie  du  lieu  naturel,  telle  qu'Aristote  I'avait  proposee, 
etait  une  bonne  theorie  de  Physique,  car,  au  moyen  d'un  petit 
nombre  d'hypoth6ses,  elle  permettait  de  classer  une  multi- 
tude de  phenomenes  connus,  de  prevoir  une  foule  de  repos 
ou  de  mouvements. 

Cependant,  peu  a  peu,  les  experiences  dont  la  theorie 
peripateticienne  ne  pouvait  rendre  compte  se  sont  multipliees 
et  precisees.  Alors,  il  a  fallu  la  remplacer  par  une  theorie 
plus  complexe,  mais  plus  comprehensive  ;  Roger  Bacon  a 
construit  cette  theorie  nouvelle. 

La  theorie  proposee  par  Roger  Bacon  etait  une  bonne 
theorie  physique  ;  a  partir  d'un  petit  nombre  de  principes 
simples,  elle  rendait  compte  de  tous  les  phenomenes  d'equi- 
libre  et  de  mouvement  que  Ton  connaissait  alors,  aussi  bi«i 
de  ceux  qu'interpretait  deja  la  theorie  d'Aristote  que  de  ceux 
dont  Philon  avait  donne  la  description.  Aussi  cette  theorie 
a-t-elle  joui  d'une  faveur  longue  et  merit ee.  Au  milieu  du 
xvi®  siecle,  Jules-Cesar  Scaliger  se  plaira  a  la  developper  ' 
dans  ses  diatribes  contre  Cardan. 

Un  jour,  cependant,  I'hypothese  de  la  continuite  univer- 
selle, proposee  par  Roger  Bacon,  connaitra  le  sort  qu'a  connu 
I'hypothese  du  lieu  naturel,  proposee  par  Aristote  ;  I'obser- 
vation  revelera  des  phenomenes  dont  elle  ne  peut  rendre 
compte  ;  les  fontainiers  de  Florence  remarqueront  qu'une 
pompe  aspirante  ne  peut  soulever  I'eau  au-dela  de  trente- 
deux  pieds  ;  Evangelista  Torricelli  realisera  I'experience  du 
vif-argent. 

'  JULii  Caesaris  ScALiGERi  Exotericarum  exercitationum  liber  XV 
De  Subtilitate  adversits  Cardanum.  Exercitatio  V  :  De  materia.  De 
vacuo. 


L'HORREUR  DU  VIDE  269 

Alors,  apres  avoir  ete  longtemps  une  bonne  theorie  de 
Physique,  le  systeme  de  Bacon  deviendra,  a  son  tour,  une 
theorie  insuffisante,  que  les  faits  contredisent,  qu'il  faut 
re  Jeter  et  remplacer  par  une  doctrine  plus  comprehensive. 
Ceux  qui  s'obstineront  a  professer  cette  theorie  en  depit  du 
dementi  de  I'experience  feront  preuve  d'une  illogique 
routine  ;  c'est  ce  que,  durement,  mais  justement,  Pascal 
reprochera  au  P.  Noel. 

Mais  le  temps  ou  le  systeme  de  Bacon  devra  etre  abandonne 
est  bien  eloigne  de  celui  oil  I'auteur  de  cette  theorie  la 
formule.  Voyons  comment  I'idee  nouvelle  a  ete  accueillie 
par  les  successeurs  immediats  du  Franciscain  anglais. 

IV.  La  Tr.\dition  de  Roger  Bacon  et  l'Horreur  du  Vide 

Nous  chercherons  d'abord  la  trace  de  la  doctrine  de 
Bacon  dans  cette  Stinima  philosophiac  que  certains  manuscrits 
attribuent  a  Robert  Grosseteste,  mais  ou  Ton  reconnait  sans 
peine  I'oeuvre  d'un  disciple  de  Roger  Bacon. 

Voici  un  premier  passage  interessant,'  que  nous  relevons 
dans  ce  que  cette  Sotmne  dit  du  vide  : 

'  Heron,  cet  eminent  philosophe,  s'efforce,  a  I'aide  de 
clepsydres,  de  siphons  et  d'autres  instruments,  de  mettre  en 
evidence  I'existence  du  vide  ;  ce  n'est  pas  chose  qu'il  faille  re- 
prouver  de  toute  fa^on.  II  ne  se  propose,  en  effet,  d'etablir 
qu'une  chose,  c'est  que,  par  un  certain  artifice,  le  plein 
pent  etre  ote  d'un  lieu  ;  cela  fait,  il  faudra  necessairement 
que  le  vide  reste  en  ce  lieu.  Mais  c'est  seulement  pendant  la 
duree  instantanee  de  la  transformation  que  cela  se  peut  faire 
veritablement.  La  cause  de  cet  effet,  c'est  la  vertu  du  lieu 
naturel  qui,  de  la  circonference  au  centre,  est  partout  re- 
pandue.' 

Ce  texte  nous  apprend,  tout  d'abord,  que  le  Tractatus  de 
inani  et  vacuo  ou  Bacon  avait  lu  les  experiences  qui  se  font 

'  LiNCOLNiENSis  Summa,  cap.  cxviii,  ed.  Baur,  p.  417.  [Ludwig 
Baur,  Die  philosophischen  Werke  des  Robert  Grosseteste,  Bischofs  von 
Lincoln  {Beitrdge  zur  Geschichte  der  Philosophie  des  Mittelalters, 
Bd.  ix,  Miinster,  19 12).] 


270  ROGER  BACON 

avec  des  clepsydres  et  des  siphons  etait  donne  sous  le  nom 
de  Heron  d'Alexandrie,  ou,  tout  au  moins,  citait  ce  nom. 
Nous  avons  reconnu  qu'il  devait  contenir  certaines  ex- 
periences f aites  par  Philon  et  ignorees  de  Heron  ;  qu'il  devait 
egalement  decrirc  des  experiences  que  Heron  rapporte  et 
dont  Philon  ne  parlc  pas.  Nous  sommes  ainsi  conduits  a 
penser  que  les  Arabes  avaient  donne  aux  Chretiens,  sous  le 
nom  de  Heron  d'Alexandrie,  une  compilation  oil  les  emprunts 
faits  a  cet  auteur  se  melaient  a  ceux  que  Philon  avait 
fournis. 

Nous  voyons,  en  outre  (et  la  lecture  de  Bacon  nous  le 
faisait  deja  soup9onner),que  ce  traite  decrivait  les  experiences 
de  H^ron  et  de  Philon  a  I'envers,  si  Ton  peut  le  dire,  et,  par  ce 
retournement,  presentait  des  effets  contraires  a  ceux  que  les 
mecaniciens  ont  observe  comme  des  artifices  propres  a  realiser 
un  espace  vide. 

Le  disciple  de  Bacon  parait  avoir  ete  vivement  frappe  par 
I'hypothese  de  cette  nature  universelle  a  laquelle  son  maitre 
attribuait  les  mouvements  qui  violentent  les  natures  particu- 
lieres  afin  d'empecher  le  vide  de  se  produire.  U  en  met  la 
notion  a  la  base  meme  de  sa  Cosmologie. 

'  La  nature,  dit-il,'  en  tant  qu'elle  est  meme  chose  que  la 
force  active  et  que  la  forme,  ...  est  ou  bien  nature  universelle 
ou  bien  nature  particuliere  .  .  . 

'  Cette  nature  universelle,  c'est  une  force  qui  reside  dans 
la  substance  celeste,  c'est-a-dire  dans  cette  intelligence  creee 
qui,  au-dessous  du  Createur  beni,  gouverne  et  modere  toute 
la  nature  corporelle  et  inferieure  .  .  . 

'  Avec  cette  nature  universelle  conspirent  toutes  les  choses 
qui  gisent  au-dessous  d'elle,  qui  plongent  en  elle  leur  racine, 
qui,  par  elle,  ont  regu  en  partage  la  propriete  d'agir  ;  ces 
choses  conspirent  avec  la  nature  universelle  au  point  de 
suspendre,  parfois,  les  natures  qui  accompagnent,  en  elles, 
la  nature  universelle,  les  proprietes  qui  leur  sont  particulieres, 
et  d'empecher  les  actions  et  les  effets  qui  leur  sont  propres. 

'  Cette  particularity  qui  distingue  la  nature  particuliere 
de  la  nature  universelle  n'est  pas  une  particularite  individuelle, 

'  LiNCOLNiENSis  Siwima,  cap.  ccxliv,  ed.  Baur,  pp.  590-91. 


L'HORREUR  DU  VIDE  271 

si  ce  n'est,  peut-etre,  par  accident ;  c'est  une  pure  propriete 
operative  qui  accompagne  toutes  les  choses  d'une  meme 
espece  . . .  Toute  espece,  en  effet,  peut  etre  appelee  particuliere 
a  regard  du  genre  auquel  elle  appartient  .  .  .,  bien  qu'ellc 
soit  veritablement  universelle  a  I'egard  des  individus. 

'  La  nature  particuliere,  done,  est  une  force,  une  propriete 
operative  qui  accompagne  I'espece,  bien  que  I'effet  qu'elle 
produit  ne  se  rencontre  pas  tou jours  en  tout  indi\ddu  de 
cette  espece.  Par  exemple,  de  ce  que  rhomme  est  raison- 
nable,  il  n'en  resulte  pas  que  tout  homme,  necessairement 
et  d'une  maniere  habituelle,  use  de  la  raison,  mais  plutot  qu'il 
est  naturellement  apte  a  en  user.  De  meme,  le  feu,  par  sa 
nature  particuliere,  est  chaud  et  tend  a  etre  place  aussi  haut 
que  possible  ;  il  se  peut,  cependant,  que  le  feu  soit,  parfois, 
prive  de  chaleur,  et  qu'il  se  trouve  en  un  lieu  bas.' 

'  La  nature  universelle,  poursuit  notre  auteur,'  a  une  pre- 
miere action  qui  lui  est  propre  et  qui  tend  a  un  but  determine; 
mais  elle  a  aussi  une  autre  action  qui  se  trouve  repandue  dans 
toute  operation  de  la  nature  particuliere  ;  celle-ci  ne  meut 
aucunement,  en  effet,  qu'elle  ne  soit  mue,  tout  d'abord,  par 
la  nature  universelle. 

'  Ainsi,  d'une  maniere  universelle,  causale,  premiere,  mou- 
voir  et  operer  sont  choses  qui  appartienncnt  a  la  force  et 
a  la  nature  universelles  ;  mais  il  leur  appartient  egalement 
de  produire  des  effets  contraires  a  ceux  de  la  nature  particu- 
liere, et  cela  de  multiple  fagon. 

'  C'est  le  propre  de  la  terre  d'occuper  le  lieu  le  plus  bas  ; 
il  est  parfois  possible,  cependant,  qu'elle  se  trouve  logee  au 
sein  de  la  sphere  de  I'air,  voire  au  supreme  faite  de  la  sphere 
du  feu  .  .  .  L'air  et  le  feu  peuvent  se  trouver  transportes  fort 
loin  de  leurs  spheres  respectives  ;  I'eau,  qui  a  pour  propriete 
de  surpasser  la  sphere  de  la  terre,  a  pu  etre  renfermee  dans 
les  entrailles  de  la  terre,  afin  de  laisser  apparaitre  la  terre 
ferme.' 

De  ces  mouvements,  contraires  aux  mouvements  naturels, 
que  determine  la  nature  universelle,  notre  auteur  aurait  pu 
prendre  exemple  en  citant  les  experiences  ou  cette  nature 
universelle  met  obstacle  a  la  production  du  vide.  Ces  exem- 
ples,  il  les  laisse  a  son  maitre  Roger  Bacon,  et  il  en  cite  un 
autre  que  nous  n'avons  jamais  rencontre  hors  de  sa  Somme 
de  philosophie. 

■  Ibid.,  cap.  ccxlv,  p.  591, 


272  ROGER  BACON 

On  salt  comment  Aristote  cherchait  dans  I'air  ebranl^  la 
force  motrice  qui  maintient  le  mouvcment  du  projectile, 
apr^s  que  celui-ci  a  quittc  la  main  ou  la  machine  balistique. 
Au  xiii'-'  siecle,  la  Scolastique  tout  enti^re,  ycompris  Roger 
Bacon,  admettait  cette  etrange  theorie.  Notre  auteur  n'a 
pas  manqu^  de  lui  donner  son  assentiment  ; '  et  cependant, 
elle  I'etonne.  Que  I'air,  qui  est  grave,  puisse  porter  un 
projectile  vers  le  haut,  cela  ne  saurait  6tre  un  effet  de  sa 
nature  particuliere  ;  il  faut  done  qu'il  tienne  cette  propriete 
de  la  nature  universelle.  Mais  citons  le  curieux  passage  * 
ou  se  d^veloppe  cette  explication  : 

'  Aristote  affirme  qu'cntre  deux  mouvements  contraires, 
comme  I'ascension  d'un  grave  et  la  chute  de  ce  m^me  grave, 
un  repos  intermediaire  doit  s'intercaler  necessairement, 
d'une  necessite  de  nature  ;  aussi  voit-on  que  les  graves  jetes 
en  I'air  demcurcnt  en  repos  lorsqu'ils  parviennent  au  terme 
de  leur  trajectoirc  vers  le  haut.  Or  voila  deux  choses 
[I'ascension  et  le  repos  en  I'air]  qui  sont  fort  contraires  a  la 
nature  particuliere  du  grave. 

'  De  meme.  dans  le  jet  d'une  pierre,  d'une  fleche  ou  d'un 
objet  quelconque,  mii  de  mouvement  violent,  I'air,  qui  est 
tres  mobile  et  tres  leger,  re9oit,  de  la  violence  du  premier 
moteur,  une  impression  par  laquelle  il  puisse  conduire  le 
mobile  jusqu'au  terme  du  mouvement.  Suivant  Aristote, 
a  la  fin  du  mouvement  aussi  bien  qu'au  milieu,  c'est  ce  meme 
air,  mis  en  branle  au  debut  par  le  moteur  violent,  qui  meut 
naturellement  le  mobile,  lors  meme  que  la  pierre  lanceeserait 
de  la  taille  d'une  meule  de  moulin  ou  incomparablement  plus 
grande.  Platon  pensait  que  le  premier  air  ebranle  en  mou- 
vait  un  second  et  ainsi  de  suite  jusqu'a  la  fin  ;  mais  un 
mouvement  de  cette  sorte  serait  un  mouvement  violent. 
Selon  ce  qu'affirme  Aristote,  au  contraire,  tant  au  milieu  du 
mouvement  qu'a  la  fin,  la  force  motrice  active,  en  ce  qui 
concerne  I'air  qui  maintient  le  mouvement,  serait  natureUe. 
Le  meme  Aristote  et  les  autres  Peripateticiens  attribuent 
a  I'eau  une  nature  qui  a  meme  facilite  pour  recevoir  d'un 
moteur  violent  une  impression  quelconque,  et  meme  propriete 
de  mouvoir  ensuite  par  sa  nature. 

'  Mais  cela  ne  pent  appartenir  uniquement  a  la  nature 

'  LiNCOLNiENSis  Siimma,  cap.  clxxxi,  ed.  Baur,  p.  510. 
-  Ibid.,  cap.  ccxlv,  pp.  591-2. 


L'HORREUR  DU  VIDE  273 

particuliere  de  I'air  et  de  I'eau*;    c'est  une  propriete  que  la 
nature  universelle  a  imprimee  a  relement  fluide. 

'  En  effet,  de  deux  objets  opposes,  il  en  est  toujours  un 
auquel  tend  la  nature  particuliere  ;  la  nature  universelle,  au 
contraire,  regarde  de  meme  fa9on  ces  deux  objets  opposes  ; 
lors  done  que  la  nature  particuliere  agit,  la  nature  universelle 
collabore  avec  elle  ;  mais  elle  pourra  aussi  operer  en  sens 
contraire  de  la  nature  particuliere.' 

C'est  bien  la  theorie  imaginee  par  Roger  Bacon  ;  I'inven- 
teur  ne  I'avait  appliquee  qu'aux  experiences  ou  les  corps 
graves  suspendent  leurs  mouvements  naturels  pour  eviter  le 
vide  ;  audacieusement,  son  disciple  a  tente  de  la  generaliser 
et  d'en  tirer  une  explication  du  mouvement  des  projectiles. 
Les  physiciens  qui  viendront  apres  I'auteur  de  la  Siimma 
philosophiae  ne  renouvelleront  pas  sa  tentative  ;  comme 
Bacon,  c'est  seulement  aux  experiences  relatives  a  la  fuite 
du  vide  qu'ils  appliqueront  la  notion  de  nature  universelle  ; 
seul,  Jean  de  Dumbleton  ecrira,  au  sujet  du  mouvement  des 
projectiles,  une  page  ou  Ton  pourra  peut-etrc  reconnaitre 
un  souvenir  de  la  Summa  Lincolniensis. 

Les  Commentaires  stir  la  Physique  d'Aristote  composes  par 
Gilles  de  Rome  sont  le  premier  ecrit  ou  nous  remarquions, 
au  sujet  du  vide,  I'iniiuence  des  idecs  emiscs  par  Bacon. 

Cette  influence  se  devine  deja,  croyons-nous,  dans  ce  que 
Gilles  de  Rome  dit  de  I'experience  de  la  clepsydre. 

'  On  prouve,  ecrit-il,'  que  I'air  est  quelque  chose  au  moyen 
d'un  certain  vase  qu'on  appelle  clepsydre  ;  il  a  un  trou  dans 
la  partie  superieure  et  un  grand  nombre  de  trous  dans  la 
partie  inferieure.  Le  vase  une  fois  rempli,  si  Ton  ouvre  les 
trous  inferieurs,  tout  en  maintenant  bouche  I'orifice  superieur, 
I'eau  ne  s'ecoule  pas  ;  I'air,  en  effet,  voulant  entrer  par  ces 
trous,  ne  permet  pas  a  I'eau  de  sortir.  C'est  par  la  qu'on 
demontrait  que  I'air  est  quelque  chose  ;  en  effet,  si  I'eau 
sortait  de  ce  vase  artificieusement  combine,  et  si  I'air  n'y 
entrait  pas,  il  y  resterait  le  vide.  L'air  done,  en  voulant 
entrer  par  les  trous  d'ou  I'eau  s'echapperait,  empeche  la 
sortie  de  I'eau.    Partant,  disaient-ils,  I'eau  est  quelque  chose.' 

■  Aegidii  Romani  In  libros  de  physico  auditu  Aristotelis  commen- 
taria,  lib.  IV,  lect.  x,  ed.  Venetiis,  1502,  fol.  76,  col.  a. 
1689  X 


274  ROGER  BACON 

Dans  I'insistancc  avec  laqucllc  Gilles  de  Rome,  en  I'air 
qui  veut  entrer,  met  la  cause  qui  empeche  I'eau  de  sortir, 
peut-^tre  reconnaitra-t-on  un  souvenir  de  ce  que  Bacon 
disait  de  la  clepsydre,  dans  la  premiere  serie  de  ses  Questions 
de  Physique.  Mais  I'influence  de  Bacon  se  marque  avec  une 
tout  autre  nettete  dans  ce  que  Gilles  dit  de  la  traction  exercee 
par  le  vide  {tractus  a  vacuo). 

'  On  se  demanderait  peut-etre,  ecrit-il,'  s'il  y  a  une  traction 
exercee  par  le  vide  ...  II  faut  repondre  que  la  traction  par 
le  vide  se  peut  entendre  de  deux  manieres.  En  premier  lieu, 
le  mot  vide  peut  designer  d'une  maniere  positive  une  certaine 
nature,  par  laquelle  serait  exercee  une  attraction  proprement 
dite  ;  imaginer  de  la  sorte  la  traction  du  vide,  c'est  pure- 
ment  fantastique  .  .  .  On  peut  entendre  d'une  autre  maniere 
la  traction  du  vide,  et  designer  par  la  une  traction  exercee 
alin  qu'il  n'y  ait  pas  de  vide  ;  de  cette  maniere,  il  s'exerce, 
en  effet,  une  traction  du  vide,  car  la  nature  ne  souffre  pas 
le  vide.  De  cette  fa9on,  dans  une  foule  de  circonstances,  il 
se  produit  une  traction  afin  qu'il  n'y  ait  pas  de  vide. 

'  C'est  manifeste  pour  laventouse;  si  Ton  y  metdel'etoupe 
enflammee,  ce  feu  rarefie  Fair  contenu  dans  la  ventouse ;  qu'on 
pose  alors  la  ventouse  sur  la  chair  ;  comme  le  feu  s'eteint,  cet 
air  se  refroidit  et  occupe  moins  de  place  ;  alors,  pour  que  le 
vide  ne  se  produise  pas,  il  se  fait  une  attraction  de  la  chair. 

'  Toutefois,  dans  la  ventouse  oil  Ton  met  de  I'etoupe 
allumee,  il  y  a  peut-etre  concours  de  deux  attractions,  celle 
de  la  chaleur  et  celle  du  vide.  Maintes  fois,  cependant,  la 
traction  provient  du  vide  seul ;  cela  se  voit  dans  ces  tuyaux 
recourbes  {fistulae  tortuosae)  que  certains  appellent  des 
serpents  ;  ^  si  on  les  plonge  dans  un  tonneau  de  vin,  le 
tonneau  se  trouve  vide  presque  en  entier  ;  cela  provient  de 
ce  que  ces  tuyaux  sont  recourbes,  en  sorte  que  si  I'ecoulement 
s'arretait  il  resterait  au  milieu  un  espace  vide. 

'  Mais  peut-etre  concevra-t-on,  en  outre,  le  doute  que 
voici :  ^  Attirer  est  un  certain  effet  positif ;  a  un  effet 
positif,  il  faut  assigner  une  cause  positive  ;  quelle  est  done 
cette  cause  positive  qui  tire  afin  qu'il  n'y  ait  pas  de  vide  ? 

'  Aegidii  Romani  Op.  laud.,  lib.  IV,  lect.  x,  dubitatio  5* ;  ed.  cit., 
fol.  79,  coll.  b  et  c. 

*  Au  lieu  de:  serpents  {serpentes),  ne  faut-il  pas  lire:  siphons 
{siphones)  ? 

^  Aegidius  Romanus,  loc.  cit.,  dubitatio  6^  ;  ed.  cit.,  fol.  79,  col.  c. 


L'HORREUR  DU  VIDE  275 

'  II  faut  r^pondre  que  nous  ne  pouvons  supposer  que  cette 
cause  soit  quelque  corps  mixte  ;  en  effet,  au  sein  d'un  ele- 
ment pur,  ou  il  n'y  aurait  aucun  corps  mixte,  il  pourrait 
arriver  qu'une  telle  traction  se  produisit,  A  cette  traction, 
nous  ne  pouvons,  non  plus,  assigner  comme  cause  quelqu'un 
des  elements  ;  il  arrive,  en  effet,  que  cette  traction  s'exerce 
de  n'importe  quel  cote,  en  n'importe  quelle  direction  ;  or 
il  n'advient  a  aucun  des  elements  d'avoir,  par  lui-meme,  un 
tel  mouvement.  II  reste  done  que  cette  traction  provienne 
de  la  force  du  ciel. 

'  Ainsi,  en  effet,  nous  devons  imaginer  que  toute  la  sphere 
des  choses  sujettes  a  Taction  et  a  la  passion  tient  sa  con- 
nexion de  la  force  du  ciel ;  or  ce  qui  a  la  propriete  de  con- 
joindre  a  aussi  la  propriete  d'attirer,  afin  qu'il  ne  survienne 
pas  quelque  division  la  [ou  la  connexion  doit  etre  maintenue] ; 
done  la  force  celeste,  dont  c'est  le  propre  de  conjoindre  toutes 
ces  choses,  tire  afin  qu'elles  ne  se  separent  pas  les  unes  des 
autres  et  qu'il  n'arrive  pas  a  I'intervalle  compris  entre  elles 
de  demeurer  vide.  Ainsi,  en  effet,  en  est-il  de  I'aimant,  qui 
a  la  propriete  de  s'unir  le  fer  a  lui-meme  ;  aussi,  de  quelque 
cote  qu'on  le  place,  le  fer  est-il  attire  par  I'aimant.  De 
meme,  comme  le  ciel  a  la  propriete  d'unir  entre  elles  les 
diverses  parties  de  I'Univers,  en  tout  endroit  ou  se  produirait 
une  separation  et  un  espace  vide,  en  ce  meme  endroit,  par  la 
force  celeste,  s'exercerait  une  attraction,  afin  que  cela  n'ait 
pas  lieu.' 

La  Physique  peripateticienne  enseignait  que  les  corps 
celestes  ont  communique  aux  corps  sublunaires  deux  sortes 
de  forces,  la  gravite  et  la  legerete  ;  par  I'une  ou  par  I'autre  de 
ces  forces,  chaque  corps  se  meut  de  mouvement  naturel,  vers 
le  lieu  oil  sa  forme  atteint  la  perfection  qui  lui  est  propre. 
A  cette  action,  generatrice  de  la  gravite  et  de  la  legerete, 
Gilles  de  Rome  propose  d'adjoindre  une  autre  action,  plus 
generale,  qui  a  pour  objet  de  maintenir  la  continuite  du 
monde  sublunaire  ;  cette  action,  dans  chaque  cas  ou  une 
discontinuite,  ou  un  vide  tendrait  a  se  produire,  met  en  jeu 
une  force  capable  d'empecher  cette  discontinuite,  de  prohiber 
le  vide  ;  c'est  a  cette  force  qu'on  donne,  assez  improprement, 
le  nom  de  traction  exercee  par  le  vide,  iractus  a  vacuo. 

Cette  theorie,  fort  logiquement  reliee  aux  principes.gene- 

T  2 


276  ROGER  BACON 

raux  de  la  Physique  peripateticienne,  la  completait  d'heu- 
reuse  maniere  ;  elle  permettait  de  rendre  compte  d'une  foule 
d'experiences  qui  semblaient  contredire  aux  lois  du  grave  et 
du  leger  ;  qu'elle  ait  ete  entierement  inspiree  par  la  doctrinc 
de  Bacon,  cela  saute  aux  yeux. 

Jean  de  Jandun  n'est  pas  moins  interesse  que  Gilles  de 
Rome  par  les  experiences  oil  Ton  voit  la  nature  fuir  le  vide ; 
mais  il  se  montre  moins  affirmatif  au  sujet  de  I'explication 
qu'elles  comportent. 

'  Certains  disent,  ecrit  Jean  de  Jandun,'  que  si  deux  corps 
absolument  plans  etaient  appliques  I'un  sur  I'autre  sans 
quelque  intermediaire  que  ce  soit,  jamais  ils  ne  pourraient 
dtre  separes  simultanement  en  toutes  leurs  parties  ;  pour 
qu'ils  pussent  etre  disjoints,  il  faudrait  que  ce  fut  successive- 
ment,  d'abord  une  partie,  puis  une  autre  ;  et  autant  il  y 
aurait  d'espace  entre  ces  parties,  autant  d'air  entrerait  ;  I'air 
se  glisserait  ainsi  successivement,  au  fur  et  a  mesure  que 
ces  deux  corps  seraient  disjoints.  En  effet,  a  cause  de  la 
fuite  du  vide,  il  serait  impossible  que  toutes  les  parties  se 
separassent  egalement  au  meme  instant.  Considerez  bien 
cette  question,  car  elle  est  assez  belle.  Peut-etre,  moyennant 
la  supposition  faite,  ces  deux  corps  ne  pourraient-ils  jamais 
^tre  separes  I'un  de  I'autre  ;  mais  peut-etre  aussi  dirait-on 
que  la  supposition  est  impossible.' 

Jean  de  Jandun  rapporte  une  des  experiences  qui  figu- 
raient,  nous  a  dit  Marsile  d'Inghen,  au  Tractatus  de  inani  et 
vacuo  : 

'  Qu'on  fasse  un  vase  gros  et  large  par  le  bas,  etroit  par  le 
haut  ;  qu'il  ait  une  petite  ouverture  en  la  partie  etroite  et, 
en  la  partie  large,  plusieurs  ouvertures  ;  si  Ton  plonge  ce 
vase  dans  I'eau,  il  est  manifeste  que  I'eau  le  remplira  ;  qu'on 
bouche  alors,  d'une  maniere  tres  parfaite,  I'ouverture  supe- 
rieure  et  qu'on  retire  le  vase  de  I'eau  .  .  .  Pour  la  cause 
susdite,  I'eau  ne  pourra  tomber  par  les  trous  qui  sont  au  bas 
du  vase.  Mais  qu'est-ce  done  qui  la  retiendra  ?  On  repondra 
que  c'est  la  nature  universelle,  car  cette  nature  ne  permet 

'  JoANNis  DE  Jaxduno  Super  octo  libros  Aristotelis  de  physico 
auditu  quaestiones,  lib.  IV,  quaest.  x  :  An  vacuum  esse  sit  neces- 
sarium. 


L'HORREUR  DU  VIDE  277 

point  le  vide  qui  se  produirait  necessairement  si  I'eau  tom- 
bait  ;  il  y  a  moindre  mal,  en  effet,  a  ce  que  I'eau  soit  ainsi 
retenue  en  haut  qu'a  la  production  du  vide  en  ce  lieu  .  .  .  ' 

Voici  une  autre  experience,  dont  Jean  Buridan  et  Marsile 
d'Inghen  se  plairont  a  invoquer  le  temoignage  : 

'  Supposons  qu'en  un  vase  tres  epais  et  tres  resistant  il 
y  ait  une  seule  ouverture  ;  qu'en  cette  ouverture  on  intro- 
duise  le  bee  d'un  soufflet,  et  que  ce  soufflet  n'ait  aucun  trou 
dans  ses  parois  .  .  .  Jamais  aucune  force  ne  pourrait  soulever 
les  parois  du  soufflet  ni  les  separer  I'une  de  I'autre.  Qu'est-ce 
qui  rempecherait  ?  La  nature  universelle,  en  vue  de  la  fuite 
du  vide  .  .  , 

'  Voila  ce  qu'on  pent  dire  au  sujet  de  ces  experiences,  et 
je  n'ai  pas  entendu  de  meilleures  raisons. 

'  Mais  quelle  est  cette  nature  universelle,  qui  produit  ces 
empechements  ?    Cela  n'est  pas  absolument  manifeste.' 

En  revanche,  ce  qui  est  absolument  manifeste,  c'est  que 
Jean  de  Jandun  emprunte  aux  Questions  de  Physique  de 
Roger  Bacon,  et  cela  d'une  fa9on  presque  textuelle,  tout  ce 
qu'il  dit  de  cette  nature  universelle.  II  ne  parait  pas,  d'ail- 
leurs,  qu'il  ait  connu  VOpus  tcrtium  ;  il  y  eut  trouve  des 
considerations  propres  a  dissiper  qiielque  peu  le  doute  qui 
est  demeure  dans  son  esprit. 

Apres  Jean  de  Jandun,  I'Ecole  de  Paris  ne  nous  presente 
plus,  au  xive  siecle,  de  physicien  qui  ait  tres  fidelement  suivi, 
au  sujet  du  vide,  I'opinion  de  Roger  Bacon. 

Fran9ois  de  Meyronnes  ecrit  :  ' 

'  Que  faut-il  penser  de  la  traction  du  vide  [tr actus  vacui), 
car  le  vide  ne  cause  rien  ?  .  .  .  II  ne  semble  pas  qu'une 
intelligence  produise  cette  traction.  Je  ne  vois  done  point 
de  cause,  a  moins  de  recourir  au  premier  Agent  universel ; 
car  on  voit  un  corps  de  meme  nature  se  mouvoir  tantot  vers 
le  haut,  tantot  vers  le  bas.' 

II  semble  par  la  que  Francois  de  Meyronnes  voie  une  action 
directe  de  Dieu  en  tout  mouvement  qui  tend  a  eviter  le  vide  ; 

'  Francisci  de  Mayronis  Scriptum  in  secundum  lihrum  Senten- 
tiarum,  dist.  XIV,  quaest.  vi ;  ed.  Venetiis,  1520,  p.  151,  col.  b. 


278  ROGER  BACON 

a  moins  que,  par  premier  Agent,  il  n'cntende  le  ciel  ;  sa 
pensee  rejoindrait  alors  cclle  de  Gilles  do  Rome  dont,  visible- 
merit,  il  s'est  inspire. 

A  I'imitation  de  Jean  de  Jandun,  Jean  le  Chanoine  enu- 
mere  '  les  diverses  experiences  que  renfermait  le  Tractaius  de 
inani  ct  vacuo.  Comme  son  predeccsscur,  il  les  presente, 
tout  d'abord,  sous  la  forme  de  precedes  propres  k  r^aliser  un 
espace  vide,  puis  il  explique  comment  les  choses  se  passeront 
afin  que  le  vide  nc  se  produise  pas. 

'  Qu'on  fixe  unc  cliandelle  au  fond  d'un  vase  plein  d'eau, 
de  telle  sorte  que  la  flammc  se  trouve  bien  a  la  hauteur  d'unc 
palme  au-dessus  de  I'eau  ;  puis  qu'on  la  rccouvre  d'un  Vcise  ; 
on  constate  que  la  chandclle  s'eteint  .  .  . 

'  Qu'on  prenne  quelque  vase  de  dur  metal ;  qu'on  I'em- 
plisse  d'eau  par  un  temps  froid  ;  si  la  congelation  survient, 
I'eau  congclec  occupera  moins  de  place ;  entre  les  parois  du 
vase,  il  demeurcra  un  espace  vide  .  .  . 

'  Qu'on  prenne  deux  disques  parfaitement  plans  et  qu'on 
les  applique  I'un  sur  I'autre  sans  rien  d'interpose  .  .  .  Sup- 
posons  ensuite  qu'on  attache  un  ftl  au  centre  du  disque 
superieur  ;  si  Ton  souleve  ce  disque  au  moyen  du  fil,  il  se 
produira  un  vide  dans  les  parties  centrales  ;  .  .  .  I'air,  en 
effet,  parvicndra  aux  parties  voisines  de  la  circonference 
avant  d'atteindre  les  parties  centrales.' 

'  Au  sujet  de  la  chandelle,  je  dis  qu'il  ne  se  produirait 
pas  de  vide,  car  I'eau  montcrait  et  I'air  se  rarefierait  .  .  . 
—  Mais  cela  ne  peut  etre,  car  il  est  contraire  a  la  nature 
que  I'eau  monte,  puisqu'elle  est  grave.  —  Je  reponds  que 
I'ascension  d'un  grave  est  contraire  a  la  nature  particuliere  ; 
mais  la  nature  particuliere  doit  naturellement  obeir  a  h. 
nature  universelle  et  au  regime  de  I'Univers  total,  qui  a 
horreur  [ahhorret)  d'etre  dissous  et  interrompu  ;  cela  se 
fait  done  afin  qu'il  ne  reste  pas  de  vide. 

'  A  propos  de  I'experience  suivante,  je  dis  que  s'il  y  avait 
un  tel  vase  dans  lequel  I'air  ne  put  entrer,  ce  vase  serait 
brise  par  la  force  de  I'Univers  entier,  car  la  nature  aurait, 
a  ce  point,  horreur  du  vide  [et  in  tantum  naiura  vacuum 
abhor  reret) . 

'  JoANNis  Canoxici  Quocstiones  super  VIII  libros  physicorum 
Aristotelis,  lib.  IV,  quaest.  iv,  ed.  Venetiis,  1520,  fol.  42,  coll.  c  et  d ; 
fol.  43,  col.  b. 


L'HORREUR  DU  VIDE  279 

'  A  propos  de  i'experience  suivante,  je  dis  .  .  .  que  I'air  se 
rarefie,  en  sorte  qu'avec  I'air  environnant  il  suffit  a  remplir 
I'intervalle  des  deux  disques.  Et  si  cela  etait  impossible,  il 
serait  egalement  impossible,  en  vertu  de  la  force  qui  regit  I'en- 
semble  de  I'Univers,  de  soulever  un  disque  au-dessus  de 
I'autre.' 

De  la  bouche  de  Jean  le  Chanoine  nous  venons  d'entendre 
cette  expression  qui,  apres  les  decouvertes  de  Torricelli  et 
de  Pascal,  excitera  tant  de  sarcasmes  :  La  nature  a  horreur 
du  vide.  Rien  n'indique,  d'ailleurs,  que  notre  auteur,  en 
usant  de  cette  expression,  sous-entende  toutes  les  pens^es 
ridicules  qu'on  y  a,  plus  tard,  reconnues  ;  rien  ne  laisse 
supposer  qu'il  fasse,  de  la  nature,  tin  etre  doue  de  sentiment. 
capable  de  sympathie  ou  d'antipathie  ;  il  est  clair  qu'il  n'a 
rien  voulu  signifier,  sinon  la  theorie  que  Roger  Bacon  et 
Gilles  de  Rome  avaient  exposee  plus  en  detail. 

Albert  de  Saxe,  lui  aussi,  use  de  cette  expression  ;  mais  le 
sens  qu'il  lui  conf^re  anime  encore  moins  la  nature.  II 
examine  cette  objection  :  '  '  Le  plein  existe  ;  done  le  vide 
existe  ;  la  consequence  resulte  bien  de  I'antecedent,  car  si, 
de  deux  choses  opposees,  I'une  existe  dans  la  nature,  I'autre, 
dit-on,  y  existe  aussi.'  II  repond  :  '  On  I'accorde  dans  le 
cas  ou  la  nature  n'aurait  horreur  ni  de  I'une  ni  de  I'autre  de 
ces  deux  choses  ;  mais  il  n'en  est  pas  ainsi  dans  le  cas  pro- 
pose, car  la  nature  a  horreur  du  vide  {natura  ahhorret  vacuum)  ; 
I'objection,  done,  est  sans  valeur.' 

Or,  a  cette  expression  :  '  La  nature  a  horreur  du  vide,' 
Albert  attribue  exactement  le  meme  sens  qu'a  celle-ci  :  '  Par 
aucune  puissance  naturelle,  le  vide  ne  peut  etre.'  Nous  en 
avons  I'assurance  par  les  lignes  suivantes  qui  se  lisent  entre 
I'objection  et  la  reponse  rapportees  ci-dessus  : 

'  Par  aucune  puissance  naturelle  il  n'est  possible  que  le 
vide  soit  {Per  nullum  potentiam  naturalem  possibile  est  esse 
vacuum).  .  .  On  le  prouve  par  certaines  experiences. 

'  Alberti  de  Saxonia  Quaestiones  super  libros  de  physica  aiisculta- 
tione,  lib.  IV,  quaest.  viii. 


28o  ROGER  BACON 

'  Premiercment,  si  Ton  bouchait  toutes  les  ouvertures  d'un 
soufflet,  aucune  puissance  ne  pourrait  soulever  un  des  bat- 
tants  du  soufflet  pour  le  separer  de  I'autre,  a  moins  qu'il 
ne  se  fit  quelque  rupture  par  ou  I'air  put  penetrer  ;  cette 
rupture  faite,  il  dcvient  facile  de  soulever  un  des  battants 
en  le  separant  de  I'autre,  car  il  y  a  alors  quelque  chose  qui 
peut  6tre  admis  entre  les  parois  du  soufflet  ;  cela  semble  un 
signe  que  la  nature  abhorre  le  vide  {hoc  videtur  esse  signuni 
naturam  ahhorrere  vacuum). 

'  Secondement,  on  peut  prouver  la  meme  chose  au  moyen 
de  la  clepsydre.' 

Albert  de  Saxe  se  borne,  d'ailleurs,  a  cette  affirmation  ; 
Aucune  puissance  naturelle  ne  saurait  produire  un  espace 
vide.  Pas  plus  que  Jean  Buridan,  pas  plus  que  Marsile 
d'Inghen,  il  ne  specule  sur  les  forces  que  la  nature  met 
en  jeu  afin  d'empecher,  au  prix  de  mouvements  con- 
traires  aux  propres  tendances  des  corps,  la  formation  d'un 
espace  vide. 

6videmment,  au  fur  et  a  mesure  que  le  xiii®  si^cle  recule 
dans  le  passe,  les  physiciens  de  Paris  se  montrentplus  oublieux 
des  enseignements  de  Roger  Bacon.  Peu-a-peu,  toute  la 
theorie  que  ce  dernier  avait  developpee  se  condense  en  cette 
breve  formule  :  La  nature  a  horreur  du  vide.  Ce  sont  bien 
encore  les  pensees  de  Frere  Roger  qu'on  entend  confusement 
exprimer  par  cet  aphorisme  ;  mais  on  ne  prend  plus  la  peine 
de  les  declarer  d'une  maniere  explicite. 

A  I'Universite  d'Oxford,  la  tradition  du  grand  physicien 
anglais  parait  avoir,  pendant  plus  longtemps,  garde  toute 
sa  force  ;  Jean  de  Dumbleton  va  nous  en  apporter  le  te- 
moignage. 

Au  chapitre  de  sa  Summa  logicae  et  naturalis  philosophiae 
ou  il  traite  de  I'impossibilite  du  vide  dans  la  nature,  Jean  de 
Dumbleton  ecrit  ce  qui  suit  :  ' 

'  Un  corps  naturel  peut  avoir  des  mouvements  de  deux 
sortes. 

'  JoHANNis  DE  DuMBLETON  Summa,  pars  sexta,  cap.  iii ;  Bibl. 
Nat.,  fonds  latin,  MS.  n°  16621,  fol.  60,  coll.  c  et  d,  et  fol.  61,  col.  a. 


L'HORREUR  DU  VIDE  281 

'  Un  de  ces  mouvements  lui  advient  parce  qu'il  est  de  telle 
espece  ;  ainsi  au  feu,  en  tant  qu'il  est  feu,  il  advient  d'etre 
mu  par  sa  forme  vers  la  concavite  de  I'orbe  lunaire. 

'  Le  second  mouvement  lui  appartient  en  tant  qu'il  est 
corps  naturel ;  et, sous  ce  rapport,  tous  les  corps  se  comportent 
de  meme  .  ,  . 

'  Pour  comprendre  la  seconde  proposition,  il  faut  supposer 
ce  principe  tire  de  I'experience  :  Tout  corps,  lors  m^me  qu'il 
serait  en  son  lieu  naturel,  desire  etre  conjoint  a  un  autre  corps. 
Et  cela  se  prouve  de  la  maniere  suivante  :  II  repugne  que 
le  vide  soit,  tandis  qu'il  ne  repugne  pas  qu'un  corps  se  trouve 
hors  de  son  lieu  propre.  II  est  done  plus  naturel  qu'un  corps 
se  meuve  pour  demeurer  au  contact  immediat  d'un  autre 
corps  plutot  que  pour  gagner  son  lieu  propre  ;  la  nature  d'un 
corps  est  d'etre  conjoint  a  un  autre  corps  avant  que  d'etre  en 
son  lieu  propre.  Ce  mouvement  par  lequel  un  corps  demeure 
au  contact  immediat  d'un  autre  corps  n'advient  pas  a  un 
element  en  tant  qu'element,  mais  en  tant  qu'il  est  simple- 
ment  corps  naturel.  De  cette  maniere,  tout  corps  naturel  est 
mobile  vers  tout  lieu,  que  ce  lieu  soit  en  haut  ou  en  has  ;  tout 
element  est  indifferemment  mobile  vers  tout  lieu  afin  de 
demeurer  conjoint  a  un  corps  naturel.  De  meme  que  I'ai- 
mant  induit  dans  le  fer  une  forme  grace  a  laquelle  le  fer  suit 
le  mouvement  de  I'aimant,  de  meme  le  corps  qui  en  suit  un 
autre  par  ce  mouvement  s'arrete  lorsque  cet  autre  corps 
demeure  en  repos,  comme  on  le  voit  lorsque  I'eau  monte 
dans  une  pipette  {in  fisttilam)  .  .  . 

'  Mais  le  but  de  ce  mouvement  n'est  point  naturel  a  un 
corps,  si  ce  n'est  en  vue  de  le  maintenir  immediatement 
contigu  a  un  autre  corps.' 

C'est  done  par  une  attraction  comparable  a  I'attraction 
magnetique  que  tout  corps  qui  delaisse  un  lieu  entraine,  a  sa 
suite,  le  corps  qui  lui  est  contigu,  dut-il,  pour  cela,  contrarier 
les  tendances  naturelles  de  ce  dernier  corps  ;  s'il  en  est  ainsi, 
c'est  afin  qu'il  n'y  ait  jamais,  dans  la  nature,  aucun  espace 
vide.  Cette  loi  ne  s'impose  pas  seulement  aux  elements  ;  elle 
regit  meme  la  substance  celeste  ;  Dumbleton  prevoit,  en 
effet,  qu'on  lui  adressera  I'objection  que  voici : 

'  II  resulte  de  cette  supposition  qu'afin  de  rester  conjoint 
a  un  corps  le  ciel  est  susceptible  de  mouvement  rectiligne  ; 
si,  par  exemple,  le  feu  descendait,  le  ciel  le  suivrait,  afin 


282  ROGER  BACON 

qu'il  n'y  eut  pas  de  vide  entre  eux  ;  en  effet,  I'existence  du 
vide  ne  repugne  pas  moins  au  tres  noble  corps  du  ciel  qu'a 
quelque  autre  corps  inferieur.' 

Cette  consequence  de  sa  theorie,  notre  auteur  I'admet 
pleinement  : 

'  Si  tout  I'element  qui  se  trouve  au-dessous  de  la  derniere 
surface  concave  du  ciel  venait  a  descendre,  le  ciel  le  suivrait 
naturellement,  de  telle  fagon  qu'il  serait  impossible  de 
separer  le  feu  d'avec  le  ciel  ;  en  effet,  si  le  ciel  ne  suivait  pas 
le  mouvement  du  feu,  le  vide  se  produirait  entre  eux  ;  et  il 
repugne  a  la  nature  que  le  vide  soit,  plus  que  ne  lui  repugne 
la  presence  d'une  partie  du  ciel  au  lieu  de  la  terre.  En  ce 
lieu,  toutefois,  le  ciel  continuerait  de  se  mouvoir  circulaire- 
ment,  car  le  mouvement  circulaire  appartient  au  ciel  en  tant 
qu'il  est  d'une  certaine  nature  specifique.' 

Au  contraire,  comme  nous  I'avons  vu,  s'il  est  capable,  pour 
eviter  la  production  du  vide,  de  se  mouvoir  de  mouvement 
rectiligne,  ce  n'est  pas  en  tant  qu'il  est  forme  de  substance  ce- 
leste, mais,  d'une  maniere  plus  generale,  en  tant  qu'il  est  corps. 

Deja  Gilles  de  Rome  avait  etabli  une  comparaison  entre 
les  mouvements  qui  ont  pour  objet  la  fuite  du  vide  et  les 
mouvements  du  fer  vers  I'aimant  ;  vraisemblablement,  la 
pensee  du  celebre  augustin  a  inspire  Jean  de  Dumbleton  ; 
elle  lui  a  suggere  I'hypothese  de  cette  attraction  mutuelle 
par  laquelle  les  corps  se  retiennent  les  uns  les  autres  afin  de 
demeurer  contigus. 

Une  autre  influence  se  devine  dans  les  passages  que  nous 
venons  de  citer  ;  c'est  celle  de  la  Summa  faussement  attri- 
buee  a  Robert  Grosseteste  ;  peut-etre  est-ce  cette  derniere 
influence  qui  pousse  Jean  de  Dumbleton  a  relier  sa  theorie 
du  mouvement  des  projectiles  a  son  systeme  sur  la  fuite 
du  vide.  Voici,  en  effet,  comment  cet  auteur  explique  ' 
la  persistance  du  mouvement  de  la  pierre  apres  qu'elle  a 
quitte  la  main  qui  I'a  lancee  : 

'  JoHANNis  DE  DuMBLETON  Op.  luud.,  pais  sexta,  cap.  iv  ;  MS. 
cit.,  fol.  6i,  coll.  c  et  d. 


L'HORREUR  DU  VIDE  283 

'  Les  projectiles  suivent  I'air  grace  a  la  forme  qui  leur  est 
donnee  en  propre,  afin  qu'en  un  tel  mouvement  il  ne  se 
produise  pas  de  vide  ;  en  effet,  suivant  ce  qui  a  ete  demontre, 
tout  corps  est  naturellement  mobile  afin  qu'il  demeure  au 
contact  d'un  autre  corps  naturel  ...  De  meme  que  I'eau 
suit  i'eau,  que  la  fumee,  qui  est  un  corps  igne,  suit  la  fumee, 
et  que  la  flamme  suit  la  flamme,  de  meme  les  projectiles 
suivent  I'air  ou  tout  autre  corps  qui  est  mu  devant  eux, 
comme  le  fer  suit  I'aimant  .  .  . 

'  Tout  corps  naturel  a  un  double  mouvement  ;  un  premier 
mouvement  qui  appartient  a  ce  corps  en  tant  qu'il  est  de 
telle  espece,  et  un  second  mouvement  par  lequel  ce  corps  suit 
un  autre  corps.  C'est  par  ce  second  mouvement  que  les 
projectiles  se  meuvent  en  suivant  I'eau  ou  I'air  lance  devant 
eux  ;  ensuite,  I'eau  ou  I'air  suit  le  projectile  par  derriere  et, 
par  la,  contribue  a  le  pousser.  Cette  pierre  presente  une 
surface  qui  est  immediatement  contigue  a  I'air  ;  lorsque  I'air 
qui  se  trouve  en  avant  de  la  pierre  a  ete  ebranlee  par  la  main 
et  que  la  main  est  retiree,  cet  air  continue  a  se  mouvoir  ;  si 
la  pierre  demeurait  immobile,  I'air  ne  pourrait,  en  un  instant, 
se  precipiter  dans  toute  I'etendue  de  la  face  anterieure  de 
la  pierre  ;  done,  pour  que  la  pierre  ne  cesse  pas  d'etre 
immediatement  contigue  a  un  autre  corps,  il  faut  qu'elle 
se  meuve.' 

A  la  fin  de  son  expose  Jean  de  Dumbleton  enumere 
quelques  observations,  fort  contestables  d'ailleurs,  qui 
sembleraient  reclamer,  du  mouvement  des  projectiles,  une 
explication  differente  de  celle  qu'il  a  donnee.  *  Mais, 
ajoute-t-il,'  pour  expliquer  comment  le  milieu  se  meut 
lorsque  I'impulsion  a  cesse,  il  faut  donner  une  autre  reponse, 
savoir  la  derniere,  qui  est  la  plus  commune.' 

II  etait  done  courant,  dans  I'^cole  d'Oxford,  de  donner, 
du  mouvement  des  projectiles,  cette  theorie  ou  I'hypothese 
d'Aristote  regoit  un  renfort  de  la  doctrine  proposee  par 
Bacon  touchant  I'horreur  du  vide. 

Reunissons  en  un  faisceau  tout  ce  que  Roger  Bacon,  Gilles 
deRome  et  Jean  de  Dumbleton  ont  dit  de  Taction  par  laquelle 
la  nature  assure  la  contiguite  de  tons  les  corps  de  I'Univers ; 

'  Jean  de  Dumbleton,  loc.  cit.,  MS.  cit.,  fol.  62,  col.  a. 


284  ROGER  BACON 

nous  aurons  I'expose  complet  de  cette  doctrine  qui  completait 
si  heureusement  la  theorie  peripateticienne  du  grave  et  du 
leger,  et  qui  devait  durer  jusqu'a  la  decouverte  de  la  pression 
atmospherique.  Dans  la  constitution  de  cette  doctrine,  le 
premier  role,  premier  dans  le  temps  et  premier  par  I'impor- 
tance,  appartient  a  Roger  Bacon. 


XI 

ROGER  BACON :    HIS  RELATIONS  TO 
ALCHEMY  AND  CHEMISTRY 

By  M.  M.  PATTISON  MUIR 

The  art  of  working  metals  has  been  practised  since  very- 
early  times.  By  using  mixtures  of  metals,  men  learned 
how  to  produce  instruments  more  durable  and  more  easily 
fashioned  than  the  stone  implements  of  very  early  times. 
They  discovered  that  the  colour,  the  hardness,  the  tenacity, 
the  ductility,  and  other  properties  of  a  metal  are  sometimes 
much  changed  by  the  admixture  of  small  quantities  of  other 
metals.  Men  also  learned  to  make,  from  things  found  on 
the  earth,  other  things  very  unlike  those  from  which  they 
were  made.  From  grain,  they  made  intoxicating  liquids  ; 
from  plants,  they  prepared  substances  which  changed  the 
colours  of  clothing  materials  made  from  other  plants  or 
from  the  skins  or  hair  of  animals.  By  heating  lumps  of 
stone,  used  for  building  shelters,  they  obtained  material 
useful  in  agriculture,  and  having  the  peculiar  property  of 
becoming  hot  when  rain  fell  on  it. 

Some  of  the  strange  changes  effected  in  natural  materials 
by  human  ingenuity  seemed  to  those  who  were  in  authority 
in  the  early  centuries  of  our  era  to  be  possible  only  to  men 
who  had  eaten  of  the  fruit  of  the  tree  of  knowledge  whereof 
it  was  unlawful  to  eat.  The  arts  which  changed  material 
things  into  altogether  different  things  came  to  be  regarded 
as  savouring  of  sorcery.  Some  of  the  changes  were  said 
to  be  too  wonderful  for  unaided  human  power  to  accomplish  ; 
they  who  effected  such  marvellous  transmutations  must 
be  in  league  with  bad  angels.  But  the  usefulness  of  many  of 
the  things  produced  from  what  seemed  to  be  useless  materials 


286  ROGER  BACON 

could  not  be  questioned.  A  distinction  was  gradually  made 
between  legitimate  curiosity  and  the  pursuit  of  forbidden 
knowledge. 

There  always  have  been  men  who  refuse  to  be  contented 
with  material  comforts  and  conveniences.  Such  men,  pon- 
dering the  changes  happening  around  them,  and  the  changes 
effected  by  human  power,  were  forced  to  inquire  how  these 
changes  were  accomplished.  They  asked,  Is  everything 
mutable  ?  They  answered.  There  must  be  an  unchangeable 
foundation  beneath  the  mutations  of  nature  and  the  trans- 
mutations effected  by  art.  Trying  to  discover  the  plan  on 
which  the  restless  world  of  changing  appearances  is  arranged, 
and  finding  the  ever-changing,  complicated  phenomena  of 
nature  too  hard  to  understand,  they  turned  away  from  ex- 
ternal nature,  and  decided  that  nature  must  be  fundamentally 
simple,  and  her  disconcerting  mutations  must  be  coverings 
of  an  underlying  unity,  because  the  ideas  of  simplicity  and 
unity  brought  repose  to  their  inward  longing  for  rest. 

Is  not  man,  they  exclaimed,  greater  than  matter  ?  Is 
not  the  human  mind  a  more  perfect  expression  of  the 
Creator's  thought  than  plants  and  animals,  than  earth  and 
air  and  sea  ?  Man,  they  declared,  is  the  macrocosm  of  all 
things.  '  In  the  image  of  God  created  He  him.'  Man's 
function  is  to  re-create  the  world  of  appearances  in  his  own 
image,  and  to  find  in  that  re-created  world  another  expres- 
sion of  divine  unity  and  divine  simplicity. 

In  the  oldest  alchemical  writings  we  find  exclamations 
such  as  these  :  '  The  one  is  the  all.  By  him,  the  all ;  in  him, 
the  all.'  '  Of  the  divine  water.  Two  natures,  one  essence.'  ^ 
'  The  nature  of  matter  is  both  simple  and  compound  .  .  . 
it  receives  a  thousand  names,  and  its  essence  is  one.'  ^ 

'  Zosimus,  probably  third  century  a.d.  Quoted  by  Berthelot, 
Les  Origines  de  I'Alchimie,  p.  178. 

^  Stephanus  of  Alexandria,  early  seventh  century.  Quoted  by 
Berthelot,  loc.  cit.,  p.  277. 


ALCHEMY  AND  CHEMISTRY  287 

The  alchemical  writers  of  the  early  centuries  of  our  era 
found  justification  of  their  conception  of  nature  as  funda- 
mentally simple,  while  superficially  complex,  in  writings 
of  Greek  philosophers.  Traditions  of  a  like  teaching  came 
to  them  also  from  far  Eastern  sources.  Their  conception 
of  nature's  plan  was  in  keeping  with  what  they  knew  of 
the  teaching  of  many  wise  men  who  had  lived  before  them. 
They  had  the  support  of  authority  for  their  imaginings. 

Certain  Greek  philosophers  had  taught  that  material 
things  are  made  from  four  elements,  earth,  air,  water,  and 
fire.  The  alchemists  developed  this  doctrine,  and  brought 
it  into  relation  to  their  fundamental  tenet  of  '  a  primary 
matter  ',  *  a  soul  of  bodies  ', '  a  tinctorial  spirit  ',  by  asserting 
that  the  primary  matter  works  through,  and  by  means  of, 
the  four  elements,  and  guides  their  combinations  and 
rearrangements.  The  aim  of  the  older  alchemy  was  to  get 
control  of  the  '  soul  of  bodies  ',  because,  if  this  were  done, 
it  would  be  possible  to  effect  very  diverse  material  trans- 
formations. The  '  soul  of  bodies  '  was  said  to  be  hidden  by 
the  properties  of  bodies — that  is,  by  the  appearances  which 
are  recognized  by  the  senses.  The  properties  of  bodies — their 
colour,  weight,  smell,  texture,  solidity,  fluidity,  readiness  to 
become  hot  or  cold,  and  the  like — were  regarded  as  vestures 
laid  on,  and  concealing,  the  true  substances  of  the  things. 

In  so  far  as  I  can  follow  alchemical  writings,  I  take  it 
that  the  substance  of  a  thing  was  thought  of  by  the 
alchemists  as  the  result  of  the  interplay  of  some  of  the  four 
elements.  It  is,  of  course,  to  be  remembered  that  the  word 
*  element  '  was  used  by  the  alchemists  in  a  very  vague  way  ; 
the  word  had  by  no  means  the  same  connotation  as  it  has 
in  modern  chemistry.  Element  was  rather  a  condition  of 
being  than  the  descriptive  name  of  a  particular  substance. 
The  nature  of  the  substance  of  a  material  thing  seems  to 
have  been  regarded  as  determined  by  the  directive  action 
of  '  the  primary  matter  ',  the  '  soul  of  bodies  ',  on  the  inter- 


288  ROGER  BACON 

play  of  the  elements,  or  of  some  of  the  elements,  from  which 
all  things  were  supposed  to  be  formed.  The  substance  of 
the  elements  was  some  thing,  or  some  condition,  common 
to  them  all,  and  to  all  things  produced  by  their  interactions. 
Stephanus  said  :  '  Though  the  qualities  of  the  elements 
are  contrary,  their  substances  are  not  contrary.'  Paracelsus 
spoke  thus  of  the  aim  of  alchemy  :  '  To  grasp  the  invisible 
elements,  to  attract  them  by  their  material  correspondences, 
to  control,  purify,  and  transform  them  by  the  living  power 
of  the  Spirit — this  is  true  Alchemy.' 

That  we  may  try  to  get  a  somewhat  clearer  conception 
of  alchemical  teaching  about  the  elements,  let  us  hear  what 
Stephanus  said  : 

'  God  has  made  the  universe  of  four  elements,  earth, 
air,  fire,  and  water.  These  four  elements,  being  con- 
trary one  to  another,  could  not  combine  if  it  were  not 
for  the  intervention  of  a  body  with  the  qualities  of  the 
two  extremes.  Thus,  the  fire  of  quicksilver  joins  itself 
to  the  water  by  the  mediation  of  the  earth.  .  .  .  The  water 
is  joined  to  the  air  of  quicksilver  by  the  fire  of  copper. 
Fire,  being  hot  and  dry,  produces  the  heat  of  air  and  the 
dryness  of  earth.  The  moist  and  cold  water  produces  the 
humidity  of  air  and  the  coldness  of  earth,''  and  so  on,  and 
so  on. 

The  guiding  conception  seems  to  have  been  that 
though  each  of  the  four  elements  has  its  own  properties, 
there  is  something  underlying  the  properties,  some  thing, 
some  condition,  which  is  the  matrix  wherein  these  properties 
are  set,  and  that  this  something-  is  common  to  all  the  ele- 
ments. This  hypothetical,  almost  intangible,  underlying 
something  must  be  controlled  and  directed.  By  properly 
manipulating  this  common  foundation,  the  elements — 
it  was  taught — can  be  transmuted  one  into  another.  The 
first  step  in  this  process  is  to  tear  off  the  outward  properties 
of  things.     Stephanus  wrote  thus :  ^ 

'  Quoted  by  Berthelot,  loc.  cit.,  p.  274. 
=  Ibid.,  pp.  276-7. 


ALCHEMY  AND  CHEMISTRY  289 

'  It  is  necessary  to  strip  matter  of  its  properties  in  order 
to  draw  out  the  soul,  to  separate  it  from  the  body  in  order  to 
arrive  at  perfection.  Copper  is  Hke  men,  it  has  a  soul  and 
a  body.  .  .  .  The  soul  is  the  most  subtile  part  .  .  .  that  is  to 
say,  the  tinctorial  spirit.  The  body  is  the  thing  that  is  heavy, 
terrestrial,  and  is  endowed  with  a  shadow.  After  a  series  of 
proper  treatments,  copper  becomes  without  a  shadow,  and 
better  than  gold.  ...  It  is  necessary  to  strip  matter  ;  how 
can  it  be  stripped  if  not  by  means  of  the  fiery  medicine  ? 
What  is  it  to  strip  matter  if  not  to  make  it  poor,  to  spoil  it,  to 
break  it  up,  to  put  it  to  death ...  in  order  that  the  spirit  .  .  . 
may  be  brought  into  a  fit  state  for  combining  and  so  accom- 
plishing the  desired  operation  [transmutation]  ? ' 

I  have  said  that  the  alchemists  found  the  changes  of 
material  things  too  hard  to  unravel,  and  that  they  turned 
away  from  them,  and  developed  a  scheme  on  which  they 
supposed  nature  must  proceed,  and  then  projected  their 
mind-made  scheme  on  to  external  nature.  They  found 
some  justification  of  their  scheme  in  facts  which  they 
observed.  They  certainly  found  no  great  difficulty  in 
describing  observed  facts  in  the  language  of  their  intro- 
spectively  constructed  plan.  For  instance,  when  mercury 
is  rubbed  on  a  piece  of  copper,  the  surface  of  the  copper 
becomes  white  and  very  lustrous  ;  copper  forms  alloys  with 
many  metals,  and  the  properties  of  these  alloys  differ  from 
those  of  their  constituent  metals  ;  solutions  of  copper  in 
acids  may  be  used  for  colouring  glasses  and  enamels. 
These  facts,  or  facts  like  these,  seem  to  have  been  in  the 
mind  of  Stephanus  when  he  wrote  : 

*  Copper  is  bleached  and  despoiled  by  mercury.  The  latter 
is  fixed  by  its  union  with  copper.  .  .  .  The  copper  does  not 
tint,  but  it  receives  the  tincture,  and  after  it  has  received 
the  tincture,  it  tints  [other  bodies].' 

Having  quoted  these  remarks,  and  other  observations 
like  these,  from  Stephanus,  Berthelot  says  : 

'  Here  we  put  our  finger  on  the  positive  facts  and  the  indus- 
trial processes  which  served  as  a  foundation  for  the  theories 
of  the  alchemists.  . .  .  They  gave  precision  to  their  idea  [of 

1689  u 


290  ROGER  BACON 

a  primary  matter,  one,  and  showing  many  forms],  sometimes 
by  similes  taken  from  industrial  arts  which  produce  diverse 
appearances  from  one  and  the  same  material,  sometimes 
by  more  profound  comparisons  borrowed  from  the  chemical 
industries  of  dyeing  and  making  glasses  and  enamels.'  ' 

The  older  alchemists  turned  away  from  natural  events, 
too  hard  for  them  to  bring  into  order  by  looking  at  them 
directly,  and  formed  a  plan  on  which,  they  said,  nature 
ought  to  work,  on  which,  therefore,  nature  works.  They 
returned  to  natural  events  with  their  plan  in  their  hands, 
and  grubbed  about  till  they  found  facts  which  could  be 
fitted  into  their  plan. 

I  suppose  their  argument  ran  somewhat  thus.  The 
human  mind  craves  simplicity.  If  external  nature  is  not 
a  deceitful  show,  we  must  find  simplicity  there.  All  the 
changing  and  perplexing  appearances  which  trouble  us 
are  manifestations  of  an  underlying  simplicity  and  unity. 
What  is  that  underlying  unity  ?  Wise  men  of  old  have  told 
us  that  all  material  things  are  formed  by  the  interplay 
of  four  elements — earth,  water,  fire,  air — dryness,  wetness, 
hotness,  coldness.  The  four  elements  are  contrary  one 
to  another  ;  knowledge  of  them  is  a  step  to  knowledge  of 
The  One  Thing  of  which  they  are  expressions  ;  there  must 
be,  there  is,  a  primary  matter  whereof  the  four  elements 
are  the  simplest  forms.  The  interactions  of  the  elements 
are  directed  by  The  One  Thing  which  is  common  to  them  all, 
and  to  all  things  formed  by  the  union  of  them.  The  One 
Thing  is  hidden  under  the  four  expressions  of  itself.  The 
four  outward  forms  of  the  internal  unity  are  concealed  by 
the  variegated  coverings  which  nature  has  laid  on  them, 
in  order  to  incite  men  to  search  for  her  hidden  simplicity, 
a  simplicity  she  reveals  only  to  those  who  are  not  lured 
from  the  quest  by  the  fascinating  complexity  of  superficial 
appearances.    The  first  step  in  the  quest  of  The  One  Thing 

'  Berthelot,  loc.  cit.,  p.  278. 


ALCHEMY  AND  CHEMISTRY  291 

is  to  destroy  the  outward  vestments  which  hide  that  portion 
of  the  universal  essence  which  is  contained  in  this  or  that 
particular  kind  of  matter.  The  concealing  garments  are 
many,  perplexing,  diverse  ;  when  some  of  them  have  been 
removed,  the  four  elements  are  discovered.  They  also  must 
be  tortured  until  they  reveal  their  secret.  When  that  secret 
has  been  grasped,  and  its  activities  have  been  controlled, 
the  inquirer  will  be  able  to  effect  in  a  brief  time  those 
changes  which  nature  accomplishes  very  slowly.  The  sage, 
the  adept,  must  not  hope  to  make  whatever  changes  in 
material  things  his  fancy  may  lead  him  to  desire  ;  he  must 
follow  nature. 

It  is  evident,  the  alchemists  argued,  that  nature  aims  at 
perfection.  To  attain  to  perfection  is  to  find  rest,  repose, 
immutability.  '  With  Him  is  no  changeableness,  neither 
shadow  of  turning.'  To  obtain  rest  in  this  changing  world, 
a  man  must  have  the  means  of  purchasing  freedom  from 
hunger,  fatigue,  unhealthy  occupations,  fretting  cares, 
constant  thought  for  to-morrow  ;  he  must  have  the  means 
of  satisfying  his  intellectual  aspirations,  his  longing  for 
beautiful  things,  his  desire  for  a  comfortable  home  ;  he  must 
be  able  to  shield  himself  from  storm,  from  cold  and  heat, 
from  the  attacks  of  enemies,  from  the  nagging  impor- 
tunities of  those  who  profess  to  be  his  friends.  Should  a  man 
obtain  these  defences  against  ill-fortune,  he  will  still  find 
life  too  short  ;  when  he  is  beginning  to  enjoy  these  good 
things,  death  comes,  and  he  must  leave  them  all.  If  the 
perfection  which  human  beings  may  hope  for  is  to  be  found, 
the  life  of  those  who  seek  it  must  be  prolonged.  The 
two  necessities  of  him  who  seeks  perfection  are  gold,  to  be 
wisely  used,  and  an  elixir  which  shall  prolong  the  time  of 
enjoying  what  the  wise  man's  gold  can  purchase. 

The  alchemists  said  that  gold  is  the  perfect  metal.  Other 
metals  rust  in  the  earth,  and  are  destroyed  by  acrid  liquids  ; 
gold  is  unchanged  in  the  earth  and  is  untouched  by  acids. 

u  2 


292  ROGER  BACON 

Gold  is  the  type  of  restful  perfection  ;  therefore  nature 
means  all  metals  to  become  gold.  In  his  dealings  with 
metals,  the  adept  must  try  to  do  in  a  moment  what  nature 
does  in  ten  thousand  years  ;  he  must  transmute  them  into 
gold.  When  the  sage  has  found  the  instrument  which 
effects  the  great  transmutation,  he  will  have  found  the  elixir 
which  will  bestow  on  himself,  and  on  other  men  worthy 
to  receive  it,  the  blessing  of  a  long,  healthful,  happy  life. 
'  For  ',  Roger  Bacon  says  in  Opus  Tertium,  '  we  die  much 
sooner  than  we  ought  to  die  ;  and  this  is  because  of  defec- 
tive regimen  of  health  from  youth  onward,  and  because  our 
fathers  give  us  a  corrupt  constitution,  because  of  the  same 
defect  in  their  regimen  ;  hence  old  age  comes  sooner,  and 
death  before  the  time  God  hath  appointed.'  ' 

The  discovery  of  the  elixir,  and  of  the  means  of  controlling 
it,  was  the  central  aim  of  practical  alchemy. 

In  the  Speculum  Alchimiae,  generally,  though  doubtfully, 
attributed  to  Roger  Bacon,  alchemy  is  defined  thus  :  ^ 

'  Alchemy  is  the  Art  or  Science  teaching  how  to  make 
or  generate  a  certain  kind  of  medicine,  which  is  called  the 
Elixir,  and  which,  being  projected  upon  Metals,  or  imperfect 
Bodies,  by  thoroughly  Tinging  and  fixing  them,  perfects 
them  in  the  highest  degree,  even  in  the  very  moment  of 
Projection.' 

In  the  Opus  Tertium,  undoubtedly  written  by  him,  Roger 
Bacon  says  (I  quote  from  p.  Ixxx  of  Brewer's  preface  to 
Fr.  Rogeri  Bacon  opera  quaedam  hactenus  inedita)  : 

'  There  is  an  operative  or  practical  alchemy  which  teaches 
man  how  to  make  noble  metals  and  colours,  and  many  other 
things,  better  and  more  copiously  by  art  than  by  nature.  And 
this  science  is  more  important  than  all  that  have  preceded 

'  Opus  Tertium,  xii.  40  (Brewer's  edition). 

^  I  quote  from  p.  622  of  the  translation  of  Speculum  Alchimiae 
made  by  William  Salmon,  '  Professor  of  Physick,  Living  at  the 
Blue-Ball  by  the  Ditchside,  near  Holborn  Bridge,'  pubhshed  in 
1692. 


ALCHEMY  AND  CHEMISTRY  293 

[he  has  already  spoken  of  many  sciences]  because  it  is  produc- 
tive of  more  advantage.  It  not  only  provides  money  for 
a  State,  but  teaches  the  art  of  prolonging  life,  so  far  as  nature 
will  allow  it  to  be  prolonged.' 

How  is  the  Elixir  to  be  made?  How  shall  he  proceed  who 
seeks  to  produce  the  '  fiery  medicine  '  (as  some  alchemists 
called  it)  which  brings  imperfect  bodies  to  the  highest 
degree  of  perfection  ? 

The  writer  of  Speculum  Alchimiae  begins  by  complaining  of 
'  the  many  ways  and  diverse  manners  in  which  the  Ancient 
Philosophers  .  .  .  have  delivered  themselves  '  ;  of  '  the 
Aenigmas  or  Riddles  wherewith  they  have  wholly  Clouded, 
and  left  shadowed  to  us,  the  most  Noble  Science,  and  as 
it  were  under  a  Veil  of  Desperation,  have  wholly  denyed 
Us  the  knowledge  thereof '.  While  admitting  that  the 
ancient  philosophers  had  cause  for  hiding  their  secrets 
from  '  the  unlearned  crew  ',  the  writer  of  Speculum  Al- 
chimiae claims  that  the  directions  which  he  will  give  can  be 
understood  by  those  who  are  fitted  to  understand  them. 
He  says,  '  I  have  in  the  following  Chapters  declared  (more 
plainly  than  is  taught  in  any  other  writings)  the  whole  Art 
of  the  Transformation  of  Metals.' 

In  the  sequel  I  will  quote  some  of  Roger  Bacon's  direc- 
tions for  making  the  Philosopher' s  Egg.  Meanwhile,  let  us 
notice  his  protest  against  those  who  practised  magical  arts, 
and  claimed  alchemy  to  be  one  of  these  arts.  The  Epistolae 
Rogerii  Baconis  de  secretis  operibus  artis  et  naturae  et  de 
nullitate  magiae  appeared  in  English  in  1659,  with  the 
title  Frier  Bacon  his  Discovery  of  the  miracles  of  Art,  Nature, 
and  Magick,  faithfully  translated  out  of  Dr.  Dees  own  copy, 
by  T.  M.,  and  never  before  in  English.  In  that  book,  Roger 
Bacon  warns  his  readers  against  being  deluded  by  untrust- 
worthy evidence.  He  says  :  '  When  inanimate  things  are 
violently  moved,  either  in  the  morning  or  evening  twi- 
light, expect  no  truth  therein,  but  downright  cheating  and 


294  ROGER  BACON 

cousenage.' '  That  warning  should  be  taken  to  heart  by  all 
inquirers  into  what  are  called '  occult  phenomena'.  He  speaks 
of  '  the  damnable  practice  '  of  '  calling  up  wicked  spirits  '. 
Of  books  which  deal  with  strange  and  wonderful  things, 
he  says  :  '  The  Book  which  discovers  natural  or  artificial 
operations,  embrace  ;  that  which  is  void  of  either,  leave, 
both  as  suspitious  and  unworthy  the  consideration  of 
any  wise  man.'  ^  He  then  proceeds  :  '  That  I  may  the  better 
demonstrate  the  inferiority  and  indignity  of  magical  power 
to  that  of  Nature  and  Art,  I  shall  awhile  discourse  on  such 
admirable  operations  of  Art  and  Nature  as  have  not  the 
least  magick  in  them,  afterwards  assign  them  their  causes 
and  Frames.  And  first  of  such  Engines  as  are  purely 
artificial.'  He  says  it  is  possible  to  make  a  chariot  move 
'  with  an  inestimable  swiftness  .  .  .  and  this  motion  to  be 
without  the  help  of  any  living  creature  '.  '  It  is  possible 
to  make  Engines  for  flying,  a  man  sitting  in  the  midst 
whereof,  onely  turning  about  an  Instrument,  which  moves 
artificial  Wings  made  to  beat  the  Aire,  much  after  the 
fashion  of  a  Bird's  flight.'  ^  He  describes  instruments 
for  use  in  optics,  magnifying  and  reducing  glasses,  burning- 
glasses,  instruments  for  so  refining  silver  and  other  metals 
that  at  last  gold  is  obtained  ;  an  explosive  powder  which 
causes  '  hideous  cracklings  ',  and  is  able  to  destroy  armies  ; 
and  other  marvellous  '  Engines  '.'' 

These  things  are  wonderful,  but — Roger  Bacon  insists — 
they  are  not  magical ;  they  are  produced  by  human  art 
applied  to  the  results  of  the  study  of  natural  events.  Bacon 
asserts  that  art  can  improve  on  nature.  *  Nature  is  potent 
and  admirable  in  her  working,  yet  Art,  using  the  advantage 
of  nature  as  an  instrument  (experience  tells  us)  is  of  greater 
efficacy  than  any  natural  activity.'  ^  '  Nature  does  not 
know  how  thoroughly  to  cleanse,  and  is  ignorant  how  to 

'  Secrets  of  Nature  and  Art,  chap.  i.  -  Ibid.,  chap.  iii. 

^  Ibid.,  chap.  iv.  *  Ibid.,  chap.  vi.  ^  Ibid.,  chap.  iii. 


ALCHEMY  AND  CHEMISTRY  295 

Purifie  and  perfect,  because  it  works  after  a  simple  manner 
upon  what  it  hath.'  Imperfect  matter  can  be  made  *  more 
than  perfect  by  the  help  of  our  art '.'  *  Our  art  '  has  nothing 
magical  about  it.  He  who  pursues  the  art  which,  basing 
itself  on  the  mysteries  of  nature,  works  more  quickly  and 
more  thoroughly  than  nature,  must  separate  himself  from 
the  '  unlearned  crew  '.  In  The  Secrets  of  Nature  and  Art, 
Bacon  says  :  '  That  which  all  men,  which  wise  and  the  more 
noted  men  affirme,  is  truth.  That  therefore  which  is  held 
by  the  multitude,  as  a  multitude,  must  be  false  ;  I  mean  of 
that  multitude  which  is  distinct  from  knowing  men.'  -  Were 
the  mysteries  of  nature  and  art  told  plainly  to  the  multitude, 
they  would  deride  these  mysteries,  and,  because  of  their 
ignorance,  would  use  them  wrongly.  '  Wise  and  knowing 
men  '  have,  therefore,  purposely  obscured  their  writings  : 
sometimes  they  have  used  enigmatical  and  figurative 
words  ;  sometimes  they  have  written  consonants  without 
vowels ;  sometimes  they  have  mixed  different  sorts  of  letters ; 
sometimes  they  have  invented  letters  ;  sometimes  they  have 
used  geometrical  characters  in  place  of  letters.  '  Thus  we 
find  multitudes  of  things  obscured  in  the  writings  and  sciences 
of  men,  which  no  man  without  his  Teacher  can  unvail.' 
Bacon  says  he  has  given  these  hints  about  the  various 
ways  used  by  wise  men  to  hide  their  secrets  from  the  vulgar, 
because  '  it  may  fall  out,  I  may  thorow  the  magnitude  of 
our  secrets  discourse  this  way  '  ? 

As  illustrative  of  Bacon's  knowledge  of  the  human  mind, 
it  is  interesting  to  notice  that,  while  he  strongly  condemns 
and  scorns  the  use  of  magical  arts,  he  admits  that  '  figures 
and  charmes  '  may  sometimes  be  used  by  physicians  with 
good  effects  '  ;  not  from  any  prevalency  in  them,  but  that 
the  raising  of  the  soul  is  of  great  efficacy  in  the  curing  of  the 
body,  and  raising  it  from  infirmity  to  health,  by  joy  and 

*  Speculum  Alchimiae,  chap.  iv. 

-  Secrets  of  Nature  and  Art,  chap,  viii.  ^  Ibid. 


296  ROGER  BACON 

confidence  done  by  charmes  ;  for  they  make  the  Patient 
receive  the  medicine  with  greater  confidence  and  desire, 
exciting  courage,  more  Hberal  beUef,  hope  and  pleasure.'  ' 
Without  saying  that  they  act  as  '  figures  and  charmes  ' 
act  in  medicine.  Bacon  recommends  the  use  of  holy  water, 
and  other  similar  practices  allowed  by  the  Church. 

The  object  of  practical  alchemy  was  held  by  the  alchemists 
to  be  the  preparation  of  the  Elixir,  the  Heavenly  Water,  the 
Fiery  Medicine,  the  Phoenix,  the  Magistery,  which  would  bring 
to  perfection  all  imperfect  bodies,  and  confer  on  him  who  knew 
how  rightly  to  use  it  a  long,  healthy,  and  vigorous  life.  How 
was  this  medicine  to  be  made  ?  When  giving  directions 
for  making  the  Elixir,  the  alchemists  never  forgot  that  their 
secrets  were  not  to  be  made  known  to  the  multitude.  They 
expressed  themselves  in  obscure,  misleading  language. 
One  of  their  favourite  devices  was  to  hide  their  meaning 
in  an  allegory.  As  illustrative  of  alchemical  allegories, 
I  give  a  quotation  from  Pretiosa  Margarita,  written  by 
Bonus  of  Ferrara,  who  probably  lived  in  the  first  half  of 
the  fourteenth  century.  The  quotation  is  taken  from 
pp.  38-47  of  Mr.  A.  E.  Waite's  translation,  published  in 
1894,  with  the  title  The  New  Pearl  of  Great  Price.  I  have 
omitted  parts  of  the  original,  in  order  that  the  quotation 
should  not  be  over-long  : 

'  Three  rules  must  be  carefully  observed  in  our  art  ;  first 
prepare  the  right  substance  ;  then  carry  on  the  work  con- 
tinuously, so  that  it  may  not  be  marred  by  interruption  ; 
thirdly,  be  patient,  and  follow  always  in  the  footsteps 
of  Nature.  Get  (on  your  substance)  highly  purified  Water 
of  Life,  and  keep  it  ;  but  do  not  suppose  that  the  liquid 
which  moistens  all  things  is  the  bright  and  limpid  liquid 
of  Bacchus.  For  while  you  anxiously  look  about  in  out-of- 
the-way  places  for  extraordinary  events,  you  pass  by  the 
sparkling  waves  of  the  blessed  stream.  Enter  the  Palace 
in  which  are  fifteen  mansions,  where  the  king,  his  brow 
circled  with  the  diadem,  sits  on  a  lofty  throne,  holding 

'  Secrets  oj  'Nature  and  Art,  chap.  ii. 


ALCHEMY  AND  CHEMISTRY  297 

in  his  hand  the  sceptre  of  the  whole  world  ;  before  him, 
his  son  and  five  servants  kneel  in  robes  of  different  colours, 
imploring  him  to  bestow  on  his  son  and  his  servants  a  share 
of  his  power  ;  but  he  does  not  even  reply  to  their  request. 
The  son,  incited  by  the  servants,  stabs  the  father  as  he  sits 
on  the  throne.  (Let  an  amalgam  be  made  with  highly  purified 
water,  &c.)  The  son  catches  his  father's  blood  in  his  robe. 
...  A  grave  is  dug  in  the  fourth  mansion.  ...  In  the  fifth 
mansion,  the  son  thought  to  throw  his  father  into  the  grave, 
and  to  leave  him  there  ;  but  (by  means  of  our  art)  both  fell 
in  together.  The  sixth  mansion  is  that  in  which  the  son 
still  strives  to  get  out,  but  one  .  .  .  comes,  and  prevents  him 
from  so  doing.  While  the  father  and  the  son  are  in  the 
tomb,  which  is  called  the  seventh  mansion,  there  follows 
putrefaction  in  their  ashes,  or  a  very  hot  bath.  In  the 
eighth  mansion,  that  which  happened  during  the  putre 
faction  is  inspected,  the  vase  having  become  cold,  &c.  In 
the  ninth  mansion,  the  bones  are  taken  from  the  tomb. 
This  happens  when  the  whole  body  has  been  dissolved  by 
successive  solution,  which  being  done,  keep  it  carefully. 
In  the  tenth  mansion,  the  bones  are  divided  into  nine  parts, 
the  dissolved  substance  being  subjected  to  gentle  coction 
for  nine  days,  till  a  portion  of  it  turns  black.  Remove  this 
latter,  and  keep  it  in  another  vessel  in  a  hot  place.  Subject 
the  water  to  gentle  heat  for  another  nine  days.  Again 
remove  that  v/hich  has  turned  black,  and  put  it  with  the  rest. 
Continue  the  operation  till  the  water  is  clear  and  pure.  Let 
its  Water  of  Life  be  poured  over  the  black  substance  in 
a  small  glass  vessel,  so  that  it  shall  float  over  it  to  the 
height  of  an  inch,  and  let  it  stand  nine  days  over  a  gentle 
fire,  renewing  the  water  every  day,  if  necessary.  .  ,  .  An 
angel  is  sent,  who  casts  the  bones  on  the  purified  and 
whitened  earth.  ...  In  the  eleventh  mansion  the  servants 
pray  to  God  to  restore  their  king.  Henceforth  the  whole 
work  is  concerned  with  his  restoration.  ...  A  second  angel 
is  sent  in  the  twelfth  mansion,  who  places  the  other  part 
of  those  bones  on  the  earth,  till  they  are  all  thickened  ; 
then  a  wonderful  thing  happens.' 

The  allegory  then  tells  of  the  coming  of  many  angels  who 
cast  other  portions  of  the  bones  on  the  earth,  and  proceeds 
thus  :  '  Then  the  king  rises  from  the  tomb,  full  of  the 
grace  of  God.  His  body  is  now  all  spiritual  and  heavenly, 
and  he  has  power  to  make  all  his  servants  kings.' 


298  ROGER  BACON 

The  allegory  finishes  with  this  warning  and  encourage- 
ment :  '  Let  no  impostor,  greedy  or  wicked  person,  touch 
this  glorious  work  with  his  unclean  hands.  Let  the  honest 
man  and  him  of  a  wise  heart  come  hither,  and  him  who  is 
capable  of  exploring  the  most  hidden  causes  of  things.' 

The  Pretiosa  Margarita  of  Bonus  was  edited  by  Janus 
Lacinius,  and  published  in  1546  by  the  Venetian  press  of 
Aldus.  In  his  book,  Lacinius  includes  extracts  from  the 
works  of  Arnald  de  Villanova,  in  which  the  composition  of 
the  Philosopher's  Stone  '  is  practically  and  lucidly  set 
forth  '.  To  show  what  alchemists  considered  a  lucid  setting 
forth  of  the  practice  of  their  art,  I  give  a  few  extracts  from 
Arnald  de  Villanova,  quoting  from  Mr.  Waite's  New  Pearl 
of  Great  Price  (pp.  313-16)  : 

'  Our  physical  Stone  .  .  .  may  be  obtained  from  all  metals  ; 
but  it  is  found  in  the  highest  perfection  in  gold  and  silver. 
.  .  .  Gold  is  the  father,  and  silver  the  mother  of  the  proximate 
substance  of  our  Stone,  for  out  of  these  bodies,  prepared 
with  their  sulphur  or  arsenic,  is  our  medicine  elicited.  .  .  . 
It  is  found  nearer  to  the  hand,  and  more  easily,  in  quick- 
silver, which  is  .  .  .  the  root  of  all  metals.  .  .  .  That  which 
is  now  our  Stone  is  not  quicksilver,  but  once  formed  part 
of  it.  ...  Do  not  work  with  anything  except  Mercury  and  the 
Sun  for  the  Sun,  and  Mercury  and  the  Moon  for  the  Moon. 
Your  first  step  must  be  to  bring  about  the  dissolution  of 
gold  and  silver  into  quicksilver.  .  .  .  Unless  the  bodies 
become  incorporeal,  and  the  spirits  corporeal,  no  progress 
will  be  made.  .  .  .  Bodies  when  dissolved  become  spiritual 
in  their  nature  .  .  .  solution  of  the  body  means  the  coagula- 
tion of  the  spirit,  and  vice  versa.' 

Directions  are  given  for  cleansing  Mercury  :  '  Pound  and 
cook  with  patience,  and  reiterate  the  process  again  and 
again,'  At  last  the  Mercury  will  be  dissolved  ;  it  is  then 
to  be  exposed  to  a  gentle  heat  '  for  its  better  putrefaction 
and  digestion  '  '  during  the  space  of  a  month  of  the  Sages  '. 
It  is  then  to  be  sublimed,  then  subjected  '  to  a  coction  till 
it  is  reduced  to  its  first  nature,  that  is,  till  we  have  sulphur 
and  quicksilver  '  (Waite's  translation,  pp.  319,  320,  321). 


ALCHEMY  AND  CHEMISTRY  299 

The  substance — by  this  time  the  reader  may  well  ask,  what 
substance  ? — is  then  washed  and  purified  by  water,  and  air, 
and  fire,  and  is  fermented,  and  digested,  and  putrefied,  and 
at  last  is  fixed. 

I  do  not  think  it  possible  to  translate  alchemical  directions 
for  making  the  Stone  into  words  which  convey  any  definite 
meaning  to  a  chemist.  The  terms  Mercury,  Sulphur,  Arsenic, 
Gold,  Silver,  certainly  did  not  mean  to  alchemists  what  they 
now  mean  to  chemists.  Take  the  word  Solution.  Arnald 
de  Villanova  says  :  '  When  I  speak  of  solution,  you  must 
not  think  that  the  elixir  is  to  be  altogether  resolved  into 
water  [does  this  mean,  is  to  be  completely  melted  ?]  but 
is  only  to  be  subtilized  as  far  as  possible  to  have  its  parts 
divided,  that  which  is  dry  in  it  made  humid,  and  that 
which  is  gross  made  simple,  since  dissolution  is  practised  .  .  . 
for  the  purpose  of  uniting  the  body  and  the  spirit '  (Waite's 
translation,  p.  346). 

Arnald  concludes  with  the  remark  :  '  You  will  not  find 
in  all  the  books  of  the  Sages  anything  clearer  and  plainer 
than  what  I  have  told  you  '  (p.  349). 

Let  us  turn  to  Roger  Bacon,  and  see  whether  he  tells  us 
how  to  make  the  Elixir  in  words  to  which  we  can  attach 
any  clear  meaning. 

In  chapter  iii  the  writer  of  Speculum  Alchimiae,  who  may 
possibly  have  been  Roger  Bacon,  gives  vague  and  elusive 
directions  for  making  the  Philosopher' s  Egge,  as  he  calls  the 
Elixir.  He  says  that  the  Egg  must  be  made  from  mineral 
substances,  because  they  only  are  formed  by  the  union  of 
quicksilver  and  sulphur,  and  it  is  only  by  the  '  joint  and 
proportionate  mixture  of  these  two  principles  '  that  the  Egg 
can  be  produced.  The  inquirer  must  find  those  bodies  in 
which  the  two  principles  are  '  justly  proportionated,  coagu- 
lated, and  joyned  together  in  one,  as  their  Natures  require  '. 

Chapter  ix  of  De  secretis  operibus  artis  et  naturae  deals 
with  *  The  Manner  to  make  the  Philosopher's  Egge '     This 


300  ROGER  BACON 

tractate  is  generally  attributed  to  Roger  Bacon  ;  some 
authorities  doubt  the  authenticity  of  the  later  chapters. 
The  directions  for  making  the  Egg  begin  as  follows  (I  quote 
from  the  English  translation  published  in  1659)  : 

'  Make  a  diligent  purification  of  the  Calx  with  the  water  of 
Alkali,  and  other  acute  waters,  grind  it  by  several  contri- 
tions with  the  salts,  and  burn  it  with  many  assations,  that 
the  earth  may  be  perfectly  separated  from  other  elements. 
.  .  .  Understand  if  you  can.  .  .  ,  Then  take  oyl  of  the  form 
of  a  saffron-cheese,  and  so  viscous  as  not  to  be  smitten 
asunder  by  a  stroak,  divide  the  whole  fiery  virtue,  and 
separate  it  by  dissolution,  and  let  it  be  dissolved  in  acute 
water,  of  a  temperate  acutenesse,  with  a  slight  fire,  and  let 
it  be  boyled  till  his  fatnesse,  as  the  fatnesse  of  flesh  be 
separated  by  distillation,  that  nothing  of  the  unctiousnesse 
may  issue  forth  ;  and  let  this  fiery  virtue  be  distilled  in 
the  water  of  Urine  ;  '  and  so  on  for  three  or  four  pages. 
'  Mind  and  search  what  I  say,  for  the  speech  is  difficult.  .  .  . 
You  must  observe  whether  I  speak  aenigmatically  or  accord- 
ing to  the  truth.'  The  directions  for  making  the  Egg 
finish  thus  :  '  Farewell  :  Whoever  unlocks  these,  hath 
a  key  which  opens  and  no  man  shuts  ;  and  when  he  hath 
shut,  no  man  opens.' 

In  those  writings  which  are  acknowledged  by  all  authorities 
to  be  genuine,  Roger  Bacon  insists  on  the  need  of  observa- 
tion and  experiment  for  attaining  to  real  knowledge  of 
natural  events.  For  instance,  in  Opus  Tertium  (xiii.  43, 
Brewer's  edition)  he  says  :  '  Besides  these  sciences,  there 
is  one  more  perfect  than  them  all,  on  which  the  others 
attend,  which  certifies  [certificat)  them  all  in  a  wonderful 
way  ;  and  this  is  called  experimental  science  {scientia  experi- 
mentalis).'  He  declares  that  this  science  is  superior  to  other 
sciences,  in  that  it  tests  arguments  by  appealing  to  experi- 
ence. In  discussing  natural  phenomena,  the  only  test, 
according  to  Bacon,  is  experience ;  argument  alone  is 
worthless.  This  science  not  only  gives  to  those  who  use  it 
a  sound  knowledge  of  nature,  it  also  teaches  the  possibilities 
of  nature  and  art  and  the  nullity  of  magic. 


ALCHEMY  AND  CHEMISTRY  301 

Roger  Bacon's  mental  attitude  toward  natural  events 
was  nearer  to  that  of  the  scientific  student  than  to  that  of 
the  alchemists  either  before  or  after  his  time.  We  do  not 
find  in  his  writings  vague  talk  about  stripping  matter  of 
its  properties,  about  invisible  elements,  about  the  soul  of 
bodies,  about  The  One  Thing,  and  so  on.  He  opposes  the 
alchemical  doctrine  of  one  primary  matter,  as  being  harmful 
to  the  investigation  of  nature.  We  shall  appreciate  the 
importance  of  this  denial  of  primary  matter  more  fully  as 
we  proceed.  The  directions  for  making  the  Philosopher's 
Egg  given  in  the  Mirror  of  Alchemy,  and  in  The  Secrets  of 
Nature  and  Art,  closely  resemble  those  contained  in  ordinary 
alchemical  writings.  There  is  in  them  the  vague  talk,  the 
haziness,  the  thinking  in  images  of  words  rather  than  in  images 
of  things,  which  are  the  marks  of  most  books  on  practical 
alchemy.  When  one  contrasts  the  directions,  parts  of  which 
I  have  quoted,  with  the  writings  of  Bacon  on  speculative 
and  practical  alchemy,  one  has  grave  doubts  as  to  the 
genuineness  of  these  directions  ;  they  do  not  read  like 
what  one  would  expect  Bacon  to  have  written,  judging  from 
his  other  works.  His  remarks  on  speculative  and  practical 
alchemy  in  the  Opus  Minus  and  Opus  Tertium  incline  one 
to  place  Bacon  among  the  chemists  rather  than  among  the 
alchemists.  Certainly  we  need  not  go  to  him  to  find  definite 
directions  for  making  the  wonder-working  Stone  of  the 
Philosophers. 

In  his  book  Gunpowder  and  Ammunition,  and  also  in 
his  essay  in  this  volume,  Colonel  Hime  establishes  a  large 
probability  in  favour  of  regarding  the  chapters  of  De  Secretis 
which  profess  to  set  forth  two  methods  for  making  the 
Philosopher's  Egg,  as  really  containing  directions  for 
purifying  saltpetre  and  making  gunpowder,  concealed  in 
a  setting  of  alchemical  jargon.  I  have  quoted  from  these 
chapters  for  the  purpose  of  showing  that  no  light  is  to  be 
obtained  from  the  words  as  they  stand  on  the  process  they 


302  ROGER  BACON 

are  supposed  to  describe.  It  is  to  be  remembered  that  no 
intelligible  directions  for  making  the  Stone  can  be  obtained 
from  any  alchemical  writing. 

What  was  Roger  Bacon's  conception  of  alchemy  ?  In 
attempting  to  answer  this  question,  it  will  be  necessary  to 
refer  to  his  notions  about  matter,  substance,  form,  and 
activity  ;  I  shall  bear  in  mind  that  the  exposition  of  his 
teaching  on  these  subjects  belongs  more  to  the  essays  on 
Bacon's  relations  to  physical  science,  and  to  philosophy, 
than  to  that  on  the  chemical  aspects  of  his  work. 

Alchemists,  both  before  and  after  Roger  Bacon,  formed, 
from  their  intellectual  and  emotional  longings,  a  scheme 
of  nature's  method  of  working,  and  then  observed  natural 
changes  through  the  distorted  glass  of  their  imaginings. 
Bacon  at  least  tried  to  look  first  at  external  realities,  and  to 
base  his  intellectual  explanation  of  material  changes  on 
observed  facts.  In  his  Opus  Tertium  (xiii.  46,  Brewer's 
edition)  he  says  of  experimental  science  :  '  This  science 
works  by  perfect  experiments,  not  by  arguments  as  purely 
speculative  science  does,  not  by  weak  and  imperfect  experi- 
ments as  operative  science  does.  Therefore,  this  is  the  lord 
of  all  sciences,  and  the  end  of  all  speculation.'  Again,  in 
the  same  place,  he  says  :  '  The  man  who  rejects  anything 
ought  to  know  the  nature  and  circumstances  of  that  thing, 
and  so  reject  what  is  false,  that  what  is  true  may  remain 
unimpaired.'  In  the  preceding  chapter  (p.  41)  of  the  Opus  Ter- 
tium, he  asserts  that  many  labour  to  make  metals,  and 
colours,  and  other  things,  without  a  real  practical  acquain- 
tance with  the  methods  of  the  laboratory.  '  There  are  few 
who  know  how  to  distil  properly,  how  to  sublime  and  to 
calcinate,  how  to  separate  things.'  There  are  not  three 
men  among  the  Latins  who  have  given  themselves  to  this 
that  they  may  know  speculative  alchemy,  which  cannot 
be  known  without  the  operations  of  practical  alchemy. 
*  There  is  only  one  man  ',  Bacon  says,  *  who  is  instructed 


ALCHEMY  AND  CHEMISTRY  303 

in  all  these  questions  ;  as  so  few  people  know  these  things, 
he  does  not  deign  to  communicate  with  others,  nor  to 
associate  with  them,  because  he  regards  them  all  as  asses 
and  fools  {asinos  et  insanos)  delivered  over  to  quibbles,  and 
as  charlatans  who  dishonour  philosophy,  medicine,  and 
theology  '  (p.  41,  Brewer's  edition). 

Bacon  often  insists  on  the  necessity  of  beginning  with  the 
study  of  the  simpler  inanimate  things,  of  examining  how 
'  simple  and  compound  liquids,  gems,  marbles,  gold,  and 
other  metals  '  are  generated  from  their  elements.  It  is 
impossible,  he  asserts,  to  gain  any  knowledge  of  the  '  genera- 
tion of  animate  things '  without  having  first  acquired 
a  knowledge  of  the  generation  of  the  simpler  inanimate 
things.  Of  this  preliminary  knowledge,  he  says,  '  we  find 
nothing  in  the  books  of  Aristotle  '  [Opus  Tertium,  xii.  39, 
Brewer). 

In  discoursing  of  the  many  errors  of  medical  men. 
Bacon  lays  stress  on  their  ignorance  of  alchemy.  A  know- 
ledge of  alchemy,  he  says,  enables  men  to  recognize  the 
differences  between  medicines,  and  the  virtues  of  different 
medicines  ;  this  knowledge  also  is  necessary  for  the  proper 
preparation  of  medicines.  Here,  as  elsewhere.  Bacon  lays 
much  importance  on  alchemy  as  a  practical  art  which 
deals  with  real  things.' 

Bacon's  leaning  to  the  practical  and  useful  side  of  know- 
ledge should  be  noticed,  as  it  is  characteristic  of  him,  and 
marks  him  off  both  from  his  contemporaries  and  his  pre- 
decessors. In  Opus  Tertium  he  says  that  practical  alchemy 
is  more  important  than  all  the  other  sciences,  because  '  it 
is  productive  of  more  advantages '  than  they.  '  The 
utility  of  everything  must  be  considered  ;  for  this  utility 
is  the  end  for  which  the  thing  exists  '  (Brewer's  translation). 

'  De  Erroribus  Medicorum  secundum  Fratrem  Rogerum  Bacon  de 
or  dine  Minorum.  The  editor  of  this  volume  has  kindly  allowed  me 
to  see  the  typescript  of  the  forthcoming  edition  of  this  tractate. 


304  ROGER  BACON 

How  different  this  is  from  the  gibe  of  the  modern  absolutist 
philosophers  against  the  '  irrelevant  appeals  to  practical 
results  which  are  allowed  to  make  themselves  heard  ' !  Of 
the  many  experiences  which  philosophers  of  the  absolutist 
school  say  create  '  a  passing  show  of  arbitrary  variation  ', 
these  same  philosophers  assert  that  '  they  themselves,  and 
the  manner  of  their  connexion,  are  excluded  from  the  theory 
of  knowledge  '.  Not  only  was  Roger  Bacon  in  advance  of 
his  predecessors  and  his  contemporaries  in  his  method 
of  seeking  knowledge,  he  was  also  far  in  advance  of  those 
who  to-day  reject  the  experience  of  the  seven  centuries 
which  separate  them  from  him. 

The  following  quotation  from  Communia  Naturalium 
gives  a  vivid  picture  of  the  genuinely  scientific  character 
of  Roger  Bacon.  It  shows  clearly  the  great  importance 
he  placed  on  the  careful  examination  of  external  facts, 
and  makes  us  realize  his  skill  in  determining  the  tind  of 
facts  which  ought  to  be  studied  for  this  or  that  particular 
purpose.  Bacon  divides  natural  philosophy  into  separate 
sciences.  The  fi.fth  of  these  separate  sciences  is  agriculture. 
Of  this  department  of  knowledge  he  writes  as  follows  (I  quote 
from  Brewer's  translation  in  the  preface  to  his  Fr.  Rogeri 
Bacon  opera  quaedam  hactenus  inedita,  p.  li,  note) : 

'  Next  [after  alchemy]  comes  the  special  science  of  the 
nature  of  plants  and  all  animals,  with  the  exception  of 
man  ;  who,  by  reason  of  his  nobleness,  falls  under  a  special 
science  called  medicine.  But  first  in  the  order  of  teaching 
is  the  science  of  animals  which  precede  man  and  are  necessary 
for  his  use.  This  science  descends  first  to  the  consideration 
of  every  kind  of  soil  and  the  productions  of  the  earth,  distin- 
guishing four  kinds  of  soil,  according  to  their  crops  ;  one 
soil  is  that  wherein  corn  and  legumina  are  sown  ;  another 
is  covered  with  woods  ;  another  with  pastures  and  meadows  ; 
another  is  garden  ground  wherein  are  cultivated  trees  and 
vegetables,  herbs  and  roots,  as  well  for  nutriment  as  for 
medicine.  Now  this  science  extends  to  the  perfect  study 
of  all  vegetables,  the  knowledge  of  which  is  very  imper- 
fectly delivered   in  Aristotle's  treatise  on   that   subject ; 


ALCHEMY  AND  CHEMISTRY  305 

and  therefore  a  special  and  sufficient  science  of  plants  is 
required,  which  should  be  taught  in  books  on  agriculture. 
But  as  agriculture  cannot  go  on  without  an  abundance 
of  tame  animals  ;  nor  the  utility  of  different  soils,  as  woods, 
pastures  and  deserts,  be  understood,  except  wild  animals  be 
nurtured  ;  nor  the  pleasure  of  man  be  sufficiently  enhanced, 
without  such  animals  ;  therefore  this  science  extends  itself 
to  the  study  of  all  animals.' 

In  these  words.  Bacon  draws  the  outlines  of  a  true  science 
of  agriculture,  based  on  observation  and  experiment,  fitted 
to  yield  results  useful  to  mankind. 

By  using  the  method  of  observation  and  experiment, 
and  reasoning  on  the  results  obtained,  Roger  Bacon  arrived 
at  just  and  fruitful  conceptions  regarding  plant  life,  the 
growth  and  nutrition  of  animals,  tides,  rainbows,  the 
density  of  air,  and  other  natural  events.  This  method  also 
led  him  to  the  invention  of  instruments  of  much  usefulness 
in  optics,  astronomy,  and  other  branches  of  physical  science. 
Bacon  often  insists  on  the  need  of  mathematics  in  the 
investigation  of  physical  occurrences.  He  tried  to  form 
a  general  science  which  should  bring  the  actions  of  bodies, 
and  of  natural  agents,  under  the  principles  of  mathematics. 
Nevertheless,  he  taught  that  the  experimental  sciences  are 
more  useful  to  men  than  mathematics,  for  they  stir  curiosity 
and  make  possible  the  understanding  of  many  things. 
Without  experience,  he  said,  no  satisfactory  investigation 
is  possible.  Experience  shields  us  from  erroneous  judge- 
ments. His  own  discoveries,  made  by  experimenting  and 
observing,  had  shown  him,  he  says,  that  there  is  nothing  too 
hard  to  believe  either  in  human  or  divine  things.' 

Most  of  the  alchemists  appealed  to  the  authority  of  men 
of  renown  who  had  gone  before  them  for  justification  of  their 
outlook  on  nature.      Roger  Bacon  opposed  the  custom  of 

'  Compare  Roger  Bacon  ord.  min.,  erne  Monographic  als  Beitrag 
zuY  Geschichte  dcr  Philosophic  des  drcizehnten  Jahrhunderts,  by 
Dr.  Leonhard  Schneider  (1873). 

1689  X 


3o6  ROGER  BACON 

constantly  discussing  ideas,  generalities,  principles,  stated 
by  Aristotle  and  other  ancient  writers.  He  insisted  on  the 
need  of  observing  and  discussing  facts.  He  said  that 
scholastic  science  was  too  greatly  concerned  with  intellectual 
definitions,  and  the  supposed  causes  of  natural  events, 
and  neglected  the  accurate  observation  of  these  events 
[Non  oportet  causas  investigare).  He  altogether  rejected 
occult  causes.  He  taught  that  undue  respect  to  worthless 
authority  is  one  of  the  causes  of  ignorance,  and  that  the 
conceit  of  learned  men,  which  makes  them  hide  their 
ignorance  under  a  display  of  apparent  knowledge,  is  another 
potent  cause  of  error  and  mental  darkness  {Opus  Minns, 
pp.  322-4,  Brewer). 

It  was  impossible  that  Bacon  should  shake  himself  quite 
free  from  the  trammels  of  authority.  He  taught  the  need 
of  obedience  to  the  Church,  although  he  v/as  imprisoned 
for  a  supposed  lack  of  proper  humility  to  authority.  He 
despised  the  ignorance  and  stupidity  of  the  multitude. 
'  Men  are  so  ready  to  go  astray  ',  he  said,  '  that  they 
must  have  some  trustworthy  guide.'  He  placed  theology 
at  the  head  of  his  hierarchy  of  sciences,  and  though 
he  appealed  again  and  again  to  observation  and  experi- 
ment, he  carried  over  theological  methods  into  scientific 
inquiries. 

Bacon  was  obliged  to  paint  his  mental  picture  of  the  muta- 
tions of  material  things  with  the  pigments  he  found  in  his 
colour-box.  He  could  not  do  otherwise.  We  all  do  that. 
He  could  not  but  use  the  conception  of  the  four  elements — 
hotness,  dryness,  coldness,  wetness — as  guides  in  his  attempt 
to  make  an  intellectual  arrangement  of  the  facts  he  had 
to  set  in  order.  Roger  Bacon  was  necessarily  influenced  by 
the  intellectual  conceptions  of  his  time.  Nevertheless, 
Charles  can  justly  say  of  him  :  '  His  greatest  discovery 
is  that  of  the  feebleness  and  faults  of  scholasticism  ; 
his   originality   is   to   belong   as    little   as   possible   to   his 


ALCHEMY  AND  CHEMISTRY  507 

own  time.'  '  In  the  thirteenth  century  there  were  no 
methods,  no  instruments,  for  making  minutely  accurate 
investigations  of  material  changes.  Bacon  was  born  into 
a  mental  atmosphere  of  vague  principles,  and  grew  up  in 
that  environment.  Desirous  of  finding  how  the  changes  of 
things  happen,  he  thought  of  these  changes  in  terms  of  fire, 
air,  earth,  and  water  ;  for  these  were  at  once  the  simplest 
and  the  most  ingathering  conceptions  which  came  to  his 
hand.  The  instruments  which  he  found  in  use,  and  used 
for  investigating  natural  changes  were  not  sufficiently 
incisive,  not  sufficiently  plastic,  not  penetrative  nor  scarify- 
ing enough,  to  be  completely  effectual  for  sweeping  away 
the  images,  the  prejudices,  the  mental  atmosphere,  in  which 
his  intellectual  life  was  steeped.^  He  had  to  do  his  best 
with  the  mental  apparatus  which  he  inherited.  He  accom- 
plished much, 

Roger  Bacon  divided  alchemy  into  two  departments  : 
speculative  alchemy,  which,  he  says,  has  to  do  with  the  genera- 
tion of  all  inanimate  things  from  their  elements,  and  lays 
bare  the  broad  lines  on  which  that  generation  proceeds  ; 
and  practical  alchemy,  which  is  chiefly  concerned  with  the 
purification  of  metals.  When  one  looks  to  the  experimental 
work  of  Roger  Bacon  on  optical  and  other  instruments, 
the  magnet,  the  rainbow,  the  growth  and  propagation  of 
plants,  and  remembers  the  mechanical  devices  which  he 
invented,  one  expects  to  find  him  dealing  with  metals  by 

'  Roger  Bacon,  sa  vie,  ses  ouvrages,  ses  doctrines,  by  fimile  Charles 
(1861),  p.  162. 

^  It  is  rather  perplexing  to  find  Bacon  saying  in  Opus  Tertium 
that  the  four  elements  are  sometimes  to  be  taken  literally,  some- 
times metaphorically.  When  taken  metaphorically, '  they  mean  the 
four  spirits,  or  the  four  humours,  or  the  four  parts  of  the  compass, 
or  the  four  seasons,  or  the  four  principal  parts  of  an  animal ;  because 
there  is  a  complexional  correspondence  between  each  set  of  these 
things.'  {Part  of  'Opus  Tertium',  including  a  fragment  now  printed 
for  the  first  time,  edited  by  A.  G.  Little :  British  Society  of  Franciscan 
Studies,  vol.  iv.     See  Summary,  pp.  xlvii  and  xlviii.) 

X  2 


3o8  ROGER  BACON 

the  method  of  observation  and  experiment.  But  one  finds 
him  hedged  in  by  the  conception  of  four  elements  or  prin- 
ciples ;  he  cannot  break  through  that  barrier.  His  remarks 
on  the  differences  between  metals  are  more  like  those  of  the 
ordinary  alchemist  than  might  be  expected. 

In  a  small  book,  printed  at  Frankfurt  in  1603,  entitled 
Sanioris  Medicinae  Magistri  Rogeri  D.  Baconis  Angli  de  Arte 
Chymiae  Scripta,  Roger  Bacon  discourses  of  the  elements, 
of  metals,  and  of  transmutation,  more  fully  than  in  his 
longer  writings.'  He  says  that  each  of  the  four  elements 
has  its  special  quality  ;  dryness  predominates  in  earth, 
wetness  in  water,  coldness  in  air,  hotness  in  fire  ;  but  each 
element  can  receive  some  portion  of  the  quality  which 
particularly  distinguishes  another  element  (pp.  314-15). 
He  speaks  of  various  degrees  of  hotness,  coldness,  dryness, 
and  wetness,  and  distinguishes  primary,  secondary,  tertiary, 
&c.,  degrees  of  each  quality  (pp.  322-5).  The  Elixir  com- 
bines in  itself  all  the  qualities  of  the  four  elements,  equally 
and  perfectly  balanced.  The  Elixir  is  able  to  give  hotness 
to  things  that  need  hotness,  coldness  to  things  that  need 
coldness,  wetness  to  things  that  need  wetness,  dryness  to 
things  that  need  dryness,  to  bring  them  to  perfection. 
The  aim  of  the  alchemist  is  to  bring  things  to  their  most 
perfect  state  ;   this  can  be  done  only  by  using  each  element 

'  This  book  contains  the  following  tractates  by  Roger  Bacon  : 
(i)  Breve  breviarium  fratris  Rogeri  Bacon  ;  ad  Raymunduni  qui 
scripsit  de  viridi  Leone  (pp.  95-264)  ;  (2)  Tractatus  Trium  Verborum 
R.  Bacon  (pp.  292-387)  ;  (3)  Speculum  Secretorum  (pp.  387-408). 
Breve  breviarium  deals  with  the  composition  of  metals,  the  trans- 
mutation of  metals,  the  nature  and  purification  of  particular  metals 
(gold,  silver,  copper,  lead,  tin,  iron),  curative  medicines,  mineral 
spirits  and  sulphur,  methods  of  operating  with  mercury  and  sulphur, 
preparation  of  arsenic  and  the  effects  of  it,  and  of  salts  (alkali,  salt- 
petre, nitre — de  sale  nitri — common  salt,  alumina,  borax),  and 
stones.  Tractatus  Trium  Verborum  treats  of  (a)  the  composition 
of  things  from  the  four  elements,  (6)  mixing,  (c)  weights.  Speculum 
Secretorum  deals,  very  briefly,  with  the  secret  of  the  transmutation 
of  things.    I  refer  to  this  book  as  Art.  Chym. 


ALCHEMY  AND  CHEMISTRY  309 

in  its  proper  degree  of  humidity,  coldness,  dryness,  or  hot- 
ness,  and  by  conjoining  the  elements  in  their  due  propor- 
tions. The  Elixir  is  a  kind  of  happy  mean  ;  the  metals 
are  extremes  in  reference  to  the  Elixir.  Some  metals  have 
too  much  coldness,  some  too  much  hotness,  and  so  on. 
The  Elixir  is  able  to  cure  their  sicknesses.* 

The  passages  I  have  referred  to  are  almost  purely  argumen- 
tative. In  them  Roger  Bacon  tries  to  refine  the  ordinary 
alchemical  doctrine  of  the  four  elements.  He  ignores  the 
alchemical  notion  of  a  something  common  to  all  the  elements 
and  to  all  things  formed  by  conjoining  elements.  When  one 
remembers  how  strongly  Bacon  insists  on  the  superiority 
of  observation  and  experiment  over  mere  argument,  as 
means  for  acquiring  genuine  knowledge  of  natural  events 
(see,  for  instance,  the  quotation  from  Opus  Tertium,  p.  43, 
Brewer's  edition,  given  on  p.  300),  one  is  certainly  sur- 
prised to  find  him  saying  [Art.  Chym.,  p.  345)  :  '  Dimitte 
experimenta  ;  cape  rationes  et  invenies.' 

When  one  thinks  one  has  obtained  an  inkling  of  Bacon's 
meaning,  one  is  much  nonplussed  by  such  words  as  these 
{Art.  Chym.,  p.  301)  :  '  Sed  omne  quod  dico  est  falsum,  ergo 
nihil  dico  verum  .  .  .  sed  quando  dico  verum,  intellige 
falsum.'  Like  other  alchemists,  Bacon  feared  lest  the 
'  unlettered  crew  '  should  understand  his  secrets.- 

Roger  Bacon  did  not  think  of  the  elements  as  forms  or 
expressions  of  a  universal  primary  matter,  but  rather  as 
particular  conditions  each  of  which  acts  on  its  own  account 
and  in  its  own  way.  He  did  not  think  of  an  element  as 
a  particular  substance  which  has  not  been  separated 
into  unlike  parts — no  one  thought  thus  of  an  element  till 

'  Art.  Chym.,  p.  319  :  '  Omnia  metalla  sunt  extrema  ad  Elixir. 
Elixir  vero  medium,  sic  ergo  agit  nominaliter.' 

"  In  the  part  of  Opus  Tertium  edited  by  A.  G.  Little,  Bacon  says 
(p.  81)  :  '  Quadriga  una  non  portaret  libros  alkimiae,  quorum  tamen 
omnium  virtus  in  his  paucis  verbis  continetur  ;  et  ideo  est  obscuritas 
infinita.' 


310  ROGER  BACON 

about  five  and  a  half  centuries  after  Bacon's  time — he  thought 
of  an  element  rather  as  a  condition  of  being  of  this  or  that 
particular  substance,  such  as  gold,  silver,  copper,  or  lead. 
It  might  be  more  accurate  to  say,  he  thought  of  an  element 
as  a  form   of  activity  determining  the   production,  from 
other  substances,  of  this  or  that  particular  thing.     He  cer- 
tainly attempted  to  picture  material  changes  as  causally 
connected  with  the  inflowing,  or  with  the  outgoing,  of  more 
or  less  of  this  or  that  condition,  or  form,  of  activity.     He 
did  not  seek,  as  almost  all  alchemists  before  and  after  him 
sought,  for  an   inchoate   something,  '  the  soul  of  bodies.' 
He  did  not  regard  the  appearance,  texture,  taste,  smell, 
relative  heaviness,   &c.,   of  particular  bodies  as  garments 
hiding  the  essential  natures  of  the  bodies  ;    he  regarded 
such  properties  rather  as  marks  by  which  one  material 
thing  can  be  distinguished  from  another,  as  signs  by  which 
each  material  thing  can  be  recognized.    But  these  properties 
were  not  enough  for  Bacon.    He  thought  that  this  substance 
has  such  and  such  properties,   has  a   particular  texture, 
colour,  weight,  taste,  and  so  on,  because  it  has  been  formed 
by  the  influence,  on  more  remote  substances,  of  particular 
quantities  of  two,  or  it  may  be  more  than  two,  of  the  four 
elements  by  the  activities  of  which  all  inanimate  things  are 
produced.    Bacon  did  not  think  of  the  generating  interplay 
of  the  elements  as  directed  by  a  something  more  vague  and 
more  universal  than  they,  a  something  which  other  alche- 
mists called  '  primary  matter  ',  and  dreamed  of  as  the  one 
abiding,  immutable  reality  behind  all  changing  appearances. 
The  genuinely  scientific  spirit  of  Roger  Bacon  appears 
in  his  endeavour  to  use  proximate  causes — the  four  elements 
— which  he  could  in  some  degree  control,  in  forming  his 
intellectual  scheme  of  material  mutations,  rather  than  call 
in  a  vague  ultimate  cause,  such  as  primary  matter,  which 
no  one  was  able  to  bring  down  into  vivifying  contact  with 
observed  realities. 


ALCHEMY  AND  CHEMISTRY  311 

I  think  it  may  be  justly  said  that  not  many  students  of 
natural  events,  nowadays,  have  shaken  themselves  quite 
free  from  the  fascination  of  the  alchemical  primary  matter. 
Omitting  the  qualifying  word  primary,  most  men,  including 
men  of  science,  think  of  matter  (if  they  think  of  it  at  all  apart 
from  special  kinds  of  matter)  as  an  indefinite  something 
which  is  the  intangible  basis  of  phenomena.  No  one  can 
say  clearly  what  he  means  by  matter.  All  one  can  say  is 
that  one  gives  a  particular  name  to  each  definite  collocation 
of  sense-impressions,  no  one  of  which  changes  without 
others  of  them  changing  too,  no  one  of  which  is  present  with- 
out the  others  being  present  also  ;  and  that,  for  the  sake  of 
convenience  and  avoidance  of  many  words,  one  calls  each  of 
such  collocations  of  properties  a  particular  kind  of  matter. 

One  word  more  about  Roger  Bacon's  use  of  the  notion 
of  the  four  elements.  I  said  that  he  seemed  to  think  of  an 
element  as  a  condition  of  being  of  this  or  that  particular 
substance,  as  a  condition  which,  interacting  with  another 
condition,  or  with  other  conditions,  determines  the  effects 
that  the  particular  substance  produces  on  the  senses. 
Inasmuch  as  Bacon  speaks  of  natural  agents,  and  places 
coldness,  hotness,  wetness,  and  dryness  among  these,  we 
might  perhaps  translate  his  elements  into  modern  phrase- 
ology by  calling  them  forms  of  energy.  It  would  not, 
perhaps,  be  too  fanciful  to  think  of  Bacon  as  groping  for 
something  which  has  been  made  more  tangible  by  the  pene- 
trative methods  of  investigation,  and  the  modes  of  reasoning 
based  on  the  results  of  such  investigation,  that  have  become 
possible  in  these  later  times.  Might  one  carry  this  fancy 
a  little  further  ?  Several  men  of  science,  notably  Ostwald 
(of  Leipzig) ,  have  recently  set  themselves  the  task  of  changing 
the  language  of  physical  science,  and,  instead  of  thinking  and 
speaking  in  terms  of  matter,  are  endeavouring  to  speak  and 
think  in  terms  of  energy.  Were  Roger  Bacon  living  now, 
one  can  picture  him  joining  in  the  Ostwaldian  adventure. 


312  ROGER  BACON 

In  speaking  of  that  particular  class  of  things  called 
metals,  Roger  Bacon  uses  the  ordinary  alchemical  doctrine 
that  metals  are  formed  by  conjoining  mercury  and  sulphur. 
From  the  directions  which  he  gives  for  purifying  mercury  and 
sulphur,  it  seems  as  if  he  used  the  words  '  mercury '  and 
'  sulphur '  as  names  of  two  definite,  tangible  substances.'  He 
taught  that  the  relative  quantities  of  the  two  components 
have  a  determining  influence  on  the  nature  of  a  metal ;  and 
that  the  degree  of  purity,  of  humidity,  of  coldness,  of  dryness, 
of  hotness  of  each  component  has  an  effect  in  determining 
what  metal  is  produced  by  the  interplay  of  mercury  and 
sulphur.^  Apparently  he  held  that  the  essential  nature  of 
all  metals  is  one  and  the  same,  that  the  differences  between 
metal  and  metal  are  differences  of  accidents,  not  of  essences. 
'  You  can  change  the  accidents,  not  the  substance.'  ^  '  The 
nature  of  all  metals  is  one  in  the  unity  of  species  ;  for  quick- 
silver is  always  of  one  species,  and  there  are  not  found  diverse 
species  of  sulphurs.'  ■*  '  It  may  reasonably  be  concluded  that 
the  diversity  of  natures  and  of  metallic  species  does  not 
come  from  diversity  of  matter,  which  is  always  one  and  the 
same,  but  from  diversity  of  depuration  and  digestion.'  ^ 

In  common  with  all  alchemists,  Roger  Bacon  regarded 
gold  as  the  most  perfect  metal,  and  taught  that  gold  is 
formed  by  the  interaction  of  the  proper  proportion  of  the 
purest  forms  of  quicksilver  and  sulphur.^  If  all  metals  are 
made  of  the  same  two  things — quicksilver  and  sulphur — 
then  all  that  is  needed  to  get  gold  from  other  metals  is  to 
remove  the  infirmities,  to  cure  the  sicknesses,  of  the  other 
metals.  This  seems  to  have  been  Roger  Bacon's  view,  at 
least  when  he  wrote  De  Arte  Chymiae:''     Some  of  the  other 

'  See,  for  instance.  Art.  Chym.,  p.  217. 

^  Art.  Chym.,  pp.  98-102.  ^  Ibid.,  p.  104. 

*  Ibid.,  p.  105.  =  Ibid.,  p.  122. 

*  See,  for  instance,  Optis  Minus,  pp.  375-83  (Brewer's  edition). 

'  See  Art.  Chym.,  pp.  13S-42,  where  he  talks,  somewhat  vaguely, 
of  making  gold. 


ALCHEMY  AND  CHEMISTRY  313 

metals  are  too  humid,  some  are  too  dry,  in  some  coldness  is 
too  predominant,  in  some  there  is  too  much  hotness.  In 
De  Arte  Chymiae,  he  regards  silver  as  a  kind  of  lead  burdened 
by  imperfections.  The  directions  (entitled  De  preparatione 
Lunae  ad  Sulphur)  for  making  silver  from  lead  are  not  very 
unlike  the  modern  method  for  obtaining  pure  silver  from 
argentiferous  lead,  by  cupellation.' 

It  is  not  easy  to  put  an  exact  and  definite  meaning  on 
Bacon's  remarks  about  the  transmutations  of  material  things. 
He  deals  with  transmutation  more  fully  in  De  Arte  Chymiae 
than  in  his  other  writings.     Take  this  passage,  for  instance  : 

'  Let  all  workers  in  alchemy  know  that  true  species  cannot 
be  transmuted.  For  they  say,  and  it  is  said  also  here,  that 
lead  is  always  lead,  even  granted  that  its  impurities  are 
purged  away  so  that  silver  may  be  seen  ;  thus  they  deceive 
men  not  understanding  the  words  of  Aristotle  on  solution. 
To  whom  it  may  be  answered  that  it  is  not  for  us  to  be 
labouring  about  the  transmutation  of  bodies  in  order  to 
make  some  sort  of  being  from  non-being  {ut  faciamus  aliquod 
ens  de  non  ente),  and  to  make  something  from  this  mineral 
that  is  not  of  this  mineral.  But  that  wc  may  reduce  a 
corrupted  mineral  to  an  incorrupted  mineral  .  .  .  Since  lead 
is  a  species  of  silver,  the  sicknesses  of  which  mineral — to  wit, 
softness,  blackness,  and  foulness — have  invaded  it,  when 
these  are  put  aside,  there  is  silver  true  and  good  ;  and  so  it 
is  reduced  to  its  true  mineral,  and  in  accordance  with  its  first 
primary  origin  {secundum  primam  radiccm)  it  is  not  translated 
nor  transmuted  from  its  own  mineral.  Similarly  iron  is  silver, 
but  it  is  corrupted  ...  by  the  power  of  its  impure  sulphur  and 
of  its  impure  quicksilver.  From  which  source  hurtful  things 
enter  it.  to  wit,  blackness,  hardness,  dryness  ;  which  being 
removed,  there  is  good  silver.  In  like  manner  copper  is  the 
soul  and  sister  of  silver,  in  all  its  dispositions,  to  wit,  in  soft- 
ness, in  hardness,  in  fusibility  and  malleability,  but  it  is  red  ; 
we  take  away  from  it  its  redness,  and  then  there  is  genuine 
silver.  Similarly  tin  has  softness,  the  grating  sound  of  teeth, 
and  blackness,  which  being  removed  it  is  reduced  to  silver. 
In  like  manner  silver  is  gold  save  in  its  colour,  because  the 
colour  of  gold  was  taken  away  from  it,  in  its  mineral  state, 

'  Ibid.,  pp.  181-3.    But  on  p.  103  he  says,  '  Lead  will  remain  lead 
even  if  it  looks  like  silver.' 


314  ROGER  BACON 

by  the  power  of  its  quicksilver.  But  we  give  colour  to  it, 
and  then  there  is  good  gold.  This  is  in  keeping  with  what 
is  said  by  Aristotle.  If  the  quicksilver  be  pure  and  bright, 
and  the  sulphur  be  clean  and  red,  and  a  temperate  heat  be 
used,  mineral  gold  is  made  from  these,  in  nature,  after  a  long 
time.  Similarly  if  the  (juicksilver  be  impure,  and  the  sulphur 
be  not  clean,  some  other  mineral  body  is  made  from  these,  in 
accordance  with  the  inward  disposition  of  that  body.  What 
nature  does  in  a  thousand  years,  we  are  able  to  accomplisli 
artificially  in  a  short  time,  perhaps  in  one  day,  or  in  some 
hours,  with  the  proper  medicine,  that  takes  a  long  time  to 
prepare,  by  the  use  of  which  bodies  suffering  fnjm  mineral 
corruptions  arc  reduced  to  uncorrupted  mineral  substances.'  ' 

There  is  an  interesting  passage  on  p.  342  of  De  Arte 
Chymiae  : 

'  Some  speak  of  transmutation.  Some  speak  of  improving 
{de  corrcctione)  .  .  .  Some  say  it  is  necessary  to  transmute, 
they  say  that  form  gives  the  essence  of  a  thing  [dicunt  quod 
forma  dat  esscrei),  but  that  the  essence  of  gold  is  different 
from  the  essence  of  lead  :  therefore  there  is  here  made  a 
transmutation  of  form.  They  who  speak  of  improving  say 
that  when  a  sick  man  is  cured  of  his  sickness  he  is  not 
transmuted  from  one  species  into  another.  Either  reasoning 
is  good.  But  one  of  them  is  better.  .  .  .  Read  what  Avicenna 
says,  and  read  again,  and  fmd  wisdom.' 

Roger  Bacon  taught  that,  in  reasoning  about  natural 
events,  we  have  to  pay  heed  to  matter  as  that  which  may 
become  any  particular  thing,  and  form  as  that  which  differen- 
tiates and  specifies  each  particular  thing.  Matter,  he  said, 
has  a  potentiality  of  becoming  this  or  that  thing  ;  form  is  the 
act  of  becoming  a  special  thing.  He  would  have  observers 
of  nature  study  all  the  conditions  of  existence  of  each 
object  of  sense,  all  the  conditions  by  which  each  is  distin- 
guished from  other  objects.  He  was  never  tired  of  insisting 
on  activity,  effort,  change  ;   he  tried  to  get  at  general  rules 

'■  Art.  Chym.,  pp.  389-95.  On  pp.  217-28  directions  are  given 
for  preparing  the  Elixir.  These  directions  are  untranslatable  into 
definite  words  ;  but  they  often  mention  particular  substances  and 
are  more  practical  than  most  alchemical  receipts  for  making  the 
Elixir. 


ALCHEMY  AND  CHEMISTRY  315 

expressive  of  the  activities  of  natural  agents,  such  as  heat, 
cold,  humidity,  dryness.  The  action  of  an  agent  he  held 
to  be  limited  ;  an  agent  acts  for  a  limited  time  on  a  particular 
object  ;  but  one  action  may  be  followed  by  another,  so  that 
change  may  continue  as  long  as  there  is  any  matter  to  be 
acted  on/ 

On  the  whole  it  seems  to  me  that  while  Bacon  recognized 
the  possibility  of  effecting  many  unlooked-for  changes  in 
material  things,  he  also  recognized  that  there  are  limits  to 
the  changes  which  can  be  effected.  Again  and  again  he 
asserts  that  one  species  of  things  cannot  be  transmuted  into 
another  species.  The  ordinary  alchemical  doctrine  was 
that  species  can  be  transmuted.  This  doctrine  rested  on 
the  conception  of  one  primary  matter,  underlying,  and 
present  in,  all  things.  To  change  one  species  of  things  into 
another  could  be  done,  it  was  commonly  taught,  because  it 
was  possible  to  get  at  the  primary  matter  common  to 
different  species.  Arnald  de  Villanova  said  :  '  Species  can 
be  transmuted  only  by  the  reduction  of  their  matter  to  the 
generic  First  Matter.'  ^ 

Roger  Bacon's  mental  picture  of  material  changes  was 
constructed  without  the  help  of  the  elusive  notion  of  a 
common  substance,  without  the  will-o'-the-wisp  conception 
of  an  invisible,  intangible  basis  of  properties  which  remains 
unchanged  when  properties  change,  is  independent  of  pro- 
perties, and  cannot  be  got  hold  of  by  observing  and  comparing 
properties  of  different  things.  Bacon  condemned  the  notion 
of  a  universal  primary  matter  ;  if  this  notion  were  true,  he 
said  that  everything  in  nature  would  be  essentially  the  same 
as  everything  else.-'  There  are,  it  is  true,  sentences  in  his 
writings  which,  taken  alone,  might  be  read  as  if  he  favoured 
the   notion   of   a   common   matter  ;     but   considering   how 

'  Cf.  Schneider,  loc.  cit. 

■  Waite's  translation  of  The  New  Pearl  of  Great  Price,  p.  315. 

'  Cf.  Opus  Tertium,  xxxviii.  121  (Brewer's  edition). 


3i6  ROGER  BACON 

definitely  he  speaks  against  the  notion  of  one  primary  matter, 
I  do  not  think  stress  can  be  laid  on  a  few  detached  remarks." 

Considering  the  differences  between  the  language  used  by 
Roger  Bacon  and  that  used  by  chemists  now,  it  is  not  unfair 
to  say  that  the  general  aspects  of  the  picture  which  he 
formed  of  material  changes  resemble  those  of  the  picture- 
drawn  by  modern  chemistry.  Ceaseless  change  is  the  mark 
of  both  conceptions  of  natural  events.  Chemists  represent 
the  changes  of  material  things  as  combinations  of  distinct 
kinds  of  matter,  which  they  call  elements  because  none  <jf 
them  has  been  separated  into  unlike  portions  ;  as  decomposi- 
tions of  compounds,  and  as  re-combinations  of  the  unlike 
parts  of  these  compounds.  In  all  these  never-ceasing  muta- 
tions they  trace  the  activity  of  something  which  they  call 
energy,  and  they  recognize  different  kinds  or  forms  of  energy. 
Roger  Bacon  came  nearer  to  this  conception  of  chemical 
changes  than  any  of  his  predecessors,  than  most  of  his 
successors  till  Lavoisier  gave  definite  form  to  the  science  of 
chemistry  towards  the  end  of  the  eighteenth  century. 

Before  summarizing  those  aspects  of  Roger  Bacon's  con- 
ception of  alchemy  which  have  been  dealt  with  in  the 
preceding  pages,  I  ask  the  reader  to  notice  the  place  which 
Bacon  gave  to  alchemy  in  his  arrangement  of  the  sciences. 
He  had  a  passion  for  tracing  connexions  between  the  special 
sciences  which  he  placed  under  the  guidance  of  the  great 
science  Communia  Naturaliiim,  and  for  arranging  the  special 
sciences  in  order  of  dignity  and  importance.     He  placed 

•  One  of  these  passages  occurs  in  Opus  Tertium,  A.  G.  Little's 
edition,  pp.  86-7  :  '  The  hidden  spirit  ...  is  one  of  the  humours, 
namely  that  which  is  blood  in  animals  ;  but  it  has  not  the  name 
of  blood  in  all  [things]  ;  and  therefore  when  reduced  to  the  matter 
common  to  animate  and  inanimate  things  it  loses  the  name  of  blood, 
and  is  called  the  humour  of  warm  and  humid  complexion,  which 
becomes  blood  in  animals,  and  into  which  blood  corrupts  when  it  is 
transformed  from  its  own  heat  and  is  reduced  to  the  original  nature 
of  that  humour  which  is  found  in  all  things.' 


ALCHEMY  AND  CHEMISTRY  317 

alchemy  fourth  of  the  special  sciences.     In  the  Covimunia 
Naturalium,  he  says  :  ' 

*  Of  natural  philosophy  there  are  many  separate  sciences 
.  .  .  for  besides  the  Communia  Naturalium  (i.  e.  conditions 
of  being  common  to  all  the  material  world,  as  motion, 
place,  vacuum,  time,  &c.)  there  are  special  divisions  of  the 
physical  sciences  :  (i)  optics  ;  (2)  astronomy,  judicial  and 
operative  ;  (3)  gravity  {scientia  ponderum  de  gravihus  et 
levihus)  ;  (4)  alchemy  ;  (5)  agriculture  ;  (6)  medicine  ; 
(7)  experimental  science.' 

'  The  study  of  wisdom  ',  Bacon  said,  '  has  two  parts,  one 
speculative,  and  the  other  practical  and  operative.'  Some 
sciences,  he  said,  are  essentially  speculative ;  some  are 
concerned  with  practical  operations.  Alchemy  he  declared 
to  be  partly  speculative  and  partly  practical.  The  follow- 
ing is  Bacon's  description  of  the  scope  of  speculative 
alchemy  :  ^ 

'  There  is  another  science  which  treats  of  the  generation 
of  things  from  the  elements,  and  of  all  inanimate  bodies  ; 
such  as  the  elements,  and  simple  and  compound  liquids 
{humoribus) ;  common  stones,  precious  stones,  marbles  ;  gold 
and  other  metals ;  sulphurs,  salts  and  inks  ;  blue,  vermilion 
and  other  colours ;  oils  and  combustible  bitumens,  and 
an  infinity  of  other  matters  of  which  Aristotle  has  not 
spoken,  of  which  the  natural  philosophers  know  nothing. 
.  .  .  Ignorance  of  these  matters  involves  ignorance  of  every- 
thing about  natural  things.  .  .  .  The  generation  of  man, 
and  beasts,  and  vegetables  is  from  elements  and  humours 
{ex  humoribus)  and  corresponds  with  [commmiicat  cum) 
the  generation  of  inanimate  things.  .  .  .  This  science  is 
speculative  alchemy,  which  reasons  about  all  inanimate 
things,  and  the  whole  generation  of  things  from  elements.' 

It  is  instructive  to  compare  Bacon's  description  of  the 
business  of  speculative  alchemy  with  what  Paracelsus  said  of 
the  aim  of  alchemy,    Paracelsus  lived  about  three  centuries 

•  I  quote  from  Brewer's  translation  in  the  preface  to  his  edition 
of  Opera  inedita,  p.  li. 

-  Opus  Tertium,  xii.  39  (Brewer). 


3i8  ROGER  BACON 

after  Roger  Bacon  ;  he,  too,  was  a  student  of  nature,  and 
a  rebel  against  authority.  His  conception  of  alchemy  was 
much  hazier,  mucli  less  scientific,  than  Bacon's.  He  said  : 
'  To  grasp  the  invisible  elements,  to  attract  them  by  their 
material  correspondences,  to  control,  purify,  and  transform 
them  by  the  power  of  the  Spirit — this  is  true  Alchemy.' 

I  have  already  quoted  from  Opus  Tcrtiujn  what  Bacon 
says  of  practical  alchemy  (p.  302).  It  teaches  how  to  make 
'  noble  metals  and  colours,  and  many  other  things,  better 
and  more  copiously  by  art  than  nature.  ...  It  provides 
money  for  a  state. ...  It  teaches  the  means  of  prolonging  life.' 

From  what  Bacon  says  about  speculative  alchemy,  it  is 
evident  that  he  did  not  regard  that  science  as  purely  intro- 
spective. He  founded  it  on  observation  and  experiment. 
Its  business  is  to  reason  on  the  data  of  experience,  so  as  to 
come  at  just  general  conclusions  regarding  '  the  generation  of 
all  things  '.  Practical  alchemy  takes  some  of  the  results 
of  the  reasoning  of  speculative  alchemy,  and  applies  them 
to  certain  specific  practical  purposes. 

Let  me  now  bring  together  wliat  I  have  said  about  Roger 
Bacon's  attitude  toward  alchemy  and  chemistry. 

I.  Roger  Bacon  laid  stress  on  the  usefulness  of  alchemical 
knowledge.  He  said  that  the  importance  of  a  branch  of 
knowledge  is  largely  dependent  on  the  utility  of  it.  He 
therefore  sought  to  base  his  reasoning  about '  the  generation 
of  things  ' — which  study  he  took  to  be  the  business  of 
alchemy — on  facts  gained  by  observation  and  experiment. 
He  was  not  altogether  happy  in  his  treatment  of  what  we 
now  call  chemical  changes.  He  does  not  appear  to  have 
studied  these  events  much  at  first-hand.  He  followed  the 
footsteps  of  others.  At  the  same  time  he  insists  on  the 
necessity  to  the  alchemist  of  a  practical  acquaintance  with 
the  methods  of  distilling,  calcining,  separating,  and  the  like. 
He  recognized  and  unhesitatingly  recommended  the  only 
way  to  accurate  and  fruitful  knowledge  of  the  changes  of 


ALCHEMY  AND  CHEMISTRY  319 

material  things.  In  some  branches  of  nature-knowledge 
he  showed  wise  judgement  in  selecting  the  kind  of  facts 
which  ought  to  be  studied  if  real  advance  was  to  be  made. 

II.  When  one  remembers  that  Roger  Bacon  lived  before 
the  ferment  of  the  Renaissance  had  become  fully  active,  and 
that  he  was  a  Franciscan  monk,  trained  in  scholastic  ways 
of  thinking,  and  vowed  to  obedience,  one  cannot  but  be 
admiringly  astonished  at  his  boldness  in  pleading  for  freedom 
of  reasoning  on  the  results  of  experience.  It  is  true  that  he 
told  the  '  unlearned  crew  '  that  they  must  follow  authority, 
and  that  he  professed  intellectual  obedience  to  the  Church  ; 
nevertheless,  his  writings  are  singularly  outspoken  and  bold. 

III.  That  he  might  form  an  intellectual  picture  of  how 
natural  changes  proceed,  Roger  Bacon  used  the  instrument 
that  his  predecessors  used,  namely,  the  four  elements — earth, 
fire,  air,  water  ;  dryness,  hotness,  coldness,  wetness.  But 
he  used  this  mechanism  in  a  manner  different  from,  and  more 
suggestive  than,  that  wherein  it  was  used  by  other  alchemists. 

IV.  Roger  Bacon  protested  against,  and  completely  dis- 
carded, the  central  conception  of  alchemy.  He  would  have 
nothing  to  do  with  the  universal  primary  matter,  which  was 
the  chief  stock-in-trade  of  his  predecessors  and  of  most  of 
those  alchemists  who  came  after  him. 

V.  Having  abolished  the  primary  matter,  the  '  soul  of 
bodies  ',  Roger  Bacon  recognized  the  existence  of  distinct 
material  things,  each  characterized  and  distinguished  from 
all  others  by  its  own  particular  properties. 

VI.  Roger  Bacon  realized,  more  fully  than  most  of  the 
alchemists,  that  effort,  activity,  change,  are  the  marks  of 
physical  things.  He  seems  to  have  been  feeling  his  way 
toward  a  universal  activity,  a  conception  not  wholly  unlike 
the  modern  notion  of  energy. 

By  his  abandonment  of  the  conception  of  a  primary  matter, 
by  his  insistence  on  dealing  with  particular  objects  of  sense 
and  their  interactions,  by  his  recognition  of  the  importance 


320  ROGER  BACON 

of  the  actions  of  natural  agents  on  particular  substances 
whereby  other  substances  are  produced,  and  by  the  breadth 
and  scientific  character  of  his  conception  of  the  objects  and 
range  of  speculative  alchemy,  Roger  Bacon  stands  out  from 
the  crowd  of  ordinary  alchemists,  and  is  worthy  of  being 
placed  among  the  chemists.  The  justness  of  classing  him 
as  a  chemist,  rather  than  as  an  alchemist,  is  supported  by 
his  avoidance  of  many  of  the  purely  speculative  questions 
which  were  the  life  and  soul  of  the  scholastic  philosophy 
wherein  he  was  born  and  bred. 


XII 

ROGER  BACON  AND  GUNPOWDER 

By  Lieut.-Colonel  H.  W.  L.  HIME,  (late)  Royal 
Artillery 

The  exact  date  of  Roger  Bacon's  Epistola  de  Secretis 
Operihus  Artis  et  Naturae  ct  de  Nullitate  Magiac  is  uncertain  ; 
but  it  is  quite  certain  that  the  work  was  written  many  years 
before  the  Opus  Majus  and  the  Opus  Tcrtiiim,  both  of  which 
lie  within  the  period  1265-8.  In  the  latter  works  Bacon 
says  that  certain  play-toys,  '  crackers,'  were  well  known  in 
many  places,  and  in  the  Opus  Tcrtiurn  he  explains  to  the 
Pope  that  the  explosive  contained  in  them  was  a  mixture 
of  saltpetre,  charcoal,  and  sulphur.'  On  the  other  hand, 
in  the  De  Secretis  he  took  extraordinary  care  to  conceal,  by 
cryptic  methods  and  anagrams,  the  names  and  proportions 
of  the  ingredients  which  formed  the  explosive.  Circum- 
stances had  totally  changed  in  the  lapse  of  years  ;  the  com- 
position of  gunpowder,  which  must  have  been  known  all 
along  to  his  laboratory  assistants,  had  been  divulged,  and 
the  first  use  made  of  the  deadly  mixture  was  for  the  amuse- 
ment of  children.-  We  shall  not  be  far  wrong  in  dating  the 
De  Secretis  at  1248  ;  a  date  which  would  receive  considerable 
support  from  the  dedication  of  the  tract  to  William,  Bishop 
of  Paris,  who  died  in  1249,  if  the  dedication  should  prove 
to  be  authentic. 

Bacon  attacks  Magic  in  this  book  on  the  ground  that 

'  Un  Fragment  inedit  de  I'Opus  Teriiiim  de  Roger  Bacon,  ed.  by 
Prof.  P.  Duhem,  1909,  p.  154. 

-  '  Experimentum  hujus  rei  capimus  ex  hoc  ludicro  puerili,' 
Opus  Majus,  1733,  p.  474. 

1689  Y 


322  ROGER  BACON 

science  and  art  can  exhibit  far  greater  wonders  than  the 
alleged  wonders  of  the  Black  Art,  and  to  prove  his  point  he 
enumerates,  in  the  first  eight  chapters,  a  number  of  wonders 
which  (he  believed)  art  could  produce  and  magic  could  not. 
Everything  is  sufficiently  clear  until  we  reach  the  ninth, 
tenth,  and  eleventh  chapters,  and  these  are  unintelligible  as 
they  stand.  Now,  it  is  past  belief  that  a  man  of  commanding 
genius  should  have  deliberately  stooped  to  write  page  after 
page  of  nonsense.  The  three  chapters,  therefore,  must 
have  some  meaning,  hidden  from  us  though  it  be.' 

There  is  nothing  extraordinary  in  lighting  upon  cryptic 
writing  of  the  thirteenth  century.  During  that  period,  and 
for  long  afterwards,  '  superior  knowledge  excited  only 
terror  and  suspicion.  If  it  was  shown  in  speculation,  it  was 
called  heresy.  If  it  was  shown  in  the  study  of  nature,  it 
was  called  magic'  -  Alchemy  was  considered  a  diabolical 
art,  and  was  condemned  by  the  Pope  in  1307,^  a  few  years 
after  Bacon's  death.  The  alchemists  therefore  were  forced 
in  self-defence  to  hide  their  dangerous  lore  as  best  they  might, 
and  seven  of  the  methods  they  employed  are  mentioned  by 
Bacon  in  a  moment  of  suspicious  candour  : 

(i)  Characteres  ct  carmina  ; 

(2)  Enigmatic  and  figurative  words  ; 

(3)  Consonants  only,  without  vowels  ; 

(4)  Letters  from  different  alphabets  ; 

(5)  Specially  devised  letters  ; '' 

'  '  Quand  le  sens  litteral  est  absurde,  incoherent  ou  obscur  .  .  . 
on  doit  presumer  un  sens  detourne.'  Langlois  et  Seignobos,  Introd. 
aux  Etudes  Historiqiies,  p.  127. 

-'  Lecky's  Rise,  &c.,  of  Rationalism  in  Europe,  i.  275. 
^  Prof.  J.  B.  Bury,  History  of  Freedom  of  Thought,  191 3,  p.  65. 
A  century  after  Bacon,  Langland  wrote  : 

Ac  astronomy e  is  an  hard  thyng,  and  jn-el  for  to  knowe  ; 
Geometrie  and  geomesie,  so  gynful  of  speche,  &c. 

Vision  of  Piers  the  Plowman,  Passus  x. 
*  '  Lines,  circles,  scenes,  letters,  and  characters.'    Marlowe,  Doctor 
Faustus,  Sc.  i. 


GUNPOWDER  323 

(6)  Prearranged  geometric  figures  ; 

(7)  Ars  notatoria,  a  system  of  abbreviations. 

Bacon  has  occasionally  availed  himself  in  chaps,  ix,  x,  and 
xi  of  some  of  these  methods,  which  apply  chiefly  to  words 
and  phrases  ;  but  he  has  not  dropped  a  hint  to  indicate  the 
general  method  which  underlies  the  whole  of  chaps,  ix  and  x. 
Some  of  the  early  cryptic  methods  were  too  tedious  and 
some  were  too  complicated  to  be  used  throughout  the  whole 
of  these  two  chapters  ;  and  the  method  he  adopted  (as  the 
result  will  show)  was  that  clearly  described  long  afterwards 
by  G.  B.  della  Porta,'  and  called  in  England  '  the  Argyle 
cipher  '.-  Thackeray  has  given  a  capital  example  of  this 
cipher  in  Esmond  : 

'  \The  King  will  take]  medicine  on  Thursday.  His  Majesty 
is  better  than  he  hath  been  of  late  .  .  .  Madame  Maintenon 
continues  well  .  .  .  [the  Viscount  Castlewood's  passports]  were 
refused  to  him,  'twas  said  ;  his  lordship  being  sued  by 
a  jeweller  for  Vaisselle  plate  .  .  .  'Tis  a  pity  such  news  should 
get  abroad  [atid  travel  to  England]  about  our  young  nobility 
here.  Mademoiselle  Meruel  has  been  sent  to  Fort  I'Evesque  ; 
they  say  she  ordered  not  only  plate,  but  furniture,  and  a 
carriage  and  horses  [u7ider  that  lord's  name],  of  which  extrava- 
gance his  unfortunate  Viscountess  knows  nothing,'  &c. 

The  essential  words  are  within  brackets  ;  and  it  is  evident, 
even  from  this  much  abridged  version  of  Colonel  Esmond's 
letter,  that  the  cipher  is  one  which  it  is  almost  impossible 
to  solve  without  the  key,  unless  the  matter  in  question  is 
known  beforehand — the  subject  of  the  cryptic  statement. 
Here,  then,  we  should  have  found  ourselves  left  in  utter 
darkness  were  it  not  for  a  ray  of  light  afforded  by  chap.  xi. 
There  we  are  told  that  something,  in  connexion  with  saltpetre 

'  De  Occultis  Literarum  Notis,  1606,  p.  140.  On  p.  143  Porta  gives 
a  plate  showing  the  key  to  the  cipher,  which  is  simply  a  blank  sheet 
of  paper  exactly  the  same  size  as  the  paper  on  which  the  cryptic 
statement  is  written.  Rectangular  slits  are  cut  in  the  key  in  such 
a  way  that  when  it  is  laid  on  the  statement  only  the  essential  words 
are  visible.  -  Penny  Encyclopaedia,  art.  '  Cipher,' 

Y  2 


324  ROGER  BACON 

and  sulphur,  produces  an  explosion,'  and  we  know  that  this 
something  is  charcoal.     Since  chap,  xi  is  concerned  with  the 
composition  and  effects  of  this  mixture,  what  more  probable 
than  that  chaps,  ix  and  x  should  deal  with  its  ingredients 
separately — or  at   least   with  saltpetre  and  charcoal,   for 
sulphur  was  so  simple  and  common  a  drug  that  Bacon  was 
not  likely  to  dwell  upon  it  ?    Now,  towards  the  end  of  chap,  x 
Bacon  speaks  without  disguise  of  charcoal  under  the  name 
of  the  wood  from  which  it  is  made,-  and  mentions  the  two 
trees,  hazel  and  willow,  which  give  the  best.     He  significantly 
adds  that  when  charcoal  is  added  to  proper  proportions  of 
certain  other  substances,  something  noteworthy  happens.^ 
Since,  then,  charcoal  is  one  of  the  subjects  of  these  two 
chapters,  it  becomes  all  the  more  probable  that  saltpetre 
forms  another.     Bacon  was  writing  but  a  few  years  after 
its  discovery,  and  nothing  could  be  more  natural  than  that 
the  great  alchemist  should  bestow  his  attention  upon  the 
preparation   of   the   new   salt.     This   hypothesis   explains 
simply   and   completely   the   most   remarkable   feature  of 
chaps,   ix  and  x — the  series  of  common  and  well-known 
alchemical  terms  and  phrases,  referring  undoubtedly  to  the 
preparation  of  either  saltpetre  or  gold,  which  are  scattered 
and  hidden  among  incoherent  maunderings  about  chalk  and 
cheese,  philosophic  eggs  and  Tagus  sand.     But  how  could 
the  preparation  of  gold  lead  up  to  the  recipe  for  an  explosive 
with  which  chap,  xi  ends  ?    There  is  no  connexion  whatever 
between  gold  and  gunpowder,  while  the  connexion  between 
saltpetre  and  gunpowder  is  of  the  closest  possible  kind. 
Before  giving  a  recipe  for  gunpowder  it  was  absolutely 
necessary  for  Bacon  to  describe  the  method  of  refining  the 

'  '  Tonitruum  et  coruscationem.' 

-  Aeneas  Tacticus  adopts  the  same  mode  of  expression,  Polior- 
ketikon,  XXXV.  79. 

'  Si  vero  partes  virgulti  coryli  aut  salicis  multarum  just4  rerum 
serie  apte  ordinaveris,  unionem  naturalem  servabunt  :  et  hoc  non 
tradas  obhvioni,  quia  valet  ad  multa. 


GUNPOWDER  325 

lately  discovered  saltpetre,  without  which  his  recipe  would 
.have  been  worthless  ;  and  he  took  advantage  of  the  close 
similarity  between  the  alchemical  preparation  of  gold  and 
the  refining  of  saltpetre  to  conceal  the  real  import  of  his  tract. 
By  the  title  of  the  last  three  chapters — '  On  the  Method  of 
Making  the  Philosopher's  Stone  ' — and  by  constantly  harping 
on  gold,  he  endeavoured  to  distract  and  deceive  his  ordinary 
readers,  leading  them  to  believe  that  he  was  writing  about 
gold  when  he  was  really  treating  on  saltpetre. 

The  unnamed  substance  saltpetre,  then,  is  the  principal 
subject  of  chaps,  ix  and  x,  and  our  course  is  clear.  We  must 
treat  these  chapters  as  we  should  treat  Colonel  Esmond's 
letter  were  the  brackets  omitted  ' — we  must  make  shift  to 
insert  them.  We  must  bracket  together  the  phrases  and 
sentences  relating  to  the  real  subject  of  these  chapters,  the 
familiar  alchemical  expressions  relating  to  saltpetre.  On 
doing  so  we  shall  find  a  connected  and  rational  method  of 
refining  the  salt. 

In  the  following  reproduction  of  chaps,  ix  and  x  I  have 
used  the  Esmond  brackets,  but  I  have  not  thought  it 
necessary  to  reprint  all  the  padding  which  connects  them. 
All  omissions,  however,  are  shown  by  dots.  No  word  of 
the  bracketed  phrases  has  been  changed,  altered,  added, 
or  suppressed,  nor  has  the  order  of  the  words  been  altered. 
Nothing  has  been  done  but  to  indicate  by  brackets  the  mis- 
leading interpolations. 

Cap.  IX 
De  modo  faciendi  ovum  philosophorum. 

Dico  igitur  tibi  quod  volo  ordinari  ^  quae  superius  narravi 
exponere,  et  ideo  volo  ovum  philosophorum  et  partes 
philosophici  ovi  investigare,  nam  hoc  est  initium  ad  alia. 

'  That  is,  supposing  we  knew  the  subject  of  his  letter. 
'  Another  reading  is  '  ordinate  '. 


326  ROGER  BACON 

[Calcetn  '  igituy  diligenler]  aquis  alkali  et  aliis  aquis  acutis 
[purifica],  et  variis  contritic^nibiis  cum  salibus  confrica  '  et 
pluribus  assationibus  concrcma,  [ut  Jiat  terra  pur  a  penitus 
lihcrata  ah  aliis  dementis  ^],  quam  tibi  pro  meae  longitudinis 
statura  diKnam  duco.  Intellige  si  pcjtcs,  quia  proculdubio 
erit  compositum  ex  elementis,  et  ideo  est  pars  lapidis  qui  non 
est  lapis/  et  est  in  quolibet  homine  et  in  quolibet  loco 
hominis.  .  .  .  Deinde  oleum  ad  modum  crocei  casei  et  viscosi 
accipias/  primo  ictu  insecabile,  cujus  tota  virtus  ignea 
dividatur  et  scparetur  per  distillationem  ;  [dissolvatur '' 
aiitcm  in  atjiia]  acuta  temporatae  acuitatis  [cum  igne  levij 
ut  dccoqiiatur  quatcnus  scparetur  pinguedu  sua  '],  sicut 
pinguedo  in  carnibus.  .  ,  .  Melius  CNt  tamen  ut  decoquatur 
in  aquis  temporatis  in  acuitate  [donee  purgetur  et  dealbctur]. 

'  To  lull  suspicion  he  calls  natural  saltpetre  chalk,  a  verbum 
figurativutn.     Other  manuscripts  read  '  sal  '. 

■  '  Tere  ipsum  fortiter  cum  aqua  salis  communis.  .  .  .  Ablue  in 
aceto  acerrimo.'  The  section  '  Nitri  Separatio  '  of  '  Aristoteles,  de 
Perfect©  Magisterio  ',  in  the  Theatrum  Chemiciim,  ed.  by  Zetzner  ; 
a  collection  of  alchemical  tracts  of  the  Middle  Ages,  iii.  68. 

Almost  literally  translated  by  Whitehorne  :  '  clarified  and  from 
earthc  and  grosse  matter  diligently  purged.'  Certain  Waits  jor  the 
ordering  of  Souhiiers  in  Battelray,  London,  1560. 

••  i.e.  the  lapis  Assius  =  saltpetre.  We  have  here  unmistakably 
a  verbum  aenigmaticxtm.  The  efflorescence  of  the  stone  of  Assos, 
which  was  unknown  to  the  crowd,  was  of  course  '  not  a  stone  ', 
although  called  so.  The  philosopher's  stone,  which  was  well  known 
by  name  to  the  crowd,  was  likewise  '  not  a  stone  ',  although  called  so : 

.  .  .   'tis  a  stone 
And  not  a  stone  ;  a  spirit,  a  soul,  and  a  body. 

Jonson's  Alchemist. 
Bacon  avails  liimself  of  the  ambiguity  of  the  phrase,  '  stone  which  is 
not  a  stone,'  to  support  the  delusion  created  by  the  title  of  the 
chapter,  and  confirm  the  unwary'  in  the  belief  that  the  philosopher's 
stone  is  under  discussion,  instead  of  saltpetre. 

■^  He  passes  suddenly  from  chalk  to  cheese — yellow  cheese,  laughing 
openly  in  his  reader's  face. 

*  i.  e.  the  cleansed  natural  saltpetre. 

'  '  Put  the  jar  on  a  gentle  fire.'  Hassan-er-Rammah  (1275-95)  in 
Reinaud  and  Fave's  Dii  Feu  Gregeois,  Paris,  1875,  P-  20. 

^  '  The  mother  liquid  is  boiled  until  the  scum  ceases  to  rise.' 
Waltham  Abbey  process,  in  the  ofi&cial  Handbook  of  the  Manufacture 
of  Gunpowder,  by  Capt.  F.  M.  Smith,  R.A.,  1871. 


GUNPOWDER  ^27 

Aquae  vero  salutaris  exaltatio  fit  ex  igne  sicco  vel  humido  ; 
et  [iteretur  distillatio]  ut  eft'ectum  bonitatis  recipiat  sufficicnter 
[donee  rectificctur  :  rcctificationis  novissima  signa  sunt  candor 
ct  crystallina  scrcnitas  '] ;  et  cum  caetera '  nigrescunt  ab  igne 
hoc  albescit,  mundatur,  serenitate  nitescit  et  splendore 
mirabUi.  [Ex  hac  aqua]  et  terra  sua  argentum  vivum 
generatur,  quod  est  sicut  argentum  vivum  in  mineralibus, 
et  quando  incandidit  hoc  modo  [materia  congclatur.  Lapis 
vero  Aristotelis,  qui  non  est  lapis,  ponitur  in  pyramide  in  loco 
calido  '.] 

Cap.  X 

De  codem,  sed  alio  modo.* 

Transactis  annis  Arabum  sexcentis  et  duobus,  rogasti  me 
de  quibusdam  secretis.  [Accipe  igitur  lapidem^  ct  calcina 
ipsum]  assatione  leni  et  contritione  forti  sive  cum  rebus 
acutis.  [Sed  in  fine  parum  commiscc  de  aqua  dulci ;  ct 
medicinam  laxativam '  componc  de]  septem  rebus  .  .  .  vel  de 
cjuot  vis  ;  sed  quiescit  animus  mens  in  [duabus  rebus 
quarum  proportio  melior  est  in  sesquialtera  proportionc  '']  vel 
circiter,  sicut  te  potest  docere  experientia.  [Resolve^]  tamen 
aurum  ^  [ad  ignem  et  mollius  cale/ac].     Sed  si  mihi  credas, 

'  '  Clear  and  fair  and  of  an  azure  colour.'     Whitehome. 

■  i.  e.  the  scum  and  impurities. 

'  i.e.  '  to  drie  throughly.'     Wliitehorne. 

*  This  repetition  corresponds  with  Whitchorne's  second  process. 

'  i.e.  the  crystals  just  obtained. 

'  A  powder  to  purge,  or  to  purify  and  clarify.  '  Prencz  de  la 
chaulx  vive  et  de  I'eau  de  pluye  .  .  .  et  les  brouillez  bien  ensemble,  et 
puis  le  laissez  reposer  .  .  .  et  se  fera  forte  lexive  .  .  .  Prenez  de  la 
lexive  dessus  dicte,  et  mettez  vostre  salpetre  dedans,'  &c.  '  Livre  de 
Canonnerie.'  &c.,  which  although  not  published  until  1 561 ,  appears  to 
belong  to  the  end  of  the  fifteenth  century.  In  Reinaud  and  Fav6, 
pp.  146-7. 

'  Bacon  does  not  name  the  two  substances  he  alludes  to,  but 
Whitehome  names  two  and  prescribes  the  same  proportions  :  '  Two 
parts  of  unslacked  lime  and  three  of  oke  asshes.' 

^  Treating  ostensibly  on  gold.  Bacon  is  obliged  to  use  resolve  for 
dissolve. 

''  The  alchemical  preparation  of  gold  had  much  in  common  with 
the  refining  of  saltpetre.  In  the  '  Nitri  Preparatio  '  of  Bernard 
and  Penoti's  Theatrum  Chemiciim,  iii.  78,  we  read  :  '  Fac  postmodum 


328  ROGER  BACON 

accipias  unam  rem,  hoc  est  secretum  secretorum,  et  naturae 
potcns  miraculum.  [Mixto  '  if^itur  ex]  duobus,  aut  ex 
pluribus,  aut  [Phocnicc  -],  quod  est  animal  singulare, 
[adjuni^c,  et  incorpora  per  fortcm  mutiim  ;  cui  si  liquor  calidus 
adhibeatur/  habebis  proposilum  ultimum  *\.  Sed  postea 
coelestis  natura  debilitatur  si  aquam  infundis  ter  vel  quater. 
Divide  igitur  debile  a  forti  in  vasis  diversis,^  bi  mihi  credas. 
yEvacuato  '■  if^iiur  quod  bonum  est.]  Iterum  adhibe  pulvcrem, 
et  aquam  (juac  remansit  diligenter  exprime,  nam  pro  certo 
partes  puhcris  dcducet  nun  incorporatas.  Et  ideo  illam 
aquam  per  se  coUige,  quia  pulvis  exsiccatus  ab  ea  habet 
incorporari  medicinae  laxativae  .  .  .  [Re^yra  cum  pistillo,^ 
et  conf^rei^a  inatcriam  ut  potes,  et  aquam  separa  paulatim]  et 
rcdibit  ad  statum.  Quam  acjuam  exsiccabis,  nam  continet 
pulvcrem  •'  et  aquam  medicinae,  quae  sunt  incorporanda 
sicut  pulvis  principalis. 

When  the  bracketed  words  and  phrases  in  the  foregoing 
pages  are  read  or  written  consecutively.'  it  will  be  found 

de  CO  per  omnia  ut  dicam  in  preparatione  auri,  id  est,  destilla  per 
alambicum  et  congcla,'  &c. 

'  i.  e.  to  the  laxative. 
A  verbxtm  aenigmaticnm.  The  Phoenix  is  a  singular  animal,  as 
Bacon  justly  observes,  inasmuch  as  it  springs  from  its  own  ashes.  Its 
name,  therefore,  may  be  figuratively  used  with  perfect  propriety  to 
denote  animal  charcoal,  an  efficacious  agent  in  clarifying  solutions  of 
impure  saltpetre.     Bloxam's  Chemistry,  8th  ed.,  p.  488. 

'  Bacon  appears  to  have  poured  the  hot  solution  upon  the  laxative, 
precisely  as  Clarke  directs  in  his  Natural  History  of  Nitre,  London, 
1670,  p.  42  :  '  Pour  the  hot  liquid  on  ashes  .  .  .  'tis  no  matter  how 
soon  you  let  it  run  off  the  ashes  again.' 

*  i.  e.  the  removal  of  the  insoluble  impurities. 

5  '  Then  pour  it  into  the  other  jar.'  Hassan,  in  Reinaud  and 
Fav6's  Du  Feu  Gregeois,  p.  2 1 . 

''  i.e.  into  a  cr^-stallizing  jar. 

'  '  The  solution  is  kept  in  constant  agitation  by  poles  while  cooling.' 
Waltham  Abbey  Regs. 

^  '  The  mother  liquid,  from  which  the  saltpetre  flour  has  been 
deposited,  is  boiled  dowTi  and  cr\-stallized.'  Bloxam's  Chemistry, 
8th  ed.,  p.  488. 

^  They  will  be  found  collected  and  translated  in  Gunpowder  and 
Amviunition,  by  the  present  writer,  Longmans,  1904,  chap,  ii  ;  where 
the  Waltham  Abbey  method  is  given  also,  to  admit  of  comparison, 
in  Table  I. 


GUNPOWDER  329 

that  the  method  of  refining  saltpetre  devised  about  124S 
by  a  persecuted  monk  falls  little  short  of  the  modern  method 
pursued  at  Waltham  Abbey,  though  founded  on  the  experi- 
ence of  centuries  and  supported  by  all  the  help  a  Government 
could  give. 

It  would  be  presumptuous  to  suggest  that  the  foregoing 
solution  of  Bacon's  steganogram  is  free  from  error  ;  but 
whatever  errors  may  be  found,  there  can  at  least  be  little 
doubt  that  the  occult  meaning  of  the  two  chapters  is  the 
refining  of  saltpetre.  One  sentence,  two  sentences,  or  even 
more,  might  be  selected  from  the  description  of  almost  any 
long  chemical  process  which  would  apply  with  equal  pro- 
priety to  some  other  process  ;  but  it  is  incredible  that  a 
long,  varied,  and  connected  process,  such  as  the  refining  of 
saltpetre,  could  be  extracted  by  any  method  from  documents 
professedly  devoted  to  the  philosopher's  stone,  unless  this 
process  had  been  designedly  inserted  there,  piecemeal  or 
whole,  by  the  author  himself.  For  the  figurative  interpre- 
tation given  of  two  or  three  words  and  phrases,  we  have 
Bacon's  own  warrant.  He  threatened  to  employ  verba 
acniomatica  and  verba  figurativa,  and  he  has  been  taken  at 
his  word  ;  with  the  result  that  a  rational  chemical  process 
has  been  extracted  from  what  was  previously  unintelligible. 

Having  said  all  he  had  to  say  about  the  ingredients, 
Bacon  proceeds  to  deal  with  their  mixture  in  chap,  xi,  in 
which  he  employs  a  different  cryptic  method. 


Cap.  XI 

De  eodem,  tamen  alio  nwdo. 

Annis  Arabum  630  transactis,  petitioni  tuae  respondeo  in 
hunc  modum  .  .  .  Item  pondus  totum  30.  Sed  tamen  salis 
petre  luru  vopo  vir  can  utriet  sulphuris  ;  et  sic  facies 
tonitruum  et  coruscationem,  si  scias  artificium.  Videas 
tamen  utrum  loquor  enigmate  aut  secundum  veritatem. 


330  ROGER  BACON 

Omitting  the  anagram,  the  translation  is  :  'In  this  630th 
year  of  the  Hijra  I  comply  with  your  request  as  follows.  .  .  . 
Let  the  total  weight  (of  the  ingredients)  be  30.  However, 
of  saltpetre  ...  of  sulphur  ;  and  with  such  a  mixture  you 
will  produce  a  bright  flash  and  a  thundering  noise,  if 
you  know  "the  trick".  You  may  find  (by  actual  experi- 
ment) whether  I  am  writing  riddles  to  you  or  the  plain 
truth.' 

The  mention  of  a  flash  and  a  l(jud  noise  indicates  plainly 
that  we  have  here  to  do  with  an  explosion.  But  a  mixture 
of  saltpetre  and  sulphur  will  not  explode.  Therefore  the 
name  of  some  third  substance  which  will  render  the  mixture 
explosive  must  be  concealed  in  the  anagram,  luru  vopo  vir 
can  utrict.  The  construction  of  the  second  clause  of  the 
second  sentence,  ct  sic  fades,  Ike,  shows  that  the  anagram 
must  contain  some  verb,  such  as  take  or  mix,  in  the  impera- 
tive mood.  We  may  expect  the  name  of  some  unit  of 
weight,  or  the  word  partes  (parts),  and  the  numbers  of  the 
weights  or  parts.  Now,  so  much  information  could  not 
be  conveyed  to  us  by  the  twenty  letters  of  the  anagram. 
Therefore  Bacon  must  have  had  recourse  to  the  seventh 
and  last  of  the  methods  of  concealing  secrets  enumerated 
in  the  eighth  chapter  of  the  Dc  Secretis,  the  ars  notatoria  or 
shorthand,  of  which  he  thought  highly.' 

Rearranging  the  letters  of  the  anagram,  we  get : 

RVIIPARrVNOLXORULVET 

and  combining  these  letters  into  groups  : 

R.   VII.    PART.   v.    NOV.    CORUL.   V.    ET 

The  second  sentence  of  the  above  passage  therefore  reads  : 
'  sed  tamen  salis  petre  recipe  vii  partes,  v  novelle  coruli,''  v 

'  Majus  artificium  occultandi  .  .  .  que  est  ars  notandi  et  scribendi 
ea  brevitate  qua  volumus  et  ea  velocitate  qua  desideramus  ;  cap.  viii. 
-  In  chap.  X  he  says  '  willow  or  hazlewood  '  ;    having  discovered 


GUNPOWDER  331 

et  sulphuris,'  that  is,  '  but  take  7  parts  of  saltpetre,  5  of 
young  hazelwood  (charcoal),  and  5  of  sulphur  '  ;  and  the 
recipe  for  the  explosive  is  : 

Saltpetre  .41-2  parts 

Charcoal       ....       29-4 
Sulphur  29-4      „ 


loo-o 


This  mixture  will  explode  '  if  you  know  the  trick  '  ;— if  you 
use  pure  saltpetre,  incorporate  the  ingredients  thoroughly, 
keep  the  powder  dry,  and  avoid  subjecting  it  to  undue 
pressure. 

It  is  clear  that,  though  invariably  attached  to  iitri,  the 
word  et  does  not  belong  to  the  anagram,  which  thus  consists 
of  eighteen  letters.  Now,  the  solution  of  these  eighteen 
letters  yields  thirty  letters,  a  fact  which  probably  explains 
the  first  short  sentence,  item  pondus  totum  jo.  Bacon 
wished  thereby  to  make  known  to  his  correspondent  the 
number  of  letters  in  the  solution. 

Such  is  the  solution  of  Bacon's  first  anagram.  The  second 
anagram,  which  is  contained  in  the  same  chapter,  remains 
unsolved. 

It  is  not  to  be  supposed  that  Bacon's  claim  to  the  posses- 
sion of  gunpowder  rests  solely  upon  the  foregoing  solution 
of  his  first  anagram  ;  for  it  can  be  proved  quite  independently 
that  he  possessed  an  explosive  when  the  Dc  Secretis  was 
written. 

The  igneous  bodies  of  which  Bacon  speaks  fall  into  two 
classes.  The  first  class  are  incendiaries.  '  Incendiaries  ',  he 
tells  us,   '  may  be  made  from  saltpetre,  or  petroleum,  or 

experimentally  that '  light  woods  (should  be)  selected  for  the  prepara- 
tion of  charcoal  for  gunpowder,  because  they  yield  a  lighter  and  more 
easily  combustible  charcoal.'  Bloxam's  Chemistry,  8th  ed.,  1895, 
p.  490- 


J32  ROGER  BACON 

maltlui,'  or  naphtha,  mixed  with  other  substances.  ...  To 
these  are  aihed  Greek  fire  and  many  other  incendiaries.' ' 

But  side  by  side  with  these  passages  we  find  descriptions 
of  igneous  compositions  of  a  totally  different  kind.  '  There 
arc  other  natural  W(jndcrs.  We  can  produce  in  the  air 
sounds  loud  as  thunder  and  flashes  bright  as  lightning — nay, 
even  surpassing  the  p)owers  of  nature.  A  small  quantity  of 
(a  certain)  composition,  n<j  bigger  tlian  one's  thumb,  will  give 
forth  (on  ignition)  a  deafening  noise  and  a  vivid  flash.'  We 
have,  too,  the  passage,  already  quoted,  in  the  eleventh 
chapter,  where  he  says  that  saltpetre  and  sulphur  and  some- 
thing else  give  forth  (on  ignition)  '  a  thundering  noise  and 
a  vivid  flash  '.* 

The  consequences  of  igniting  these  two  classes  of  composi- 
tion are  described  so  clearly  as  to  preclude  all  ix)ssible 
misunderstanding  :  the  incendiary  burns  fiercely,  while  the 
other  mixture  gives  forth  a  bright  flash  and  a  loud  noise. 
In  the  latter  case.  Bacon  was  describing  an  explosion,  and, 
as  he  has  elsewhere  spoken  of  saltpetre,  charcoal,  and 
sulphur,  the  reasonable  conclusion  is  that  the  explosive 
was  gunpowder. 

It  has  been  said  that  the  first  of  the  foregoing  passages — 
'  there  are  other  natural  wonders,'  &c. — describes  a  rocket. 
As  everybody  knows,  a  rocket  in  its  flight  makes  a  whizzing 
noise  and  is  followed  by  a  trail  of  heated  gas  and  sparks. 

'  '  Malta,  quae  est  genus  bituminis.'  Opus  Majus,  London, 
W33>  P-  474  (ed.  Bridges,  ii.  217). 

-  '  Possumus  artificialiter  componere  ignem  comburentem,  scilicet, 
ex  sale  petrae  ...  ex  oleo  petroleo  ...  ex  maltha  et  naphta  et  con- 
similibus  .  .  .  His  vicinus  est  ignis  graecus  et  multa  comburentia.' 
De  Secretis,  cap.  vi. 

'  '  Sunt  alia  stupenda  naturae.  Nam  soni  velut  tonitrua  et  corus- 
cationes  fieri  possunt  in  aere ;  immo  majori  horrore  quam  ilia  quae  fiunt 
per  naturam.  Nam  modica  materia  adaptata,  scilicet  ad  quantitatem 
unius  pollicis,  sonum  facit  horribilem  et  coruscationem  ostendit 
vehementem.'     De  Secretis,  cap.  vi. 

"*  See  p.  156. 


GUNPOWDER  333 

The  whizzing  noise  can  only  be  compared  to  tluinder  by 
a  total  disregard  of  fact,  for  no  sound  resembles  thunder 
less.  The  fiery  trail  can  only  be  called  a  flash  by  an  equal 
disregard  of  fact  :  it  gives  a  continuous  light.  But  if  the 
rocket  carries  a  bursting  charge  which  explodes  in  mid-air, 
the  explosion  may,  with  venial  exaggeration,  be  said  to 
produce  a  flash  like  lightning  and  a  noise  like  thunder. 
Bacon  was  alluding  to  a  bursting  charge  consisting  of  an 
explosive,  and  that  explosive  was  gunpowder. 

Had  Bacon  considered  the  possibility  of  controlling  and 
utilizing  the  explosive  force  of  gunpowder  ;  of  projecting  by 
its  means  a  heavy  body  from  a  strong  tube  through  a  certain 
distance  in  a  certain  direction  ? 

There  is  nothing  in  his  works  (so  far  as  I  am  acquainted  witli 
them)  which  suggests  that  he  had.  He  knew  that  gun- 
powder exploded,  and  he  believed  that  an  army  might  be 
either  actually  blown  up  by  it,  or  put  to  flight  by  the  terror 
inspired  by  its  explosion  ;  '  but  he  seems  to  have  gone 
no  further.  He  experimented,  probably,  with  very  small 
quantities  of  it  ;  and  the  behaviour  of  gunpowder  when 
fired  in  large  quantities  under  pressure  is  so  unlike  its 
behaviour  when  lired  in  small  quantities  in  the  open  air, 
that  its  projective  force  could  neither  have  been  predicted 
by  abstract  reasoning  nor  realized  by  even  his  powerful 
imagination. 

The  famous  Greek  fire  was  not  an  explosive,  but  an  incen- 
diary mixture.  The  claims  to  the  invention  of  gunpowder 
which  have  been  made  for  the  Arabs  and  Hindus  collapse 
when  critically  examined.  The  invention  has  always  been 
disavowed  on  the  part  of  their  countrymen  by  sober  Chinese 
historians,  though  in  despite  of  them  a  claim  was  raised  in 
the  eighteenth  century  by  some  Jesuit  missionaries  who 

'  This  is  M.  Berthelot's  view  :  Sur  la  Force  dcs  Maiitres  Explosives, 
Paris,  1883,  ii.  358  ;  and  it  is  probably  the  right  one. 


J34  ROGER  BACON 

unwittingly  confounded  explosive  and  incendiary  mixtures.' 
By  whom,  then,  was  gunpowder  invented  ? 

If  gunpowder  had  been  invented  by  another  and  if  Bacon 
was  induced  by  love  of  science  to  write  about  it,  there  is  no 
apparent  reason  why  he  slumld  have  done  more  than  describe 
it  fully  in  the  metaphorical  language  of  the  alchemists.  But 
not  content  with  the  free  use  of  figurative  terms,  he  buried 
the  facts  in  the  laborious  cipher  of  chaps,  ix  and  x  and 
in  the  two  anagrams  of  chap,  xi,  one  of  which  still  defies 
the  ingenuity  of  man.  It  was  a  strong  motive,  surely,  that 
moved  him  to  act  in  this  way,  and  there  is  but  one  rational 
explanation  of  his  behaviour  ;  namely,  that  he  himself  was 
the  inventor  of  gunpowder,  and  that  he  was  driven  to  employ 
cryptic  methods  by  fear  of  the  Inquisition,  which  had  been 
founded  by  Pope  Gregory  IX  about  the  year  1233.  The 
Church,  he  well  knew,  would  exact  a  dreadful  retribution 
from  the  man  who  discovered  and  recorded  the  composition 
of  a  substance  believed  to  possess  magical  properties,  and 
who  broadly  hinted  at  its  possible  utility  in  warfare.*  No 
precautions  could  be  too  ample  or  too  minute  to  shelter  such 
a  man  from  the  wrath  of  the  Holy  Office.  Unhappily  his 
elaborate  devices  mystified  friend  and  foe  alike  :  they 
enabled  him  to  evade  the  grasp  of  the  Inquisition,  but  they 
deprived  him  for  centuries  of  the  honour  of  his  discovery. 

In  all  probability  gunpowder  was  not  invented,  but 
discovered  accidentally  by  Bacon  ;  ^  just  as  the  structure 
of  crystals  was  discovered  accidentally  b}-  Haiiy,  the 
polarization  of  light  by  Malus,  galvanism  by  Galvani,  and 
the  decomposition  of  water  by  Nicholson.     WTiilst  he  was 

'  Oa  the  subject  of  this  paragraph  see  Gunpowder  and  Ammunition, 
by  the  present  writer,  Longmans,  1904. 

-  De  Secretis,  cap.  vi. 

^  Hallam  {Middle  Ages,  12th.  ed.,  i.  479)  suggested  that  gunpowder 
was  discovered  accidentally ;  but  he  added,  '  perhaps  in  some 
remote  age  and  distant  region,'  not  having  been  aware  that  saltpetre 
was  unknown  before  the  period  a.d.  1225-50. 


GUNPOWDER  335 

experimenting  with  some  incendiary  composition  containing 
saltpetre,  charcoal,  and  sulphur,  the  mixture  suddenly 
exploded,  shattering  the  glass  and  scattering  the  brazen 
apparatus  that  lay  around.  Traces  of  such  a  mischance  may 
perhaps  be  detected  in  the  explosion  which  followed  the  fall 
of  the  brazen  head  in '  The  Famous  Historic  of  frier  Bacon  '  :  ' 
'  therewith  (the  Brazen  Head)  fell  downe,  and  presently 
followed  a  terrible  noyse,  with  strange  flashes  of  fire.-  At 
this  noyse  the  two  Fryers  awaked,  and  wondered  to  see  the 
whole  room  so  full  of  smoake.'  Thus  Bacon  became  acciden- 
tally possessed  of  a  dangerous  secret ;  and  if  his  passion  for 
science  impelled  him  to  record  it  in  writing,  common  prudence 
obliged  him  to  do  so  in  a  manner  that  would  sliield  him  from 
persecution.' 

Enough  has  been  said  to  show  that  until  new  and  unex- 
pected facts  are  brought  to  light  in  favour  of  another,  we 
are  justified  in  liolding  that  gunpowder  was  discovered  by 
Roger  Bacon. 

'  Thorns'  Early  Prose  Romances. 
Almost  the  words  of  the  De  Secretis  :   '  modica  materia  adaptata 
.  .  .  sonum  facit  horribilem  et  coruscationem  ostendit  vehementem,' 
cap.  vi. 

^  '  Insanus  est  qui  aUquod  secretum  scribit  nisi  ut  a  vulgo  celetur, 
et  ut  vix  a  studiosissimis  et  sapientibus  possit  intclligi,'  cap.  viii. 


XIII 

ROGER  BACON  AND  MEDICINE 

By  E.  WITHINGTON 

The  Medicine  of  the  Thirteenth  Century 

Richer,  monk  of  Rheims,  in  his  valuable  History  of  his 
own  Times,  relates  a  curious  contest  between  an  ecclesiastical 
and  a  lay  physician,  which  may  form  an  appropriate  preface 
to  some  estimate  of  Friar  Bacon's  attitude  towards  the 
practitioners  of  his  age  and  a  brief  account  of  the  state  of 
medicine  in  the  thirteenth  century. 

'  In  A.  D.  946  died  Derold,  Bishop  of  Amiens,  an  honourable 
courtier,  beloved  of  the  king  and  very  skilled  in  medicine. 
The  story  is  told  that,  when  he  served  the  king,  he  had  a 
contest  in  cunning  with  a  certain  Salernitan.     Both  were 
excellent  physicians,  but  while  Derold  was  in  greater  favour 
with  the  king,  the  queen  considered  the  Salernitan  more 
skilful.    So  the  king  contrived  a  way  to  test  their  respective 
ability  without  their  knowing  it.    He  invited  both  to  dinner, 
and   put   questions   to   them   on   medical   matters.     They 
answered  as  best  they  could  :   Derold,  being  a  man  of  learn- 
ing,  gave  satisfactory   definitions  ;    while  the   Salernitan, 
though   without   any  literary   knowledge,   possessed  great 
talent  and  practical  experience.     By  royal  command  they 
came  to  dinner  every  day,  and  sat  next  to  one  another. 
Now,  they  were  disputing  one  day  over  the  dynamidiae 
(potencies)  of  drugs,  and  the  respective  provinces  of  phar- 
maceutics, botanies,  and  chirurgics.  The  Salernitan  had  never 
heard  those  strange  names,  so  he  blushed  and  was  silent. 
Thenceforth  he  became  so  jealous  that  he  plotted  to  poison 
his  rival,  while  pretending  special  friendship  for  him.    Having 
prepared  a  poison,  he  anointed  the  nail  of  his  middle  finger 
therewith,  and  put  it  in  the  pepper  water  [liquorem  piperis) 
in  which  they  both  dipped  their  food.     Derold,  carelessly 
tasting  thereof,  soon  began  to  feel  unwell ;   so  he  was  led 
oui  by  his  friends  and  cured  himself  in  three  days  with 
theriac.     On  his  return  he  concealed  his  knowledge  of  the 
trick,  and  when  the  Salernitan  inquired  after  his  health 
1689  z 


338  ROGER  BACON 

said  he  had  had  a  slight  catarrh,  treating  him  with  great 
courtesy  so  as  to  put  him  off  his  guard.  Then  he  (Derold) 
strewed  some  poison,  which  he  held  between  his  little  and 
ring  fingers,  on  his  neighbour's  meat,  which  being  absorbed 
drove  out  the  vital  heat,  and  the  sick  Salernitan  was  led 
away  by  his  friends.  He  tries  to  expel  the  poison,  but  in 
vain.  Now  he  praises  Derold  as  the  best  of  physicians  and 
entreats  his  aid.  Derold,  at  the  king's  command,  gave  him 
antidotes,  but  purposely  left  the  cure  incomplete  ;  for  the 
theriac  drove  the  poison  down  into  his  left  foot,  where  it 
caused  a  swelling  and  afterwards  an  open  wound,  so  that, 
finally,  his  foot  was  miserably  amputated  by  the  surgeons.' ' 

The  worthy  monk  is  thought  sometimes  to  have  put 
edification  before  accuracy,  and  some  details  of  this  story 
may  be  doubted,  but  it  represents,  in  part.  Bacon's  attitude 
in  the  most  interesting  of  his  medical  treatises,  the  De 
erroribus. 

He  is  there  exposing  the  defects  of  the  inheritors  of  the 
Salernitan  tradition,  the  Latino-harbari  as  they  were  after- 
wards called,  men  who  knew  no  Greek  and  had  read  but 
little  even  of  the  Latin  versions  of  Avicenna,  Rhazes,  and  the 
other  Moslem  physicians.  These  were  contrasted  with  the 
Latini  elegantes  et  docti,  who  knew  Aristotle  and  the  Arabs, 
and  with  whom  the  Doctor  mirabilis  would  doubtless  have 
classed  himself,  though  the  elegance  of  his  Latin  would 
scarcely  have  satisfied  Linacre.  In  the  tract  De  erroribus 
Bacon  deals  with  these  Latino-barb ari,  the  vulgus  medicorum, 
much  in  the  style  in  which  the  Bishop  of  Amiens  probably 
addressed  the  Salernitan.  But  the  dynatnidiae  and  phar- 
maceutics have  been  raised  to  a  higher  plane  by  aid  of  the 
mathematics  of  Alkindi,  botanies  has  become  agricultura 
philosophica,  and  two  fresh  sciences,  alchemy  and  astrology, 
have  been  introduced  under  Greek  and  Arabic  authority, 
not  to  mention  Bacon's  own  scientia  experimentalis.  Well 
might  the  Latino-barbari  blush  and  be  silent !  Bacon, 
however,  though  he  seems  to  have  suffered  much  from 
'  Pertz,  Monumenta  Germaniae,  iii.  600. 


MEDICINE  339 

a  Salemitan  purgative,  is  more  merciful  than  the  bishop. 
Errors  become  defects,  defects  impediments,  and  many  of 
these  natural  and  excusable  in  the  circumstances. 

To  return  to  the  Salemitan.  His  practical  knowledge  and 
deficient  general  culture  characterized  the  school  of  which 
he  is  one  of  the  earliest  known  members,  through  its  whole 
course.  When  Rudolf  the  monk  (Raoul  Leclerc)  went  to 
Salerno  about  1040,  the  '  Hippocratic  city '  was  rising  to 
the  height  of  its  fame,  yet  we  are  told  he  could  find  none 
who  could  meet  him  in  argument  save  a  certain  learned 
matron.'  But  he  gained  much  practical  knowledge  there,  and 
on  entering  the  abbey  of  St.  Martin,  taught  the  healing  art 
with  a  success  shown  by  the  number  of  his  pupils,  who  were 
scattered  through  the  monasteries  of  Anjou  and  Touraine 
and  obtained  much  wealth  for  their  communities  by  medical 
services  to  neighbouring  nobles.^ 

This  development  of  monastic  medicine,  the  most  im- 
portant of  which  we  have  any  record,  was  suppressed  in 
the  twelfth  century  by  repeated  decrees  of  Church  councils 
(Clermont,  1130  ;  Rheims,  1131  ;  Lateran,  1139  ;  Mont- 
pellier,  1162),  which  denounced  it  not  only  as  leading  to 
love  of  lucre  and  a  vagabond  life,  but  also  as  necessarily 
deaJing  with  matters  de  quibus  loqui  erubuit  honestas,  and 
which  therefore  non  debet  Religio  pertractare. 

Meanwhile  the  practical  Salernitans  made  little  progress. 
They  collected  the  popular  and  proverbial  medicine  of  the 
age  in  their  famous  Regimen  Sanitatis,  and  they  handed  down 
the  old  forms  of  treatment  in  medical  families  and  in 
therapeutic  Compendia.  Though  they  claimed  the  heritage 
of  the  classical  tradition,  they  possessed,  according  to 
Constantine,  no  Latin  version  of  '  Galen '  when  he  came 

•  Ord.  Vitalis,  Hist.  EccL,  II.  iii.  11. 

=  '  La  medecine  en  Touraine  au  xi«  siecle,'  Dubreuil-Chambardel ; 
'  Les  medecins  angevins  au  moyen  age,'  C.  Ballu,  La  France  MSdicale, 
191 1  (11  and  22). 

Z  2 


340  ROGER  BACON 

to  Salerno  about  1060,  and  they  paid  little  attention  to  the 
translations  from  the  Arabic  which  that  remarkable  man, 
Orientis  et  Occidenlis  magister,  novusque  effulgens  Hippocrates, 
issued  as  his  own  compositions  from  the  monastery  of  Monte 
Cassino.  In  the  next  century  they  produced  little  more 
than  books  on  drugs,  and  when  one  of  their  most  learned 
'  masters',  Gilles  of  Corbeil,  attempted  at  the  close  of  that 
epoch  to  give  lectures  at  Montpellier,  he  was  howled  down 
by  the  students  '  as  a  teacher  entirely  out  of  date.  For  the 
great  revival  had  begun  which  marks  the  thirteenth  century, 
and  which,  among  other  things,  saved  medicine  from 
degenerating  into  the  hands  of  rustici  and  Latino-bar  bar  i. 

From  east,  west,  and  south  ;  from  Constantinople,  taken 
by  the  Crusaders  in  1204,  from  Toledo,  long  lost  to  Islam 
but  still  retaining  many  relics  of  the  studia  Saracenorum, 
from  the  Sicilian  court  of  the  Emperor  Frederick,  stupor 
mundi,  the  writings  of  Aristotle  and  the  Arabs  poured  like 
a  flood  over  the  schools  of  western  Europe. 

The  triumphal  progress  of  Aristotle  is  one  of  the  marvels 
of  man's  mental  history.  The  Physica  and  Metaphysica  of 
the  pagan  philosopher,  who  taught  the  eternity  of  the 
universe,  the  mortality  of  the  soul,  and  the  non-intervention 
of  the  Deity  in  the  fate  of  the  world  or  the  affairs  of  men, 
were  promptly  and  naturally  condemned  by  the  Church  in 
1209,  1215,  and  later.  Yet,  in  less  than  a  century,  the 
greatest  of  Catholic  theologians  had  converted  them  into 
a  bulwark  of  orthodoxy,  and  the  greatest  of  Catholic  poets 
had  given  their  author  the  immortal  title,  '  Master  of  those 
who  know.' 

The  influence  of  Aristotle  on  medicine  w^as  diverse. 
Indirectly  he  contributed  to  the  unfortunate  dominance  of 
Avicenna,   whose   Canon  became    the   rule   of    European 

'  '  Postquam  eum  fortiter  verberaverunt,  clamabant  post  ipsum 
ac  si  esset  rusticus  vel  calcifex.'  Quoted  by  Pansier,  Janus, 
September  1904. 


MEDICINE  341 

practice  for  three  centuries,  mainly  because  it  was  thought 
to  harmonize  Aristotle  with  Galen,  just  as  St.  Thomas 
harmonized  him  with  Catholic  truth.  The  harmony  was 
far  from  complete,  as,  indeed,  Bacon  points  out,  but  was 
sufficient  to  impress  the  mediaeval  physician,  who  held  that 
where  Galen  and  Aristotle  differed  none  could  decide,  and 
where  they  agreed  none  could  dissent. 

But,  on  the  other  hand,  the  study  of  '  the  Philosopher  ' 
gave  a  new  freedom  to  thought  and  the  investigation  of 
Nature — hitherto  largely  looked  upon  as  a  ruin,  beset  with 
pitfalls  and  haunted  by  demons,  into  whose  clutches  the 
rash  explorer  of  its  mysteries  was  certain  to  fall,  if  he  had 
not  made  an  unlioly  compact  with  their  master,  the  Prince 
of  this  world.  This  was  now  replaced,  in  part,  by  the 
Greek  view  of  the  universe  as  a  harmonious  whole,  '  the 
diapason  closing  full  in  man,'  who  is  himself  a  little  universe 
or  microcosm. 

Bacon's  attitude  towards  Aristotle  differs  somewhat  from 
that  of  contemporary  physicians  such  as  Peter  of  Abano, 
the  great  Conciliator,  who  attempted  to  complete  the  work 
of  Avicenna.  He  speaks  with  disparagement  of  such 
treatises  as  the  Topics  and  Sophistici  Elcnchi  as  leading  only 
to  vain  disputations,  and  pays  more  honour  to  the  Secretum 
Secreiorum  and  other  spurious  productions  in  which  the 
pseudo-Aristotle  hints  at  marvellous  remedies,  praises  the 
virtue  of  viper's  flesh,  and  recommends  Alexander  the  Great 
to  take  rhubarb.  This  pleased  Bacon's  practical  mind, 
especially  as  rhubarb  was  the  favourite  medicine  which  he 
took  himself.  But  Aristotle  was  an  Asclepiad,  the  member 
of  a  medical  family,  as  well  as  disciple  of  Plato,  and,  in 
the  genuine  works,  the  Asclepiad  sometimes  overcomes  the 
speculative  philosopher.  There  is  a  famous  passage,  quoted 
by  practitioners  contemporary  with  Bacon,  and  twice 
noticed  by  him  in  the  De  erroribus,  which  gives  so  clear 
a  view  of  what  he  probably  meant  by  scientia  experimentalis 


342  ROGER  BACON 

that  it  may  be  repeated  in  full  in  the  language  of  Professor 
Gomperz. 

At  the  end  of  the  Posterior  Analytics  '  a  fine  image  and 
one  of  great  significance  presents  itself.  As,  when  the  tide 
of  battle  turns,  first  one  stout-hearted  warrior  holds  his 
ground,  then  a  second,  a  third,  and  continually  more  and 
more ;  so  in  the  mind  the  first  sense-impression  of  which 
a  copy  remains  is  joined  by  a  second,  then  a  third  and  others 
in  increasing  numbers,  till  from  the  summation  of  retained 
perceptions  there  rises  the  completed  structure  of  an 
experience.  For  out  of  perception  there  is  first  produced 
memory,  while  experience  is  the  result  of  repeated  memories. 
Out  of  experience,  in  its  turn,  or  out  of  all  the  "  Universal 
that  being  a  one  as  well  as  many,  has  become  firm  rooted 
in  the  mind  "  there  proceed  art  and  science,  where  by 
"  science  "  pure  theory  is  meant,  and  by  "  art "  theory  applied 
to  practice.  In  this  context  it  is  stated  with  express  emphasis 
that  it  is  "  sense  perception  "  that  generates  universal  notions, 
and  that  we  necessarily  obtain  all  our  "  first  principles  "  by 
"  induction  ".'  {Greek  Thinkers,  iv.  55.) 

This,  with  special  emphasis  on  tangible  knowledge  and 
the  verification  of  truth  in  sense,  seems  to  be  Bacon's 
scientia  experimentalis.  (This  passage,  together  with  the 
other  referred  to  by  Bacon  as  in  principio  Metaphysice,  is 
quoted  by  his  younger  contemporary  Henry  of  Mondeville, 
Cyrurgia  ii.  8  '  Philosophus  dicit  in  fine  11^  posteriorum 
"  Ex  multis  sensibilibus  fit  una  memoria,  et  ex  multis  memoriis 
unum  experimentum ;  ex  multis  experimentis  fit  unum 
universale,  quod  est  principium  artis  et  scientiae  ..."  Similiter 
quod  ratio  sit  dehilis,  non  juncto  sihi  experimento ,  patet 
auctoritate  Philosophi  in  prohoemio  metaphysicae  "  expertos 
magis  proficere  videmus,  scilicet  sine  ratione  "  quam,  supple, 
ratione  utentes  sine  experimento.') 

Next  to  experientia  Bacon  ranks  mathematics  :  '  If  in 
other  sciences  we  would  reach  certitude  free  from  doubt. 


MEDICINE  343 

and  truth  without  error,  we  must  set  the  foundations  of 
cognition  in  mathematics  '  {Opus  Majus,  i.  io6).  Now, 
according  to  the  beliefs  of  the  age,  medicine  required  mathe- 
matics directly  for  the  proper  compounding  of  drugs  accord- 
ing to  their  dynamidiae  and  indirectly  through  astrology. 

In  the  first  centuries  of  our  era  astrology  was  the  mathesis, 
and  astrologers  the  '  mathematici '  par  excellence.  Even  the 
mind  of  Ptolemy,  the  last  great  astronomer  and  mathe- 
matician of  the  ancient  world,  was  seduced  by  its  influence. 
It  was,  however,  opposed  with  vigour  and  success  by 
Christianity.  The  signs  of  the  Zodiac  might  appear  in  the 
stones  of  her  churches,  the  embroidery  of  her  vestments, 
and  even  on  the  chair  of  St.  Peter,  but  the  intrusion  of  that 
fatalistic  and  heretical  science  into  theology  was  prevented, 
and  St.  Leo  '  speaks  with  contempt  and  abhorrence  of  its 
most  characteristic  medical  doctrine,  the  supposed  influence 
of  the  zodiacal  signs  on  the  various  parts  of  the  human  body. 
But  at  the  end  of  the  twelfth  century  it  returned  with  the 
translations  of  Ptolemy,  Aristotle,  and  the  Arabs.  Even  the 
authority  of  Hippocrates  was  invoked.  The  Father  of 
Medicine  had  declared  that  there  is  rt  da.ov  in  disease.  We 
still  hardly  know  what  he  meant,  but  the  first  Latin  trans- 
lators rendered  Q^lov,  not  by  divinum  but  by  coeleste,  so 
mediaeval  physicians  understood  at  once  that  he  referred 
to  the  influence  of  the  heavenly  bodies.  The  doctrine  of 
the  microcosm,  of  man  whose  every  element  corresponds 
to  some  part  of  the  universe,  of  a  general  solidarity  and 
sympathy  between  all  things,  and,  for  men  like  Bacon, 
the  exactness  of  mathematical  calculation  which  could  be 

•  Epistola  XV.  John  of  Salisbury  has  a  chapter  which  might  have 
warned  Bacon,  '  Quod  mathesis  via  damnationis  est '  {Policraticus, 
ii.  26).  '  Hanc  vanitatem  (says  the  bishop)  CathoHca  et  universalis 
Ecclesia  detestatur,  et  eos  qui  earn  ulterius  exercere  presumpserint 
legitimis  poenis  mulctat.  .  .  .  Plurimos  audivi,  novi  multos,  sed 
neminem  in  hoc  errore  diutius  fuisse  recolo,  in  quo  manus  Domini 
condignam  non  exercuerit  ultionem.' 


344  ROGER  BACON 

brought  in,  helped  towards  this  second  triumph  of  astrology 
which  was  no  longer  so  strongly  opposed  by  theologians. 
Those  who  went  too  far,  or  were  otherwise  heretical,  like 
Peter  of  Abano,  might  incur  the  severest  censures  of  the 
Church,  but  a  Dante  might,  without  rebuke,  put  almost  on 
a  level  with  Divine  providence  the  '  opra  delle  rote  magne, 
che  drizzan  ciascun  seme  ad  alcun  fine,  secondo  che  le  stelle 
son  compagne  '.' 

Practical  men,  however,  who  had  to  earn  their  Hvings, 
were  not  yet  carried  away  by  the  current,  and  Mondeville 
treats  the  matter  with  his  usual  humour,  good  sense,  and  eye 
for  the  fee.  He  knows  that  Hippocrates  had  said  in  the 
Prognostics,  '  Est  etiam  quoddam  coeleste,'  in  disease,  which 
means  that  a  surgeon  must  keep  his  eye  on  the  moon  (p.  I20), 
that  Ptolemy  had  written  in  centilogio  propositione  20" 
'  Secari  tnembra  ferro,  luna  exeunte  in  signo  signanie  super 
ipsa,  horribilc  est'  (p.  342),  and  that  physicians  recognized 
the  absurdity  of  giving  a  '  laxative  downwards  '  when  the 
moon  is  in  the  ram,  bull,  or  he-goat,  for  they  are  ruminant 
animals,  and  everything  then  naturally  tends  to  return  to 
the  mouth.  But,  for  the  practitioner,  his  patients'  needs 
(and  his  own)  are  supreme.  There  are  '  times  of  election  ', 
indicated,  doubtless,  in  part  by  the  stars,  but  there  are 
also  times  of  necessity.  We  must  often  operate  without 
troubling  about  the  moon  and  the  zodiac,  or  the  patient 

'  Purgatorio,  xxx.  109.  The  importance  attributed  to  astrology 
even  in  the  most  enhghtened  circles  is  well  seen  in  the  following 
extract  from  a  contemporary  account  of  the  marriage  of  the  Emperor 
Frederick  II  with  Isabella  of  England,  1235.  '  Nocte,  vero,  qua 
concubuit  imperator  cum  ea,  noluit  earn  carnaliter  cognoscere  donee 
competens  hora  ab  Asirologis  ei  nunciaretur.  Consummata  autem 
•carnali  commixtione  summo  mane,  deputavit  eam  quasi  pregnantem 
diUgenti  custodiae  dicens  ei,  "  Custodi  te  diligenter,  quia  habes 
in  utero  masculum:  "  '  Matthew  Paris,  Chronica  Majora,  ad  annum 
1235  (iii.  324).  The  emperor  reported  all  this  to  Henry  III,  by  the 
Bishop  of  Exeter  and  J.  de  Sancto  Egidio,  O.P.  The  prophecy  was 
correct,  but  the  boy  died  in  infancy. 


MEDICINE  345 

may  die  (p.  343)  ;  while  if  he  hesitates,  and  seems  likely 
to  call  in  some  other  practitioner,  the  prudent  surgeon  may 
point  out  that  the  celestial  aspects  are  just  now  at  their 
very  best,  or,  similarly,  postpone  operation  till  he  has 
assurance  of  payment,  if  he  is  doubtful  of  getting  it  after- 
wards (p.  350).  How  far  Bacon's  practical  mind  would  have 
led  him  in  the  same  direction  in  similar  circumstances  we 
can  only  conjecture,  but  we  are  still  far  from  the  time  when 
these  theories  were  carried  to  greater  lengths,  when,  in  the  full 
blaze  of  the  Renaissance,  the  most  learned  of  the  reformers, 
Melanchthon,  published  a  new  edition  of  Ptolemy's  Tetra- 
biblos  et  centilogium,  and  when  decrees  of  town  councils 
forbade  men  to  be  bled  or  shaved  on  days  marked  '  danger- 
ous '  in  astrological  almanacs. 

The  higher  criticism  has  played  havoc  among  mediaeval 
alchemists.  The  mysterious  Geber,  magister  magistrorum, 
as  Bacon  called  him,  has  almost  vanished,  most  treatises  on 
alchemy  attributed  to  Albertus  Magnus,  Raimon  Lull,  and 
Arnald  of  Villanova  are  declared  spurious,  and  the  last 
great  figure,  the  '  pious  Spagyrist  ',  Basil  Valentine,  is 
pronounced  to  be  the  shadow  of  an  imposing  name  made 
to  cover  comparatively  modern  productions.  There  is  little 
doubt,  however,  that  the  best  influence  of  the  Arabic 
writers  on  medicine  was  the  importance  they  attributed  to 
alchemy  for  the  discovery  of  new  drugs,  and  the  proper 
synthesis  and  '  fermentation  '  of  compound  remedies.  Leo 
Africanus,  at  a  later  period,  describes  a  chemical  society 
at  Fez  as  '  a  most  stupid  set  of  men  {stupidissimi  homines) 
who  contaminate  themselves  with  sulphur  and  other  horrible 
stinks.  They  are  wont  to  meet  in  the  evening  at  the  principal 
mosque,  and  there  dispute  over  their  vain  imaginations  '.' 
Doubtless  there  were  similar  associations  in  the  golden  age  of 
'  Saracenic  studies  ',  and  many  *  Arabists  '  of  the  thirteenth 
century  were  eager  to  continue  their  labours. 

'  Descripiio  totius  Africae,  lib.  3.  s.  v.  '  Alchymistae.' 


346  ROGER  BACON 

Of  the  two  great  medical  schools  which  replaced  Salerno, 
Padua  represented  Aristotelianism  and  astrology  in  Peter  of 
Abano,  while  Montpellier  claimed  as  pupil  the  chief  exponent 
of  the  alchemy  of  the  period,  Arnald  of  Villanova.  It  is 
interesting  to  compare  Bacon  with  Arnald.  Both  believe  in 
the  possibility  of  transmuting  metals,  and  Arnald  is  alleged 
by  a  contemporary  to  have  made  gold.'  But  a  science 
which  teaches  (as  Bacon  says)  how  to  resolve  quodlihet  ex 
quolihet,  and  to  analyse  the  mimdus  inferior  into  its  elements, 
may  accomplish  greater  things  than  this.  Curiously  enough, 
the  older  man  seems  ignorant  of  Arnald's  favourite  alcohol, 
the  aqua  vini  or  vitae  of  the  Arabs,  to  which  he  attributes 
wonderful  powers  of  extracting  the  active  principles  of  drugs 
and  of  restoring  youth  to  the  aged,  matters  which  attracted 
Bacon's  special  attention.  Yet,  of  the  two,  Bacon  seems  to 
have  greater  faith  in  drugs  as  distinguished  from  the  dietetics 
and  hygiene  of  the  old  Salernitans.  At  present,  he  says,  there 
are  men  and  nations  with  few  or  no  drugs  or  doctors,  who 
are  stronger,  bolder,  more  beautiful,  and  longer  lived  than 
those  who  have  them  ;  when,  however,  medicines  discovered 
or  improved  by  alchemy  have  been  combined  by  aid  of  that 
science  and  mathematics  into  proper  compounds,  and  are 
administered  by  physicians  who,  being  perfect  astronomers, 
know  the  right  times  and  influences,  this  state  of  things  will 
naturally  and  necessarily  be  reversed  {De  errorihus). 


Bacon's  Medical  Treatises 

Two  prominent  peculiarities  may  be  noticed  in  Roger 
Bacon's  medical  treatises :  first,  they  are  the  production  of 
a  man  of  singularly  practical  mind  who  was  not  in  practice, 
and  had,  as  he  complains,  few  opportunities  of  getting 
'  certitude  by  experience  '  as  to  the  matters  of  which  he 

'  J.  Andreas  in  Durandus,  '  Speculum  Juris,'  cap.  '  De  Crimine 
falsi.' 


MEDICINE  347 

speaks  ;  secondly,  the  writer,  though  by  nature  a  rebel 
against  authority,  '  nullius  addictus  jurare  in  verba  magistri,^ 
nevertheless  accepts  without  question  a  theory  of  medicine 
eminently  based  on  authority,  the  system  of  Galen,  as 
further  formularized  and  stereotyped  by  Avicenna  and 
the  Arabs. 

Bacon's  energetic  and  sanguine  temperament,  unsobered 
by  the  experiences  of  the  general  practitioner,  is  shown  by 
his  confidence  in  the  power  of  drugs,  known  or  discoverable. 
He  proclaims,  as  did  Francis  Bacon  after  him,  the  vast 
potentialities  of  natural  things,  and  the  mastery  which  he 
believes  may  be  obtained  over  them  by  methodic  and  diligent 
investigation.  The  contemporary  medicine,  indeed,  abounds 
in  errors  :  there  are  '  thirty-six  great  and  radical  defects 
with  infinite  ramifications  '  in  one  department  alone.  We 
expect  a  root  and  branch  demolition  in  Paracelsic  style, 
but,  after  describing  seven  of  these  defects,  he  passes  over 
the  other  twenty-nine  with  an  almost  ludicrously  pathetic 
non  sufficio,  an  utterance  which  has  more  than  its  immediate 
implication.  Roger  did  not  think  himself  '  sufficient  ' — as 
did  Paracelsus  and  Van  Helmont — '  to  overthrow  the  entire 
philosophy  of  the  ancients  and  establish  a  new  science  of 
nature.'  On  the  contrary,  he  believes  that  these  ancients, 
the  antiqui,  had  a  sort  of  primitive  medical  revelation,  which, 
after  passing  through  Chaldeans  and  Greeks,  still  shines  in 
the  writings  of  the  Arabs,  though  dimmed  by  the  errors 
and  defects  of  the  Latini  rustici.  To  expose  these  errors,  to 
reveal  with  caution  certain  secreta  of  the  ancients,  thus 
adding  something  to  the  tradition  of  the  wise  as  represented 
by  Rhazes,  Avicenna,  and  the  Halys,  and  to  show  that  the 
path  of  progress  lies  through  the  study  of  astrology,  alchemy, 
and  scientia  experimentalis  are  the  ends  of  his  ambition. 

Gilbert  the  Englishman,  Roger's  contemporary,  declared 
that  were  it  not  for  the  singularity  of  the  thing,  he  would 
rather    follow    Hippocrates    than    the    Arabs,    and    wrote 


348  ROGER  BACON 

an  Expositio  of  the  Aphorisms.  But  Bacon  is  an  Arabist 
on  principle,  the  principle  being  that  capable  men  who 
follow  the  path  above  mentioned  are  bound  to  make  progress. 
Even  in  the  case  of  Aristotle,  greatest  of  the  Greeks,  it  was 
only  in  his  old  age,  when  he  began  to  pay  serious  attention 
to  astrology  and  alchemy,  that  he  could  produce  the  Secretum 
Secretoriim,  the  most  valuable  of  his  works  in  Bacon's  opinion. 

The  Arabs  had  made  further  progress  in  the  same 
direction.  Rhazes,  as  Bacon  probably  knew,  was  called 
'  the  Experimentator  '  ;  Avicenna,  as  he  points  out,  had, 
'  through  the  experience  of  alchemy,'  corrected  Galen's 
erroneous  opinions  concerning  the  humours  and  other 
matters,  while  Haly  of  the  '  Super  Tegni '  had  been  a  greater 
astrologer  than  either  Galen  or  Hippocrates,  and  even  earned 
his  living  by  the  art,  good  evidence  of  its  practical  value. 

Bacon's  familiarity  with  the  Greek  medical  authors 
appears  slight.  He  knows  the  Aphorisms  of  Hippocrates, 
but  pays  less  attention  to  them  than  to  those  of  Dama- 
scenus,  and  his  acquaintance  with  the  bulk  of  the  Corpus 
Hippocraticum  seems  indirect.  Thus,  its  most  famous 
saying  (next  to  '  Life  is  short  but  the  Art  long  '),  'Do  good, 
or  at  least  do  no  harm  ',  is  quoted  '  testante  Haly  super  Tegni ', 
and  he  follows  Avicenna  in  attributing  to  Hippocrates 
a  remark  on  the  evils  of  purgation  which  occurs  in  Galen's 
commentary.'  The  references  to  Galen  are  scanty  and 
often  indirect  'testante  Isaac',  'testante  Avicenna\  while  some 
of  those  he  appears  to  quote  at  first  hand  are  from  spurious 
mediaeval  treatises,  the  dynamidiae  and  secreta.  For 
example,  Galen  tells  four  interesting  stories  of  the  cure  of 
'  leprosy '  which  were  condensed  into  one  by  Arabic  and 
mediaeval  writers.^    Roger  might  have  read  this  version  in 

'  He  also  quotes  it  in  an  incorrect  form  derived  from  the  Arabic 
or  old  Latin  version.  This  is  given  in  Burton's  Anatomy  of  Melan- 
choly, ii.  4.  I.  A  reference  to  the  original,  In  Hipp.  Vict.  Acut.,  ii.  12 
(Kiihii's  Galen,  xv.  540),  will  show  how  the  mistranslation  arose. 

*  De  Simp.  Med.,  xi.  i. 


MEDICINE  349 

his  youth  in  William  of  Canterbury's  account  of  the  miracles 
of  St.  Thomas,'  but  he  gives  it  ' testante  Isaac\  Similarly 
two-thirds  of  the  references  to  Aristotle  are  to  the  Secretum, 
while  Dioscorides  is  quoted  twice  'testante  Haly  super  TegnV . 

A  striking  instance  of  this  ignoring  or  ignorance  of  the 
classical  writers,  as  compared  with  the  Arabs,  is  seen  in  the 
story  of  the  poisonous  Persian  tree,  which  though  told  by 
Dioscorides,  Pliny  (who  declares  it  false),  Galen  (three 
times),  Plutarch,  Columella,  and  the  pseudo-Aristotle  {De 
Plantis)  is  quoted  by  Bacon  '  testante  Avicenna\ 

Passing  to  Arabic  writers  we  find  a  great  contrast.  He 
knows  them  well  and  quotes  them  (as  a  rule)  honestly  and 
accurately,  more  so  than  did  many  contemporary  physicians 
and  surgeons  who  use  Avicenna  and  Alhucasis  much  more 
frequently  than  they  name  them. 

First,  in  what  may  be  called  density  of  quotation,  come 
two  of  the  great  little  books  of  mediaeval  medicine,  the 
Aphorisms  of  Damascenus  and  the  Commentary  of  Haly 
ben  Rodwan.''  John  of  Damascus  is  doubtfully  identified 
with  the  elder  Serapion,  and  certainly  belonged  to  one  of 
those  ninth-century  Syrian  medical  families  who  translated 
Greek  works  into  Syriac  or  Arabic.  The  i6o  short  aphorisms, 
afterwards  printed  as  a  preface  to  Serapion's  Practica,  were 
probably  learnt  by  heart  by  most  mediaeval  medical 
students,  and  are  largely  quoted  by  all  professional  writers 
of  the  age.  They  are  dedicated  to  the  writer's  '  son  ',  who 
is  translating  Galen's  Megategni  (the  De  Methodo  medendi), 
'  I  return  thanks  to  God  that  I  have  found  thee  such 
a  translator.' 

'  '  Nunquam,  inquit  Galenus,  vidi  in  vita  mea  hominem  a  lepra 
plenarie  sanatum  nisi  qui  vinum  biberit  ubi  tyria  incident,  et  ibidem 
computruerit.  Hunc  enim  vidi  excorticari  et  cute  expoliari  cum 
vinum  ilium  biberit.'  This  is  clearer,  but  not  more  correct  than 
Bacon's  version. 

^  The  other  two  were  the  Isagoge  of  Joannitius,  and  the  Noniis 
Almansoris  of  Rhazes. 


350  ROGER  BACON 

We  know  more  about  the  commentator  on  the  Microtegni. 
Haly  ben  Rodwan  (about  980-1060),  the  son  of  a  poor 
Egyptian  baker,  earned  a  living  at  firsi  by  astrology,  which 
indicated  correctly  that  he  would  become  a  famous  physician, 
but  failed  to  warn  him  of  the  imprudence  of  adopting  a  young 
girl  left  orphan  by  a  plague,  who,  on  reaching  years  of 
discretion,  collected  all  his  portable  property,  amounting 
to  20,000  dinars  or  ducats,  and  disappeared,  doubtless  with 
some  local  Lorenzo,  thus  reducing  the  aged  physician  to 
his  primitive  poverty.'  But  he  was  an  irascible  man,  troubled 
by  an  excess  of  that  cholera  of  which  he  speaks  so  much, 
and  which,  if  a  reference  in  the  Super  Tegni  applies,  as  is 
probable,  to  himself,  was  shown  by  a  '  lupinosity  '  of  temper 
which  he  may  not  have  controlled  so  well  as  he  says  he  did. 
His  best  known  works  are  an  astrological  commentary  on 
Ptolemy's  Tctrahihlos  ei  Ccntilogium,  quoted  elsewhere  by 
Bacon,  and  the  famous  Exposition  of  Galen's  Ars  medica, 
which  gave  him  almost  a  title,  Haly  super  Tegni. 

Accounts  of  the  three  greater  Moslem  physicians,  Rhazes, 
Haly  Abbas  (Regalis,  of  the  Royal  Book),  and  Avicenna, 
may  be  readily  found  elsewhere,  while  of  Isaac  ben  Solomon 
it  need  only  be  said  that  he  lived  a  century  (about  850-950), 
was  of  Solomonic  temperament  (except  that  he  remained 
unmarried),  and  that  his  two  great  works  on  diet  and  fevers 
respectively  are  considered  the  best  Arabic  productions  on 
those  subjects.  But  half  of  the  references  to  Isaac  are  from 
the  works  of  his  pupil,  Ahmed  ben  al  Gezzar,  a  highly 
practical  man  and  physician  to  Saracen  Corsairs,  who  wrote 
the  Viaticum  and  the  De  Gradibus  books  which  Constantine 
translated  and  attributed  to  himself.== 

Bacon's  medical  writings  are  based  upon  these  authorities, 

'  Leclerc,  Histoire  de  la  midecine  arahe,  i.  523.  See  also  Brockel- 
mann,  Geschichte  der  arabischen  Literatur,  and  Super  Tegni,  ii.  2.  13. 

-  Steinschneider,  Constantinus  Africanus  und  seine  arabischen 
Quellen,  in  Virchow's  Archiv,  27- 


MEDICINE  351 

and  though  he  sees  the  weak  points  of  Avicenna,  he  calls 
him  elsewhere  '  dux  et  princeps  philosophorum '  and  makes 
him  his  chief  guide  in  medical  matters,  quoting  him  as 
frequently  as  all  other  authors  combined.  But  we  may 
note  that  the  references  include  the  two  most  interesting 
and  practical  passages  in  that  huge  methodica  inanitas  (as 
Haller  too  severely  calls  it),  the  Canon,  viz.  the  accounts  of 
the  cure  of  a  consumptive  lady  by  unlimited  sugar-eating, 
and  of  how  Galen  obtained  sleep  in  his  old  age.' 

The  bulk  of  the  treatises  deal  with  the  retardation  of 
old  age  and  the  conservation  of  youth,  and  Bacon's  usual 
honesty  of  quotation  helps  us  to  conclude  both  that  they 
form  the  most  complete  compilation  on  the  subject  then 
known,  and  that  they  are  essentially  a  compilation,  in  spite 
of  the  author's  reiterated  claim  to  originality,  or,  rather, 
to  be  the  revealer  of  '  secrets  '  long  forgotten  or  concealed. 
These  secrets,  with  one  exception,  are  well-known  sub- 
stances often  named  openly  by  Roger's  predecessors,  viz. 
gold,  pearls,  ambergris,  viper's  flesh,  bone  of  stag's  heart, 
rosemary  and  lign-aloes.  The  exception  is  the  minera 
nobilis  animalis  or  fumus  jiiventutis,  terms  referring  to  the 
contagiousness  of  health  by  the  close  application  of  the 
body  of  a  healthy  adolescent,  preferably  with  crisp  yellow 
hair  (the  Galenic  mark  of  a  good  temperament)  to  the  sick 
or  aged.  Though  this  forms  his  most  novel  contribution  to 
the  medicine  of  the  age,  he  is  unusually  anxious  to  disclaim 

■  Roger's  frequent  repetitions  and  occasional  unacknowledgements 
interfere  with  the  accuracy  of  quotation  statistics,  but,  roughly 
speaking,  Avicenna  (who  includes  Aboaly  and  filius  principis)  may 
claim  1 00  references ;  '  Aristotle  '  36  (but  25  of  them  to  the  Secretum) ; 
Rhazes  and  the  two  Halys  have  about  1 5  each  ;  Isaac  and  Ahmed 
12  between  them,  and  J.  Damascenus  9.  No  other  writer  comes 
up  to  the  last  of  these  '  Arabs  '.  Practically  the  whole  chapter 
De  regimine  senum,  by  Haly  Abbas  (II.  i.  24),  is  quoted  by  Roger  in 
his  treatises  on  the  subject,  usually  with,  but  sometimes  without 
acknowledgement,  and  the  same  may  be  said  of  the  corresponding 
section  of  the  other  Haly's  Super  Tegni  {in.  123). 


352  ROGER  BACON 

originality,  bringing  in  Solomon  (apparently  Eccles.  iv.  ii), 
as  well  as  Damascenus  and  Galen,  to  his  support.  But,  as 
he  admits,  they  mention  the  subject  obscurely,  and  the 
next  plain  and  emphatic  reference  to  the  restorative  value 
of  balsamic  exhalations  a  sano  et  athletico  corpore  seems  to 
be  that  by  our  English  Hippocrates,  Sydenham,  whose 
language  closely  resembles  Bacon's,  except  that  he  fears 
ridicule  rather  than  scandal  [Obs.  Med.,  i.  4.  40). 

We  may  briefly  notice  the  relation  of  the  Epistola  and  its 
companion  treatises  to  the  current  theory  of  old  age,  and 
to  two  later  works  on  the  same  subject,  the  authors  of  which 
probably  knew  some  of  them,  and  held  opposite  opinions 
as  to  their  value. 

According  to  the  humoral  physiology,  the  fiery  and  watery 
elements  of  the  body,  innate  heat  and  radical  moisture,  are 
relatively  greatest  at  birth,  and  after  full  growth  begin  to 
diminish,  while  the  cold  and  dry  earthy  constituent  increases.' 
This  is  the  natural  cause  of  old  age  and  death.  But  the 
Greeks,  from  Heraclitus  and  Hippocrates  downwards,  laid 
stress  on  heat  as  the  principle  of  life.  '  According  to  Hippo- 
crates (says  his  editor,  Littre),  the  human  body  is  pervaded 
by  a  heat  which  he  calls  innate  {^ixcpvTov).  Its  amount  is  at 
the  maximum  in  infancy,  and  continually  exhausts  itself 
by  the  processes  of  life  till  it  arrives  at  a  minimum  in  old  age. 
This  change,  corresponding  to  the  yearly  variation  of  the 
sun's  heat,  gave  rise  to  an  analogy  of  ages  and  diseases  with 
the  seasons.'  ^  Galen,  with  unusual  brevity,  defines  death  as 
the  extinction  (o-yS^'crts)  and  old  age  as  the  wasting  {fxapaa-ixos) 
of  the  innate  heat  {De  Temp.,  ii.  2).  The  Galenic,  or  pseudo- 
Galenic  History  of  Philosophy  concludes  with  the  statements 
that  '  the  Stoics  and  all  physicians  declare  with  one  voice 
that  old  age  is  due  to  a  decrease  of  the  innate  heat ',  and 

*  See  especially  Galen's  commentary  on  the  14th  Aphorism,  quoted 
by  Roger  (Kuhn,  17  b,  405). 
-  CEuvres  d'Hippocrate,  i.  443. 


MEDICINE  353 

*  Asclepiades  pointed  out  that  the  natives  of  Britain  whose 
bodies  are  made  dense  by  their  climate,  retain  their  innate 
heat  for  an  immense  period,  and  only  grow  old  at  120  years  '.^ 
Finally,  the  pseudo- Aristotle,  as  Bacon  points  out,  urges 
Alexander  by  all  means  to  keep  up  his  caloric. 

Arabic  writers,  influenced,  perhaps,  by  their  climate  and 
neighbouring  deserts,  accentuate  the  other  factor,  moisture. 
Rhazes  puts  it  clearly  and  succinctly,  '  Homo  a  nativitate 
usque  ad  senium  desiccari  non  cessat,  donee  nihil  fiat.  Senium 
namque  non  est  aliud  nisi  magnum  in  corpore  siccitatis 
dominium.'  ^  This  exaggerates  Galen's  statement,  while 
the  heat  element  is  comparatively  ignored.  Both  factors, 
and  their  combination  in  the  burning  lamp  metaphor,  were, 
of  course,  generally  recognized,  but  the  reader  may  notice 
the  dominance  of  one  or  the  other  according  as  Bacon  is 
quoting  from  Greek  or  Arabic  sources. 

Within  twenty  years  of  Roger's  death,  Arnald  of  Villanova 
dedicated  to  Robert  the  Wise  of  Naples  and  Jerusalem  his 
De  Conservatione  juventutis  et  Retardatione  senectutis,  the 
best  known  mediaeval  treatise  on  the  subject.  Any  one  who 
reads  this  after  the  Baconian  treatises  will  be  struck  by  its 
close  resemblance  in  matter  and  style  to  the  one  entitled 
Dejuvene  a  senectute  tardando,  et  sene  ad  juventutem  reducendo 
Liber.  Whole  passages  are  verbally  alike.  Some  of  these 
are  quotations  from  the  Latin  versions  of  Arabic  writers, 
but  the  similarity  in  transitions,  and  the  introduction  of 
extraneous  subjects  such  as  the  use  of  white  hellebore  for 
wounds  (Roger  says  it  is  his  own  experience,  Arnald  has  'Est 
homo  qui  vidif),  seem  to  prove  that  Arnald  saw  and  used 
his  predecessor's  work. 

The  peculiarities  of  the  later  treatise  are  the  hints  or 

'  tips  '  characteristic  of  the  man  '  in  practice  ',  and  the  first 

clear  and  emphatic  notice  of  distilled  spirits  of  wine.    Thus, 

Arnald  says  that  the   Rosemary  elixir,  highl}/  praised  by 

'  Kiihn's  Galen,  19.  344.  ^  Almansoris,  2.  15. 

1689  A  a 


354  ROGER  BACON 

Roger,  is  greatly  improved  if  taken  '  in  aqua  vini  cum 
scientia  et  sapientia  facta\  which  he  afterwards  explains 
is  aqua  vini  distillata,  while  the  clyster  de  succo  foliorum 
(praised  by  Bacon)  is  more  effective  with  the  addition 
of  half  an  ounce  of  hiera-picra  :  '  quod  est  secretum 
magnum.^  Black  hellebore,  doubtless,  '  changes  a  bad 
"  complexion  "  into  a  good  one,'  as  Avicenna  (and  Bacon) 
says,  but  is  too  violent  a  drug  for  '  corporibus  delicatis  et 
nobilis  complexionis ',  and  the  advantages  of  potable  gold 
may  cheaply  and  conveniently  be  got  by  '  extinguishing  ' 
hot  gold  coins  in  your  wine.  But  Arnald's  potable  gold  was 
brandy.  '  Ex  vino  fit  aqua  vitae,  multum  diversa  a  vino  in 
colore,  substantia  et  operatione.'  This  is  a  '  res  magna,  faciens 
operationes  super  omnem  estimationem  \  It  is  particularly 
good  for  the  old,  since  it  opposes  putrefaction  *  propter  ejus 
sinceritatejn  et  puritatem '.  On  account  of  its  '  simplicity ',  it 
readily  extracts  the  flavours  and  virtues  of  other  drugs, 
'faciens  eis  acquirere  in  eorum  operationibus  additamentum.^ 
Its  only  defect  is  that  it  is  a  little  over  '  temper  '  as  regards 
heat,  and  it  should  therefore  be  taken  in  small  doses  and 
with  other  things.' 

If  the  Epistola  de  sanguine  humano  be  genuine,  Amald 
had  equal  faith  in  Bacon's ' /a^is  nobilis animalis',  the  'lapis 
qui  non  est  lapis,  et  est  in  quolibet  homine  et  in  quolibet  loco 
hominis  '.    His  elixirs  of  life,  in  short,  were  blood  and  brandy. 

Francis  Bacon  declared  that  part  of  medicine  which  relates 
to  the  prolongation  of  life  to  be  the  most  noble  of  all,^  and 
^vrote  a  special  treatise  on  the  subject,  History  Natural  and 
Experimental  of  Life  and  Death,  or  of  the  Prolongation  of  Life. 
That  he  had  seen  Roger's  Epistola  (printed  at  Oxford,  1590) 

'  He  says  his  immediate  predecessors  knew  more  about  the  aqua 
vini  than  they  chose  to  tell,  conceahng  it  under  the  name  aurum. 
As  he  quotes  Roger's  whole  account  of  potable  gold  (except  the 
directions),  and  applies  it  to  his  own  spiced  brandy,  he  perhaps  had 
Bacon  specially  in  mind. 

'  De  Augmentis  scientiarum,  iv.  2. 


MEDICINE  355 

is  highly  probable,  and  by  no  means  contra-indicated  by 
his  sweeping  condemnation  of  all  writers  on  the  subject 
since  Aristotle  as  having  '  handled  it  so  idly  and  super- 
stitiously,  that  by  reason  of  their  vanity  the  argument  itself 
has  come  to  be  reputed  vain  and  senseless.  For  they  tell  us 
that  death  consists  in  the  destitution  of  warmth  and  mois- 
ture ;  and  therefore  that  the  natural  warmth  should  be 
comforted,  and  the  radical  moisture  cherished.  Just  as  if 
this  could  be  done  by  broths,  or  lettuces,  or  mallows,  or 
starch,  or  jujubes,  or  spices,  or  generous  wine,  or  even  spirits 
of  wine  and  chemical  oils  ;  all  of  which  are  rather  injurious 
than  beneficial '.  His  own  theory  is  that  old  age  and  death 
are  due  to  '  two  depredations  ',  that  of  the  native  spirit  and 
that  of  the  surrounding  air,  '  the  spirits  like  a  gentle  flame 
continually  preying  upon  our  bodies,  conspiring  with  the  out- 
ward air.'  But  '  both  those  things  which  vulgar  physicians 
talk  of.  Radical  Moisture  and  Natural  Heat,  are  but  mere 
Fictions  '.'  AU  this  evidently  applies  to  Roger  and  Arnald, 
though  he  mentions  neither,  and  the  following  may  be 
particularly  directed  at  the  former.  '  When  I  hear  dis- 
courses touching  medicines  made  of  Gold,  because  Gold  is 
not  subject  to  corruption,  and  that  a  certain  man  when  he 
had  found  an  ointment  hidden  under  the  ground,  and  had 
anointed  himself  therewith  from  head  to  foot  (excepting 
only  the  soles  of  his  feet),  did  by  his  anointing  live  three 
hundred  years  without  any  disease  save  only  some  tumours 
on  the  soles  of  his  feet — (a  story  Roger  tells  at  least  twice) 
— and  such-like  fabulous  and  superstitious  vanities,  I  wonder 
exceedingly  that  men  should  so  much  dote  as  to  suffer 
themselves  to  be  deluded  with  these  things.'  ^ 

But,  in  spite  of  his  contemptuous  references  to  '  the 
unprofitable  rabble  of  cordials  ',  and  to  '  the  credulity  of 
thinking  that  the  course  of  Nature  can  be  delayed  or  turned 
back  by  a  morning  draught,  or  the  use  of  some  precious 

'  History,  Preface.  ^  History,  '  The  Intentions.' 

A  a  2 


356  ROGER  BACON 

drug,  by  potable  gold,  or  essence  of  pearls,  or  such  like 
toys  ',  the  chancellor  has  almost  as  great  faith  as  the  friar 
in  certain  substances.'  His  favourite  was  nitre, '  which  cools 
and  condenses  the  spirits  making  them  less  eager.  .  .  .  There- 
fore, as  strong  wines  and  spices  do  burn  the  spirits  and 
shorten  life,  nitre  doth  compose  and  refresh  them  and  is  of 
prime  force  to  long  life.'  ^  He  took  a  morning  draught 
containing  three  grains  of  it  every  day  for  thirty  years. ^  He 
values  saffron  even  more  highly  than  does  Roger  :  '  Our 
ancestors,  who  were  longer  lived  than  we,  did  use  saffron 
much  in  their  cakes,  broths  and  the  like.  The  Irish, 
especially  the  wild  Irish,  even  at  this  day  live  very  long  .  .  . 
and  use  to  wear  saffroned  linen  and  shirts,  which,  though 
it  were  at  first  devised  to  prevent  vermin,  yet  howsoever 
I  take  to  be  very  useful  for  the  lengthening  of  life.'  * 

It  is  strange  that  none  of  these  writers  mentions  what 
seems  to  us  the  most  important  premature  '  accident  '  of  age, 
and  one  which  the  progress  of  science  has  done  most  to 
remedy,  partly  by  aid  of  gold — dental  deficiency. 

Roger's  scientific  genius  is  less  prominent  in  the  treatises 
on  old  age  than  in  the  fragment  De  Graduacione  medicinarum. 
According  to  Gomperz,^  we  are  first  confronted  by  the 
conception  of  an  exact  science  in  the  Hippocratic  writings,, 
where  the  author  of  the  De  Prisca  medicina  says,  '  One 
must  aim  at  a  standard,  but  a  standard,  weight  or  number, 
which  shall  serve  thee  as  a  sure  guide  thou  shalt  not  find, 
seeing  there  is  no  other  than  the  sensibility  of  the  body.'  ^ 
Later  writers,  e.  g.  Plato  in  the  PhilehusJ  accentuate  the  same 
point.  Galen  makes  an  attempt  to  get  a  fixed  starting- 
point  for  measuring  the  hot-cold,  moist-dry.  Mix,  he  says, 
equal  volumes  of  boiling  water  and  ice,  also  equal  volumes 

'  De  Augmeniis,  iv.  2.  '  History,  ii.  i. 

^  Rawley's  Life,  end.  *  History,  ii.  2. 

^  Greek  Thinkers,  i.  299.  ^  Littre,  i.  588. 

^  Arithmetic,  mensuration,  and  weighing  being  taken  from  any- 
art,  the  rest  will  be  only  conjecture  ;  p.  55  E. 


MEDICINE  357 

of  dry  earth  and  water,  and  you  get  the  exact  '  means  ' 
between  these  respective  qualities/  Fix  them  in  your 
memory  by  feeUng  them  (he  thinks  they  represent  the  exact 
normal  temperature  and  consistency  of  the  palm  of  the 
human  hand),  and  it  will  not  be  difficult  to  use  them  as 
*  canons  and  criteria  '  for  the  degrees  of  deviation.  This  is 
a  very  imperfect  escape  from  conjecture  and  bodily  sensation, 
and  Bacon,  returning  to  the  Hippocratic  ideal,  points  out 
the  necessity  both  for  a  certus  terminus  and  an  exact  uniform 
scale.  With  better  opportunity  and  material  he  might  have 
gone  further,  but  the  world  had  to  wait  three  centuries  for 
Galileo's  thermometer. 

Perhaps  the  most  interesting,  original,  and  typically 
Baconian  of  the  treatises  is  the  De  Errorihiis.^  There  is,  of 
course,  nothing  original  in  findmg  fault  with  physicians,  but 
Roger,  as  we  have  seen,  does  it  in  an  unusually  moderate 
fashion,  and  adds  much  valuable  advice  culminating  in  his 
most  characteristic  aphorism  that,  of  the  three  ways  in 
which  men  think  they  acquire  a  knowledge  of  things, 
authority,  reasoning,  and  experience,  only  the  last  is  effective 
and  able  to  bring  final  peace  to  the  intellect  ;  a  startling 
utterance  for  that  age,  and  well  calculated  to  disturb  the 
minds  of  his  brethren.  It  is  expressed  more  briefly  in  a 
phrase  of  Hobbes,  which,  according  to  a  modern  writer,^ 
'  ought  to  be  inscribed  in  golden  letters  over  the  head  of 
every  talking  philosopher — No  discourse  whatsoever  can  end 

'  De  Temp.,  i.  9. 

-  De  Erroribus  Medicorum.  He  begins  to  describe  36  '  defects ' 
as  regards  drugs,  but  after  the  seventh  passes  to  '  external  defects  ', 
lack  of  proper  books — translations  of  Aristotle  criticized — waste  of 
time  in  verbal  disputes  to  the  neglect  of  astrology,  alchemy,  and 
agricultura  philosophica.  Much  of  this  is  repeated  under  the  heading 
'  Causes  of  their  defects  '.  The  treatise  concludes  with  an  emphasis 
of  '  experience  ',  and  has  an  appendix  of  notes  on  drugs,  prescriptions 
for  cordials,  and  methods  of  extracting  the  '  virtue  '  of  rhubarb, 
and  their  essential  oils  from  herbs. 

^  Santayana,  The  Life  0/  Reason,  iii.  198. 


358  ROGER  BACON 

in  absolute  knowledge  of  fact.  Absolute  knowledge  of  fact  is 
immediate  ;  it  is  experiential.'  So  understood,  it  seems 
a  valuable,  time-saving  truth,  in  no  way  opposed  to  religious 
faith  ;  but  if  Bacon  went  about  trying  to  fix  this  novel 
halo  over  the  heads  of  the  talking  theologians  of  his  time, 
as,  judging  from  his  combative  temper  and  love  of  repetition, 
he  probably  did,  we  can  understand,  and  f)erhaps  even 
sympathize  with,  some  of  the  motives  for  his  temporary 
seclusion. 

The  fragment  of  an  Antidotarius  compares  favourably  in 
clearness  and  directness  of  language  with  the  corresponding 
work  of  Arabic  and  other  mediaeval  writers,  and  it  is, 
perhaps,  in  these  disjecta  membra  rather  than  in  the  Epistle 
that  we  find  sufficient  evidence  of  greatness  to  justify  the 
conclusion  gigantis. 


XIV 

ROGER   BACON    IN    ENGLISH   LITERATURE 

By  Sir  JOHN  EDWIN  SANDYS 

In  English  literature  the  reputation  of  Roger  Bacon  has 
rested  mainly  on  his  magical  powers  and  his  imaginary 
mechanical  inventions.  In  the  Palice  of  Honour,  written 
early  in  the  sixteenth  century  by  the  Scottish  poet  Gavin 
Douglas,  he  is  named  as  one  of  three  noted  necromancers  : 

The  nigromancie  thair  saw  I  eik  anone 
Of  Benytas,  Bongo,  and  Frier  Bacone, 
With  mony  subtill  point  of  juglary.' 

Before  the  end  of  the  century  only  three  of  the  works 
ascribed  to  Roger  Bacon  had  been  printed  :  (i)  the 
Speculum  Alchemiae,  of  uncertain  authorship,  printed  at 
Niirnberg  in  1541,  and  translated  into  English  in  1597  ;  - 
(2)  the  treatise  De  mirahili  potestate  artis  et  naturae,  Paris, 
1542 ;  Oxford,  1594,  also  translated  in  the  same  volume  as 
the  Speculum  above  mentioned  ;  '  and  (3)  the  Libellus  de 
retardandis  senectutis  accidentihus,  Oxford,  1590. •*  Towards 
the  close  of  the  century  some  of  the  legendary  traditions 
respecting  Roger  Bacon's  inventions  were  collected  in 
a  popular  work  published  in  London,  of  which  more  anon. 
Conspicuous  among  the  inventions  there  mentioned  was 
his  wonderful  '  Perspective  Glass  '  and  his  '  Brazen  Head  '. 
For  the  latter  there  is  no  authority  in  any  of  his  extant 
works.     But  magical  inventions  of  this  kind  had  already 

'  Vol.  i,  p.  65,  ed.  Small,  1874. 

'  Cf.  A.  G.  Little,  Appendix  de  Operibus  Rogeri  Bacon,  in  Fran- 
ciscan Studies,  iii,  (191 1)  104.  '  Ibid.,  91.  ■•  Ibid.,  93. 


36o  ROGER  BACON 

been  ascribed  to  other  persons  of  intellectual  eminence. 
Thus  among  the  legends  associated  with  the  name  of 
Virgil,  mention  is  made  of  '  a  mirror  in  which  one  could 
see  everything  that  happened  at  a  distance  '  ;  '  and  in 
the  Image  du  Monde  the  poet  is  said  to  have  constructed 
a  '  talking  head  ',  which  he,  from  time  to  time,  consulted 
as  to  future  events.'  The  same  story  is  told  of  Gerbert  of 
Aurillac,  who,  in  999,  was  raised  to  the  papacy  as  Sil- 
vester II,  while  in  the  thirteenth  century  Albertus  Magnus 
is  said  to  have  made  a  '  talking  head  ',  which  was  destroyed 
by  his  distinguished  pupil,  Thomas  Aquinas.^  Roger  Bacon's 
eminent  friend,  Robert  Grosseteste,  bishop  of  Lincoln,  is 
described  by  Gower  in  the  Con/essio  Amantis  (1393)  as 
having  constructed  a  brazen  head  that  could  speak  : 

For  of  the  grete  Clerc  Grossteste 
I  rede  how  besy  that  he  was 
Upon  clergie  a  Hed  of  bras 
To  forge,  and  make  it  forto  telle 
Of  suche  thinges  as  befelle/ 

Similar  inventions  were  ascribed  to  Roger  Bacon  in  '  The 
famous  historic  of  Fryer  Bacon,  containing  the  wonderful 
things  that  he  did  in  his  life,  also  the  manner  of  his  death, 
with  the  lives  and  deaths  of  the  two  conjurers,  Bungye  and 
Vandermast  '.  One  of  the  earliest  of  the  many  editions  was 
that  '  printed  at  London  for  Francis  Grove  by  E.  A.',  that 
is  Elizabeth  Aide,  late  in  the  sixteenth  century,*  or  more 
probably  early  in  the  seventeenth.  It  was  also  printed  in 
1627  (for  Francis  Grove)  and  in  1630. 

'  Comparetti,  Virgilio  nel  medio  evo,  ii.  74,  ed.  1872  (p.  303,  E.T.). 

"^  Ibid.,  80  (p.  307,  E.T.)  ;  L'Image  du  Monde  de  Maitre  Gossouin, 
p.  185,  ed.  O.  H.  Prior,  Lausanne,  191 3. 

'^  Ibid.,  p.  80,  n.  4. 

■•  Liber  iv,  234  f.,  ed.  G.  C.  Macaulay,  1900. 

^  W.  J.  Thorns,  Early  English  Prose  Romances,  ed.  1858,  i.  179- 
250.  An  edition  of  Greene's  play  on  Friar  Bacon  was  printed  for 
Elizabeth  Aide  in  1630,  with  the  Brazen  Head  forming  part  of 
a  scene  represented  on  the  title-page. 


ENGLISH  LITERATURE  361 

It  is  here  stated  that  Roger  was  '  borne  in  the  west  part 
of  England,  and  was  sonne  to  a  wealthy  farmer,  who  put 
him  to  schoole  to  the  parson  of  the  town  where  hee  was 
borne.  .  .  ,  Young  Bacon  tooke  his  learning  so  fast,  that  the 
priest  could  not  teach  him  any  more,  which  made  him  desire 
his  master  that  he  would  speake  to  his  father  to  put  him 
to  Oxford'.  The  father  refused,  whereupon  'young  Bacon 
.  .  .  gave  his  father  the  slip,  and  went  to  a  cloyster  some 
twenty  miles  off,  where  he  was  entertained,  and  so  con- 
tinued his  learning,  and  in  small  time  came  to  be  so  famous, 
that  he  was  sent  for  to  the  University  of  Oxford,  where  he 
long  time  studied,  and  grew  so  excellent  in  the  secrets  of 
art  and  nature,  that  not  England  onely,  but  all  Christen- 
dome  admired  him.'  .  .  . 

The  king,  being  at  a  nobleman's  house  in  Oxfordshire, 
on  hearing  of  Friar  Bacon's  fame,  sent  for  him.  Bacon 
modestly  said  to  the  king,  that  '  fame  had  belide  him, 
and  given  him  that  report  that  his  poor  studies  had  never 
deserved  '.  Asked  to  show  the  king  and  queen  '  some  of 
his  skill ', 

'  he  waved  his  wand,  and  presently  was  heard  such  excellent 
musicke  that  they  were  all  amazed  '....'  Waving  his  wand 
againe,  there  was  lowder  musicke  heard,  and  presently  five 
dancers  entered.  .  .  .  These  did  divers  excellent  changes  .  .  ., 
and  having  done  their  dances,  they  all  vanished  away.  .  .  . 
Then  waved  he  his  wand  againe,  and  there  was  another 
kind  of  musicke  heard,  and  whilst  it  was  playing,  there 
was  sodainly  before  them  a  table  richly  covered  with  all 
sorts  of  deiicates.  .  .  .  Then  waved  he  his  wand  againe, 
and  sodainly  there  was  such  a  smell,  as  if  all  the  rich  per- 
fumes of  the  whole  world  had  bin  there  prepared  in  the 
best  manner  that  art  could  set  them  out.  .  .  .  He  waved 
his  wand  againe,  and  there  came  divers  nations  in  sundry 
habits  .  .  .,  all  bringing  sundry  kinds  of  furres.'  .  .  . 

'  Fryer  Bacon  reading  one  day  of  the  many  conquests  of 
England,  bethought  himselfe  how  he  might  keepe  it  here- 
after from  the  like  conquests,  and  so  make  himselfe  famous 
hereafter  to  all  posterities.  This  (after  great  study)  hee 
found  could  be  no  way  so  well  done  as  one  ;    which  was 


362  ROGER  BACON 

to  make  a  head  of  brassc,  and  if  he  could  make  this  head 
to  speake  (and  heare  it  when  it  speakes)  then  might  hee 
be  able  to  wall  all  England  about  with  brasse.  To  this 
purpose  hee  got  one  Fryer  Bungey  to  assist  him,  who  was 
a  great  scholler  and  a  magician  (but  not  to  bee  compared 
to  Fryer  Bacon)  ;  these  two  with  great  study  and  paines 
so  framed  a  head  of  brasse,  that  in  the  inward  parts  thereof 
there  was  all  things  like  as  in  a  naturall  mans  head.'  .  .  . 

They  '  went  one  evening  to  a  wood  thereby  ',  where,  in 
answer  to  their  '  words  of  conjuration  ',  the  devil  appeared 
and  told  them  that  '  with  the  continual  flame  of  the  six 
hotest  simples  it  would  have  motion,  and  in  one  month 
space  speak.'  .  .  .  After  watching  for  three  weeks  himself, 
with  Fryer  Bungey,  he  set  his  man  Miles  to  watch  the  head. 
At  last,  '  after  some  noyse  the  head  spake  these  two  words, 
TIME  IS  '  ;  and  again,  after  an  interval,  '  time  was  ;  and 
again,  time  is  past  ;  and  therewith  fell  downe,  and  presently 
followed  a  terrible  noyse,  with  strange  flashes  of  fire,  so 
that  Miles  was  half  dead  with  feare  ;  at  this  noyse  the  two 
Fryers  awaked.  .  .  .  Out  on  thee  villaine  (said  Fryer  Bacon) 
thou  hast  undone  us  both,  hadst  thou  but  called  us  when  it 
did  speake,  all  England  had  been  walled  round  about  with 
brasse,  to  its  glory,  and  our  eternal  fames,'  .  .  . 

'  In  those  times,  when  Fryer  Bacon  did  all  his  strange 
trickes,  the  Kings  of  England  had  a  great  part  of  France.  .  .  . 
The  King  of  England  .  .  .  did  beseige  a  strong  towne  and 
lay  before  it  full  three  months  ',  and  offered  a  reward  to 
any  one  that  would  '  deliver  this  towne  into  his  hand '.  .  .  . 

'  Fryer  Bacon  hearing  of  it,  went  into  France,'  and  in- 
formed the  king  '  that  art  oftentimes  doth  those  things  that 
are  impossible  to  armes  '  .  .  .  '  I  will  speak  onely  of  things 
performed  by  art  and  nature,  wherein  shall  be  nothing 
magical :  and  first,  by  the  figuration  of  art,  there  may  be 
made  instruments  of  navigation  without  men  to  rowe  in 
them,  as  great  ships  to  brooke  the  sea,  only  with  one  man 
to  steere  them,  and  they  shall  sayle  far  more  swdftly  than 
if  they  were  full  of  men  :  also  chariots  that  shall  move 
with  an  unspeakable  force,  without  any  living  creature  to 


ENGLISH  LITERATURE  363 

stirre  them.  Likewise,  an  instrument  may  be  made  to  fly 
withall,  if  one  sit  in  the  midst  of  the  instrument,  and  doe 
turne  an  engine,  by  which  the  wings  being  artificially  com- 
posed, may  beat  the  ayre  after  the  manner  of  a  flying 
bird.'  '  .  .  . 

'  But  physicall  figurations  are  farre  more  strange  :  for 
by  that  may  be  framed  perspects  and  looking-glasses,  that 
one  thing  shall  appeare  to  be  many,  as  one  man  shall  appeare 
to  be  a  whole  army,  and  one  sunne  or  moone  shall  seem 
divers.  Also  perspects  may  be  so  framed,  that  things  farre 
off  shall  seem  most  nigh  unto  us  :  with  one  of  these  did 
lulius  Caesar  from  the  sea  coasts  in  France  marke  and 
observe  the  situation  of  the  castles  in  England.'  -  .  .  . 

'  It  appertaineth  to  a  higher  power  of  figuration,  that 
beams  should  be  brought  and  assembled  by  divers  flexions 
and  reflexions  in  any  distance  that  wc  will,  to  burne  any 
thing  that  is  opposite  unto  it,  as  is  witnessed  by  those 
perspects  or  glasses  that  burne  before  and  behinde  ;  but 
the  greatest  and  the  chiefest  of  all  figurations  and  things 
figured,  is  to  describe  the  heavenly  bodies,  according  to 
their  length  and  breadth  in  a  corporall  figure,  wherein  they 
may  corporally  move  with  a  daily  motion.  These  things 
are  worth  a  kingdom  to  a  wise  man.'  ^  .  .  . 

In  two  days  the  king's  '  pioniers  '  had  raised  a  mound 
'  rather  higher  than  the  wall '....'  In  the  morning  Fryer 
Bacon  went  up  to  the  mound  and  set  his  glasses,  and  other 
instruments  up  .  .  .  Ere  nine  of  the  clocke  he  had  burnt 
the  state-house  of  the  towne,  with  other  houses,  only  by 
his  mathematical!  glasses.'  .  .  , 

We  also  learn  '  how  Fryer  Bacon  overcame  the  German 
conjurer  Vandermast,  and  made  a  spirit  of  his  owne  carry 
him  into  Germany  '  ;  .  .  .  and  also  '  how  two  young  Gentle- 
men that  came  to  Fryer  Bacon,  to  know  how  their  fathers 

'  This  is  taken  from  the  EngUsh  translation  of  cap.  iv  of  De 
mirabili  potestate  artis  et  naturae,  p.  533  of  Opera  Inedita,  ed.  Brewer  ; 
and  similarly  in  the  ca^e  of  the  next  two  passages. 

-  Ibid.,  cap.  V,  p.  534. 

^  Ibid.,  p.  535.  In  the  Opus  Tertium,  p.  18,  ed.  Little  (19 12), 
he  speaks  briefly  of  burning-glasses,  flying  machines,  sailing  machines, 
and  scythed  chariots  moving  without  animals  to  draw  them. 


364  ROGER  BACON 

did,  killed  one  another  ;  and  how  Fryer  Bacon  for  griefe 
did  breake  his  rare  Glasse,  wherein  he  could  see  any  thing 
that  was  done  within  fifty  miles  about  him  '  ;  and,  lastly, 
'  how  Fryer  Bacon  burnt  his  books  of  Magick,  and  gave 
himselfe  to  the  study  of  Divinity  only.' 

'  And  that  all  the  world  should  know  how  truly  he  did 
repent  his  wicked  life,  he  caused  to  be  made  a  great  fire  ; 
and  sending  for  many  of  his  friends,  schollers,  and  others, 
he  spake  to  them  after  this  manner  :  My  good  friends  and 
fellow  students,  it  is  not  unknowne  unto  you,  how  that 
through  my  art  I  have  attained  to  that  credit,  that  few 
men  living  ever  had  :  of  the  wonders  that  I  have  done,  all 
England  can  speak,  both  king  and  commons  ;  I  have 
unlocked  the  secret  of  art  and  nature,  and  let  the  world 
see  those  things,  that  have  laycn  hid  since  the  death  of 
Hermes,  that  rare  and  profound  philosopher  :  my  studies 
have  found  the  secrets  of  the  starres  ;  the  bookes  that 
I  have  made  of  them,  doe  serve  for  presidents  (sic)  to  our 
greatest  doctors,  so  excellent  hath  my  judgment  beene 
therein.  I  likewise  have  found  out  the  secrets  of  trees, 
plants  and  stones,  with  their  several  uses  ;  yet  all  this 
knowledge  of  mine  I  esteeme  so  lightly,  that  I  wish  that 
I  were  ignorant,  and  knew  nothing  :  for  the  knowledge  of 
these  things,  (as  I  have  truly  found)  serveth  not  to  better 
a  man  in  goodnesse,  but  onely  to  make  him  proud  and 
thinke  too  well  of  himselfe.  What  hath  all  my  knowledge 
of  natures  secrets  gained  me  ?  Onely  this,  the  losse  of 
a  better  knowledge,  the  losse  of  divine  studies,  which 
makes  the  immortall  part  of  man  (his  soule)  blessed.  I  have 
found,  that  my  knowledge  has  been  a  heavy  burden,  and  has 
kept  downe  my  good  thoughts  :  but  I  will  remove  the  cause, 
which  are  these  bookes  ;  which  I  do  purpose  here  before 
you  all  to  burne.  They  all  intreated  him  to  spare  his 
bookes,  because  in  them  there  were  those  things  that  after 
ages  might  receive  great  benefit  by.  He  would  not  hearken 
unto  them,  but  threw  them  all  into  the  fire,  and  in  that 
flame  burnt  the  greatest  learning  in  the  world.' 

Friar  Bacon's  '  Brazen  Head  '  is  repeatedly  mentioned 
by  the  Elizabethan  dramatists.  In  Ben  Jonson's  Every 
Man  in  his  Humour  (159S),  Cob  says  :  '  Oh,  an'  my  house 
were  the  Brazen-head  now  !    faith  it  would  e'en  speak  Moe 


ENGLISH  LITERATURE 


o"D 


fools  yet '  (Act  ii,  Sc.  iii) ;  and  in  Robert  Greene's  Tii  Quoque 
(printed  1614)  we  find  :  '  Look  to  yourself,  sir  ;  the  brazen 
head  has  spoke,  and  I  must  leave  you.'  Far  more  important 
than  these  passing  allusions  is  Robert  Greene's  Honourable 
History  of  Frier  Bacon  and  Frier  Bongay,  first  printed  in 
1594,  but  performed  as  early  as  February  1592  and  probably 
earlier. 

It  has  been  assumed  by  the  learned  editor  of  this  play  ' 
that  '  the  story  of  Friar  Bacon  and  Friar  Bungay  was  taken 
by  Greene  from  a  popular  story-book  ',  namely  the  '  Famous 
Historic  '  already  quoted.-  An  examination  of  the  printed 
text  of  this  '  Historie  '  proves,  however,  that  parts  of  it 
are  taken,  word  for  word,  from  chapters  iv  and  v  of  the 
translation  of  Roger  Bacon's  treatise  '  on  the  marvellous 
power  of  nature  and  art  '.  This  translation  was  not  printed 
until  1597,  five  years  after  the  death  of  Greene  in  1592,  and 
more  than  that  time  after  the  first  recorded  performance 
of  the  play.  Hence,  in  accepting  the  '  Historie  '  as  the 
source  of  the  play,  we  must  assume  that  the  translation 
had  already  been  in  existence  in  a  manuscript  form,  and 
that  the  manuscript  of  the  '  Historie  ',  partly  derived  there- 
from, was  accessible  to  the  author  of  the  play  at  least  five 
years  before  the  translation  was  printed.  The  ultimate 
printing  of  the  '  Historie  '  may  have  been  prompted  by 
the  interest  excited  by  the  play.  Both  were  printed  by  the 
same  person,  Elizabeth  Aide. 

In  the  first  scene  of  this  play  the  king's  fool  says  : 
*  Weel  ride  to  Oxford  to  Frier  Bacon  ;  oh,  he  is  a  brave 
scholar,  sirra  ;   they  say  he  is  a  brave  nigromancer  '  (i.  96).^ 

'  A.  W.  Ward,  Old  English  Drama,  Select  Plays,  in  'Clarendon 
Press  Series',  1878,  Introduction  to  Greene's  Friar  Bacon  and  Friar 
Bungay,  pp.  xcvi  ff. 

=  p.  360,  supra. 

'  I  have  mainly  followed  Churton  Collins 's  edition  (Oxford,  1905)  ; 
but  I  have  added  the  references  to  the  scenes  and  lines  of  the 
'  Clarendon  Press  Series  ',  ed.  A.  W,  Ward. 


j66  ROGER  BACON 

The  second  scene  is   '  Friar  Bacon's  cell    at   Brasenose  ', 
where  the  Friar  asks  the  Oxford  doctors  : 

Why  flocke  you  thus  to  Bacons  secret  Cell, 
A  frier  newly  stalde  in  Brazennose  ? 

One  of  the  doctors  replies  : 

Bacon,  we  hear,  that  long  we  have  suspect, 

That  thou  art  read  in  Magicks  mysterie  ; 

In  Piromancie  to  divine  by  flames  ; 

To  tell  by  Hadromaticke,'  ebbs  and  tides  ; 

By  Aeromancie  to  discover  doubts, 

To  plaine  out  questions,  as  Apollo  did  (ii.  10-18).  .  .  . 

I  tell  thee,  Bacon,  Oxford  makes  report. 

Nay,  England  and  the  court  of  Hcnric  sales, 

Thart  making  of  a  brazen  head  by  art. 

Which  shall  unfold  strange  doubts  and  Aphorismes, 

And  read  a  lecture  on  Philosophic  ; 

And,  by  the  hclpe  of  divels  and  ghastly  fiends, 

Tiiou  meanst,  ere  many  yeares  or  dales  be  past, 

To  compasse  England  witli  a  wall  of  brasse  (23-30). 

Bacon  admits  that  he  liad  *  contrivd  and  framde  a  head 
of  brasse  '  (55),  and  speaks  as  follows  of  Friar  Burden  : 

As  the  colledge  called  Brazennose 

Is  under  him,  and  he  the  Maister  there, ^ 

So  surely  shall  this  head  of  brasse  be  framde, 

And  yeeld  forth  strange  and  uncouth  Aphorismes  (172-5). 

In  the  fourth  scene  King  Henry  III,  at  Hampton  House, 
says  to  the  German  sorcerer  Vandermast  : 

In  Oxford  shalt  thou  find  a  iollie  frier, 

Cald  Frier  Bacon,  Englands  only  flower  (iv,  59  f.). 

In  the  rest  of  this  play  the  scene  is  laid  sometimes  at 
Oxford,  sometimes  in  Suffolk,  but  the  difference  is  immaterial, 
for  Friar  Bacon's  '  glass  prospective  '  enables  him  to  show 
at  Oxford  '  what  's  done  this  day  in  merry  Fressingfield  ' 
(vi.  III). 

'  Hydromancy,  Ward. 

-  Friar  Burden  is,  by  an  anachronism,  described  as  '  Master  ' 
(instead  of  Principal)  of  Brasenose,  which  was  not  founded  until  1509. 


ENGLISH  LITERATURE  367 

In  the  ninth  scene  Kmg  Henry  is  thus  addressed  by  the 
Emperor  : 

Trust  me,  Plantaget,  those  Oxford  schooles 
Are  richly  seated  neare  the  river-side  :  .  .  . 
The  towne  gorgeous  with  high-built  coUedges, 
And  schollers  seemely  in  their  grave  attire, 
Learned  in  searching  principles  of  art. — 
What  is  thy  iudgment,  Jaquis  Vandermast  ? 

Vandermast  replies  : 

That  lordly  are  the  buildings  of  the  towne, 
Spatious  the  romes  and  full  of  pleasant  walkes  ; 
But  for  the  doctors,  how  that  they  be  learned. 
It  may  be  meanly,  for  aught  I  can  heere. 

Whereupon  Friar  Bungay  retorts  : 

I  tell  thee.  Germane,  Hapsburg  holds  none  such, 
None  red  so  deepe  as  Oxenford  containes  (ix.  1-14). 

Vandermast  and  Bungay  have  a  contest  in  conjuring,  in 
which  Vandermast  is  victorious,  when  Bacon  comes  on  the 
scene,  and  is  thus  addressed  by  Vandermast : 

Lordly  thou  lookest,  as  if  that  thou  wert  learned  ; 
Thy  countenance,  as  if  science  held  her  seate 
Betweene  the  circled  arches  of  thy  browes  (123-5). 

Vandermast,  in    turn,  is    vanquished    by  Bacon,  who    is 
thus  congratulated  by  the  king  : 

Bacon,  thou  hast  honoured  England  with  thy  skill. 
And  made  faire  Oxford  famous  by  thine  art  (168  f.). 

The  king  dines  with  Bacon,  who  promises  His  Majesty 
and  the  Emperor  a  right  royal  entertainment,  with  delicate 
viands  from  distant  Egypt  and  Candy  and  Persia  and 
Spain  and  Judaea  (255-76). 

In  the  eleventh  scene  Friar  Bacon  is  discovered  lying  on 
a  bed,  with  a  white  wand  in  one  hand  and  a  magic  book 
in  the  other.  The  scene  also  discloses  the  Brazen  Head 
and  Bacon's  servant.  Miles.     Bacon,  in  the  course  of  his 


368  ROGER  BACON 

speech,  refers  to  his  '  nigromanticke  charmes '  (xi.  17), 
and  to  the  '  monstrous  head  of  brasse  ', 

That,  by  the  inchaunting  forces  of  the  Devil, 
Sluill  tell  out  strange  and  uncoth  Aphorismes, 
And  girt  faire  England  with  a  wall  of  brasse  (20  f.). 

In  the  hearing  of  the  servant  Miles,  three  times,  after 
three  long  pauses,  the  Brazen  Head  makes  a  great  noise,  and, 
after  each  noise,  utters  the  words  time  is,  time  was,  time 
IS  PAST.  'A  lightning  flasheth  forth,  and  a  hand  appeares 
that  breaketh  down  the  Head  with  a  hammer.'  As  the 
voice  had  not  been  heard  by  Bacon  himself,  all  was  in 
vain  ;   and  the  Friar  soliloquizes  on  time  is  past  : 

'Tis  past  indeed.     Ah,  villaine  !    time  is  past  : 

My  life,  my  fame,  my  glorie,  all  are  past. — 

Bacon, 

The  turrets  of  thy  hope  are  ruin'd  downe. 

Thy  seven  yeares  study  lieth  in  the  dust  : 

Thy  Brazen  Head  lies  broken  (xi.  96-101). 

In  the  thirteenth  scene  he  complains  to  Friar  Bungay  : 

Ah,  Bungay,  my  Brazen  Head  is  spoild, 
My  glorie  gone,  my  seven  yeares  studie  lost ! 
The  fame  of  Bacon,  bruted  through  the  world, 
Shall  end  and  perish  with  this  deepe  disgrace. 

But  Bungay  reassures  him  : 

Bacon  hath  built  foundation  of  his  fame 

So  surely  on  the  wings  of  true  report. 

With  acting  strange  and  uncoth  miracles. 

As  this  cannot  infringe  what  he  deserves  (xiii.  4-11). 

In  the  same  scene  the  '  glass  prospective  '  enables  two 
scholars  of  Oxford  to  see  their  fathers  slay  one  another  in 
Suffolk,  and  Bacon  sorrowfully  admits  : 

This  glasse  prospectiv'e  worketh  manie  woes ;  .  .  . 
End  all  thy  magicke  and  thine  art  at  once  .  .  . 
So  fade  the  glasse,  and  end  with  it  the  showes 
That  Nigromancie  did  infuse  the  christall  with  (77-84). 


ENGLISH  LITERATURE  369 

He  breaks  the  glass,  and  tells  Bungay  that  he  repents 

That  ever  Bacon  meddled  in  this  art. 

The  houres  I  have  spent  in  piromanticke  spels, 

The  fearfull  tossing  in  the  latest  night 

Of  papers  full  of  Nigromanticke  charmes  (87-90). 

In  the  fifteenth  scene,  laid  for  the  last  time  in  Friar 
Bacon's  cell,  the  stage  direction  runs,  ''Enter  a  DeviW 
(almost  the  last  appearance  of  any  devil  on  the  English 
stage),  and  the  Devil  explains  his  presence  thus  : 

Bacon  hath  raisd  me  from  the  darkest  deepe. 
To  search  about  the  world  for  Miles  his  man, 
For  Miles,  and  to  torment  his  lasie  bones 
For  careles  watching  of  his  Brasen  Head  (xv.  6-9). 

In  the  sixteenth  and  last  scene,  Bacon  appears  in  silence 
at  Court,  at  the  marriage  of  Prince  Edward  to  Elinor  of 
Castile,  and  the  king  asks  : 

But  why  stands  Fryer  Bacon  here  so  mute  ? 

and  Bacon  confesses  himself 

Repentant  for  the  follies  of  my  youth. 

That  Magicks  secret  mysteries  misled  (xvi.  35-37). 

We  cannot  part  from  this  play  without  recalling  the  fact 
that  its  author,  a  member  of  St.  John's  College,  Cambridge 
(incorporated  at  Oxford  in  1588),  actually  anticipated  the 
proposal  to  set  up  a  statue  in  honour  of  Roger  Bacon  at 
Oxford,  a  proposal  now  liappily  in  course  of  fulfilment. 

In  the  cell  at  Brasenose  one  of  the  Doctors  of  Oxford 
thus  addresses  the  Friar  : 

Bacon,  we  come  not  greeving  at  thy  skill. 
But  ioying  that  our  Academic  yeelds 
A  man  supposde  the  woonder  of  the  world  ; 
For  if  thy  cunning  worke  these  myracles, 
England  and  Europe  shall  admire  thy  fame. 
And  Oxford  shall  in  characters  of  brasse. 
And  Statues,  such  as  were  built  up  in  Rome, 
Eternize  Frier  Bacon  for  his  art  (ii.  36-43). 
16K9  B  b 


370  ROGER  BACON 

Miles  Windsorc,  in  the  Elizabethan  age,  connects  the 
story  of  the  Brazen  Head  witli  the  '  brazen  nose  '  in  the 
face  over  Brasenose  College  gate,  and  reports  that  a  like- 
ness, either  of  Bacon  or  of  the  Head,  was  kept  in  the  secret 
recesses  of  the  Hall  of  Philosophy,  which  occupied  part  of 
the  site  of  Brasenose.'  In  the  title  of  the  Elizabetiian  transla- 
tion of  '  the  admirable  force  and  efficacie  of  Art  and  Nature ', 
the  author  is  described  as  '  sometime  fellow  of  Merton 
CoUedge,  and  afterwards  of  Brasen-nose  CoUedge ',  whereas 
Brasenose  was  not  founded  until  1509,  although  Merton  had 
been  founded  in  1264-74,  during  the  lifetime  of  Roger  Bacon. 

In  the  seventeenth  century,  '  Bacon's  Study  ',  on  the 
south  side  of  Oxford,  was  reverently  visited  by  the  Danish 
scholar  and  votary  of  cliemistry,  Olaus  Borrichius  ;  and  it 
was  used  as  a  point  of  observation  when  Oxford  was 
besieged  by  the  Parliamentary  forces  in  1644. 

In  Hcarne's  Diary  for  September  23,  1724,  we  read  that 
'  the  Place  known  now  by  the  name  of  Bacon's  Study  (the 
lower  Part  whereof  is  certainly  very  old)  was  used  by  him 
chiefly  for  his  Astronomical  Studies,  and  here,  I  believe, 
he  penn'd  many  of  his  writings  that  any  thing  related  to 
that  Subject,  whilst  what  he  did  in  Chymistry  was  carried 
on  by  him  in  places  more  private,  sometimes  in  the  Suburbs 
...  in  which  there  was  also  a  fine  Grove  of  trees,  now  a  bare 
Meadow,  and  sometimes  at  Sunningwell,  then  much  more 
retired  than  even  at  this  time,  abundance  of  woods  having 
been  destroyed  thereabouts.  ...  At  Sunningwell  they  have 
the  tradition  of  Fryer  Bacon's  studying  there  to  this  day, 
where  (according  to  the  same  tradition)  he  had  an  Obser- 
vatory, and  that,  too,  upon  the  Tower  of  the  Church. 
Other  Scholars  of  Oxford  had,  in  those  times,  likewise  their 
retiring  Places,  in  imitation  of  Fryer  Bacon,  whose  Example 
was  much  followed,  he  being,  indeed,  a  Prodigy  of  Learning, 

'  Hearne's  Diary,  cxxxii.  73  f.  (A.  W.  Ward's  Introduction  to 
Greene's  Friar  Bacon,  p.  xxi). 


ENGLISH  LITERATURE  371 

which  made  him  so  much  taken  notice  of  by  all  sorts  of 
people  that  he  was  prosecuted  as  a  magician,  tho'  he  writ 
against  that  practice  '.' 

The  Oxford  Almanack  of  1780  lias  a  view  of  '  Folly  Bridge  ' 
and  the  curious  gateway  and  chamber  called  '  Bacon's  Study ' , 
and  a  drawing  of  the  latter  is  preserved  in  the  Bodleian." 
Both  of  these  are  reproduced  opposite  pages  43  and  48 
of  the  '  Book  of  Words  '  of  the  Oxford  Pageant  of  1907. 

In  the  '  Apology  concerning  the  Earl  of  Essex  '  {1604), 
the  Friar's  great  namesake,  Francis  Bacon,  makes  a  pointed 
reference  to  the  Brazen  Head  in  the  advice  which  he  offers 
to  Queen  Elizabeth  : — '  Madam,  if  you  will  have  me  to 
speak  to  you  in  this  argument,  I  must  speak  to  you  as 
Friar  Bacon's  head  spake,  that  said  First,  Time  is,  and 
then  Time  was,  and  Tinic  would  never  be  '.'  At  the  end 
of  the  '  New  Atlantis'  (1627),  Bacon  mentions  '  your  monk 
that  was  the  inventor  of  ordnance  and  of  gunpowder'.  Sir 
Thomas  Browne,  in  his  History  of  Vulgar  Errors  (1646),  says 
that  '  every  ear  is  filled  with  the  story  of  Friar  Bacon,  that 
made  a  Brazen  Head  to  speak  these  words,  Time  is  ',  for 
which  story  Sir  Thomas  devises  an  ingenious  alchemistic 
explanation/  Butler,  in  the  second  part  of  Hudibras 
(1664),  refers  to  Friar  Bacon's  '  noddle  '  of  brass,  and  aptly 
couples  together  '  Old  Hodge  Bacon  and  Bob  Grosted  '.^ 
Pope,  in  line  104  of  the  third  book  of  The  Dunciad  (1728), 
speaks  of  '  Bacon  trembling  for  his  brazen  head  '.  Johnson, 
in  '  The  Vanity  of  Human  Wishes '  (1749),  referring  to  the 
tradition  that  Friar  Bacon's  Study  would  fall,  when  a  man 
greater  than  Bacon  passed  under  it,  applies  to  '  the  young 

'  Hearne's  Diary,  viii.  271,  Oxford  Hist.  Soc,  1907. 

-  There  is  also  an  engraving  in  Skelton's  Oxonia  Antiqua,  ii.  9 
(1823),  and  on  the  title-page  of  Oxoniana,  vol.  i,  and  in  Alden's 
Oxford  Guide,  ed.  1882,  p.  108. 

^  Spedding's  Life  and  Letters  of  Bacon,  iii.  152  (A.  W,  Ward's 
Introduction,  lib.  cit.,  p.  xxvi  n.). 

*  Book  VII,  c.  xvii,  §  7.  ^  Cantos  i  and  ii. 

1689  B  b  2 


372  ROGER  BACON 

enthusiast',  burning  for  a  scholar's  fame,  the  memorable 
couplet : 

O'er  Bodley's  dome  his  future  labours  spread, 
And  Bacon's  mansion  trembles  o'er  his  head. 

Lastly,  wc  find  Lord  Byron,  in  Don  Juan  (1818),  using  tlic 
phrase  : 

Now,  like  Friar  Bacon's  brazen  head,  I've  spoken.' 
Time  was,  Time  is,  Timers  past. 

Tlie  references  to  Roger  Bacon  in  English  literature,  as 
set  forth  in  this  paper,  show  little,  if  any,  appreciation  of 
the  value  of  his  real  discoveries.  Even  in  the  science  of 
Optics,  to  which  he  devoted  ten  years  of  study,  one  of  his 
most  important  discoveries  has  been  ignored  by  a  German 
of  world-wide  reputation.  Humboldt,  in  his  Cosmos,"  has 
attributed  to  Francis  Bacon,  in  the  second  book  of  the 
Novum  Organum,^  the  discovery  that  light  must  have  an 
appreciable  velocity.  But  this  discovery  was  really  due  to 
the  earlier  Bacon.  In  the  Opus  Ma  jus  of  Roger  Bacon  we 
read  that  all  the  authors,  including  Aristotle,  hold  that 
the  propagation  of  light  is  instantaneous  ;  but  the  truth  is 
that  its  propagation  is  effected  in  a  very  short  but  appreci- 
able interval  of  time.*  A  former  Master  of  Trinity,  in  the 
supplementary  volume  to  his  History  of  the  Inductive 
Sciences,  resting  his  opinion  on  the  Opus  Majus  alone, 
describes  that  work  as  '  the  Encyclopaedia  and  the  Novum 
Organum  of  the  thirteenth  century  '.'"  The  present  Master 
of  Trinity  has  assured  me,  on  the  authority  of  his  brother, 
Mr.  Spencer  Perceval  Butler,  that  one  of  the  eminent  editors 
of  the  works  of  Francis  Bacon,  Mr.  Robert  Leslie  Ellis, 
once  said  to  Dr.  Whewell :  '  I  have  lately  been  reading  some 
of  Roger  Bacon's  writings,  and  I  am  inclined  to  think  that 
he  may  have  been  even  a  greater  man  than  our  Francis.' 

'  Canto  i,  217.  -  iii.  90,  ed.  1850.  ^  ii.  46. 

"  pp.  298,  300  (ii.  67,  71,  Bridges)  ;  Charles,  p.  295. 

-  Whewell,  On  the  Philosophy  of  Discovery  (ed.  i860),  p.  65. 


APPENDIX 


Bb3 


ROGER  BACON'S  WORKS 

WITH  REFERENCES  TO  THE  MSS.  AND  PRINTED 
EDITIONS 

Any  one  who  has  attempted  to  compile  a  bibHography  of 
Roger  Bacon  will  be  inclined  to  echo  Leland's  saying,  that 
'  it  is  easier  to  collect  the  leaves  of  the  Sibyl  than  the  titles  of 
the  works  written  by  Roger  Bacon  '.  The  difficulty  is  partly 
due  to  Bacon's  habit  of  re-writing  his  treatises  '  four  or  five 
times '  before  he  could  get  a  satisfactory  version,  and  to  his 
using  the  same  material  over  and  over  again  in  different  con- 
nexions. The  same  works  recur  with  different  titles  and 
different  incipits,  and  different  works  with  the  same  title  ; 
and  the  number  of  fragments  and  unfinished  works  is 
enormous.  Many  spurious  writings  are  attributed  to  Bacon, 
and  some  genuine  ones  are  hidden  under  other  names. 

The  following  bibliography  is  a  revised  edition  of  that 
printed  in  vol.  iii  of  the  British  Society  of  Franciscan  Studies 
(191 1),  which  in  turn  was  based  on  the  account  of  Bacon's 
works  given  in  The  Grey  Friars  in  Oxford,  pp.  195-21 1 
(1892).  My  appeal  in  1911  for  'additions  and  corrections' 
has  met  with  a  ready  response,  and  I  desire  to  record  my 
indebtedness  to  Dr.  M.  R.  James,  Mr.  Robert  Steele, 
Rev.  H.  M.  Bannister,  Rev.  Father  Delorme,  Cardinal  Gasquet, 
Monsieur  J.  A.  Col,  Mr.  Gilson,  Mr.  Madan,  Mr.  Craster,  and, 
above  all,  to  the  Rev.  Father  Michael  Bihl,  who  generously 
placed  at  my  disposal  the  results  of  his  researches  in 
Italian  libraries.  Further  additions  and  corrections  would 
still  be  welcome,  and  many  points  remain  obscure.  Perhaps 
some  one  will  be  moved  to  bring  order  into  the  chaos  of 


376  APPENDIX 

the  alclicmical  works  attributed  to  Bacon  :    and  I   would 

specially  draw  the  attention  of  Aristotelians  to  tlie  Amiens 

MS.  (Nos,  1-3,  40);  of  mathematicians  to  Nos.  17,  44,  45; 

of  philologists  to  the  '  Summa  Grammaticae  '  in  No,  34,  and 

to  the  very  interesting  MS.  Touhnise  402  mentioned  in  the 

note  to  No.  33. 

The  discovery  in  the  Vatican  Library  of  what  appears  to 

be  a  complete  copy  of  Bacon's  Mctaphysica,  news  of  which 

reached  me  as  these  pages  were  in  the  press,  raises  hopes  of 

still  further  Imd^. 

A.  G.  LITTLE. 

RlSBOROUGH, 

Sevenoaks. 

I.  GENUINE 

la.  Quaestiones  super  libros  i-v  Physicorum  Aristotelis. 

Inc.  tabula  :  '  Incipiunt  questiones  naturales  et  primo 
qut'stiones  libri  Phisicorum  Aristotelis.'  Inc.  lib.  i  ; 
'  Oucstiones  primi  Phisicorum  Rogeri  Bachun. 
Ouoniam  quidem  intclligcre,  etc.  Hie  prime  queritur 
utrum  de  corpori'  mobili.' 
MSS.  :  Amiens  406,  11.  r>-28  [ends  imperf.]  (sec.  xiii  ex.). 
Described  by  V  ictor  Cousin  in  Journal  des  SavatUs,  1848, 
pp.  459-72. 

lb.  Quaestiones  super  libros  i-vi  Physicorum  Aristotelis.' 

'  Incipiunt  questiones  supra  librum  Phisicorum,  a  magistro 
dicto  Bacuun.  Ouoniam  intelligerc  et  scire  circa 
omnes   scientias   accidit,   etc.     Iste   hber,   cujus   sub- 

'  Digb\-  MS.  150  (sec.  xiii  ex.)  contains  t^vo  treatises  ascribed  in  later 
hands  to  Roger  Bacon.  The  first  is  the  Sttmma  philosophiae  naturaiis  or 
Philosophia  pauperum  often  attributed  to  Albertus  Magnus,  inc.  '  Phylo- 
sophia  dividitur  in  tres  partes,  videhcet  in  logicam  ethicam  et  phisicam. .  .  .' 
expl.  '  Hanc  summam  composuit  fr.  Rogerus  Bagount.'  The  second 
(' scrip  turn  Bakon  super  libros  phisicorum')  is  an  analysis  of  the  eight 
books  of  the  Ph5'sics  of  Aristotle  {i»c.  '  Naturaiis  philosophic  principales 
partes  sunt  viii'),  ascribed  to  Bacon  in  two  hands  of  the  fifteen^  and 
sixteenth  centuries.  The  latter  treatise  appears  to  be  contained  in  MS. 
Amplon.  F.  297  (sec.  xiv),  where  it  is  attributed  to  Walter  Burley  (/?.  1275- 
1345),  but  the  date  of  the  Digby  MS.  makes  this  ascription  improbable 
if  not  impossible.  The  work  seems  to  have  been  written  by  a  religious  ; 
e.g.  Digby  MS.  f.  100  :  '  Hec  igitur  dicta  de  Ubro  phisiconim  breviter 
suflficiant  que  quandoque  repetendo  hunc  librum  quibusdam  nostris 
fratribus  hec  modica  extraximus.' 


ROGER  BACON'S  WORKS  377 

stantivum  est  corpus  mobile.     Qucritur  primo  utrum 

de  naturalibus  possit  esse  scientia.'  ' 
MS.  :   Amiens  406,  ff.  29-56,  63"^-74''  (sec.  xiii  ex.). 
Described  by  V.  Cousin. 

2.  Quaestiones  super  librum  de  Plantis  (or  Vegetabilibus). 

'  Incipiunt  questiones  supra  librum  de  plantis,  a  magistro 
^ogero  Baccon.  Tria  ut  ait  Empedocles  in  tota  rerum 
varietate  principia,  etc.  Supposito  quod  hec  scientia 
de  corpore  mobili,  animate,  composite' 

MS.  :   Amiens  406,  ff.  57-63  (sec.  xiii  ex.). 

Described  by  V.  Cousin  (cf.  Charles,  Roger  Bacon,  p.  284). 

3 .  Quaestiones  in  Aristotelis  Metaphysica. 

'  Incipiunt  questiones  supra  primum  Metaphysice,  a 
magistro  Kogero  Bacco.  Omnes  homines  natura  scire 
desiderant,  etc.  Dubitatur  de  ista  scientia,  primo  de 
substantive' 

MS.  :    Amiens  406,  ff.  78-113',  74,  166-76  (sec.  xiii  ex.). 

Described  by  \ .  Cousin. 

Another  series  of  questions  on  books  i,  ii,  and  iv  of  the 
Metaphysics  is  contained  in  the  same  MS.,  f.  176''  seq.  : 
'  Hie  incipiunt  questiones  supra  primum  Metaphisice 
Aristotehs.  Omncs  homines  .  .  .  Queritur  hie  primo 
utrum  hec  propositio.'  It  is  not  clear  whether  these 
are  by  Bacon. 

4.  *  Summa  M.  Rogeri  Bacon  de  sophismatibus  et  distinctionibus. ' 

Inc.  :   '  Potest  queri  de  difticultatibus  accidentibus.' 
MS.  :   Bodl.  Digby  67,  If.  117-24'  (sec.  xiii)  :   fragment. 

5.  'Questiones    naturales    mathematice    astronomice,    etc.,'    or 

'  reprobationes  Rogeri  Bacon.' 

MS.  :   Paris  :   Bibl.  Nat.  16089,  ^f-  9^'-?'  (secc.  xiii-xiv). 

These  quaestiones  relate  to  rapidity  of  movement,  circles,  weights 
and  measures,  astronomy,  rubrics,  dominical  letters,  solar  year. 
The  passage  e.xpressly  attributed  to  Bacon  is  that  on  weights 
and  measures.  Inc.  f.  91^':  '  Mensura  ut  dicitur  est  quidquid 
ponderis  capacitate,  longitudine,  altitudine  comprehenditur ;  ' 
f .  93V :  '  ExpUciunt  reprobationes  Rogeri  Baconis.'  This  is 
immediately  followed  by  :  '  Rogerus.  Nunc  iuvandum  [?  mi- 
randum]  est  quod  in  diversis  scientiis  multa  tractantur  eadem  ; ' 
fragments  on  astronomy,  rubrics,  dominical  letters,  solar  year, 
ending  on  f.  97""  with  the  words  :  '  ut  anni  dividantur  per  60  ut 
fiant  hore  et  resultant  8  hore  '  (from  information  kindly  sup- 
pUed  by  Monsieur  J.  A.  Col). 

6.  Tractatus  ad  declaranda  quaedam  obscure  dicta  in  libro  Secret! 

Secretorum  Aristotelis.     Inc.  :    '  Propter  multa  in  hoc  libro 

'  Cf.  Worcester  Cathedral  MS.  Q.  13,  ff.  2-4^,  79-116. 


37«  APPENDIX 

contcnta  qui  liber  dicitur  Sccretum  Sccretorum  Aristotelis 

sive  liber  de  regimine  principum.' 

MSS.  :  Oxford  :  Bodl.  Tanner  ii6,  If.  1-6'  (sec.  xiii  ex.)  ; 
the  same  MS.,ff .  i3''-65'',  contains  the  Secretum  Secrdorum 
attributed  to  Aristotle  '  cum  (juibusdam  declarationibus 
fratris  Rogt-ri  Bacon  '. — Corpus  Chr.  Coll.  149  (sec.  xv). 
Cambridge  :  Trin.  Coll.  1036  (sec.  xv  ex.),  'ff.  1-20^  ; 
ff.  25-130,  '  expl.  liber  secreti  secretorum  Arist.  .  .  . 
qui  liber  intitulatur  liber  decern  scienciarum  cum 
quibusdam  declaracionibus  Fr.  Hogeri  Hacun  de  ord. 
minoruni." — iMtzwilliam  Museum,  McCIean  153  (sec.  xv). 
(These  three  MSS.  apjxjar  to  be  copies  of  Tanner  Il6.) 
(Cf.  Bridges,  i,  10  n.,  258  n.,  403  n.,  ii.  64.) 

Edition  by  Mr.  Steele  is  in  the  press. 

7.  Computus  Naturalium,  a  treatise  on  the  calendar,  in  three 

parts,  containing  respectively  21,  20,  and  8  chapters, 
written  A.D.  I2()3.  Inc.  'Omnia  Icmpus  habent,  etc.,  ut 
Salomon  testatur.  Igitur  omnia  sive  sint  producta.' 
Expl.  '  ut  simplices  instructionem  ct  sapientes  pluris 
investigationis  capiant  occasionem.' 

MSS.    British   Museum  :      Royal    7   F.  viii,    ff.  99-163   (sec. 
xiii  ex.).' 
Oxford  :    Bodl.  Seldcn  supra  79,  I.  150  (excerpta). — Univ. 

College  48  (sec.  xvii). 
Douai  691,  §  2  (sec.  xvii). 

Cf.  Erfurt  :  Amplon.  F.  394,  If.  145-7  (^c.  xiv  in.)  :  '  Liber 
Bachonis  de  compoto.'  Inc.  '  Si  locatis  ahquibus 
volueris  scire  in  circulo  '  :  expl.  '  latitudinem  australem 
multam  a  via  solis.' 
Summary  printed  by  E.  Charles,  Roger  Bacon,  pp.  335-8. 
This  is  perhaps  the  work  mentioned  in  the  (Catalogue  of 
the  Austin  Friars'  Library,  York,  No.  196,  as  '  tractatus 
Rogeri  bacon  de  tempore  '  (ed.  M.  R.  James,  in  the 
Fasciculus  Joanni  Willis  Clark  dicatus). 

8.  De  termino  Paschali,  an  earUer  work,  to  which  Bacon  refers 

in  the  Computus  naturalium  (Charles,  p.  78  :  '  In  praece- 
denti  opere  ubi  de  termino  Paschali  inquisivimus,' 
Computus,  cap.  iii),  does  not  seem  to  be  extant. 

'  The  following  article  in  this  MS.,  fi.  164-91,  is  a  '  Calendar  beginning 
with  September,  showing  lunar  conjunctions,  etc.,  for  four  cycles  of  nineteen 
years,  beginning  1254.  The  canon  below  is  very  incorrectly  transcribed, 
but  fixes  the  date  as  1268.  Among  the  very  few  saints  inserted  are 
SS.  Francis,  Denys  and  Germain  '  (Mr.  Gilson's  Catalogue).  Cf.  Vienna, 
Bibl.  Palat.  MS.  2510,  calendar  compiled  '  circa  1254  '. 


ROGER  BACON'S  WORKS  379 

9.  De  cometis. 

Inc.  '  Occasione  cuiusdam  comete  que  nuper  apparuit.' 
MS.  Florence  :   Riccardi  885,  ff.  1 13-14. 
(Cf.  Bridges,  i.  385.) 

Cf.  a  passage  on  the  comet  of  1264  inserted  in  Royal  7  F.  vii,  f .  109'^, 
and  re-copied  in  Royal  7  F.  viii,  f.  11,  intended  for  insertion 
at  the  end  of  Part  I,  cap.  ii,  of  the  De  Multiplicatione  Specierutn. 
Inc.  '  Deinde  queritur  an  ahquod  agens  '  :  e.xpl.  '  spirituali  et 
corporali  '  (not  printed  by  Bridges,  ii.  431). 

10.  OpusMajus  :  wTitten  .\.D.  1266-8  :  7  parts.     Inc. '  Sapientiae 
perfecta  consideratio  consistit  in  duobus.' 

{A)   MSS.   and  editions   of    the    whole    work    or  of  several 
parts  : 

British  Museum :  Cotton  Jul.  D.  v.  If.  71-151'  (sec.  xiii  ex.), 
injured  by  fire,  contains  l*arts  I,  II  (f.  S^),  III  (f.  91^), 
and  a  large  portion  of  Part  IV  (f.  108')  ;  ends  '  et  ideo 
philosophi  (universahter  dampnant) ',  Bridges,  i.  241. 
— Add.  35253  :  a  photographic  copy  of  Witican  MS. 
(see  below). 

Oxford  :  Bodl.  Di^by  235  (secc.  xv  et  xiv),  containing 
opus  Miijus,  Parts  I-\',  Tractatus  dc  Midtiplicaiione 
specierutn.  Opus  Majus,  Parts  VI,  VII. 

Winchester  College  39  (sec.  xv),  ff.  85-180,  containing 
Opus  Majus,  Parts  I-IV,  ending  abruptly  in  the  middle 
of  the  word  'Cih[ciam]',  Bridges,  i.  150;  '  ciam  ' 
forming  the  catchword  of  the  next  (lost)  quire. 

Dubhn  :  Trinity  College  381  (sec.  xvi  ex.),  copied  from 
Digby  MS. 

Cambridge  :  Trinity  College  1294  (sec.  xvii),  copied  from 
Dublin  MS. 

Rome  :  Vatican  4086,  If.  1-74  (sec.  xiv  in.),  containing 
Parts  I,  II.  Ill,  and  IV  (except  the  astrological  treatise 
beginning  '  Post  locorum  descriptionem  ',  Bridges,  i. 
376-403).  It  ends  '  principalem  scripturam  ', 
Bridges,  i.  376.  This  closely  resembles  Cott.  Jul.  D.  v, 
but  is  not  a  copy  of  it. 

Paris :  Bibl.  Nat.  :  Nouv.  Acq.  Lat.  1715  (sec.  xv), 
a  copy  of  Vatican  MS.  (?) — Bibl.  Mazarine  3488 
(sec.  xviii). 
Printed  :  Parts  I-VI,  ed.  S.  Jebb,  London,  1733  :  re- 
printed Venice,  1750.  Parts  I-VII,  ed.  J.  H.  Bridges, 
2  vols.,  Oxford,  1897,  with  a  (3rd)  supplementary  vol., 
London,  1900. 


38o  APPENDIX 

{B)  MSS.  and  editions  of  separate  parts  : 

I.  On  the  four  general  causes  of  human  ignorance.    Inc.  cap.  \, 
'  Sapientiae  perfecta  consideratio.' 

MS.  Brit.  Museum  :  Colt.  Jul.  F.  vii,  11.  i8f>-20o(sec.  xv).' 
Tlic  leaves  have  been  misplaced  in  binding  ;  the  work 
ends  with  the  words  '  facilius  adimplere  '  on  f.  19b 
(Bridges,  i.  32,  iii.  35).  Fol.  197'  begins  '  manifestis. 
Quemadmodum  '  (Bridges,  p.  b)  ;  f.  200  ends  with  the 
w(jr<ls  '  sieul  ipsemet  confttetur  et  '  (Bridges,  p.  15). 

II.  On  the  connexion  of  philosophy  with  theology.      Inc.  cap.  i, 
'  Relegatis  igitur  [in  internum]  quatuor  causis.' 

No  separate  MSS. 

III.  On  the  study  of  language   or   De  utililate    grammaticae. 
Inc.  cap.  I,  '  Declarato  igitur  quod  una  est  sapientia.' 

No  separate  MSS. 

IV.  On  mathemuiical  science,  or  De  utililate  mathematicae.    Inc. 
'  Manifestato  quod  multae  praeclarae  radices  sapientiae.' 

The  part  contains  several  sections  :  (a)  Utilitas  mathe- 
maticae in  physicis,  in  4  '  distinctiones  ',  Bridges,  i. 
97-174  ;  inc.  ut  supra,  (b)  Utilitas  mathematicae  in 
divinis,  Bridges,  i.  175-238  ;  inc.  '  Postquam  manifesta 
est  necessitas.'  (c)  fudicia  astronomiae,  Bridges,  i. 
238-69  ;  inc.  '  Manifestato  quomodo  mathematica 
necessaria  est.'  {d)  Correctio  calendar ii.  Bridges,  i. 
269-85  ;  inc.  '  Sed  haec  hactenus.  Nunc  vero  inferam 
secundum  '  (cf.  Op.  Tert.,  cap.  68,  p.  274).  (<?)  Geo- 
graphia,  Bridges,  i.  286-376  ;  ijic.  '  Postquam  declara- 
tum  est  quomodo  mathematica.'  (/)  Astrologia. 
Bridges,  i.  376-403  ;  inc. '  Post  locorum  descriptionem. 
MSS.  Brit.  Museum  :  Royal  7  F.  vii,  ff.  2-62  (sec.  xiii,  ex.)  : 
'  Pars  quarta  compcndii  studii  theologie.'  Inc.  '  Mani- 
festo   {sic)    quod    multe,'     &c.       Expi.    '  principalem 

'  This  seems  to  be  the  MS.  wliich  Renan  consulted  in  the  library  of 
St.  Gregory  in  Clivo  Scauri  at  Rome  (Avcrrots  et  I'Averroisme,  p.  263  : 
Archives  des  Missions,  &c.,  i.  377).  Father  Livarius  Oliger,  O.F.M., 
informs  me  that  no  MS.  of  Roger  Bacon  is  mentioned  in  the  catalogue  of 
the  St.  Gregory  MSS.  which  are  now  in  the  Bibhoteca  Nazionale  at  Rome  ; 
nor  is  it  at  St.  Gregory's.  Like  many  of  the  St.  Gregory  MSS.,  this  Paris 
MS.  originally  came  from  Venice.  The  passage  quoted  by  Renain,  A  verrois 
et  I'Aierroisme,  u.s.,  will  be  found  in  Bridges,  iii.  47. 

=  In  Jul.  D.  V,  and  Vat.  4086  the  transition  from  Part  III  to  Part  IV 
is  not  clearly  marked.     See  Bridges,  iii.  pp.  viii,  Lx. 

"^  This  section  (/)  is  not  found  in  Vat.  4086,  nor  in  Tib.  C.  v,  but  occurs 
in  Digby  235  and  in  E^corial  g.  iii.  17.  The  substance  of  it  agrees  with 
what  is  said  in  Opus  Tert.  (Brewer,  96-9)  of  the  section  '  De  Caelestibus  ' 
in  the  Opus  Minus,  of  which  work  it  originally  formed  a  part.  Cf.  Little, 
Part  of  the  '  Opus  Tertium  '  (1912),  pp.  xvii-xviii,  18.     (See  below,  No.  12.) 


ROGER  BACON'S  WORKS  381 

scripturam.'  Ibid.  f.  68,  '  Tractatus  dc  corporibus 
celestibus  '  (fifteenth  century  title)  ;  inc.  '  Post  locorum 
descriptionem  '  :  expl.  '  natura  obedit  cogitationibus,' 
Bridges,  i.  376-402  (i.e.  Art.  (/)  above). 

G)tton  Tib.  C.  v,  ff.  49-119  (sec.  xv)  :  '  Incipit  4'-^  pars 
maioris  operis  fratris  Rogeri  Bacon  in  qua  ostenditur 
potestas  mathematice  in  scientiis  et  rebus  mundi.' 
Inc.  '  Manifesto  (sic)  quod  multe.'  Expl.  '  principalem 
scripturam,'  Bridges,  p.  376. 

Cotton  Otho  D.  i,  ff.  209-21  (injured  by  fire),  the  section 
'  Geographia  ',  Bridges,  i.  286-376,  ending  '  de  locis  et 
gentibus  totius  habitabihs  '. 

Cotton  Jul.  F.  vii,  11.  178-82  (sec.  xv)  :  '  Declaratio 
effectus  vere  mathematice  in  4'^  parte  majoris  operis 
fratris  Rogeri  Bacon  distinctione  ^^'-^  inter  aUa  sic 
declarat.  Veri  mathcmatici  considerans  (?)  scitus  et 
loca  planetarum  '  (not  identified)  :  '  De  moribus 
hominum  secundum  complexiones  causatas  a  con- 
stellationibus  supracelestibus  prout  allegat  doctor 
Rogerus  Bacon  in  quarta  parte  majoris  operis  .  .  .  ut 
in  fine  capituli  4"  et  in  principio  cap.  5''.  .  .  .  Com- 
plexiones locorum — maxime  a  juventute,'  Bridges,  i. 
137-9,  ',  ^'t  nunc  ponam  unum  cxemplum  .  .  .  tam  sanis 
quam  infirmis,'  Bridges,  i.  139-43. 

Add.  8786  (sec.  xiv),  ff.  I2''-I3',  containing  cap.  xv,  and 
part  of  cap.  xvi,  of  Dist.  iv.  Bridges,  i.  167-72. 

Sloane  2629,  ff.  17-53  (sec.  xvii) :  '  Incipit  tractatus  fratris 
Rogeri  Bacon  de  utilitate  astronomic,'  'Superius  quidem 
dictum  est  .  .  .  plura  conscribere,'  Bridges,  i.  377-403.' 

Lambeth  Palace,  200,  ff.  2-37''  (sec.  xv)  :  '  De  commcnda- 
tione  artis  mathematice  '  :  inc.  '  Manifesto  quod  '  ; 
expl.  '  principalem  scripturam.  Explicit  liber  lohannis 
(sic)  Bacon  de  commendatione  artis  mathematice,' 
Bridges,  i.  97-376,  omitting  the  section  '  Correctio 
Calendarii  ',  and  perhaps  other  passages. 

Oxford  :  Bodl.  :  Digby  183,  f.  49  (sec.  xiv,  ex.),  fragm. 
beginning  '  et  virtutis  a  loco  ',  and  ending  '  plane  vel 
concave  non  ',  Bridges,  i.  111-56. — E.  Musaeo  155, 
p.  185  (sec.  XV,  in.)  :  '  Pars  quarta  in  qua  ostendit 
potestatem  mathematicae/  &c.,  expl.  '  principalem 
scripturam.' — Laud.  Misc.  674,  f.  7  (sec.  xv)  :  '  Nota 
de  correctione  Calendarii  ex  Rogeri  Baconis  libro  ad 

■  Cf.  Bale,  Index  Brit.  Script.,  p.  396:    '  Introd.  in  Astrologiam.'     Inc. 
Fusius  quidem,'  &c.  ('  fusius  '  is  a  mistake  for  '  superius  '). 


382  APPENDIX 

Clcmentem  papam  '  (one  page  only). — Seld.  supra  79, 
pp.  42-84  (sec.  xvii),  excerpts. — Univ.  Coll.  49  (sec. 
xvii),  ff.  105-50,  164-76. 

Cambridgi-  :  Corpus  Christi  Coll.  426,  ii  (sec.  xv)  :  Tract. 
fratris  Kogrri  Bacon  in  quinta  parte  mathematical 
(Je  situ  orhis.  '  Post(juam  doclaratum  est  .  .  .  tociu 
habitabilis,'  Bridges,  i.  286-376. — Peterhouse  277 
(sec.  XV),  f.  185'  :  '  I)e  utilitate  arismetrice  \x.-t  Kogerum 
Bacon.  De  utilitate  arismetrice  potest  sumi  per  infra 
scripta  '(!)...'  10°  luna  11°  mrTcurius.  Et  sic  est  finis 
huius  operis  Magistri  Kogcrii  bakonis  ut  pattt  in  sua 
snmma  ad  Clcmontcm,'  Bridges,  i.  224-36. 

l^aris  :  Bibl.  Nationale  7455,  A.  (sec.  xv)  :  '  De  utili- 
tatibus  scientiae  mathematicae  verae.' 

Wolfenbiittel  :  Herzogl.  Bibl.  4125  (41  Weiss.),  ff.  91-120 
(sec.  xv),  '  Kogeri  Baconis  dc  rt-gionibus  ad  papam 
Clcmentem.'  Inc.  '  Sed  hoc  hactcnus.  Nunc  vero 
inferam.'  Expl.  '  principalem  scripturam,'  &c.  (i.e.  Cor- 
rectio  Calendarii  and  Geographia,  Bridges,  i.  269-376). 

Escorial,g.  iii.  17  (sec.  xiii),  f.  i, '  Pars  quarta  in  qua  osten- 
ditur  potcstas  mathematice  in  scienciis  et  rebus  et  occupa- 
tionibus  huius  mundi.'    Inc.    '  Manifesto  quod  multc* 
(inchides  also  Geographia,  f.  50',  and  Asirologia,  f.  72). 
Printed  by  Combach,  Frankfurt,   1614,  under  the  title  : 
Specula    viathematica    in    quibus    de    specierum    mtdti- 
piicatione  .  .   .  agitur,    dec,  as  far  as  Bridges,  p.  174 
(i.e.  §  a,  Mathematicae  in  Physicis  Utilitas). 
V.    Optics,  or  De  Scientia  Perspectiia.     Inc.  cap.  i,  '  Propositis 
radicibus  sapientiae.' 

(In  some  MSS.,  and  in  the  edition  of  1614,  this  part 
begins  :  '  Cupiens  te  et  alios,'  a  preface  perhaps  to 
a  later  cop}'  of  the  Pcrspectiva,  addressed  to  some  person 
unknown,  not  to  the  Pope.    See  Bridges,  ii.  i,  n.) 

Divided  into  three  parts  :  (i)  explains  the  general 
principles  of  vision,  and  has  ten  disiinctiones  :  inc. 
'  Propositis  radicibus  '  ;  (2)  deals  with  direct  vision,  and 
has  three  disiinctiones  :  inc.  cap.  i,  '  Et  quoniam  eadem 
est  scientia  oppositorum  ;  '  (3)  deals  with  reflected  and 
refracted  vision,  and  has  three  distinctiones  :  inc.  cap.  i, 
'  Habito  de  visu  facto  secundum  lineas  rectas.' 
MSS.  :  Brit.  Museum  '  :  Royal  7  F.  viii  (sec.  xiii),  ff.  47-98' : 
'  Tractatus  perspective  habens  tres  partes  prima  est 

'  The  treatise  '  de  visu  et  speculis  '  in  Royal  7  F.  vii,  f.  64  {inc.  '  De 
speculonim  miraculis  .  .  .  Nichil  ab  oculo  ')  is  not  by  Bacon,  but  probably 
by  Henry  of  Southwark.  (Assisi  MS.  673,  Pars  Perspective,  inc.  '  Prima  pars 
perspective  que  est  de  radio  directo ',  seems  to  be  by  Pecham.) 


ROGER  BACON'S  WORKS  383 

de  commuRibus.'      Inc.  'Hie  aliqua  dicenda  sunt  de 

perspectiva.     Autores  quidem  multi  tractant  '  (i.e.  in 

the  preface  beginning  elsewhere,  '  Cupiens  te  et  ahos  ')  ; 

expl,  '  non  posset  sustinere,'  Bridges,  ii.  1-166. 
Cotton  Fragments  iv,  ft".  23-6  (sec.  xiv).     Inc.  *  Sciendum 

vero   quod   xisio  '  :    expl.    '  speculo  '    (i.e.   Bridges,  ii. 

148-63). 
Sloane  2156,  ff.  1-41'  (A.  d.  1428)  :    '  Hie  incipit  tractatus 

perspective  .  .  .  Hie  ahqua  dicenda  sunt.'     Expl.  '  non 

posset  sustinere.    Ecce  finis  perspective  summe  bonitatis 

ilhus  mirabiHter  nobihs  et   nobihter  mirabihs   Rogeri 

Bachon  Anno  Christi  1428.' 
Sloane   2542,    ff.   1-54  (sec.  xv),    imperfect,    beginning 

illegible  :   expl.  '  non  posset  sustinere.  Explicit,  etc' ' 
Harl.  80,  ff.  1-33'  (sec.  xv):  'Tractatus  perspective  habens 

tres  partes  .  .  .  Propositis  radicibus.'    Expl.  '  non  posset 

sustinere.' 
Add.  8786,  ff.  84-107  :  '  Incipit  tractatus  de  modo  videndi. 

Quoniam  precipua  delectatio  '  (i.e.  Bridges,  ii.  2,  1.  4). 

Expl.  '  non  posset  sustinere.' 

Oxford  :  Bodl.  :  Bodley  874,  pp.  1-71  (sec.  xv)  :  Inc. 
'  Cupiens  te  et  alios  '  ;  expl.  '  aliqualiter  sustinere.' — 
Digby  77,  ff.  1-56'  (sec.  xiv) :  Inc.  '  Cupiens  te  et  alios.' — 
Digby9i(sec.  xvi). — Corpus Chr.  Coll.,  223,  f.  3  (sec.  xv). 

Cambridge  :  Magdalene  College,  Pepysian  Library,  1207 
(sec.  xv).'' — Trinity  College  1418,  f.  66  (sec.  xv)  :  Inc. 
'  Prepositis  iudicibus  (!)  sapiencie  '  ;  expl.  f.  96^,  '  mul- 
tum  (!)  nativitatis  sue  in  speculo,  etc'  (Bridges,  ii.  163). 

Paris  :  Bibl.  Nat.  2598,  ff.  57-86  (sec.  xv). — Nouv.  Fonds 
Lat.  10260  (sec.  xvi). 

'  This  is  followed  in  Sloane  254J,  ff.  54'-55'' by  two  paragraphs:  (i) 
'  Quod  autem  candela  appareat  maior .  . .  sicud  fumus  habctur,  etc.  Explicit 
perspectiva  fr.  Rogeri  Bakun '  (cf.  Bridges,  ii.  158);  (2)  '  Auctores  autem 
perspective  asseruerunt  .  .  .  quare  pcius  videantqui  habentoculos  proemi- 
nentes',  &c.  (cf.  Bridges,  ii.  83). 

-  I  am  indebted  to  Mr.  S.  Gaselee,  Pepysian  Librarian,  for  the  following 
notes  on  this  MS.,  which  is  very  badly  written.  It  was  obtained  by 
Dr.  Dee  at  Oxford  in  1559,  and  was  perhaps  intended  as  a  working  copy 
for  the  Oxford  schools.  Title  :  '  Tractatus  perspective  habens  tres  partes  : 
prima  est  de  communibus  ad  ceteras  2"^ :  secunda  pars  descendit  in 
speciali  ad  visionem  rectam  principaliter :  3"'  ad  reflexam  visionem.' 
[Inc.  prol.]  '  Nunc  igitur  ad  instanciam  tuam  quedam  meduUaria  '  [i.e.  in 
the  letter  elsewhere  beginning  'Cupiens  te'.]  [/nc.  Opus]  'Quoniam 
precipua  delectacio  nostra  est  in  visu  '  [i.e.  Bridges,  ii,  p.  2,  1.  4].  Expl. 
'  languide  conspicientibus  rem  visum.  Possunt  etc.  sicut  (?)  superius 
habetur  [cf.  Bridges,  ii,  p.  159,  1.  i].  Explicit  perspectiva  fratris  Rogeri 
Bakun,' 


384  APPENDIX 

Erfurt  :  Amplon.  F.  393,  If.  1-22  (sec.  xiv  ex.) :  Inc. 
'  Cupiens  te.' 

Prag  :  Bibl.  Publ.  et  Univ.  1552  (sec.  xiv)  :  Inc.  '  Pro- 
positis  radicibus.' — 1601  (sec.  xiv),  '  Tractatus  perspec- 
tive habens  tres  partes.' 

Florence  :  Riccardi  885,  ff.  144-98  (sec. xiv).  Inc. '  Cupiens 
te  et  alios.'  Hxpl.  '  aliqualiter  sustinere.'  (Cf.  Arch. 
Franc.  Hist.  iii.  554,  where  reference  is  made  to  a 
fifteenth-century  copy  of  this  work  at  Toledo,  mentioned 
in  Revista  de  Archtvos,  Bibliotecas  y  Museos,  An.  Ill.n.  6, 
ser.  i.) 

Milan  :  Ambrosiana  R.  47  sup.,  f.  61  (sec.  xiii)  :  Inc. 
'  Propositis  radicibus.' 

Rome:  Vatican  Palat.  828,  f.  49  (a. D.  1349).  -^"C- 
'  Propositis  radicibus  sapientie.' — Vat.  Lat.  3102 
(sec.  xiv),  ff.  1-27  :  Inc.  '  Hie  aliqua  sunt  dicenda.' 
— Cf.  Vat.  Lat.  2975  (sec.  xvi),  Tract,  perspect.  a  fr. 
Rog.  Baco  :    Inc.  '  Ouoniam  inter  gradus  sapientiae.' 

Venice  :  S.  Marco,  Lat.  vi,  133  (Vol.  IV,  CI.  xi.  Cod.  10) 
(sec.  xiv)  :    Inc.  *  Cupiens  te  et  alios.'  ' 

Printed  by  Combach,  Frankfurt,  1614,  under  the  title: 
Rogerii  Baconis  Angli  .  .  .  Pcrspectiva.     Inc.  '  Cupiens 
te  et  alios,' 
VI.  Experimental    Science.     Inc.    cap.     i,     '  Positis    radicibus 
sapientiae  Latinorum.' 

MSS.  Brit.  Museum  :  Sloane  2629  (sec.  xvii),  ff.  2-16  : 
'  Tractatus  fratris  Rogeri  Bacon  extractus  de  VP.  parte 
compendii  studii  theologie  quem  librum  fecit  ad 
instanciam  Clementis  et  est  tractatus  de  materia  prius 
tractata  et  extrahitur  de  capitulo  quod  intitulatur  de 
scientia  experimentali  :  et  si  quis  velit  pleniorem 
habere  doctrinam  et  responsionem  ad  dif&cultates  que 
possunt  in  contrarium,  querat  scripta  principaha, 
viz.  librum  vi  scientiarum  et  librum  quem  intitulatur 
compendium  studii  theologie  et  inveniet,'  &c.  Inc. 
'  Corpora  vero  Ade  et  Eve  post  peccatum  '  {Opus 
Minus,  p.  373) :  expi.  '  et  alibi  multis  modis ',  &c. 
{Opus  Majus,  ii.  204-13). 

Oxford  :  Bodl.  :  Can.  Misc.  334,  f.  53,  '  Alius  tractatus 
ejusdem  Fratris  Rogeri  extractus  de  sexta  parte 
compendii  studii  theologiae  '  :   inc.  '  Corpora  vero  .  .  . 

'  The  same  MS.  contains  (ft.  50-72)  Tractatus  de  velocitate  tnotuum  ;  inc. 
'  Omnis  racionabilis  opinio  de  velocitate',  two  treatises — (i)  algorismus 
proportionum,  (2)  de  quibusdam  subtilibus  inferioribus  ex  praedictis. 
Is  this  by  Bacon  ?    or  WilUam  de  Heytesbury  ?     (Cf.  Bruges  MS.  497.) 


ROGER  BACON'S  WORKS  385 

multis  modis '  {ut supra).  Bodl.  438,  ft.  29''-3i''  (sec.  xv) ; 
Selden  supra  94,  f.  256''  (sec.  xiv)  :  E'Musaeo  155, 
p.  689  (secc.  xiv-xv),  and  Arch.  Seld.  B.  35,  f.  39" 
(sec.  xiv),  the  same  extract. — University  College  49, 
f.  151  (sec.  xvii). 
Cambridge  :  Trinity  College  1389  (sec.  xv),  f.  39"'  : 
'  Alius  tractatus  eiusdem  fr.  Rogeri  Bakon  extractus 
de  sexta  parte,'  &c.  '  Corpora  vero  .  .  .  |  multis  modis  ' 
(ut  supra).  (Ibid.  922,  f.  sb""  (sec.  xv),  contains  an 
EngUsh  translation  of  the  same  passage.)  Ibid.  11 19, 
f.  56'  (secc.  xvi,  xvii)  :  '  Here  followeth  the  first  part 
of  the  great  work  namely  the  experimental  science  of 
Roger  Bacon  written  to  Clemens  ye  Pope.'  '  Now  that 
I  have  set  forth  ye  rotes  of  the  science  of  knowledge 
of  the  Latines  in  respect  of  toungs.'  Ends  unfinished, 
f.  68\ 
Manchester  :   Chetham  Library  A.  5.  24  (sec.  xv),  f.  61"  : 

'  Corpora  vero  ',  ut  supra. 
Douai  691,  §  3  (sec.  xvii). 

Rome  :  Vatican  4091  (sec.  xvi),  ff.  49-61,  contains  cap.  i-vii 
(cf.  Bridges,  iii,  pp.  xii,  182).  Inc.  '  Positis  radicibus  '.' 
VII.  Moral  Philosophy.  Inc.  '  Manifestavi  in  praeccdentibus 
quod  cognitio  linguarum.'  Six  parts  :  (i)  duty  to  God,  to 
neighbour,  and  to  self  :  (2)  '  Secunda  pars  descendit  ad 
leges  et  statuta  hominum  inter  se  '  :  (3)  '  De  regimine 
hominis  in  comparatione  ad  se  ipsum  '  :  (4)  '  consistit 
in  persuasione  sectae  fidelis  credendae  ct  amandae  et 
operibus  comprobandae  quam  debet  humanum  genus 
recipere,'  or  the  grounds  for  accepting  the  Christian  religion  : 
[(5)  '  Ouinta  pars  est  de  sectae  jam  persuasae  et  probatae  ex- 
hortatione  ad  implendum  in  opcre  et  ad  nihil  faciendum 
in  contrarium,  et  hie  exigitur  modus  pracdicationis  :  (6) 
Sexta  vero  pars  moralis  philosophiae  est  de  causis  venti- 
landis  coram  judice  inter  partes  ut  fiat  justitia  :  sed  hanc 
solum  tango  propter  causas  quas  assigno.']  Parts  (5)  and 
(6)  are  unknown  ;  the  description  of  them  is  taken  from 
Opus  Tert.,  cap.  xiv  :  cf.  also  ibid.,  pp.  266,  304-8.  A  brief 
summary    of    them    is    contained    in    Professor    Duhem's 

*  This  MS.  Vat.  Pal.  4091,  ff.  49-88,  copied  in  a  late  sixteenth-century 
hand  '  ex  oper.  perg.'  presents  a  curious  combination.  It  contains  '  Rogeri 
Bachonis  Tractatus  in  quo  fit  sermo  de  experientia  in  communi  habens 
4  distinctiones  et  i*  habet  7  capita'.  Part  VI  of  Opus  Majus,  capp.  1-7 
(the  seventh,  on  haloes,  differs  from  Bridges,  cap.  vii).  The  four  distinctions 
are  :  f.  49,  de  experientia  in  communi  :  f.  62,  de  potestate  artis  et  naturae 
(  =  No.  18)  :  f.  71,  de  retardanda  senectute  (  =  No.  23)  :  f.  88,  de  mirabili 
artificio  quod  fit  per  lapidem  magnetem  (  =  No.  70). 


386  APPENDIX 

op.  Tert.,  and  Little,  Op.  Tcrt.  (sec  below).    The  last  part  (6) 
was  never  written  :     '  excusavi   me  ab  expositione  istius 
partis  '  :   Duliem,  p.  179. 
MS.    Brit.    Musuum  :    Royal    8    F.    ii  (sec.    xv),  f.  167.   Inc. 
'Manifestavi  (etc.)  .  .  .  eius  quod  est  postse'  (Bridges, 
ii.  223-75)  ;  it  includes  Farts  (i)  and  (2),  and  capp.  i-v 
of  Part  (3). 
This  part,  omitted  by  Jebb,  was  first  printed  by  Bridges,  ii. 
223-403.     (It  was  not  printed  at  Dublin  in  18O0,  but 
described  by  Dr.  Ingram  in  a  paper  printed  in  vol.  viii 
of  the  Proceedini^s  of  the  Royal  Irish  Academy.) 

II.  Tractatus  de  Multiplicatione  Specierum. 

A  treatise  on  this  subject  was  sent  to  the  Pope  in  1267-8  apparently 
in  two  versions:  e.g.  Op.  Tert.,  p.  227,  'tractatus  de  radiis 
quem  vobis  misi  separatim  ab  Opcrc  Majori  ;  '  ibid.  230,  '  in 
tractatu  de  radiis  quem  Johannes  extra  principalia  opera  de- 
portavit  ;  '  ibid.  38,  '  sed  completiorem  tractatum  mitto  vobis 
de  hac  multiphcatione  ;  '  ibid.  99,  '  Tractatus  de  speciebus  et 
virtutibus  agentium  quem  dupliciter  misi  vobis,  et  tertio  mode 
incepi  sed  non  potui  consummare.'  Either  at  this  time  or 
later  it  formed  part  of  a  larger  work.  At  the  beginning  of  the 
treatise,  as  printed  by  Jebb  (p.  358)  and  Bridges  (ii.  408), 
are  the  words  :  '  Recolendum  est  igitur  quod  in  tertia  parte 
hujus  operis  tactum  est,  cjuod  essentia,  substantia,  natura, 
potestas,  potentia,  virtus,  vis  significant  eandem  rem,  sed 
differunt  sola  comparationc.'  There  is  nothing  about  this  in 
the  third  part  of  the  Opus  .\Iajus,  but  it  is  found  in  the  Com- 
munia  Naturalium  (Lib.  I,  pars  ii,  p.  80,  in  Steele's  edition), 
to  which  Bacon  refers  elsewhere  in  the  same  treatise  (Bridges,  ii. 
424,  '  ut  prius  in  Communibus  Naturahum  demonstratum  est '), 
while  in  tlie  Communia  Naturalium  he  frequently  refers  to  the 
De  Mult.  Specierum  (e.g.  Steele,  pp.  38,  203,  272,  &c.).  The 
treatise  was  therefore  included  in  a  work  of  which  the  Communia 
Naturalium  formed  the  third  (or  a  portion  of  the  third)  part. 
This  was  the  Scriptum  Principalc  or  Compendium  Philosophiae 
(see  No.  35  below). 

The  versions  of  the  De  Mult.  Spec,  differ  considerably, 
and  the  treatise  is  divided  sometimes  into  six,  some- 
times into  ten  parts.  Tw-o  distinct  recensions  are 
extant,  marked  in  this  hst  (.4)  and  {B). 

{A )  Inc.  prol. :  '  Postquam  habitum  est  de  principiis  rerum 
naturalium.'  Inc.  opus  :  '  Primum  igitur  capitul\im 
circa  influentiam  agentis  habet  tres  veritates.' 
MSS.  :  British  Museum  :  Royal  7  F.  viii  (sec.  xiii  ex.), 
ff.  13-46''.  Inc.  '  Primum  igitur  capitulum  ; '  expi. '  rece- 
perit.'  This  is  followed  by  a  passage  marked  vacai,  which 
Bridges  prints  at  the  end  of  the  treatise  (pp.  551-2), 
and  which  is  inserted  in  MS.  Royal  7  F.  vii,  f.  109  ; 


ROGER  BACON'S  WORKS  387 

inc.  '  Sed  hoc  est  intelligendum.'  On  the  same  leaf, 
109^,  is  a  passage  for  insertion  in  Royal  7  F.  viii,  f .  16, 
at  the  end  of  cap.  ii  of  the  De  Mult.  Spec,  and  recopied 
in  7  F.  viii,  f.  11  (not  printed  in  Bridges,  p.  431)  ; 
inc.  '  Deinde  queritur  an  ahquod  agens  '  :  expi.  '  spiri- 
tuaU  et  corporali.' — Add.  8786,  ff.  21^-45^  (sec.  xiv) : 
inc.  'Postquam,'  &c. — Sloane2i56,  ff.42-7i(A.D.  1428) : 
inc.  '  Primum  igitur,'  &c.  :  expL,  cap.  31,  '  Sed  an  in 
aere  .  .  .  postquam  receperit  '  (Bridges,  ii.  551). 

Oxford :  Bodl.  Digby  235,  f .  153  (sec.  xv)  :  inc.  '  Primum 
igitur,'  &c.  :  inserted  in  Opus  Majus  :  expl. '  postquam 
receperit  '  (Bridges,  ii.  551). 

Cambridge  :  Trin.  Coll.  1294  (sec.  xvii). — Magdalene 
Coll.,  Pepysian  Lib.  1207  (sec.  xv)  :  inc.  '  Species 
multiphcata  in  medio  ahunde  vocatur  similitude  agentis 
et  ymago.'    (Cf.  Bridges,  ii.  409,  1.  7.) 

Winchester  College  39  (sec.  xv),  ff.  45-84  :  inc.  '  Primum 
igitur  capitulum.' 

DubUn  :   Trin.  Coll.  381  (sec.  xvi  ex.),  in  Opus  Majus. 

Paris  :  Bibl.  Nat.  2598,  ff.  21-56  (sec.  xv)  :  inc.  '  Post- 
quam,'  &c. — Mazarin  3488,  p.  239  (sec.  xvii). 

Bruges  490  (sec.  xiii),  called  Philosophia  Baconis  ;  inc. 
'  Primum  igitur.' 

Douai  691,  §  4  (sec.  xvii). 

Florence  :  Laurenz.  Ashburnham  957  (sec.  xv,  humanistic 
writing),  ff.  1-70  :  no  title.  Inc.  '  Primum  igitur  '  : 
expl.  '  propter  rationes  contrarias  ut  in  luna,'  Bridges,  ii. 
550. — Bibl.  Naz.,  Conventi  Soppressi  I,  IV,  29  (sec.  xv), 
ff.  2-47  (from  San  Marco),  contains  same  as  Ash- 
burnham MS. 

Milan  :  Ambros.  R.  47  sup.  (sec.  xiii),  f.  i  :  De  generatione 
[et  corruptione)  specierum  :   inc.  '  Postquam,'   &c. 

Venice  :  S.  Marco,  Lat.  vi.  133  [Vol.  IV,  CI.  xi.  Cod.  10], 
(sec.  xiv)  :  inc.  '  Primum  igitur.' 

Vienna  :  Bibl.  Palat.  531 1  (secc.  xiv,  xv),  ff.  101-6 
(excerpts),  followed  by  Roger  Bacon,  De  muUiplicatione 
lucis,  ff.  io8'"-i3''. 
Printed  by  Jebb,  between  Part  V  and  Part  VI  of  Opus 
Majus  (pp.  358-445)  :  and  by  Bridges,  at  the  end  of 
Opus  Majus,  ii.  407-552.  Extracts  from  the  prologue 
in  Bridges,  ii.  183-5. 

{B)  The  beginning  of  another  recension  exists  in  two 
versions  ;   these  differ  somewhat  from  each  other,  but 
still  more  from  the  printed  edition. 
1689  C  c 


388  APPENDIX 

MSS.  :  Brit.  Museum,  Royal  7  F.  viii,  ff.  2-12  (sec.  xiii), 
an  amplified  version  of  the  earlier  part  of  the  De  Mult. 
Speciefum.  Inc.  '  Dato  prologo  istius  quinte  partis 
huius  voluminis  quod  voco  compendium  studii  theologie, 
in  quo  quidem  comprehendo  in  summa  intentionem 
totius  operis,  extra  partem  ejus  signans  omnia  impedi- 
menta totius  studii  et  remedia,  nunc  accedo  ad  tractatum 
exponens  ea  que  necessaria  sunt  theologie  de  perspectiva 
et  de  visu  '  :  it  includes  Dist.  I,  capp.  1-5,  Dist.  II, 
capp.  1-2,  with  references  to  the  remaining  parts  of  the 
treatise. 
Rome  :  Bibl.  AngeHca  1017  (sec.  xv),'  ff.  76-92.  Inc. 
'  [C]onpletis  4°''  partibus  3"  libri  de  compendio  studii 
theologie  sequitur  4*^  [sic)  pars  istius  Ubri  que  est  de 
perspectiva  que  fundatur  in  actionibus  agentium  et 
virtutibus  eorum  quas  influunt  in  materiam  mundi 
et  in  contrarium  in  sensum  et  intellectum  humanum  et 
angelicum  ' — ending  apparently  with  cap.  iv  of  Pars 
(or  Dist.)  II  :  Bridges,  ii.  478. 
12.  Opus  Minus,  written  in  1267,  was  both  an  introduction 

and  a  supplement  to  the  Opus  Majus.     It  seems  to  have 

consisted  of  the  following  parts  : 

i.  Introduction  or  dedicatory  letter.  Bacon  describes  this  in  the 
Opus  Tert.,  p.  7  :  '  Primo  igitur  in  Opere  Secundo,  secundum 
foririam  epistolae  Marci  TuUii  post  exihum  revocati,  .  .  .  recolens 
me  jam  a  decern  annis  exulantem  quantum  ad  famam  studii 
quam  retroactis  temporibus  obtinui,  .  .  .  vestramque  sapientiam 
admirans  .  .  .  ;  secundo  assurgens  vestrae  clementiae,  exordium 
sermonis  capiens,  post  pedum  oscula  beatorum,  stylum  altius 
elevando,  propter  vestram  celsitudinem,  sub  his  verbis  incepi 
perorare  :  "  Cum  tantae  reverentiae  dignitas  sapientiae  sca- 
turiens  plenitudine,"  '  &c.  The  introduction  therefore  began 
with  some  autobiographical  reminiscences.  This  appears  to  be 
lost ;  but  perhaps  to  it  is  to  be  referred  the  passage  quoted  by 
Anthony  Wood  from  the  Opus  Minus :  '  Praelati  enim  et 
fratres  me  jejuniis  macerantes  tuto  custodiebant,  nee  aUquem 
ad  me  venire  voluerunt,  veriti  ne  scripta  mea  aUis  quam  summo 
pontifici  et  sibi  ipsis  divulgarentur.'  "  The  second  part  of  the 
introduction  began  with  the  words  '  Cum  tantae  reverentiae  ', 
&c.,  and  is  quoted  in  the  Opus  Tertium.     The  fragment  dis- 

'  This  appears  to  be  in  an  EngUsh  hand  and  may  be  the  MS.  which 
Bale  refers  to  as  being  at  Peterhouse,  Cambridge  :  Leges  multiplicationum  ; 
inc.  '  Expletis  quatuor  partibus  Ubri '  :  Index  Brit.  Script.,  p.  394.  I  am 
indebted  to  Cardinal  Gasquet  for  a  rotograph  of  the  AngeUca  MS. 

^  Wood,  Antiq.  Univ.  Oxon.,  ed.  1674,  p.  138.  Browne,  The  Cure  of 
Old  Age,  1683,  quotes  the  passage,  with  the  alteration  of  one  word,  evi- 
dently from  Wood,  on  whom  his  '  Life  of  Roger  Bacon',  prefixed  to  The 
Cure  of  Old  Age,  is  based.  The  passage  is  probably  to  be  found  somewhere 
in  the  MSS.  of  Brian  Twyne,  where,  however,  I  have  searched  for  it  in  vain. 


ROGER  BACON'S  WORKS  389 

covered  by  Cardinal  Gasquet'  in  Vatican  MS.  4086,  and  printed 
in  the  Eng.  Hist.  Rev.  xii,  represents  probably  a  revised  and 
partially  expurgated  edition  of  this  part.  The  earlier  portion 
of  it  is  almost  identical  with  Op.  Tert.,  pp.  7-12.  The  latter 
portion  is  occupied  by  a  brief  summary  of  the  Opus  Majiis, 
the  sciences  being  treated  in  inverted  order  or  according  to 
their  dignity,  moral  philosophy  first. 

ii.  An  addition  de  notitia  caelestium  was  made  to  the  section  on 
Mathematics.  This,  there  seems  no  doubt,  was  identical  with  the 
treatise  on  astrology  printed  by  Bridges,  i.  376-403,  at  the  end 
oiOpus  Majus,  Part  IV,  beginning  '  Post  locorum  descriptionem ' 
(see  above).  That  treatise  is  found  in  the  Escorial  MS.  (sec.  xiii) 
of  the  Opus  Majus,  and  in  the  Digby  MS.  (sec.  xv)  and  those 
copied  from  it :  not  in  the  Vatican  MS.  nor  in  the  Cotton 
(Tib.  C.  v),  Bodl.  E  Musaeo,  Lambeth  and  Wolfenbuttel  MSS. 
of  Part  IV,  while  in  MS.  Royal  7  F.  vii  it  is  separated  from  the 
rest  of  the  mathematics  by  two  treatises  occupying  four  leaves. 
And  in  the  Optcs  Tert.  ed.  Little,  p.  18,  Bacon  says  that  the 
geographia  (de  locis  tantum)  was  included  in  the  Opus  Majus, 
the  Astrologia  (de  alter ationibus  locorum  et  rerum  per  celestia,  &c.) 
was  included  in  the  Opus  Minus.  It  should  be  noted  that 
the  Digby  MS.  at  the  end  of  the  preceding  section  (Geographia) 
has  '  Finitur  quarta  pars  majoris  operis ',  though  it  goes  on 
directly  to  the  Astrologia. 

iii.  Practical  alchemy,  '  in  enigmatibus.' 

iv.  Notes  on  the  chief  points  in  Opus  Majus  to  which  Bacon 
wished  to  call  the  Pope's  special  attention,  beginning  with  moral 
philosophy. 

V.  Treatise  on  the  seven  sins  in  theological  study. 

vi.  Speculative  alchemy  or  De  rerum  generatione  ex  elementis," 
inserted  in  the  sixth  peccatum. 

vii.  Remedia  studii. 

The  fragment  edited  by  Brewer,  Op.  Ined.,  pp.  311-90,  from  Digby 
MS.  218,  includes  a  few  pages  of  Part  iii,  all  of  iv,  most  of  v, 
and  part  of  vi. 

The  omission  in  Part  vi  (Brewer,  p.  375)  on  the  prolongation  of 
human  life  may  be  partly  filled  in  from  Opus  Majus,  Part  VI, 
Exemplum  ii  (Bridges,  ii.  205),  where  the  passage  '  Est  autem 
.  .  .  curabit  et '  occurs  word  for  word.  How  much  of  Opus  Majus 
was  here  inserted  is  doubtful ;  probably  to  the  end  of  Exem- 
plum ii :  '  et  alibi  multis  mod  is  '  (Bridges,  ii.  213).  Several 
MSS.  quote  the  passage  beginning  '  Corpora  vero  Adae  et  Evae  ' 
(Op.  Min.  p.  373),  and  ending  '  et  aUbi  multis  modis  '  (Op. 
Majus,  ii.  213).-^  The  substance  of  some  of  the  lost  part  of 
the  De  rerum  gen.  is  contained  in  Lihellus  de  retardandis  acci- 
dentibus  senectutis.     Cf.  also  the  Breve  breviarium  below. 

•  Gasquet  considers  this  fragment  to  be  a  complete  introduction  to  the 
Opus  Majus,  distinct  from  the  Opus  Minus.  This  may  be  so,  but  I  incline 
to  think  it  is  part  of  the  Opus  Minus.  No  further  light  is  thrown  on 
this  point  by  the  parts  of  the  Opus  Tertium  edited  by  Professor  Duhem  and 
myself  (see  No.  13  below). 

-  Beginning  '  Hie  autem  volens  ponere  radicalem  generationem.' 
Brewer,  Op.  Ined.,  p.  359. 

^  See  above  No.  10  (B),  v. 

C  C  2 


390  APPENDIX 

MSS.  Rome  :  Vatican  4086,  ii.  75-82  (sec.  xiv)  ;  Part  i  ; 
inc.  '  Sanctissimo  patri  Domino  Clementi  .  .  .  Cum  tante 
reverentie  dignitas.' 

Paris  :  Bibl.  Nat.,  Nouv.  Acq.  Lat.  1715  contains  the 
same  letter  as  the  Vatican  MS. 

Oxford  :  Bodl.  Digby  218  (sec.  xiv),  f.  57,  imperfect  : 
contains  most  of  the  work  :  the  sixth  part,  on  specu- 
lative alchemy,  begins  on  f.  65  :  title  in  later  hand, 
'  De  rerum  generationibus  :  '  inc.  '  Hie  autem  volens 
ponere  radicalem  generationem  rerum.' — Corpus  Chr. 
Coll.  255  (sfcc.  xvi-x\ii),  '  De  rerum  generationibus.'  * 

(For  MSS.  of  Part  ii,  De  Caelestibus,  see  No.  10,  O^us 
Majlis,  Part  IV.) 
Printed  :  Part  i,  in  Eng.  Hist.  Rev.,  xii.  494.   Part  ii,  in 
Bridges,  Opus  Majus,  i.  376-403.     Parts  iii-vi  (incom- 
plete), in  Brewer,  Rog.  Bacon  Opera  inediia,  pp.  313-89. 

Cf.  Hody,  De  Bibliorum  Textibus,  Oxon.,  1705,  pp.  419-28 
(e.xtracts). 

Summary  in  Duhem,  Opus  Tert.,  pp.  179-81.  Little, 
Opus  Tert.,  pp.  77-9.^ 

13.  Opus  Tertium,  written  in  1267-8,  was,  like  the  Opus  Minus, 
both  an  introduction  and  a  supplement  to  the  Opus  Majus. 

As  edited  by  Brewer  it  contains  75  chapters  (but  the  divisions  of 
chapters  are  given  in  the  MSS.  in  a  modern  hand).  Chapters 
1-2 1  deal  with  Bacon's  gratitude  to  the  Pope,  his  difficulties, 
the  relative  importance  of  sciences  and  their  relations  to  each 
other,  with  special  reference  to  the  Opus  Minus.  With  chapter  22 
begins  the  commentary  on  the  Opus  Majus,  which  includes  a 
long  digression  on  vacuum,  motion  and  space,  capp.  xlii-lii.  The 
remainder  of  the  work  deals  with  the  utiUty  of  mathematics 
in  relation  to  secular  and  sacred  subjects,  as  treated  in  Part  IV 
of  Opus  Majus. 

Here  the  treatise  as  edited  by  Brewer  ends.^  Professor  Duhem 
recently  discovered  most  of  the  remainder  of  the  work  in 
a  MS.  at  Paris  (Bibl.  Nat..  Lat.  10264,  sec.  xv),  under  the  name 
of  Alpetragius  or  Al  Bitrogi  :    Liber  tertius  Alpetragii.     In  quo 

'  This  MS.  (transcripts  of  Brian  Tw>Tie)  also  contains  '  excerpta  ex 
libro  ad  Clem.  IV  de  peccatis  theologorum,'  i.e.  from  Opus  Minus. 

■  Trin.  Coll.,  Cambridge,  MS.  1363,  flf.  1-3^  (sec.  .xv),  formerly  belonging 
to  Dr.  Dee.  contains  a  passage  which  I  have  failed  to  find  ;  it  may  belong 
to  Opus  Minus.  '  Bacon  in  Epistola  ad  Clementem  papam  cap.  i.'  Inc. 
'  Secundum  quod  sunt  4°''  elementa  sic  sunt  quatuor  corpora  quorum 
quodhbet  componitur  ex  dementis  sed  ex  uno  per  dominium.'  Expl.  '  Et 
quanto  magis  iste  ordo  iteretur  tanto  magis  augmentatur  sua  claritas  et 
virtus.  Expl.  tres  medicine  lapidis.'  (But  cf.  note  to  Tract,  de  erroribus 
medicorum.  No.  2S,  below.) 

^  There  is  no  analysis  of  the  later  sections  of  Op.  Maj.  part  iv,  i.e.  of  the 
sections  on  geography  and  astrology,  nor  of  parts  v,  vi,  vii. 


i 


ROGER  BACON'S  WORKS  391 

tractat  de  perspeciiva  i  De  comparatione  scientie  ad  sapientiam. 
De  motibus  corporum  celestiiim  secundum  ptolomeum .  De 
opinione  Alpetragii  contra  opinionem  ptolotnei  et  aliorum.  De 
scientia  experimentorum  naturalium.  De  scientia  tnorali.  De 
articulis  fidei.  De  Alkimia.  This  fragment  contains  (i)  sum- 
mary of  Op.  Majus,  part  v  :  (2)  excursus  de  motibus  corporum 
celestium  {inc.  '  Hie  in  tine  perspectivarum  volo  advertere 
aliqua  de  motibus  celestibus  ')  with  a  comparison  of  the  sys- 
tems of  Ptolemy  and  Al  Bitrogi  ;  (3)  summary  of  Op.  Maj. 
part  vi,  with  a  chapter  De  scientia  quinte  essentie  ;  (4)  summary 
of  Op.  Maj.  part  vii ;  (5)  summary  of  Opus  Minus.  (6)  De 
Alchemia  [see  below.  No.  14].  {7)  Magnus  Tractatus  et  nobilis, 
De  rerum  naturalium  generatione,  &c.,  fragment,  beginning  : 
'  Hiis  habitis  volo  descendere,'  i.e.  Communia  Natural.  Lib.  i, 
pars  ii,  Dist.  2  (Steele,  pp.  65-8).  Professor  Duhem  argues 
that  this  last  treatise  formed  part  of  the  Opus  Tcrtium,  and 
that  it  was  followed  by  a  treatise  De  peccatis  et  remediis  studii 
theologiae,  which  he  identifies  with  the  Metaphysica  in  Comp. 
Phil.,  vol.  iv  (see  No.  35  below). 
A  gap  still  remained  to  be  filled  between  the  end  of  Brewer's 
fragment  and  the  beginning  of  Duhem's.  The  missing  section 
has  now  been  discovered  in  MSS.  Winchester  College  39  and 
Tanner  n6  and  edited  by  the  present  writer. 

Inc.  '  Sanctissimo  patri  ac  domino  Clementi  .  .  .  Vestrae 

[sapientiae]  magnitudini  duo  transmisi.' 
MSS.  Brit.  Museum  :  Cott.  Tib.  C.  v  (sec.  xv),  ff.  2-45. 
containing  capp.  1-75  in  Brewer's  ed. — Jul.  F.  vii 
(sec.  XV),  ff.  183-5,  containing  cap.  59  and  part  of 
60. — Royal  7  F.  vii,  ff.  106-108",  contains  a  passage  for 
insertion  at  the  end  of  Part  III  of  the  Communia  Nat., 
which  corresponds  almost  verbatim  with  Opus  TerL, 
capp.  46-9  (Brewer,  pp.  168-84). — ^'^^^-  8786,  ff.  14-19 
(sec. xiv), capp. 41-51  (Brewer,  pp.  142-98),  with  variants. 

Lambeth  Palace  200,  ff.  38-59  (sec.  xv),  containing 
capp.  1-45  of  Brewer's  edition,  entitled  Epistola  Rogeri 
Bacon  ad  Clementem  papam,^  beginning  '  Sanctissimo 
domino  patri '  and  ending  '  uti  dictum  est.  Capitulum 
53  de  mobilitate  substantie  separate  '  [Occasione  vero 
(catchword)]. 

Oxford  :  Bodl.  E  Musaeo  155  (sec.  xv.  in.),  (Brewer's 
(edition). — Tanner  116  (sec.  xiii,  ex.) :   {a)  ff.  6-8,  '  Item 

'  Mr.  Claude  Jenkins,  Lambeth  Librarian,  has  kindly  pointed  out  to 
me  that  on  f .  37^  the  explicit  of  the  Mathematics,  Opus  Majus  iv,  is  followed 
(original  hand)  by  :  'Ex  consequenti  sequitur  aUus  Uber  eiusdem  de  laude 
scripture  sancte.  Ad  Clementem  papam  liber  sequitur  et  prout  brevis 
epistola  ad  eundem  '  (and  in  a  sUghtly  different  hand)  '  vocaturque  totus 
liber  epistola  ad  Clementem  '  :  with  catchword  '  Hucusque  ' .  But  the 
next  leaf  f.  38''  begins  '  Incipit  epistola,  .  .  .  Sanctissimo  domino  patri.' 
It  looks,  therefore,  as  if  the  De  laude  scripture  sancte,  beginning  '  Hucusque ' 
were  lost.     It  is,  however,  not  clear  whether  a  new  quire  begins  with  fol.  38. 


392  APPENDIX 

capitulumextractum  dequodam  operequod  fecit  idem  fr. 
Rogerus  Bacun  de  ord.  minorum  ad  mandatum  pape  et 
valet  ad  expositionem  dictorum  ct  dicendorum  in  textu. 
Sequitur  de  scientia  experimentali  .  •  .  |  sicut  aves 
inviscatas '  (Duhem,  pp.  137-8,  148-57  ;  Little, 
pp.  43-54) :  (b)  f.  8^  '  Deinde  cogitavi  opus  .  .  .  |  et  sic 
terminatur  intentio  operis  utriusque  et  sic  explicit  ' 
(Duhem,  pp.  179-81 ;  Little,  pp. 77-9):  (c)ff.8'■-9^ 'Item 
aliud  cap.  eiusdem  fr.  Rogeri  Bacun  de  ord.  min.  de 
potestate  verbi  .  .  .  extractum  de  prima  parte  maioris 
operis  (sic).  Deinde  comparo  linguarum  utilitatem  .  .  . 
divine  operationis '  (Brewer,  Op.  Tert.,  cap.  xxvi, 
pp.  95-100)  :  {d)  ff.  ii''-i3^,  '  Post  hec  sequitur  operatio 
mathematice  .  .  .  |  veniunt  Christiani '  (Little,  pp. 1-19). 
— Corpus  Chr.  Coll.  149  (sec.  xv)  appears  to  contain  the 
same  as  Tanner  ii6(?). — Univ.  Coll.  49  (sec.  xvii),' 
a  copy  of  Bodl.  E  Musaeo. 

Cambridge  :  Univ.  Libr.  Ff.  iv,  12  (a.d.  1528-9),  f.  318  et 
seq. :  'Determinata  quarta  parte  . . .  convincere  fraudu- 
lentum  '  (Duhem,  pp.  178-90  ;  Little,  pp. 75-89). — Trin. 
Coll.  1036,  ft.  21-4''  (sec.  xv),  contains  most  of  the  first 
section  (a)  in  Tanner  116,  beginning  '  Item  capitulum 
extractum',  ending  incomplete,  '  consistit  in  duobus ' 
(Duhem,  pp. 137-8, 148-52;  Little,  pp. 43'-8). — Ibid.  1294 
(sec.  xvii),  transcript  of  Tib.  C.v. — Fitzwilliam  Museum, 
McClean  153  (sec.  xv)  contains  the  same  extracts  as 
Tanner  116,  from  which  it  is  apparently  copied. 

Winchester  College  39  (sec.  xv),  ff.  183-98  :  inc.  '  Post 
hec  sequitur  operatio  mathematice  '  (Little's  edition  of 
Opus  Tert.,  but  called  in  the  MS.  '  secundum  opus 
fratris  Rogeri  Bacon  ') :  ff.  199-206,  Opus  Tert.,  a  frag- 
ment beginning  '  Sanctissimo '  and  ending  '  de  his 
radicibus  ',  corresponding  to  Brewer,  pp.  3-38. 

Douai  691  (sec.  xvii),  Brewer,  wanting  capp.  38-52  :  this 
MS.  has  been  described  by  Victor  Cousin,  Journal  des 
Savants  for  1848  (five  articles). 

Paris  :  Bibl.  Nat.,  Lat.  10264  (sec.  xv),  ff.  186-226, 
Inc.  '  Postquam  manifestavi  mathematice  potestatem 
aspiravi  '  (  =Duhem). — Ibid.  2598  (sec.  xv),  ff.  48''-56^ 
(capp.  xli-H,  pp.  142-98,  of  Brewer's  edition),  inc. 
'  Ouoniam  circa  tempus  et  evum.' 

Escorial,  g.  Ill,  17  (sec.  xiii),  ff.  80-97,  seems  to  contain 
Brewer,  pp.  74-9,  120-35,  295  (?)-3io. 

'  Cf.  Corp.  Chr.  Coll.,  Oxford,  260  (Bryan  Twyne),  p.  lor,  '  Excerpta 
ex  preambulo  Rogeri  Bacon  ad  opus  suum  majus  et  minus  ad  Clem.  IV.' 


ROGER  BACON'S  WORKS  393 

Printed,  capp.  1-75  in  Opera  Inedita  (R.  S.),  ed.  Brewer, 
pp.  3-310.  The  latter  part  in  Un  fragment  inedit  de 
I'Opus  Tertium  de  Roger  Bacon  precede  d'une  etude  sur 
ce  fragment  par  Pierre  Duhem  (Quaracchi,  1909),  and  in 
Part  of  the  Opus  Tertium  of  Roger  Bacon,  by  A.  G.  Little 
(Brit.  Soc.  Franciscan  Studies,  iv,  1912). 

14.  Tractatus  expositorius  enigmatum  alchemiae. 

Bacon  sent  to  Clement  IV  four  treatises  on  this  subject :  two 
were  inserted  in  the  Opus  Minus,  a  third  was  sent  separately 
by  the  hand  of  John,  and  is  unknown.  The  fourth  was  first 
discovered  by  Professor  Duhem  appended  to  the  Opus  Tertium. 
It  consists  of  three  chapters  :  De  enigmatibus  Alkimie,  De 
expositione  enigmatum  Alkimie,  De  clavibus  alkimie. 

MSS.  Paris  :  Bibl.  Nat.  10264,  f.  222  (sec.  xv)  :  inc. 
'  Quoniam  vero  non  expressi  ' — expl.  '  convincere  frau- 
dulentum  '. 
Cambridge  :  Univ.  Libr.  Ff.  iv,  12,  f.  310  (a.d.  1528-9), 
inc.  '  Determinata  quarta  parte  philosophie  moralis 
addidi  de  quinta  ' — expl.  '  convincere  fraudulentum  ' 
(Duhem,  pp.  178-90  ;  Little,  pp.  75-89). 
Winchester  College  39,  f.  196  (sec.  xv). 

Printed  in  Duhem 's  Op.  Tert.,  pp.  181-90 :  Little, 
Op.  Tert.,  pp.  79-89. 

15.  Treatise  on  Astrological  Judgements. 

A  separate  treatise  on  this  subject  was  sent  to  the  Pope.  '  Et  si 
vultis  copiosius  videre,  jubeatis  Johanni  ut  faciat  scribi  de 
bona  htera  tractatum  pleniorem  quem  habet  pro  vobis ;  ' 
Op.  Tert.  (Brewer),  p.  270  ;  cf.  Op.  Majus  (Bridges),  i.  393. 
This  does  not  appear  to  be  extant ;  a  passage  belonging  to 
it  may  be  preserved  in  the  De  laudibus  Mathematicae  (see  below. 
No.  16). 

Compare  also  '  Processus  fratris  Rogeri  Bacon  .  .  .  de  inpencione 
cogitacionis '  (astrological  fragment).  Inc.  '  Notandum  quod 
in  omni  judicio  quatuor  sunt  inquirenda,  scil.  natura  planete/ 
MS.  Bodl.  :  Digby  72  ff.  49^,  50  (secc.  xiv-xv).  Probably  an 
extract  from  one  of  Bacon's  larger  works. 

16.  De  laudibus  mathematicae.    A  different  recension  of  matter 

which  occurs,  for  the  most  part  word  for  word,  in  Opus 

Majus,  Part  IV. 
MSS.  Brit.  Museum  :  Royal  7  F.  vii,  ff.  72-7  (sec.  xiii  ex.). 
The  contents  are  :  (i)  Preface,  inc.  '  Post  banc  scien- 
tiam  experimentalem  ;  '  (ii)  Bridges,  p.  175,  '  Et  cum 
multis  modis  ; '  to  p.  180,  '  qualitatibus  appHcari ; ' 
(iii)  After  a  short  connecting  hnk.  Bridges,  p.  239, 
'  ideo  volo  in  praesenti ; '  to  p.  245,  '  certificare  in 
omnibus ;  '  (iv)  A  passage  on  the  uncertainty  of 
astrological  judgements,  beginning  f.  73'^  i,  '  et  si[c] 


394  APPENDIX 

astrologi  promittunt  se  certificare  non  est  eis  creden- 
dum,'  ending  f.  76'  ii,  '  quas  videmus  in  sompnis  ex 
ilia  contingunt,'  not  found  in  Opus  Majus,  but  possibly 
connected  with  the  separate  work  mentioned  in  Opus 
Tert.,  Brewer,  p.  270,  and  in  Opus  Majus,  Bridges, 
i-  393  '>  (v)  Bridges,  p.  246,  '  His  igitur  et  huiusmodi ; ' 
to  p.  253,  '  veritati  contradicit  ;  '  (vi)  After  a  short 
connecting  hnk,  Bridges,  pp.  180-1,  '  una  est  notitia 
caelestium  .  .  .  sciunt  astronomi  quod  tota  terra.' 
Ends  incompletely.  It  is  not  clear  to  what  scheme 
this  work  belongs.  In  the  Grey  Friars  in  Oxford,  p.  203, 
it  was  suggested  that  it  may  have  been  meant  as 
a  preface  to  vol.  ii  of  the  Compendium  Philosophiae ; 
but  in  that  scheme  physics  follow  mathematics,  and 
not  vice  versa.  (See  Mr.  Gilson's  catalogue  of  the 
Royal  MSS.) 
Oxford  :  Bodl. :  Digby  218,  ff.  98-103''  (sec.  xiii  ex.-xiv). 
Inc.  '  Post  banc  scientiam  '  :  expl.  '  quod  tota  terra  '. 

17a.  De  speculis  comburentibus.    Inc.  '  Ex  concavis  speculis  ad 
solem  positis  ignis  accenditur  ' :     expl.  '  de  distantia  com- 
bustionis  nihil  certum  scio  ad  praesens  '. 
MSS.  Brit.  Museum  :  Add.  8786,  ff.  49-61  (sec.  xiv). 

Oxford  :    Bodl.  874,  pp.  71-95  (sec.  xv). — Ashmole  440 

(sec.  xvi). 
Florence  :   Riccardi  885,  f.  200  (sec.  xiv). 
Printed     at     Frankfurt,    1614,     in     Combach's     Specula 
Mathematica,  pp.  168-204. 

There  is  some  connexion  between  the  De  speculis  com- 
burentibus and  two  other  works,  Liber  de  visu  and 
Liber  de  speculis,  sometimes  ascribed  to  Bacon. 
MSS.  Milan :  Ambrosiana  R.  47  (sec.  xiii),  f.  133,  Liber 
de  visu  Baco7iis,  ten  chapters  :  inc.  '  Supponatur  ab 
oculo  eductas  lineas  rectas  '  :  expl.  '  videbitur  illud  non 
latum  retrorsum  ferri  '. 

Milan  :  Ambrosiana  R.  47  (sec.  xiii),  f.  150,  Liber  de 
speculis,  thirty-four  chapters  :  inc.  '  Visu[m]  rectum 
esse  ' :  expl. '  ex  concavis  specuUs  ad  solem  positis  ignis 
accenditur.    Explicit  hber  Euclidis  de  specuHs  '. 

Rome  :  Vatican  3102  (sec.  xiv  ex.),  ff.  35'-48  [Perspectiva 
Vitalonis] :  inc.  '  Suponatur  ab  oculo  eductas  lineas 
rectas.'  |  '  Explicit  perspectiva  Vitalonis  ', 

Rome  :  Vatican  3102  (sec.  xiv  ex.),  ff.  48-51,  Tractaius  de 
speculis  Bachonii.  Inc. '  Visum  rectum  est  cuius  media  ' : 
followed  by  f.  52,  '  In  planis  specuhs  rei  vise  '  (anon.). 

Florence  :     Bibl.  Naz.,  Conventi    Soppressi,    I.   IV.    29, 


ROGER  BACON'S  WORKS  395 

ti.  ^8^-y2^  (sec.  xv)  :  no  title  :  anon.  Inc.  '  Ponatur 
ab  oculo  rectas  eductas  lineas  ...  |  ex  concavis  speculis 
ad  solem  positis  ignis  accenditur.  Esto  concavum 
speculum  a  b  .  .  .  quare  in  eis  stupa  posita  accenditur.' 
(This  seems  to  contain  both  the  Liber  de  visit  and  the 
Liber  de  speculis.  It  is  closely  aUied  to  the  Vatican  MS. 
Both  contain  the  Perspectiva  of  Bacon,  and  a  treatise 
beginning  '  Geometria  assecutiva  ',  anon,  in  Florentine 
MS.,  ascribed  (rightly)  to  Thomas  Bradwardine  in  the 
Vatican  MS.) 

Erfurt :  Amplon.  F.  37  (sec.  xiii  ex.),  ff.  60-3.  Liber  de 
naturis  speculorum  Jordatii.  Inc.  '  Visum  rectum  est.'  | 
'  ex  concavis  .  .  .  accendere.  Esto  concavum  .  .  .  stupa 
posita  accendetur.'  Cf.  Nos.  44,  45  below. 
lyb.  Notulae  de  speculis  (anon.).  Inc.  '  [Notandum  quod]  quia 
omnes  axes  ...  |  et  sic  de  omnibus  ahis  intellige.' 

MS.  Oxford  :  Bodl.  874  (sec.  xv),  p.  95,  where  title  and 
first  two  words  are  inserted  in  hand  of  sixteenth  century, 
the  rest  being  in  same  hand  as  the  De  speculis  com- 
burentibus. 

Printed  by  Combach,  ut  supra,  pp.  205-7. 

18.  Epistola  fratris  Rogerii  Baconis  de  secretis  operibus  naturae  et 
de  nullitate  magiae,  or  De  mirabili  potestate  artis  et  naturae/ 
Inc.  cap.  i,  '  Vestrae  petitioni  respondeo  diligenter.  Nam 
licet.' 

The  work  consists  of  teij  or  eleven  chapters,  the  last  five  of  which 
Charles  considered  doubtful,-  addressed  perhaps  to  William  of 
Auvergne  (died  1248)  ^  or  to  John  of  London,  whom  Charles 
identifies  with  John  of  Basingstoke  (died  1252). 

MSS.  Brit.  Museum  :  Sloane  2156  (sec.  xv),  ff.  111-16. 

Oxford  :  Bodl.  :  Digby  164,  ff.  8-12'',  containing  capp.  i-ix 
(sec.  xv). — Tanner  116  (sec.  xiii  ex.),  ff.  9''-ii'',  con- 
taining capp.  i-v  and  beginning  of  cap.  vi. — Cf .  Merton 
Coll.  230,  f.  51    (sec.  xiv). 

Leyden  :  Bibl.  Univ.  Q.  27.    Chim.  Voss.  64  (sec.  xvi). 

Quaracchi  :  MS.,  sec.  xiv,  ten  leaves,  no  title  :  inc. 
'  Vestre  petitioni  .  .  .  |  nullus  aperiet.  Explicit  Bacon 
de  potestate  artis  et  nature.' 

'  Florence,  Bibl.  Naz.,  Pal.  887  (secc.  xv,  xvi)  has  Roger  Bacon  de  secretis 
naturae.  Inc.  '  Obsequus  mihi  possibihbus  ergo  terra  aqua  et  natura 
frigida  et  humida  '  (probably  spurious) . 

'  Apparently  merely  because  they  are  'enigmatic'.  But  see  the 
ingenious  explanation  by  Lieut.-Col.  Hime,  Gunpowder  and  Ammunition 
(1904),  pp.  141-62. 

^  The  Hamburg  edition  of  1618  based  on  a  MS.  of  John  Dee  has  after 
the  ExpUcit :  [ad  GuUelmum  Parisiensem  conscripta].  I  have  not  found 
this  in  any  MS. 


396  APPENDIX 

Rome  :  Vatican  4091,  f.  62  (extracts). 
Cf.  Vienna  :  Bibl.  Pal.  11314  (sec.  xvi),  f.  75,  '  Tractatus 
Rogerii  Bachonis  de  secretissimis  naturae  misteriis 
supercoelestis  '  (?). 
Printed  at  Paris,  1542  ;  Oxford,  1594  ;  Hamburg, 
1618  ;  in  Zetzner's  Theatrum  Chemicum,  1659  ; 
Manget's  Thesaurus  (1702),  i.  616,  and  by  Brewer 
in  Rog.  Bacon  Opera  Ined.,  App.  I.  French  transla- 
tions, 1557,  1629  ;   English  translations,  1597,  ^^59- 

19.  Excerpta  de  libro  Avicennae  De  anima  per  fratrem  Rogerum 
Bacon.     Inc.  '  In  illius  nomine  qui  major  est.' 

MS.  Bodl.  :   Ashmole  1467,  ff.  1-30  (sec.  xvi). 

Printed  at  Frankfurt,  1603,  under  the  title  Sanioris 
medicinae  magistri  D.  Rogeri  Baconis  angli  de  arte 
cliymiae  scripta,  &c.,  pp.  17-86 :  reprinted,  1620, 
under  the  title  Thesaurus  Chemicus,  &c. 

Cf.  Glasgow  :  Hunterian  Museum,  MS.  253  (sec.  xiii  ex.),  f.  i, 
Avicenna  De  anima  :  inc.  '  Explanabo  tibi '  :  f.  28'-42',  Liber 
expositorius  precedentis  libri  Avicenne  Inspector  dictus  Rogeri 
Bacon  (title  in  much  later  hand)  :  inc.  prol.  '  In  nomine  Domini 
di.xit  inspector  in  hoc  libro  propter  magnum  studium  legendi 
quod  habui  in  hoc  libro  cogitavi  quod  reducerem  difficiUora  ad 
memoriam  et  acuerem  sensum  meum.'  Inc.  opus,  f.  28^  :  '  In 
nomine  Domini  hec  est  prima  clavis  que  tractat  de  calce  que 
fit  post  primam  ablutionem.'  ExpL,  f.  42',  '  plumbo  alcofoli  et 
plumbo  alcali  et  magnum.'  This  MS.  formerly  belonged  to 
St.  Augustine's,  Canterbury  (No.  1544  in  James's  Catalogue) 
and  to  John  Dee  (from  information  kindly  suppUed  by  Mr. 
J.  L.  Galbraith,  Keeper  of  Hunterian  Books). 

20.  Breve  breviarium,  or  De  naturis  metallorum  in  ratione  alki- 
mica  et  artificiali  transformatione,  or  Caelestis  alchymia, 
or  De  naturis  metallorum  et  ipsorum  transmutatione,  or 
Breviloquium  alkimiae.'  (AddressedtoRaymund  Gaufredi(?).) 
Inc.  '  Breve  breviarium  breviter  abbreviatum  sufficit  intel- 
hgenti.' 

MSS.  Brit.  Museum  :  Sloane  276,  f.  4  (sec.  xv).  Inc. 
'  Ars  alkimie  duo  principaliter  considerat '  (two  parts,  de 
miner alibus,  de  vegetahilihus  et  sensihilihus). 

'  It  seems  to  consist  of  two  principal  and  two  subsidiary  parts :  (i)  Intro- 
ductory— speculative  :  inc.  De  compositione  metallorum.  '  Incipiamus 
ergo  generationem  metallorum  ostendere.'  (2)  Practical :  Incipit  liber 
secundus  de  Practica.  '  Non  quidem  necessarium.  ..."  De  consideratione 
Alchymiae  et  aieri  proprietate.  '  Ars  ergo  Alchemiae  duo  principaliter 
considerat.  .  .  .'  This  deals  with  metals.  (3)  Tractatus  de  vegetabilibus 
et  sensibilibus  :  '  Executo  breviter  tractatu  de  spiritibus  mineralibus.' 
(4)  Incipit  de  Salibus  :  '  Executis  igitur  duabus  principaUbus  partibus.' 
Expl.  '  moribus  et  studiis  liberalibus  ad  plenum  eruditi.'  Cf.  the  treatises 
on  alchemy  in  Opus  Minus. 


ROGER  BACON'S  WORKS  397 

Oxford :  Bodl.  607,  f.  63  (sec.  xv  in.),  anon.  :  E  Musaeo 
155  (sec.  XV),  p.  513  :  Digby  119,  ff.  64-77  (sec.  xiv). 

Cambridge  :  Univ.  Library  Kk.  vi  30,  ff.  87-103  (secc.  xv, 
xvi). — Gonville  and  Caius  Coll.  181,  pp.  189-208  (sec.  xv). 

Paris  :  Bibl.  Nat.  14007  (sec.  xv),  f.  i  :  inc.  '  Arsalkimica.' 

Wolfenbiittel  3076  (sec.  xv),  ff.  125-47. 

Florence  :  Bibl.  Naz.,  MSS.  Strozzi  or  Magliabecchi, 
CI.  xvi  (11),  no.  77  (sec.  xvi).  Inc.  '  Ars  alchimie  ' 
(32  capp.). — Ibid.  XV  (8),  68  (sec.  xvi)  seems  to  contain 
extracts. — Riccardi  847,  Liber  de  Alchimia  :  inc.  '  Ars 
principaliter  duo  continet.' 

Rome  :  '  Minerva  A.V.  9,  ff.  89-113  (anon.). 
Printed^  1603,  in  Sanioris  Medicinae,  &c.,  pp.  95-263. 
21.  Verbum  abbreviatiim  de  Leone  viridi  (on  minerals,  the  com- 
position of  the  stone,  and  preparation  of  mercury  :  a  summary 
by    Raymund    Gaufredi).       Inc.    '  Verbum    abbreviatum 
verissimum  et  approbatum  de  occultis.' 
MSS.  Brit.  Museum  :   Sloane  692,  ff.  46-51''  (sec.  xv) :    '  In 
nomine   Domini  nostri  Jesu  Christi  incipit  tractatus 
fratris  Rayinundi  ord.  fr.  min.  et  eorum  ministri  generahs 
primo  compilatus  ab  egregio   doctore  Rogero  Bacon. 
Verbum  abbreviatum.  .  .  .  Istud  vero  verbum  abbre- 
viatum ab  egregio  doctore  nostro  Rogero  Bacon,  cujus 
anime  propitietur  Deus,  primo  est  declaratum,  deinde 
ego    fr.    Raymundus   Gaufredi   ord.    fr.    min.  ministri 
generalis  .  .  .  verbum  .  .  .  brevius  explanare  filiis  philo- 
sophic curavi.    In  Christi  igitur  nomine  Recipe  acetum 
fortissimum.'     Followed  on  f.  102  by  finalis  conclusio 
Rogeri  Baciin.     Inc.  '  Sume  argentum  vivum.' — Sloane 
288,  f.  167  (sec.  xvi)  :   Sloane  1842,  ff.  32-6  (sec.  xvii)  : 
Stowe  1070,  f.  22'  (sec.  xvi). 

Oxford  :  Bodl.  Digby  119,  f.  yy^'  (sec.  xiv  in.),  '  Ab  egregio 
doctore  nostro  R.  Bacon  primo  declaratum.'  Ashmole 
1450,  ff.  28-32  (sec.  xv). — Cf.  Corp.  Chr.  Coll.  277 
(sec.  xv).- 

Paris  :  Bibl.  Nat.  19070,  f.  49  (sec.  xvi). 

Wolfenbiittel :  Herzogl.  Bibl.  468  (sec.  xv),  ff.  214-16'' : 
3076  (sec.  xv),  ff.  147-9. 

'  Vatican  Pal.  Lat.  4092,  '  Liber  fratris  Rogerii  de  naturis  metallorum  ' 
seems  to  be  the  Libellus  (or  Semita  recta)  Alchemiae  ascribed  to  Alb. 
Magnus  :    inc.  '  Omnis  sapientia.'     (Cf.  MS.  Corp.  Chr.  Coll.,  Oxford,  185, 

f.  48.) 

-  Contains  alchemical  receipts,  f.  16,  Recepta  ex  Raymundo  et  Ricardo 
Fumivalle  desumpta :  '  Istud  verbum  habuit  predictus  Raymundus 
a  fr.  Rogero  Bacoun  anglice  ;  '  f.  20,  '  Baconus  comedit  Martyn,'  with 
later  note  :    '  Quidam  volunt  haec  esse  fratris  Helie.' 


398  APPENDIX 

Florence  :   Riccardi  847  (sec.  xv),  ff.  31^-4''. 
Rome  :   Minerva  A.V.  9,  ff.  89-113  (anon.). 
Printed  in  Sanioris  Medicinae,  &c,,  1603,  pp.  264-85. 

The  printed  edition  and  most  of  the  MSS.  (e.g.  the  early  Digby  1 19) 
have  the  following  note :  '  Exphcit  verbum  abbreviatum 
maioris  operis  fr.  Reymundi  Gaufredi,  ministri  ord.  fr.  minorum, 
quod  quidem  verbum  habuit  a  fratre  Rogero  Bacon  anghco, 
qui  fuit  de  ordine  fratrum  minorum.  Et  ipse  Rogerus  propter 
istud  opus  ex  praecepto  dicti  Reymundi  a  fratribus  eiustlem 
ordinis  crat  captus  et  imprisonatus.  Sed  Reymundus  exsolvit 
Rogerum  a  carcere  quia  docuit  eum  istud  opus.  Et  ipse  Rogerus 
erat  discipulus  fratris  Alberti.'  A  French  translation  of  this 
note  occurs  at  the  end  of  a  treatise  entitled  '  Le  Testament  des 
nobles  philozophes  '  (inc.  '  La  distinction  des  secr6s  des  sages 
philozophes  sur  la  tr6s  excellente  pierre  des  philozophes')  in 
MS.  Bibl.  de  1' Arsenal,  Paris,  2872,  ff.  401-15  (sec.  xiv).' 

22.  Tractatus    trium    verborum,   or    Epistolae   tres  ad  Johan- 
nem  Parisiensem :   namely,  (i) '  De  separatione  ignis  ab  oleo ' ; 
(ii)   '  De   modo   miscendi  '  ;   (iii)   '  De  ponderibus.'    hic.  i, 
'  Cum  ego   Rogerus  rogatus  a  pluribus.'     Inc.   ii,   '  Cum 
promisi    tibi    mittere   duas   cedulas.'      Inc.    iii,    '  Cum   de 
ponderibus  utilis  sit  distinctio.' 
MSS.  Brit.  Museum  :    Cott.  Jul.  D.  v  (secc.  xiii,  ex.-xiv,  in.), 
ff.  152-8,  160-4).'     Harl.  3528,  f.  8i\     Sloane  1754, 
ff.  62-74  (sec.  xiv),  '  Mendacium  primum,  secundum  et 
tertiimi.'     Sloane  2327  (sec.  xv),  ff.  25-6  (Epp.  i,  ii), 
f.  35  (Ep.  iii,  fragment). 
Oxford:  Bodl.  :  Digby  119,  f.  82  (sec.  xiv,  in.).    Ashmole 
1416,   ff.  42-51   (sec.   XV),    1433,  pp.   1-72   (sec.  xvi), 
1448,  pp.  1-25  (sec.  xv). — Corp.  (^hr.  Coll.  125,  f.  84'' 
(Ep.  i  only). 
Cambridge  :  Univ.  Lib.,  Ff.  iv.  12,  ff.  270-94   (sec.  xvi). 
Bologna  :   Bibl.  Univ.  270  (secc.  xv,  xvi),  p.  81  :    Rogerii 
Bakonis  Opus.    Inc.  '  Cum  ego  Rogerius  j  auxilio  unius 
diei.'     Ibid.  1062  (sec.  xiv),  ff.  21-33,  Rogerii  Baconis 
tract,  ad  Johannem  Parisionum.     '  Cum  ego  Rogerius 
sapientia  mundi.' — Cf.  ibid.  303  (sec.  xv),  ff.  285^-90^  : 

'  Hunterian  Mus.  MS.  253,  ff.  89-90,  contains  Liber  distinctionum sapieH' 
turn ;  anon  :  inc.  '  Distinctiones  secretonim  sapientum,'  perhaps  the 
original  of  this  French  treatise. 

-  Jul.  D.  v.  ff.  i66''-7'^  has  anon,  letter :  '  Quesivisti,  fiU  karissime,  de 
incantacione  et  adiuracione  colh  suspensione  si  quid  possent  prodesse,  et 
sicut  inveni  in  Ubris  grecorum  hec  qualiter  indorum  etiam  Ubris  invenirem, 
tue  peticioni  compendiose  in  hac  epistola  cogor  respondere.  Omnes 
inquam  antiqui  in  hoc  videntur  esse  concordati .  .  .  altitudinem.  Explicit.' 
Probably  the  letter  of  Constantinus  Africanus  to  which  Bacon  refers  in 
De  mirabili  potestate,  cap.  ii. 


i 


ROGER  BACON'S  WORKS  399 

'  Liber  trium  verbonim  qui  dicitur  liber  Trinitatis  | 
thesaurum  habet.' 
Cf.  Florence  :  Bibl.  Naz.  :  Strozzi  (Magliabecchi)  xvi  (11) 
77  (sec.  xvi),  *  Liber  trium  verborum  dicitur  liber 
divinitatis  et  trinitatis  et  hec  tria  verba  sunt  de  lapide 
pretioso  |  fovearum  paludum,  etc'  (7  leaves,  anon.). 
(These  two  last  entries  seem  to  relate  to  a  different  work.) 
Printed,  1603,  as  above  (pp.  292-387).  A  new  edition 
is  being  prepared  by  M.  J.  A.  Col. 

23.  Libellus  or  Epistola Roger ii  Bacon  . . .  de  retardandis  senectutis 

accidentibus  et  de  sensibus  conservandis  (11  or  12  chapters).* 

This  work  is  assigned  by  Charles  to  the  year  1276,  but 

it  is  referred  to  in  Opus  Majus  (Bridges  ii.  209),  and  hence 

written  before  1267.    According  to  the  Paris  MS.  (see  below) 

it  was  sent  to  Innocent  IV.    Inc.  Prol.  '  Domine  mundi  qui 

ex  nobilissima  {al.  ex  nobili  bina)  stirpe  originem  assump- 

sistis  . . .  Cogito  et  cogitavi.'  Inc.  cap.  i  (De  causis  senectutis) 

'  Senescente  mundo  senescunt  homines.' 

MSS.   Brit.    Museum  :     Sloane   2320  (sec.  xv  ex.),  ff.  56-64 

(fragment  :  ends  in  cap.  ii).^ 

Oxford  :  Bodl.  21 1  (sec.  xv)  ;  Bodl.  438,  ff.  1-12^  (sec.  xv) ; 

E  Musaeo  155,  pp.  591-637  (secc.  xiv-xv)  ;    Canonic. 

Misc.  334,  ff.  1-18  (sec.  xv),  and  480,  f.  i  (sec.  xv)  ; 

Selden  supra  94,  f.  i  (sec.  xiv)  ;    Arch.  Seld.  B.  35,  f.  i 

(sec.  xiv).     Cf.  Digby  202,  f.  87  (sec.  xvi). 

Cambridge  :   Univ.  Lib.  Dd.  v.  53,  p.  72  ;  Trin.  Coll.  922, 

f.  I  (sec.  xv),  in  Enghsh  ;  and  1389,  f.  106  (sec.  xv). 
Manchester  :   Chetham  Library,  A.  5.  24  (11366),  ff.  1-32 

(sec.  XV,  ex.). 
Paris  :   Bibl.  Nat.  6178,  ff.  22-36  (sec.  xiv,  in.),  Epistola 
.  .  .  missa  ad  Innocentium  quartum.     Inc.  '  Domine 
mundi  qui  ex  nobih  bina  stirpe  '  (anon.  :  apparently  an 
early  version). 
Milan  :  Ambrosiana  I.  210  inf.  (sec.  xv). 
Rome  :   Vatican  Pal.  Lat.  4091,  ff.  71-88  (sec.  xvi)  :  ibid. 
1 180,  f.  332  (sec.  xv) ;    and  Urbin.   Lat.   1443,   f.   i 
(sec.  xv). 

'  The  printed  editions  have  i6  chapters  :  in  the  i6th  are  included  the 
following  treatise.  No.  24. 

-  Sloane  2320,  ff.  27-29^,  and  Paris,  Bibl.  Nat.  6978,  ff.  34^-36^,  contain 
'  summaria  expositio  epistole  fratris  Rogeri  Bacon  de  Retardatione,'  &;c. 
(called  in  Paris  MS.  '  expositio  predicte  epistole ')  :  inc.  '  Rimatus  sum 
moderno  tempore  omnia  fere  armaria  latinorum  et  intellexi  per  inter- 
pretationem  quorundam  grecorum  arabum  et  caldeorum  scripta  plurima  ' 
.  .  .  '  Expositio  primi  verbi  scilicet  Olei.  Incipiamus  igitur  in  nomine 
dei . . .  verba  precedentis  epistole  vestre  sanctitati  et  clementie  aperire  .  .  .' 


400  APPENDIX 

Printed  at  Oxford,  1590  (and  in  English,  London,  1683). 
An  edition  of  this  work  and  of  Nos.  24,  25,  26,  27,  28  is 
being  prepared  by  E.  T.  Withington  and  A.  G.  Little. 

24.  De  universali  regimine  senum  et  seniorum.'  Inc.  '  Summa 
regiminis  senum  universalis  ut  dicit  Avicenna.' 

MSS.  Brit.  Museum  :   Sloane  2629,  f.  57. 

Oxford  :  Bodl.  438,  ff.  I2''-I4^  :  Can.  Misc.  334,  ff.  i8^-2iv ; 
and  480  {explicit,  f.  16)  ;  E  Musaeo  155,  p.  638 ; 
Selden  supra  94,  f.  114'.    Arch.  Seld.  B.  35,  f.  15^. 

Cambridge  :   Trin.  Coll.  1389,  f.  i  (sec.  xv). 

Manchester  :  Chetham  Library  A.  5.  24  (11366),  ff.  32^-4. 

(This  short  treatise  includes  De  balneis  senum  et  seniorum 
[inc.  '  Senes  sunt  balneandi  ')  :  and  De  compositione 
qiiarundam  mcdicinarum  in  speciali  que  iuvant  sen- 
sum,  &c.  (inc.  '  Iitcipiamus  in  nomine  domini  '),  and  is 
printed  in  cap.  xvi  of  the  editions  mentioned  above. 

25.  Antidotarius.      Inc.    '  Post   completum   universalis   sciencie 

medicacionis  tractatum.' 
MSS.   Oxford  :   Bodl.  438,  ff.  i4''-2i'  (sec.   xv)  ;    Can.  Misc. 
334,  ff.  21  -5,  and  480,  f.  16  :    E  Musaeo  155,  p.  645 ; 
Selden  supra  94,  f.  133  ;    Arch.  Seld.  B.  35,  f.  17".    Cf. 
Can.  Misc.  480,  ff.  38^-47. 
Manchester  :   Chetham  Library  A.  5.  24  (113G6),  f.  37"". 
Milan  :   Ambrosiana  L  210  inf.  (beginning  only). 

26.  Liber  Bacon  de  sermone  rei  admirabilis,  sive  de  retardatione 
senectutis.  Inc.  '  Intendo  componere  sermonem  rei  ad- 
mirabilis  domino  meo  fratri  E.,  cuius  vitam  deus  pro- 
longet.' 

MSS.  Oxford  :  Bodl.  438,  f.  17'' :  E  Musaeo  155,  pp.  655- 
66  ;  Digby  183,  f.  45  (sec.  xiv,  ex.)  imperf.  :  Can.  Misc. 
334,  ff .  25-31  ;  Arch.  Seld.  B.  35,  f .  20  :  Selden  supra  94, 

f.  156^ 
Manchester  :  Chetham  Library  A.  5.  24,  f.  45". 

27.  De  graduatione  medicinamm  (or  renim)  compositarum.  Inc. 
'  Omnis  forma  inherens.' 

MSS.  Oxford:  Bodl.  438,  ff.  21^-2^:  E  Musaeo  155,  p.  666. 

Can.  Misc.  334,  f.  32  ;   480,  f.  23'' ;    Selden  supra  94, 

f.  187  ;    Arch.  Seld.  B.  35,  f.  24^     Cf.  Ashmole  1437, 

ff.  2-3  (sec.  xv). — Corp.  Chr.  Coll.  254,  f.  178^'  (sec.  xvi). 

Cambridge  :  Trin.  Coll.  1389,  f.  20. 

[Manchester  :  Chetham  Library  A.  5.  24  (11366),  f.  45^ 

'  Bacon  refers  to  this  or  a  treatise  \\-ith  the  seime  title  as  though  be  were 
not  the  author  :    Optts  Ala  jus,  ii.  210,  213. 


ROGER  BACON'S  WORKS  401 

28.  Tractatus  de  erroribus  medicorum/    Inc.  '  Vulgus  medicorum 

non  cognoscit.' 
MSS.   Oxford  :  Bodl.  438,  ff.  22^-8  ;   Can.  Misc.  334,  t.  42  ; 
ibid.  480,  f.  30  ;   E  Musaeo  155,  pp.  669-89 ;   Selden 
supra  94,   f.    194  ;    Arch.   Seld.  B.  35,   f.  31. — Corp. 
Chr.  Coll.  127  (sec.  xv). 
Cambridge  :  Trin.  Coll.  1389,  f.  22. 
Manchester  :   Chetham  Lib.  A.  5.  24  (11366),  f.  58. 

29.  De  diebus  criticis.     Inc.  '  Ad  evidentiam  dierum  creticorum.' 

MS.  Erfurt  :  Amplon.  Q.  215,  ff.  79''-83  (sec.  xiv). 
Extracts  printed  in  Elfferding,  Roger  Bacons  Schriften 
iiher  die  critischen  Tage  (Erfurt,  1913). 

30.  De  crisi  morborum.     '  Incipit  tractatus  de  creticis  diebus 

quern  fecit  fr.  Rogerus  Bacun  de  ordine  Minorum.  Omnis 
egritudo  de  qua  curatur  homo.' 

MS,  Erfurt  :   Amplon. Q.  215,  ff.  83^-5^ 

Printed  in  Elfferding,  u.s. 

31.  Canones  practici  de  medicinis  compositis  componendis  (13  or 

15  chapters).  '  Cap.  i.  Extractum  de  libro  septimo 
Serapionis  qui  est  antidotarium  suum  et  est  theoricum 
capitulum.'  Inc.  '  Necesse  esse  illi  qui  vult  componere 
medicinas.'  '  ExpUcit  tractatus  de  compositione  medi- 
cinarum  per  fratrem  rugerium  bacon  editus.' 

MSS.  Bodl.  Can.  Misc.  480,  ff.  38^-47  (sec.  xv)  ;  Arch. 
Seld.  B.  35,  f.  43  (sec.  xiv). 

This  corresponds  for  the  most  part  with  the  translation  of  the 
Breviarium  of  the  son  of  Serapion,  Lib.  vii,  capp.  1-15,  ascribed 
to  Gerard  of  Cremona  and  preserved  in  Brit.  Museum  MS. 
Bumey  350,  f.  82^  et  seq.  (sec.  xiii  ex.).  It  probably  ought  to 
be  placed  among  the  '  Doubtful  and  Spurious  Works'. 

32.  Grammatica  Graeca. 

(i)  'Oxford  '  Greek  Grammar. 

MSS.  Oxford :  Corp.  Chr.  Coll.  148,  ff.  1-42  (sec.  xiv)  : 
*  Primus  hie  liber  voluminis  grammatici  circa  Hnguas 
aUas  a  latino  qui  est  de  grammatica  graeca  habet  tres 
partes.'  Pars  I,  Dist.  i,  cap.  i  :  inc.  '  Manifestata 
iaude   et    declarata    utihtate    cognicionis   grammatice 

'  Sloane  MS.  3744,  f.  35  (sec.  xv),  contains  Errores  secundum  Bacon. 
Inc.  '  Scito  enim  quod  omne  corpus  aut  est  elementum  aut  ex  elementis 
compositum.'  According  to  Charles  (p.  71)  it  is  the  Tract,  de  erroribus 
medicorum.  This  is  a  mistake.  It  treats  of  alchemical  errors  and  reads 
more  like  Arnald  de  Villeneuve  than  Bacon.  The  beginning  and  end 
are  wanting. 


402  APPENDIX 

quatuor    linguarum,    scil.    grece,    hebree,    arabice    et 

caldee.' — University  College  47   (abbreviated  copy  of 

Corpus  Christi  MS.). 
Brit.  Mus.  :    Cotton  Julius  F.  vii,  f.  175  (a  fragment  of 

one  leaf),  (sec.  xv). 
Douai  691  (identical  with  Univ.  Coll.  MS.). 
(2)  '  Cambridge  '  Greek  Grammar. 
MS.  Cambridge  :  Univ.  Lib.  Ff.  vi.  13,  ff.  67-9  (secc.  xiii- 

xiv),  begins  with  Greek  alphabet.' 
Printed  in  The  Greek  Grammar  of  Roger   Bacon   and   a 

Fragment  of  his  Hebrew  Grammar,  ed.  Nolan  &  Hirsch, 

Cambridge,  1902,  pp.  3-182,  183-96  (cf.  Comp.  Phil,  i. 

No.  35  below). 

33.  Grammatica  Hebraica.  . 

MS.  Cambridge  :   Univ.  Lib.  Ff.  vi.  13,  f.  66  (secc.  xiii-xiv) 

fragment.^ 
Printed  in  Nolan  and  Hirsch,  u.s.,  pp.  202-8. 

34.  Summa  Grammaticae.     Inc.    '  Oratio   grammatica   aut    fit 

mediante  verbo  prime  persone.' 
MSS.  Cambridge:   Peterhouse  191,  ff.  30-50  (secc.  xiii,  xiv) : 
Expl.  f.  50^  :  '  stabit  pro  die  dominica.    Explicit  summa 
de  grammatica  magistri  Rogeri  Bacon.' 
Worcester  Cathedral,  Q.   13,   ff.   5-24  (sec.  xiv),  anon. 
(same  as  Peterhouse  MS.).^ 

35.  Compendium  Philosophiae,  or  Scriptum  Principale. 

An   encyclopaedic  work  on  which   Bacon  seems   to   have  been 
ah-eady  engaged  before  he  received  the  Pope's  command,  and 

'  Cf.  Brit.  Museum  :  Cott.  Tib.  C.  v,  f.  46  (after  Opus  Tert.)  :  '  Decern 
et  octo  preposiciones  habent  greci  12  dissillabas  6  monosillabas  :  prime 
sunt  hec  :  apo,  ana,'  &c.  Then  follow  explanations  of  words  beginning 
with  these  prepositions  (i  page)  :  f.  47,  '  Lincolniensis  post  expositionem 
prologi  angelice  lerarchie.     In  Greca  scriptura  sunt  due  chie  '  (2  pages). 

The  Greco-Latin  Lexicon  in  College  of  Arms  MS.  Arundel  IX,  described 
by  M.  R.  James  in  Melanges  offerts  d  M.  Entile  Chatelain,  is  not  by  Bacon. 

^  The  (as  yet  unpublished)  Notes  or  Letters  to  inquirers,  chiefly  on 
Hebrew  and  Greek  grammar,  with  special  reference  to  the  Bible,  described 
by  Samuel  Berger  in  Quam  notitiam  linguae  Hehraicae  habuerint  Christiani 
medii  aevi  temporibus  in  Gallia,  Paris,  1893,  are  perhaps  by  Roger  Bacon, 
more  probably  by  Wilham  de  Mara.  (The  author  refers  to  his  lectures 
on  Lamentations — '  cum  legerem  Trenos,'  &c. — evidently  in  the  Univ. 
of  Paris.)  Inc.  '  Quoniam  quedam  glose  mencionem  faciunt  de  Uteris  et 
vocabuUs  hebreis  et  grecis.'  MSS.  Toulouse  402,  f.  233  (sec.  xiii). 
Florence  :  Laurent.  pL  xxv  sin.  4,  ff.  179-210  (secc.  xiii-xiv),  '  Compilacio 
fratris  Guillelmi  de  Mara  .  .  .'     Einsiedeln  28,  f.  212  (extracts)  (sec.  xiv). 

^  Sloane  MS.  1086,  f.  5,  a  fragment  of  a  table  of  contents,  sec.  xiv,  has 
inter  alia  :    '  Vtilis  summa  grammatice  quam  composuit  Rogerus  Bacon.' 


ROGER  BACON'S  WORKS  403 

which  if  completed  would  have  formed  a  kind  of  revised  and 
enlarged  edition  of  the  Opus  Majus,  Opus  Minus,  and  Opus 
Tertiutn.  In  the  Communia  Naturalium  (ed.  Steele,  p.  i) 
Bacon  gives  a  sketch  of  his  plan.  The  work  was  to  consist  of 
four  volumes  and  to  treat  of  six  branches  of  knowledge,  viz. 
vol.  i.  Grammar  and  Logic ;  vol.  ii.  Mathematics ;  vol.  iii. 
Physics  (Naturalia)  ;  vol.  iv.  Metaphysics  and  Morals.  This 
Compendium  seems  also  to  have  been  known  as  Liber  Sex 
Scientiarum.  The  latter  title  is  found  in  the  collection  printed 
at  Frankfurt,  1603,  in  Bodl.  MSS.  Bodl.  438,  f.  28  ;  Can.  Misc. 
334,  f .  49"'' ;  480,  f.  33  ;  Selden  supra  94,  f .  240"^  ;  Arch.  Seld. 
B-  35.  f-  37^ '  and  E  Musaeo  155,  p.  689  (cf.  Trin.  Coll.  Camb. 
922,  f.  53).  In  each  of  these  MSS.  the  same  passage  is  quoted 
as  follows  :  '  Dicta  fratris  Rogerii  Bacon  in  libro  sex  scientiarum 
in  3°  gradu  sapiencie,  ubi  loquitur  de  bono  corporis  et  de  bono 
fortune  et  de  bono  et  honestate  morum.  {Inc.)  In  debito 
regimine  corporis  et  prolongatione  vite  ad  ultimos  terminos 
naturales  .  .  .  miranda  potestas  astronomic  alkimie  et  perspective 
et  scientiarum  experimentalium.  Sciendum  igitur  est  pro 
bono  corporis  quod  homo  fuit  immortalis  naturahter.  . . .  (Expl.) 
ut  fiant  sublimes  operaciones  et  utilissime  in  hoc  mundo,'  &c. 
Charles  identifies  the  Liber  Sex  Scientiarum  with  the  Opus 
Minus  ;  but  this  passage  does  not  occur  in  the  extant  portion 
of  the  Opus  Minus  which  deals  with  the  same  subject  and  ex- 
presses the  same  ideas  (Brewer,  p.  370  seq.).  It  seems  prob- 
able, therefore,  that  the  passage  is  an  extract  from  the  section 
on  Alchemy  in  vol.  iii  of  the  Compendium  Philosophiae. 

Vol.  I.  Grammar  and  Logic.  The  fragment  printed  by 
Brewer  under  the  title  Compendium  Studii  Philosophiae 
may  be  a  portion  of  this  volume.  It  was  written  about 
1272,  and  contains  an  introduction  on  the  value  of 
knowledge  and  the  impediments  to  it,  and  the  beginning 
of  a  treatise  on  grammar.  Inc.  '  Quatuor  sunt  con- 
sideranda  circa  sapientiam  quae  volo  ad  praesens  in 
summa  et  sub  compendio  quasi  introductionis  modo 
tangere.' 
MS.  Brit.  Museum  :  Cotton  Tib.  C.  v,  ff.  120-51  (sec.  xv). 
Printed  :  Brewer,  Op.  Ined.,  pp.  393-519. 

For  other  treatises  on  Grammar  which  may  in  some  form  or  other 
have  formed  part  of  the  Comp.  Phil,  see  Nos.  32,  33,  34. 

Vol.  II.  Mathematics ' :  six  books  :  (i)  Communia  Mathe- 
maticae  ;  (ii-vi)  Special  branches  of  mathematics. 
Inc.  Liber  i.  '  Hie  incipit  volumen  verae  mathematicae 
habens  sex  Ubros.  Primus  est  de  communibus  mathe- 
maticae, et  habet  tres  partes  principales.' 

'  The  treatise  De  laudibus  mathematice  (No.  16)  cannot  (as  suggested  in 
The  Grey  Friars  in  Oxford,  p.  203)  have  been  intended  as  an  introduction 
to  this  volume,  as  it  begins  '  Post  hanc  scientiam  experimentalem',  &c. 
In  the  Compendium  Phil,  physics  follow  mathematics,  not  vice  versa. 

1689  D  d 


404  APPENDIX 

MSS.  Brit.  Mustum  :  Sloane  2156,  ff.  74-^7  (sec.  xv), 
ending  in  the  second  part  of  the  first  book. 
Bodl.  :  Digby  76,  f.  48  (sec.  xiii),  containing  the  remainder 
of  the  first  book(?),  or  another  recension  (?).  Inc. 
'  Mathematica  utitur  tantum  parte  '  :  expl.,  i.  64^ 
'  numorarc  convenict.'  F.  6y  :  '  Expeditis  hiis  que 
exiguntur  ad  proportiones.'  F.  Gq""  [Pars  II],  '  Deter- 
minato  de  parte  mathematice  prima  '  :  des.,i- 7()^,'sim\\ia. 
trapezeis.' 

Extracts  printed  in  Charles,  pp.  361-8. 

An  edition  of  the  Com.  Math,  is  being  prepared  by  Mr. Steele 
and  Professor  D.  Eugene  Smith. 

Libri  ii-vi.  An  extant  fragment  of  a  commentary  on 
the  Elements  of  EucHd,  probably  by  Bacon,  may  have 
belonged  to  this  part. 

MS.  Bodl.  :  Digby  76,  ff.  77-8  (sec.  xiii).  Inc.  '  Titulus 
autem  istius  libri  secundum  auctores.' 

Vol.  III.  Physics  (or  Natural  Philosophy),  four  books  : 
(i)  '  de  communibus  ad  omnia  naturalia  '  ;  (ii)  '  de 
celestibus  '  ;  (iii)  '  de  elementis  et  mixtis  inanimatis  '  ; 
(iv)  '  de  vegetabilibus  et  animalibus  '  (Steele,  Comtnunia 
NaJuraliutn,  p.  i). 

Elsewhere  (ibid.  pp.  5-8),  Bacon  enumerates  the  seven  '  special 
sciences  '  which  he  includes  in  Physics  :  namely  (i)  Perspectiva 
(or  Optics)  ;  (2)  Astronomia  judiciaria  et  opcrativa  (or  Astro- 
loRV)  ;  (3)  Scientia  ponderum  de  gravibus  et  levibus ;  (4) 
Alkimia,  or  Scientia  de  omnibus  rebus  inanimatis  que  fiunt 
primo  ex  elementis;  (5)  Agricultura  or  Scientia  de  plantarum 
natura  et  animalium  .  .  .  scilicet  de  omnibus  animatis  pretcr- 
quam  de  homine  ;  (6)  Medicina  ('  de  animali  rationaU,  scilicet 
de  homine,  et  precipue  de  sanitate  et  infirmitate  ejus,'  6cc.)  ; 
(7)  Scientia  experimentalis.  Bacon  adds  that  he  may  not 
be  able  to  treat  of  the  special  sciences,  except  Perspectiva, 
on  which  he  desires  to  compose  a  compendious  treatise,  but 
hopes  that  others  may  be  induced  by  his  labours  to  deal  with 
them. 

It  would  appear,  therefore,  that  the  special  sciences  were  not 
included  in  the  four  books  comprising  Vol.  Ill ;  all  these  would 
thus  be  devoted  to  general  principles. 

Books  i  and  ii  are  extant,  and  possibly  a  fragment  of  Book  iii ; 
of  Book  iv  there  seems  to  be  no  trace. 

No  treatises  on  the  special  sciences  seem  to  have  been  written 
for  the  Compendium  Philosophiae,  except  perhaps  a  version 
of  the  De  Multiplicatione  Specierum  (see  No.  11),  treating  of  the 
science  of  Optics.  The  compendious  treatise  on  Perspectiva 
was  written  for  and  included  in  Opus  Majus  (Part  V),  and  the 
other  sciences  mentioned  axe  treated  more  or  less  fully  in  various 
works  of  Bacon. 


ROGER  BACON'S  WORKS  405 

Liber  i.  Communia  Naturaliutn,  divided  into  four  parts. 
Inc.  Pars  i,  '  Postquam  tradidi  grammaticam  ;  ' 
Pars  ii,  '  Dicto  de  efficiente  ; '  Pars  iii,  '  Postquam  in 
prima  parte  hujus  libri ;  '  Pars  iv,  '  Nunc  tempus  est 
ut  fiat  descensus.' 
MSS.  Brit.  Museum  :  Royal  7  F.  vii,  ff.  84-112^'  (sec.  xiii 
ex.)  :  '  Hoc  est  volumen  naturalis  philosophic  in  quo 
traditur  sciencia  rerum  naturalium  secundum  potes- 
tatem  octo  scienciarum  naturalium  que  enumerantur 
in  secundo  capitulo,'  contains  Parts  i,  ii,  iii,  and 
capp.  1-7  of  Part  iv.  Inc.  '  Postquam  tradidi  gram- 
maticam secundum  linguas  diversas  '  :  expl.  '  terminus 
generacionis  '  (Steele,  p.  267). 

Cotton  Fragment  iv,  f .  22,  contains  a  copy  of  diagrams 
on  ff.  91* ,  92  of  the  Royal  MS.  (Steele,  p.  87). 

Sloane  2629,  f.  56*,  contains  a  few  lines  on  moral 
philosophy  from  Com.  Nat.  (Steele,  p.  2). 

Oxford  :  Bodl.  :  Digby  70  (sec.  xv  in.).  Inc.  '  Postquam 
tradidi  grammaticam.'    Contains  the  same  as  Royal  MS. 

Paris  :  Bibl.  Mazarine  3576,  ff.  i-90(secc.  xiv-xv),  contains 
all  the  four  parts.  Inc.  '  Postquam  tradidi,'  &c. 
Another  version '  of  parts  of  the  same  work  is  contained  in 
MSS.  Brit.  Museum  :  Royal  7  F.  vii,  f.  113  (sec.  xiii  ex.). 
Inc.  '  Ostensum  est  in  principio  cuiusdam  tractatus 
quod  necessarium  est  Latinis.' — Add.  8786,  ff.  2-10^ 
|(sec.  xiv).  Inc.  '  Ostensum  quippe  (?)  in  principio  huius 
compendii  philosophiae.'  Expl. '  terminus  generationis  ' 
(Steele,  p.  267). 

Oxford  :  Bodl.  :  Digby  190,  ff.  29-37^  (secc.  xiii-xiv), 
Rogeri  Bacon  Tract,  de  principiis  naturae.  Inc.  '  Sub- 
stancia  igitur  alia  est.  .  .  .  Item  omne  genus  '  (Steele, 
p.  50).  Expl.  '  terminus  generationis.' 
Printed  by  Robert  Steele,  Opera  hactenus  inedita  Rogeri 
Baconi,  Fasc.  II  and  III  (Oxon.,  1909, 1911). 

Extracts  in  Charles,  pp.  369-91. 

Liber  ii.  Astronomy  or  De  Coelestibus,  divided  into  five 
parts.  Inc.  Pars  i,  '  Prima  igitur  Veritas  ;  '  Pars  ii, 
'  Habito  quod  oportet  ponere  quinque  corpora  ;  ' 
Pars  iii,  '  Quinque  igitur  corporibus  mundi ;  '    Pars  iv, 

'  It  is  possible  that  this  was  meant  to  form  part  of  the  Comp.  Studii 
Theologie  (see  No.  36).  Mr.  Steele,  however,  regards  this  treatise  as  the 
first  part  of  the  Communia  Metaphys.,  and  holds  that  it  was  in  existence 
before  any  part  of  the  Com.  Nat.  was  written.  In  parts  it  is  identical 
with  Com.  Nat. 

D  d  2 


4o6  APPENDIX 

'  Nunc  invcstigandus  est  numerus  celorum  ;  '  Pars  v, 
'  Terminata  parte  in  qua  investif^avimus  numerum.' 

MSS.  Paris:  Bibl.  Mazarine  3576,  f.  91*:  '  Incipit  2"* 
liber  comnmnium  naturalium  qui  est  de  celestibus  uel 
de  celo  et  mundo  cuius  hec  est  pars  prima.'  Cap.  I, 
'  Prima  igitur  Veritas.' 
Oxford  :  Bodl.  :  Digby  76,  ff.  1-35*  (sec.  xiii),  Com- 
pendium  Philusophiac.  Inc.  '  Prima  igitur  Veritas 
circa  corpora  mundi  est  quod  non  est  unum  corpus 
continuum  et  unius  nature.'  Ibid.,  f.  36,  '  De  corporibus 
coelestibus,  sc.  de  zodiaco,  sole,'  &c.  Inc.  '  Habito  de 
corporibus  mundi  prout  mundum  absolute  constituunt  ' 
(written  in  1266.  probably  an  early  draft  made  before 
Bacon  had  settled  on  the  scheme  of  the  Opus  Majus). 
— Cf.  Ashmole  393,  I,  f.  44  (stc.  xv), '  Veritates  de  magni- 
tudine  .  .  .  planetarum.  Tractatus  extractus  de  libris 
celi  et  mundi  nobilissimi  illius  philosophi  et  doctoris 
S.  theol.  R.  B.  qui  omnia  rectiftcavit  a  tempore  primorum 
auctorum  astronomic  usque  ad  tempus  suum.'  F.  44\ 
'  Sequitur  tractatus  alius  de  eisdem  libris  celi  et  mundi 
.  .  .  de  necessariis  circulis  in  celo  ymaginatis.  .  .  .  Primo 
igitur  sciendum  quod  nuUus  cir[culus]  secundum  veri- 
tatem  est  in  celo  nisi  gallaxa  tantum.'  ' 

Printed  by  Robert  Steele,  Opera  hactenus  inediia,  Fasc.  I\' 
(O.xon.,  1913). 

Liber  iii.  Alchemy,  or  '  De  dementis  el  tnixlis  inanimatis  '. 

Cf.  '  Excerpta  ex  libro  sex  scientiarum'  in  Sanioris 
medicinae,  &c.  (Frankfurt,  1603),  pp.  7,  8.  '  Quarta 
vero  scientia  non  modicam  habet  utilitatem  .  .  .  et 
est  Alchymia  speculativa,'  &c.,  and  the  following 
passage,  pp.  9-16  :  '  Idem  Rogerus  libro  praedicto 
probat  quod  ex  his  cum  adjutorio  scientiae  exj)eri- 
mcntalis,'   &c. 

Liber  iv.  '  De  vegetahilihus  et  animalihus  '  ('  Agriculture  ' 
and  Medicine). 

Vol.  IV.  Metaphysics  and  Morals. 

A  fragment  of  the  Metaphysics  only  has  hitherto  been 
known.    This  was  wxitten  in  or  before  1266,  and  much 

*  Cf.  Digby  183,  f.  3S.     Alkindus  de  radiis  stellarum  ;    '  Omnes  homines.] 
qui  sensibilia  sensu  percipiunt ;  '   with  marginal  note,  '  quod  est  extractum 
de  libro  Rogeri  Bakun  de  celo  et  mundo,  capitulo  de  numero  celonim.' 
Cf.  Brit.  Mus.  Add.  8786,  ff.  10^-12^  :   no  title.     Inc.  '  Numerus  sperarum 
continentium.' 


ROGER  BACON'S  WORKS  407 

|of  it  is  included  in  the  Opus  Majus,  Part  VII    (see 
Preface    and    Appendix    to    Steele's    edition).      Inc. 
'  Quoniam   intentio   principalis  est   inniiere   nobis   [or 
/vobis]  vicia  studii  theologici.' 
The    discovery   of    the    whole    work    is    announced    by 
Dr.  Nogara,  Dr.  Pelzer  and  the  Rev.  H.  M.  Bannister  of 
the  Vatican  Library  as  these  pages  are  passing  through 
the  press. 
MSS.    Oxford  :      Bodl.  :     Digby    190,    f.    86^"    (fragment)  : 
title  :     '  Metaphisica   fratris   Rogeri   O.F.M.  de   viciis 
contractis  in  studio  thcologie.' ' 
Paris  :   Bibl.  Nat.  7440,  ff.  38-40,  25-32. 
Rome  :   Vatican.  2227,  ff.  48'--67'-  (sec.  xiv),  '  De  vitiis 
contractis  in  studio  theologie '  (anon.) ;  Vat.  5004  (Alb. 
Magnus). 
Printed,  in  Opera  hactcnus  inedita,  cd.  R.  Steele,  Fasc.  I 
(fragment  only). 
Extracts  in  Charles,  Roger  Bacon,  pp.  391-7. 
36.  Compendium  studii  theologiae,  Bacon's  last  work,  written 
in  1292.     In  three  or  more  parts.     Inc.  '  Quoniam  autem 
in  omnibus  causis  autoritas.' 

MSS.  Brit.  Museum  :   Royal  7  F.  vii,  ff.  78-83,  incomplete, 
containing  Part  I,  capp.  1-2,  Part  II,  capp.  1-6.    (At  the 
end  of  the  article  a  seventeenth-century  hand  adds  : 
'  quaere  residuum,  p.  221,'  referring  to  the  version  of 
XheCommunia  Naturalium  already  mentioned,  beginning 
'  Ostensum  est  '  (see  p.  405  above). 
Oxford:  Univ.  College,  47  (sec. xvii), copied  from  RoyalMS. 
Printed  in    Brit.  Sac.  of  Franciscan  Studies,  vol  iii  (ed. 
Rashdall),  1911. 
Extracts  in  Charles,  pp.  410-15. 

II.    DOUBTFUL  AND  SPURIOUS 

37.  Summulae  dialectices,  an  elementary  treatise  on  logic, 
characterized  by  Charles,  who  expresses  a  doubt  as  to  its 
authenticity,  as  very  dry,  unimportant,  and  intended  for 
lecturing  purposes.  Inc.  '  Introductio  est  brevis  et  apta 
demonstratio  in  ahquam  artem  vel  scientiam.'  '  Exph- 
ciunt  sumule  magistri  Roberti  Baccun  '  (perhaps  by  Robert 
Kilwardby  (?),  see  No.  38  :  or  Petrus  Hispanus  (?),  see 
Quetif-Echard,  Script.  Ord.  Praed.,  i.  485). 
MS.  Bodl.  :   Digby  204,  f.  48  (sec.  xiv  in.). 

'  Duhem,  Opus    Tertium,  p.  33,  argues  that  this  formed  part  of  the 
Opus  Tert.,  but  see  Little,  Part  of  the  '  Opus  Tert.',  &c.,  pp.  xxviii-xxx. 


4o8  APPENDIX 

38.  '  Sincateg[o]reumata  fratris  R.  Bacon  '  (tit.  manu  secunda). 

Inc.  '  Pare  ium  orationis  quedam  sunt  declinabiles  '  (probably 
by  KolK-rt  Kilwardby).' 
MSS.  Bodl.  :  I>i^;l)y  204,  f.  88  (sec.  xiv  in.). 
Erfurt  :  Amplun.  Q.  328,  ff.  74*^-93''  (sec.  xiii). 

39.  Tractatus  de  signis  logicalibus.     Inc.  '  Signum  est  in  pre- 

dit  aiiunto  It  l.itionis  t  i  ili.  itur  esst-ntialitLT.'     Lxpl.  '  Dicen- 
dum  est  <]U()d  duplicitcr  inttlligitur  aliquid  in  alio.' 

MS.  Bodl.  :  Digby  55,  f.  228  (sec.  xiii  ex.).  (The  ascrip- 
tion of  this  to  Roger  Bacon  is  in  a  later  hand.) 

40.  Quaestiones  super  librum  de  Causis. 

Inc.  '  Supra  librum  de  causis.  OutTiiur  circa  influcntiam 
causarum,  utrum  causa  (?)  agat  {xr  influtntiam.' 

MS.:  Amirns  406,  ff.  114-2^/.  Anon,  and  incomplete: 
a  quire  is  missing  Ixtwecn  ff.  117  and  118  :  and  ff.  125 
and  I2()  have  nothing  to  do  vAth  the  treatise. 

Described  by  V.  Cousin,  Journal  des  Savants,  1848. 

41.  De  somno  et  vigilia  (two  books). 

MSS.  Hoill.  I)igl)y  190,  ff.  77-86*  (sec.  xiv  in.).  Inc.  '  De 
somno  et  vigilia  pertractantes  Perypateticorum  sen- 
tenciam  potissime  sequcmur  '  (name  of  author  added 
in  hand  of  seventeenth  century). 

Cambridge  :  Univ.  Libr.  li.  vi.  5,  ff.  85^-8  (sec.  xiii), 
[Roi^erus  Bacon  dc  somno  et  ri^i/ia] '  ;  Inc.  '  Sompnus 
ergo  et  vigilia  describuntur  muliis  modis.  Dicitur 
enim  quod  sompnus  est  sensus  in  potentia  '  (7  chapters). 

{Tractatus  de  sompno  et  vigilia,  by  Roger  I3acon,  was 
contained  in  a  MS.  of  St.  Augustine's  Abbey,  Canter- 
bury, No.  843  in  the  catalogue  ed.  M.  R.  James.) 

42.  '  Bacon  in  Meteora  '  (tit.  manu  sec.  x\i  ex.).'    Inc.  '  Cum  ad 
noticiam  impressionum  habendam.' 

MS.  Bodl.  Digby  190,  ff.  38-43''  (sec.  xiv  in.). 

'  See  L.  Baur,  Die  philosophise  hen  Werke  GrosseUsUs ,  p.  I2i*.  Cf. 
Bale,  Index  Brit.  Script.,  p.  395,  who  mentions  among  Bacon's  works  : 
De  ccnsinutione  partium  [oraiionis']  :  inc.  '  Ad  completam  cognitionem 
constructionis.'  In  the  Syon  MS.  A.  4,  from  which  Bale  took  this  entry, 
the  treatise  appears  from  the  Catalogue  (ed.  Marj'  Bateson,  p.  2)  to  have 
been  anon},-mous  but  to  have  followed  '  Summa  grammaticalis  fratris 
Rogeri  Bakon.' 

-  The  Catalogue  attributes  it  to  Bacon,  but  I  failed  to  find  anj'thing  in 
the  MS.  itself  to  support  the  statement. 

^  Mr.  Steele  tells  me  he  thinks  this  is  not  by  Bacon.  The  writer  refers 
to  Albertus  Magnus. 


ROGER  BACON'S  WORKS  409 

43.  [Quaestiones  de  perspectiva.] 

MS.  Amiens  406,  if.  155-65,  fragment  of  a  treatise  (anon.)  * 
on  optics  in  tlie  form  of  quaestiones,  beginning  in  cap.  iv, 
quaest.  9  :  '  .  .  .  ergo  natura  communis  per  quam 
perspicuum  inest  corporibus  partimn  expansio  '  :  and 
ending  with  cap.  xii,  entitled  :  *  De  radio  exeunte  ab 
oculo  et  de  eius  natura  et  quomodo  per  ipsum  con- 
tingat  videre  et  quomodo  non,'  &c.  This  cap.  xii 
contains  ten  quaestiones,  the  tenth  beginning  :  '  X"*  est 
de  modo  secundum  quern  res  magne  rotunde  et  quadrate 
presentantur  in  oculo  qui  est  corpus  parvum  et  figure 
rotunde  '  [c/t'S.]. 

44.  '  Speculi  almukefi  compositio  secundum  Rogerium  Bacon  ' 
[or  De  sectione  conica].  Inc.  '  Quia  universorum  [al.  diver- 
sorum]  quos  de  spoculis  ad  datam  distantiam  comburentibus 
tractare  perpendi  seu  quorum  vidi  tractatus  in  scriptis, 
omnes  et  singuli  duas  supposuerunt  conclusiones  ab  Apol- 
lonio  Pergeo  allegatas,  super  quibus  tota  eorum  intentio 
fundabatur  '  [at  the  end  :  he  could  say  much  more  about 
specula,  but  fears  to  repeat  what  has  been  said  by  Apollonius, 
whose  book  he  has  never  seen]  '  quanquam  exactissimam 
dihgentiam  opposuerim  eum  vidisse,  ideo  presenti  opusculo 
cum  laude  Dei  dicta  sufficiant.    E.xplicit  feliciter.' 

MSS.  Bodl.  Can.  Misc.  480,  ff.  48-55  (sec.  xv). 

Florence:  Bibl.Naz.:  Ashburnham957,ff.95-iiov(sec.xv). 

Brit.  Mus.  :  Tib.  B.  ix  (sec.  xv  in.),  ff.  227^-30'",  injured 
by  fire  :  beginning  and  end  illegible  :  refers  to  Apol- 
lonius, Viteilo,  &c. :  f.  228^  '  In  omni  seccione  para- 
bola signato  puncto  in  medio  sagitte  '  ;  f.  228',  '  In 
speculo  concavato  concavitate  sectionis  Mukefi  omnis  ' 
(=  Prop,  ix  of  Gogava's  edition),  followed  by  '  Premissis 
autem  conclusionibus  istis  novem  .  .  .'  (f.  228^),  and  by 
De  specults  comburentibus  (see  No.  45). 
Printed  in  a  humanistic  version  by  Antonius  Gogava 
Graviensis  in  CI.  Ptolomaei  Pelusiensis  Mathematici 
Operis  Quadripartiti  in  Latinum  Sermonem  traductio  .  .  . 
Item  de  sectione  conica,  orthogona,  quae  parabola  dicitur  ; 
deque  speculo  Vstorio  Libelli  duo  hactenus  desiderati, 
Lovanii,  1548. 

Cf.  Nos.  17a,  176,  above. 

45.  [De  speculo  comburenti,  concavitatis  parabolae.]     Inc.  'De 

sublimiori  quod  geometre  adinvcnerunt  et  in  quo  antiqui 
soliciti  fuerunt  et  in  quo  bonitas  proprietatum  figurarum 

•  Possibly  by  the  author  of  the  Summa  Philosophiae  ascribed  to  Grosse- 
teste  ?     See  Baur,  Die  philosophischcn  Werkc  Grossetestes,  pp.  133*,  512. 


410  APPENDIX 

geometricarum  apparet  ct  quod  ab  eis  accidit  ex  rebus 
naturalibus  est  fabricatio  six.'Culorum  comburentium  per 
convcrsionein  radii  Solaris.  Incesserunt  (scil.  philoscjphi) 
ergo  invcnicndo  ea  modis  diversis.'  lixpl.  'super  longi- 
tudinem  (jucsitam.  Sermo  ergo  iste  coniprehendit  omnem 
operationcm  spec  ulorum  comburentium  que  sunt  secundum 
Ijanc  tiguram  et  sunt  fortioris  combustionis  omnibus  speculis 
(juoniam  radii  convertuntur  ex  tota  superftcie  eorum  ad 
punctum  unum.' 

MSS.  Brit.  Mus.  :  Vesp.  A.  ji,  ff.  140-4,  with  many  dia- 
grams on  ff.  14O,  147  (secc.  xiii  ex.-xiv  in),  anon.  Title 
(sccc.  xiv  ex. -XV  in.),  '  De  sectione  Mukefi  ;  '  inscribed 
in  John  Dee's  hand  :  '  Joannes  Dee  1555.  Antiquis- 
simus  iilK'llus  de  sjH'culis  comburentibus.'  '  Hxplicit 
de  sjx'culis  quolil)etmodo  comburentibus.' — Tib.  B.  ix 
(sec.  XV  in.),  ff.  230*-2^  injured  by  fire  ;  beginning  and 
end  illegible  :  f.  23I^  '  In  omni  seccione  parabola  latus 
erectum  duplum  est,'  contains  a  few  diagrams. 
Oxford  :    Corp.    Chr.    Coll.   260,    p.    147   (sec.   xvii   in.), 

Twyne's  copy  of  Vesp.  A.  ii. 
(Cf.  Florence  :    Bibl.  Naz.  :    Ashburnham  957  (sec.  xv), 
ff.  in^-22'^  (anon.,  no  ti^lc,  but  following  directly  on 
the  '  Spec.   Almukefi  sec.   Roggcrium   Bacon  ')  :    '  Ut 
farilius  fiant  corpira  quinquc  rcgularia  de  quibus  tractat 
Euclides  in  ultimis  suis  libris  ' :  cxpl.  '  Sermo  ergo  iste  .  .  . 
ad   punctum   suum    [cf.  supra].     Explicit  de  speculis 
comburentibus  feliciter  '  (this  seems  to  contain  matter 
not  in  Vesp.  A.  ii). 
Cf.  Bodl.  Can.  Misc.  480,  ff.  55'^-6^  :   inc.  '  Ut  facilius  fiant 
corpora  '  :    cxpl.    '  Siitis   liquerunt   ipsa   proposita   Deo 
gratias.' 
Printed,  the  earlier  part   only,  i.e.  Vesp.  A.  ii,  ff.  140-3 
(to    '  lateris    erecti,    et    illud    est    quod    demonstrare 
volumus  '),  in  a  rexHsod  version  by  Gogava,  ui  supra, 
Louvain,    1548,    under    the    title  :     Aniiqui   scriptoris 
lihcllus   dc   specula   comhurmti,    concavitaiis   parabolae. 
Inc.  '  Ex  sublimioribus  quae  Gcometrae  ' :  expl.  '  lateris 
erecti.    Atque  illud  est  quod  in  errandum  sumpsimus.* 
Cf.  Nos.  lya,  176,  above. 

46,  De  mutabilibus  pronosticoruin  elementorum.  Inc.  '  Scribo 
vobis  qui  vultis  de  mutabilibus  pronosciorum  elemen- 
torum que  ab  astris  contingunt  omni  tempore  seculi 
huius.'  'Explicit  tractatus  subtilissime  considerationis 
fratris  R.  B.  ordinis  minorum  qui  experimentarius 
dicitur.' 


ROGER  BACON'S  WORKS  411 

MS.  Winchester  College  Y.  8  (sec.  xv  ex.),  13  leaves, 
paper.  (It  consists  of  8  quaestiones  ;  i  de  humore 
aeris,  2  de  gelu  et  quando  humor  cadens  congelatur, 
3  de  tonitnio,  4  de  terre  motu,  5  de  stelhs  que  hunt  in 
aero,  6  de  vcntis,  7  de  motu  oceani,  8  de  pestilentia.) 

47.  Speculum  Astronomiae.  Inc.  '  Occasione  quorundam  libro- 
rum,'  generally  ascribed  to  Albertus  Magnus,  and  printed 
among  his  works  (Opera  Omnia,  Lugd.  1621,  vol.  v  ;  Paris, 
1891,  vol.  x),  is  ascribed  to  Roger  Bacon  by  Mandonnet, 
who  maintains  that  it  was  written  in  1277  :  Revue  nio- 
scolastiqxie  de  philosophie,  xvii.  313-35  (August  1910). 
MSS.  Bodl.  Digby  81,'  f.  102.     '  Tractatus  quern  composuit 

Albertus  fr.  prcdicator.' — Digby  228,  f.  76  (sec.  xiv), 
anon. — Can.  Misc.  517,  f.  52^  (sec.  xv),  '  Albert!  magni 
speculum  do  nominibus  librorum  astrologie.' 

Erfurt  :  Amplt>n.  Q.  223  (sec.  xiv  ex.),  ff.  105-16  :  '  Tract, 
de  nominibus  librorum  astronomic  cui  inscribitur 
speculum  .Alberti.' 

Venice  :  S.  Marco.  01.  xi,  Cod.  71  (Z.L.  337). 

Vienna  :    Bibl.  Pal.  5508  (sccc.  xiv-xv),  ff.  i6i^-8o^'. 

48.  Tractatus  de  incamatione  sive  de  secretis  philosophiae,  or  De 
probatione  fidei  Christianae  per  auctoritates  paganonmi,  or 
De  adventu  Christi  seaindum  camem  :  inc.  '  Quoniam 
occasione  cuiusdam  sermonis  qucm  ad  clerum  feceram,' 
generally  ascribed  to  John  of  Paris,  O.P.  (surnamed  '  Qui 
dort '),  is  ascrilx-d  to  Roger  Bacon  by  Father  F.  Delorme,  who 
is  preparing  an  edition  of  the  work.  Cf.  Archivum  Franc. 
Hist.,  April  1911  ;  Archiv  f.  Lit.  u.  K.-Gesch.,  iv.  312-39. 
MSS.  Oxford  :    Bodl.   Can.   Eccl.    19   (sec.    xiv). — Lincoln 

Coll.  81  (sec.  XV). 
Paris  :   Bibl.  Nat.,  Lat.  13781.     Bibl.  de  I'Arsenal,  78. 
Laon  275. 
Cf.    Bateson,   Cat.   of    Syon  Monastery,  O  60  (p.   148), 

K  18  (p.  215). 


Many  works  on  alchemy  are  attributed  to  Bacon  errone- 
ously or  without  probability.     A  few  of  the  following 
may,  however,  be  genuine. 
49,  Speculum  alchemiae  (de  transmutatione  metallorum).     Inc. 
praef.  '  Multifaric  [MultifariamJ  multisque  modis  . .  .  '  Cap.  i. 
'  In  antiquis  philosophorum  libris  '  (7  chapters). 
MSS.    Brit.  Museum  :   Addit.  8786,   f.  62  ;    15549,  f-  loi 
(with  the  introductory  letter)  ;    Sloane  1754,  ff.  62-74 
'  This  volume  formerly  contained  '  Cosmographia  R.  Bacon  21.     Scac- 
carium  morale  87.     Mathematices  vis  et  usus  67.' 


412  APPENDIX 

(sec.  xiv)  ;  Sloane  3506,  ff.  42-6  (English)  ;  Sloane  692, 
ff.i-19,  1 13-17  (sec.  XV)  ;   Sloane  3688,  ff.  87-91. 

Oxford  :  Bodl.  :  Ashmole  14x6,  f.  loi, — New  Coll.  294 
(Erench). 

Cambridge  :  Univ.  Libr.  Ff.  iv.  12,  f.  39,  called  '  Rosarium 
Johannis.' — Trin.  Coll.  915.  f.  117;  cf.  ibid.  X120,  III, 
f,  28* , '  Bacon  in  S|x.'Culo  alkynne  ;  Inter  cetera  que  dixi.' 

Paris  :  Bibl.  Nat.  (lran<;.)  2012  (sec.  xvi),  f.  34,  '  Miroir 
d'alchimie  trad,  de  Kog.  Bacon  par  Girard  de  Tornus.'" 

Montj>ellier  :  £cole  de  Mcdecme  479  (sec.  xv).  Speculum 
alchemiaeKogtriiBacconis(noiM<:i/>i>given  mCatalogue). 

Florence  :  Bibl.  Naz..  Strozzi  (Magliabecchi),  xvi  (7)  30 
(sec.  xvi),  Doctissimi  viri  Kogeri  Bacconis  de  aJchimia 
libellus  cui  titulus  speculum  alchimie.  Inc.  '  Multi- 
fariam,'  &c.,cap.  l,  '  In  pluribus antiquonmi  codicibus  ' 
(ends  imiH-rf.,  p.  16). 

Bologna  :  Bibl.  Univ.  270  (secc.  xv-xvi),  vol.  xxvi. 
Inc.  '  Mullifarium.' — Ibid.  1062  (sec.  xiv),  fi.  1-6 
[Sj)ec.  Alch.  Rog.  BaconisJ,  '  Multiphariam.' — Ibid.  303 
(sec.  XV),  ff.  157^-63*  Speculum  Alchimie.  /nc.  '  Multi- 
pharie  '  '. 

Vienna:  Bibl.  Pal.  5509  (sec.  xv).  fi.  330-1*,  Rogerius 
Bacon,  Spec.  Alchymiae  (no  mcipit  given). 
Printed  at  Niirnberg,  1541  ;  in  Zetzner's  Theairum 
Chemicxon  (1659),  vol.  ii,  pp.  377-433.  Mangel's 
Thesaurus  (1702),  i.  613,  &c.  French  translation, 
1557  ■  ;  English  translation,  1597,  and  in  Salmon's 
Mtduina  Practica  (1707),  p.  621. 

50.  Speculum  Alchemiae  (perhaps  by  Arnald  de  Villeneuve  ?) 

Inc.  '  Speculum  alchemic  quod  in  corde  meo  figuravi.' 

MS.  Brit.  Mus.  :    Harl.  3528,  f.  185. 

Cf.  Bologna  :  Bibl.  Univ.  270  (secc.  xv-xvi),  vol.  x, 
'  Speculum  Alchimie  Bakonis.  Incipit  speculum  al- 
chimie '  :  cxpl.  '  ubi  vult  spirat.' 

51.  Speculum    Alchemiae,    doubtfully    ascribed    to    Bacon    by 

Nasmith :  inc. '  Sciendum  est  quia  philosophi  per  4**  verba  hoc 
opuscompleverunt ' :  expl.  'sufiiciunt  intellectumhabentibus.' 
MS.  Cambridge  :  Corp.  Chr.  Coll.  99,  p.  189  (sec.  xv),  anon. 
Cf.  Bodl.  :    Ashmole  1416,  f.  37,  '  Libellus  alchemicus  de 
quatuor  verbis.* 

'  This  Paris  MS.  also  contains  (f.  73)  Li\Te  du  maltre  Jupiter  par  Roger 
Bacon  (possibly  extract  from  Breve  Brcviartum,  No.  20). 

-  A  copy  of  this  Sptc.  Alchem.  (sec.  xv,  anon.)  inc.  (f.  169)  '  Multipharie,' 
was  in  a  Philhpps  MS.  sold  at  Sotheby's,  April  24,  191 1,  Lot  7. 

^  Reprinted  1612,  1627,  under  the  title  Miroir  de  maistre  Jean  Mehun. 


ROGER  BACON'S  WORKS  413 

52.  Speculum  Alchemiae.  Inc.  '  Tract,  sciencie  naturalis  sive  de 
lapide  philosophorum  .  .  .  secundum  fratrem  Rogerum  Bacon. 
Salutem  [quam]  tibi  amice  karissime  et  speculum.' 

MSS.  Brit.  Mus.  :   Sloane  692,  ff.  115-7. 

Cambridge  Univ.  Lib.  Ff.  iv.  12,  ff.  267-71  (anon.). 

Cf.  Bologna  :   Bibl.  Univ.  1062  (sec.  xiv),  ff.  34-6.    Trac- 

tatus  qui  dicitur  Speculum  Baconis  :   inc.  '  Salutem  ' : 

expl.  '  valete  '. 
Cf.  Leydcn  :   Bibl.  Univ.  Q.  27,  Chim.  Voss.  64. 

53.  Speculum  Secretorum,  or  Liber  Secretorum  de  spiritu  occulto. 

Inc.   '  In   nomine  Domini   ...  ad  insiructionem  [instan- 
tiamj  multorum.' 
MSS.  Brit.   Mus.  :    Sloane  513,   ff.  178^-81,   '  Explicit  liber 
secretorum  qucm  Rogerus  Bakun  composuit.'    Sloane 
1081,  ff.  lyS-i^  (sec.  .\v)  :  Sloane  11 18,  ff.  50-6  (sec.  xv). 
Oxford  ;  Bodl.  177,  f.  54^  (sec.  xiv  ex.),  anon.  :  Digby  28, 
f.  61 ;  Digby  119,  f.  90*  ;    Ashmole  1467,  ff.  208^-13' 
^sec.   xvi)  ;    1485,   p.   117.     Corpus  Christi    Coll.  125, 
1.  86  (anon.). 
Cambridge  :    Univ.  Lib.  Ff.  iv.  12,  f.  298^,  followed  by 
'  Cedulu  dccluraiiva  Magistn  Rugcri  Bacon  ' :  inc.  '  Quia 
diximus  in  speculo  secretorum  '.' 
Florence  :    Riccardi  390,  ff.   138-44,  followed  by  Liber 
claritaiis  Rog.  Bacon  :    inc.  '  De  libro  claritatis  totius 
artis  aichimie  '  (ff.  144^-50^). 
Cf.  Florenee.  Bibl.  Naz.,  Pal.  758  (sec.  xv),  885  (sec.  xvi). 
887  (sec.  xvi). 
Printed  in  Sanioris  Medicinac,    &c.,  at  Frankfurt,   1603 
(pp.  387-408). 

54.  Secretum  secretorum  naturae  de  laude  lapidis  philosophorum. ' 

Inc.  '  hecretuni  secretorum  naturae  audiant  secreti  quae 
loquor.' 

MS.  Oxford  :    Bodl.  :    Digby  119,  ff.  80-1  (sec.  xiv  in.). 

Printed  at  Frankfurt,  1603  (pp.  285-91). 

Cf.  Leyden  :  Bibl.  Univ.  Q.  27,  Chim.  Voss.  64.  Roger 
Bacon,  Theoretica  de  lapide  philosophorum. 

55.  Radix  mundi,  or  Tractatus  alchemicus  de  lapide  philosophico.^ 

Inc.  '  Omnium  corpora  constancium  tam  perfecta  quam 
imperfecta.' 

'  Cf.  Ashmole  1478,  ff.  39-40  (sec.  xvi),  '  Cedula  declarativa  Baconis. 
Amice,  in  istis  consistit  difficultas  operis  nostri.' 

'  Winchester  College  39  (sec.  xv),  ff.  33-40,  has  anon,  treatise  beginning  : 
'  Quesivisti  quis  trium  lapidum  nobilior.' 

'  Tanner,  Bibl.  p.  64,  mentions  a  MS.  of  Roger  Bacon  Dc  philosophorum 
lapide  at  Pembroke  College,  Cambridge  :    it  is  not  there  now. 


414  APPENDIX 

MSS.  Oxford:  St.  John's  College  172,  ff.  3ir-2i  (sec.  xv). 
anon.  :  19  chapters. 
liocU.  Digby  133  (sec.  xvi).  f.  22  :  English  translation.  '  by 
Robert  Ereelove  of  L(jncion,  mercer,  the  16  of  Februarii 
a"  1550  '  :  15  chapters  ;  beginning,  ■  The  bodies  of  all 
things  being  '  (attributed  to  Roger  Bacon).  Ashmole 
1418,  ff.  47-O0  (English). 
Brit.  Mus..  Sloane  1799  (English). 

Pkinteu,  Englisii  translation,  in  Salmon's  Medicina  Practica 
(lyoy),  pp.  585-O20,  under  the  title,  '  Rogerii  Bachonis 
Radix  Mundi.  translated  out  of  Latin  into  Enghsh  and 
claused,  by  William  Salmon,'  15  chapters  (chapters  1-13 
of  the  translation  correspond  generally  to  capp.  I-13 
of  the  Latin  version). 

5^).  De  subject©  transmutationis. 

.MS.  Paris  :  Bibl.  Nat.  2598,  f.  138  (sec.  xv)  :  inc.  '  Licet 
in  (juestione  qua  (jutritur  utrum  in  materia  in  qua 
generatur  aliquid  sit  principium  activum  non  credam  te 
aliquatenus  dubitare.'  '  Explicit  de  subjecto  trans- 
mutationis  secundum  Rogerum  Bachonis.'  (It  may 
occur  in  one  of  his  largt-r  works.) 

57.  Editio  super  Geberem  '  de  tribus  ordinibus  medicine  a  Rogero 

Bacon.     Inc.    '  Tres  ^sunt   ordine^   nuilKmarum   secundum 
CielHTem.'     Expl.  '  Et  ista  duo  S.  capitula  sunt  pars  cedule 

SJK'CUli.' 

MSS.  Cambridge:  Univ.  Libr.  Ff.  iv.  12,  ff.  294^-^  (a.d. 
1528-9). 
Bologna :  Bibl.  Univ.  474  (sec.  xv),  ff.  73'-85',  '  Rogenis 
Bacum  [sic]  super  Geberem  de  tribus  ordinibus 
medicine.' 
Cf.  Oxford,  Corp.  Chr.  Coll.  226,  f.  34,  and  Cambridge 
Univ.  Lib.  Ff.  iv.  12,  f!.  63-71,  J  oh.  Pauper  de  lapide 
philosophorum ,  or  Brrciloquium  Johannis  Pauperis: 
inc.  '  Testatur  Gebar  .  .  .  quod  tres  sunt  ordines.' " 

58.  '  Compendium  Alkymie  secundum  eundem  Magistrum  Rog. 
Bacon  ut  estimatur.'    Inc.  '  Amice  accipe  artem  m  brevibus.' 

MS.  Cambridge  :   Univ.  Lib.  Ff.  iv.  12,  ff.  306^-11. 

'  i.e.  Jabir  ibn  Haiyan.  Some  of  his  works  on  alchemy  were  printed 
at  Venice  1475  (?)  together  with  poems  ascribed  to  Friar  EUas  ;  and  at 
Berne  1545  with  the  '  Spec.  Alchemiae  R.  Bachonis'.  Cf.  Cambridge, 
Corpus  Chr.  Coll.  MS.  99,  §§9,  10  ;  Ashmole  MS.  1445,  §  iv,  ff.  1-5.  On 
Get>er  and  pseudo-Geber  see  Berthelot,  La  Chimie  au  moyen  age,  i.  343, 
iii,  126. 

•  English  version  in  MS.  Ashmole,  1418,  ff.  13^-20'. 


ROGER  BACON'S  WORKS  415 

59.  '  Epistola  de  spiritu  occulto  '  in  sulphure  et  arsenico.'  Inc. 
'  Interrogationi  vestre  de  secretis  nature  taliter  vobisscribo. 
Species  purgantur  per  sua  opposita.' 

MS.  Camb.  Univ.  Lib.  Ff.  iv.  12,  ff.  310-18.  (Cf.  MS. 
Oxford.  Ashmole  1467,  ff.  213-15  (sec.  xvi),  inc.  '  Cum 
ergo  quesieris,'  anon.) 

60.  Tractatus  de  quibusdam  aquis  Alkimicis  inventus  in  antiquo 
exemplari  compilacionis  fratris  Rogeri  Bacon. ^  hic.  '  In 
principio  dicanius  do  dissolucione  formenti.  Recipe  vitrioli 
romani.'    Ii.xpl.  '  et  deveniet  quoddam  citrinum.' 

MS.  Camb.  Univ.  Lib.  Ff.  iv.  12,  ff.  326-33. 

61 .  Thesaurus  Spirituum,  four  treatises  on  the  influence  of  planets, 

6cc.  Inc.  '  Hec  est  doctrina  omnium  experimentorum.' 
MSS.  Brit.  .Mus.  :  Sloane  3853,  ff.  3-40  (sec.  xvii)  :  '  Hec 
est  tabula  libri  sequentis  ...  a  quodam  viro  vene- 
rabili  ordinis  Minorum  summa  composita  et  ordinata, 
et  a  diligencia  M.  Rogero  (sic)  Bakon  ordinis  Minorum 
nuper  recognita.'  Sec.  '  Explicit  liber  qui  secundum 
RolK-rtum  Turconem  et  Rogerum  Bakon  fratrem 
minorum  Thesaurus  spirituum  nuncupatur.'  Cf.  Sloane 
3850,  ff.  117^-29  :  3885,  f.  26. 
Cf.  MS.  Sloane  3850,  f.  I29^  De  nigromantia,  extracted 
from  the  above  ;  and  Sloane  3884,  f.  44^  (sec.  xvii), 
N ccrumantiac  Rogeri  Bachon,  inc. '  Debes  mundare  manus 
et  pedes.' 


Among  alchemical  works  ascribed  to   Bacon   which  are 
certainly  spurious  are  : 

62.  De  consideratione  quintae  essentiae  ',  2  or  3  books.  Inc.  lib,  i, 

'  Dixit  Salomon  Sap.  cap.  \ii,  Deus  dedit  mihi  horum  ;  ' 

inc.  lib.  ii,  '  Licet  liber  primus  qui  est  de  consideratione  ;  ' 

written  by  a  Franciscan  who  entered  the  Order  at  Toulouse, 

probably  Joh.  de  Rupescissa.^     A  few  only  of  the  many 

MSS.  arc  noted  below. 

MSS.    Brit.    Mus.  :     Sloane    2320    (secc.     xv-xvi),    f.    73  ; 

2322,  ff.  135-68  (sec.  XV),  ascribed  to  Roger  Bacon; 

75. 11.  101-23  (sec.  XV) ;  338,  f.  i  (sec.  xv),  hb.  i  ascribed 

to  Joh.  de  Rupescissa,  lib.  ii.  to  '  Raymundus '. 

■  Cf.  Cambridge  Univ.  Lib.  Ff.  vi.  50 (sec.  xv),  ff.  44^-46^  :  Interrogationes 
Utkesie  ad  Manam,  '  Cum  queritur  quid  est  spiritus  occultatus  in  sulphure 
ct  arsenico.' 

'  Perhaps  from  the  Semita  Recta  Alchemiae  ;    see  No.  63. 

'  Also  called  '  Defamulatu  philosophiae ' ;  e.g.  Sloane  1080,  a,  f.  6  (sec.xv). 

*  CV.  Charles,  Roger  Bacon,  p.  76.     Sbaralea,  Sup.  ad  Script.  Ord.  Min. 


4l6  APPENDIX 

Oxford  :  Bodl.  :  Can.  Misc.  334,  ff.  59^-94^, '  secundum  fr. 
Rog.  Bacun  '  :  E  Musaco  155,  pp.  431-507,'  '  secundum 
mag.  Rogerum  Bacon  '  :  Digby  43  (anon.).  St.  John's 
Coll.  172  (sec.  XV).     Corp.  Chr.  Coll.  124  (sec.  xv),  anon. 

Winchester  College  39,  f.  i  (sec.  xv),  ascribed  to  Bacon  or 
to  J.  lie  Rupescissa. 

Cambridge  :   Trin.  Coll.  1389,  f.  45'  (sec.  xv),  anon. 

Paris:   Bibl.  Nat.  7151,  &c. 

Savignano  di  Romagna  44,  f.  i  (sec.  xv),  anon. 
Printed  :  Basel,  1561,  1597. 

63.  Semita  recta  alchemiae  (or  Liber  duodecim  aquanim),  also 
attributed  to  Albertus  Magnus.  Several  different  treatises 
have  the  same  title.  One  attributed  to  Albertus  begins  : 
'  Talentum  mihi  creditum  '  (Script.  Ord.  Praed.,  i.  178, 
from  MS.  Colbert  1639)  ;  another,  '  Omnis  sapientia  a 
Domino  Deo  '  (Hunterian  Museum,  no),  cf.  No.  20  n.,  above. 

MSS.  Brit.  Mus.  :  Sloane  513,  ff.  155-68  (sec.  xv)  : 
'  Explicit  semita  recta  alkemie  Alberti '  (in  Enghsh) : 
ff.  168^-78'',  '  Nunc  videndum  est  quomodo  fiunt 
fornelli  .  .  .  expHcit  semita  recta  alkemie  Alberti  '  : 
ff.  181 '-8^\  '  Libelli  huiusmodi  aquarum  .  .  .  explicit 
semita  recta  alkemie  secundum  magistrum  Rogerum 
Bakun.'  Sloane  276,  f.  21  (sec.  xv)  (anon.)  ;  cf.  Sloane 
316  (sec.  xvi)  (Alb.  Magnus) ;  633  (sec.  xvii),  in  English, 
attributed  to  both  Roger  and  Albert. 

Cf.  Bodl.  :  Ashmole  1485,  pp.  173-88  (sec.  xvi),  '  Liber 
Aquarum  ' :  Ashmole  1490,  ff.  92,  93. 

64.  De  oleo  stibii.     Inc.  '  Stibium  secundum  philosophos  com- 

ponitur  ex  nobili  sulphure  minerali,'  ascribed  to  Bacon  but 
composed  by  Basil  Valentine. 

Printed  in  Currus  Iriumphalis  aniimonii  frairis  Basilii 
Valentini  (Toulouse,  1646),  pp.  116-26. 


Among  works  on  other  subjects  than  alchemy  sometimes 
attributed  to  Bacon  and  certainly  not  by  him  are  : 

65.  [Elementary  Treatise  on  Logic] 

'Prima  petia  magistri  p.  h.'-    Inc.  '  Quoniam  ignoratis 
communibus  necesse  est  artem  ignorare.* 

•  MS.  Bodl.  E  Musaeo  155,  p.  507,  has  De  expulsione  veneni.  Inc. 
'  Ista  subscripta  sequerentur  post  capitulum  de  hiis  que  expelluntvenenum': 
not  expressly  ascribed  to  Bacon  :  it  follows  the  De  Consid.  quintae  essentia^ 
in  the  MS.,  and  is  perhaps  a  part  of  it. 

-  In  E.  Coyecque's  Catalogue  (1893)  this  is  wTongly  given  as  '  Prima  pecia 
magistri  Petri  Bacun  .'     '  p.  h.'  may  be  Petrus  Hispanus  or  Petrus  Helyas. 


ROGER  BACON'S  WORKS  417 

MS.  :   Amiens  406  (sec.  xiii  ex.),  ff.  130-52. 

Described  by  Victor  Cousin  as  a  '  traite  de  logique  a 

I'usage  de  la  jeunesse  .  .  .  sans  aucun  titre  et  sans 

nom  d'auteur.    On  lit  seulement  en  tete  :   Prima  pecia 

magistri  S.  H.' 
(Peterhouse  MS.  195  (sec.  xiv),  at  Cambridge  formerly 

contained  '  Logica  fratris  Rogeri  Bacon  '.) 

66.  De  intellectu  et  intelligentia,  and  De  nutrimento,  ascribed  to 

Bacon  in  the  Old  Catalogue  of  the  Bodleian  MSS.,  are  by 
Albertus  Magnus. 

MSS.  Digby  55,  f.  119  (anon.)  ;  67,  f.  107  (anon.). 

Printed  in  Opera  Alb.  Magni  (ed.  Paris,  1890,  &c.),  vol.  ix, 

67.  Philosophia  Pauperum,  or    Summa   philosophiae    natiiralis 

{inc.    '  Philosophia  dividitur  in  tres   partes  '),  ascribed  to 
Bacon  in  Old  Catalogue  of  Bodl.  MSS.,  is  the  work  usually 
but  wrongly  ascribed  to  Albertus  Magnus,  really  compiled 
from  his  commentaries.     Cf.  No.  lb  n.,  above. 
MS.  Digby  150. 

68.  Rogerina  major  (inc. '  Sicut  ab  antiquis  habemus  auctoribus '), 
et  minor  {inc.  '  Cum  medicinalis  artis  '  or  '  Cum  artis 
medicinae  '),'  two  medical  treatises,  neither  by  Roger 
Bacon  ;  one  is  by  a  Roger  Baron. 

MSS.  Sloane342,  f.  146  (sec.  xiii) ;  Bodley  786  ;  Gottingen 
Bibl.  Univ.  Hist.  Nat.  12,  ff.  49-96 ;  MontpelHer  ficole 
de  Medecine  161,  &c.  For  other  MSS.  see  Hist.  Litt.  de 
France,  xx.  527  ;  xxxi.  530,  &c.  Cf.  Charles,  Roger 
Bacon,  p.  75. 

Printed  :  Venet.  1498. 

69.  Kalendarium,  1292  ;  perhaps  based  on  Bacon. 

MSS.  Brit.  Mas. :  Vesp.  A.  ii,  ff.  2-25  (sec.  xiv),  '  Kalendarium 
sequens  extractum  est  a  tabuHs  tholetanis  a.d.  1292, 
factus  ad  meridiem  civitatis  tholeti  que  in  Hispania,  scita 
est  cuius  (etc.)  .  .  .  dicta  vero  latitudo  efficitur  civitatis 
Hncolniensis.' 
Bodley  464,  ff.  58-72  (sec.  xiv)  :  '  Canon  super  sequens 
kalendarium  ad  veram  coniunctionem  soUs  et  lune 
accipiendam  compositum  a  fratre  Rogero  Bacoun. 
Kalendarium  sequens  extractum  est  a  tabulis  Tholetanis 
A.D.  1292,  factum  ad  meridiem  civitatis  Tholeti,  que 
in  Hyspania  scita  est.  Cuius  meridianus  non  multum 
distat  a  meridiano  medii  puncti  Hybernie.'  (The 
kalendar  is  English,  not  Franciscan  :    it  is  not  to  be 

'  Bale  gives  '  Humana  natura '  as  incipii. 


4l8  APPENDIX 

confused  with  the  works  of  Robert  of  Leicester  ;   Grey 
Friars  in  Oxford,  p.  i6g.) 

70.  De  magnate.     Inc.  '  Amicorum  intime,  quandam  magnetis 

lapidis,'  by  Peter  de  Maricourt. 

In  Archiv.  Franc.  Hist.  v.  22-40,  Fr.  E.  Schlund  gives 
a  Hst  of  thirty-one  existing  MSS.,  and  five  editions. 
See  also  Silvanus  P.  Thompson,  in  Proceedings  of  the 
British  Academy,  vol.  ii. 

71.  De  Musica.  Inc.  in  verbis  :  '  Consequenter  de  numero 
ahcjuantulum  similiter  prout  ad  principale  intentum  suf- 
ficientcr  explicemus  ;  et  primo  interpretando,  secundo 
diffiniendo,  tercio  dividendo,  sicut  prius  fecimus,  proce- 
damus.' 

MS.  Milan  :  Ambrosiana  R.  47  sup.,  f.  43  (sec.  xiii).' 

72.  De  sacrae  scripturae  profundis  misteriis  authore  Rogero 
Bacon. 

MS.  London  :  Gray's  Inn  17  (sec.  xv)  ;  the  title  is  in 
a  later  hand.  The  work  consists  of  an  alphabetical 
arrangement  of  certain  words  occurring  in  the  Scrip- 
tures with  their  symboHcal  meanings.  The  first  two 
leaves  of  the  first  quire  are  wanting,  and  the  text 
begins  :  '  id  est  secretorum  sacre  scripture  profunda 
misteria,'  the  word  commented  on  being  Abissus. 
The  last  word  discussed  is  Zona.  Perhaps  the  ex- 
positiones  vocabulorum  of  Roger  '  Compotista',  monk 
of  Bury  St.  Edmund's,  or  the  Disiinctiones  fratris 
Mauricii,  certainly  not  Bacon. 

73.  Tractatus  fratris  R.  Bacon  super  Psalterium.  Inc.  '  Beatus 
vir  qui  non  abiit,  etc.  Hoc  exponitur  de  uno  martire  '  : 
possibly  by  Robert  Bacon. 

MS.  Bodley  745,  f.  97  (sec.  xiv).  (The  volume  contains, 
inter  alia,  '  Tract,  fratris  B.'  =  the  Breviloquium  of 
St.  Bona  Ventura.) 

'  The  treatise  is  anonymous,  but  is  in  a  volume  containing  some  of 
Bacon's  works  and  is  attributed  to  him  in  Montfaucon's  Catalogue.  Mr. 
Steele  kindly  lent  me  his  facsimile  of  the  MS.,  and  I  agree  with  him  that 
the  work  is  not  by  Bacon.  The  author  was  a  physicist  with  some  know- 
ledge of  alchemy.  His  general  philosophical  position  may  be  inferred 
from  the  following  extracts  :  '  Iterum  forma  est  principium  individuandi 
et  ab  aliis  distinguendi  .  .  .  forma  est  principium  cognoscendi  et  sic  origi- 
nandi  in  anima  veritatem  .  .  .  forma  ultimo  est  principium  operandi.' 
[The  treatise  De  valitudine  [valore]  musices  (inc.  '  Secundum  Boethium  et 
ceteros  au tores  musices  ')  ascribed  to  Bacon  by  Bale,  Index  Brit.  Script., 
P-  395.  is  probably  an  extract  from  the  Opus  Tert.,  ed.  Brewer,  p.  296.] 


ROGER  BACON'S  WORKS  4^9 

74.  Extracts  : 

Ashmolc  346,  ff.  94^-6  (sec.  xvi),  1426,  f.  43, 1485  (sec.  xvi), 
1492,  1494,  &c. 

Sloane  238,  ff.  214^-16^  (sec.  xv),  de  fistula,  '  secundum 
Rogerum  Bacon  ut  habetur  in  libro  qui  dicitur  Thesaurus 
pauperum  '  (a  medical  work  attributed  to  Petrus 
Hispanus  and  to  Arnald  de  Villanova). 

Sloane  2629,  ff.  55-6  :  '  quatuor  sunt  sapientie  inimica 
maxime  :   primum  est  presumptio  humani  cordis  .  .  .' 

Sloane  2208,  '  the  ancient  work  of  Roger  Bacon  as  it  was 
tised  by  the  fryer  of  Glassenburie.' 

Savigno  de  Romagna  44  (sec.  xv),  f.  133  et  seq.  :  '  Inc.  opus 
probatum  in  sole  et  luna  de  quatuor  spiritibus  et  est 
experimentum  fr.  Roggerii  Baconis  de  quo  mentionem 
fecit  in  libro  suo.  In  nomine  Domini  :  Accipe  sulfur 
mundum  |  et  erit  aurum  optimum.    Deo  gratias.' 

Paris:  Bibl.  Nat.  12335,  fragments  of  Roger  Bacon. 

Wolfenbiittel  :  479  (444  Helmst.),  f.  126^-126'  (sec.  xv) : 
'  Tractatus  ciiristiani  et  rogerii  baconis  de  quatuor 
dementis  et  eorum  graduacione.'  Inc.  'Secundum 
reverendi  magistri  rogerii  baconis  posicionem  et 
omnium  tradicionem  philosophorum  Aurum  est.' 


The  following,  ascribed  to  Bacon  by  Bale,  Index  Brit. 
Script.,  p.  394,  have  not  been  identified  : 

75.  Posteriora.     Inc.  '  Dictum  est  de  syllogismo  in  universali.' 

76.  De  forma  resultante  in  speculo.     Inc.  '  Queritur  de  forma 

resultante  in  speculo.' 

77.  De  fluxu  et  refluxu  maris  Anglici.     Inc.    '  Descriptis  his 

figuris  circa  mod.'    Probably  by  Walter  Burley :  cf .  MS. 
Digby  103. 


1689  E  e 


420  APPENDIX 


INITIA  OPERUM  IN  PRAECEDENTI  CATALOGO 
CITATORUM 

AcciPE  sulfur  mundum,  74. 

Ad  completam  cof^nitionein,  38  n. 

Ad  cvidtntiain  dieruni  creticorum,  29. 

Ad  instructionem  [instantiam]  multorum.  53. 

Amice  accipc  artem  in  brcvibus,  58. 

Amice  in  istis  consistit  difficultas,  53  n. 

Amicorum  intime,  quandam  magnetis,  70. 

Ars  [ergo]  alkimiae  duo  principaliter  considerat,  20. 

Ars  principaliter  duo  continet,  20. 

Beatus  vir  qui  non  abiit.    Hoc  exponitur  do  uno  martire,  73. 
Breve  breviarum  brevitcr  abbreviatum,  20. 

CoGiTO  ct  cogitavi  .  .  .  Sencscentc  mundo,  23. 

Completis  quatuor  partibus,  11  (B). 

Complexiones  locorum,  10  [Op.  Maj.  iv). 

Corpora  vero  Ade  ct  Eve,  10  {Op.  Maj.  vi,  extract).    Cf.  12. 

Cum  ad  notitiam  impressionum,  42. 

Cum  de  ponderibus  utilis  est  distinctio.  22,  iii. 

Cum  ego  Rogerus  rogatus  a  pluribus,  22,  i. 

Cum  medicinalis  artis,  68. 

Cum  promisi  tibi  mittere  duas  schedulas,  22,  ii. 

Cum  queritur  quid  est  spiritus,  59  n. 

Cum  tantae  reverentiae  dignitas,  12. 

Cupiens  te  et  alios,  10  {Op.  Maj.  v.  i). 

Dato  prologo  istius  quinte  partis  huius  voluminis,  11  (B). 

De  anima  secundum  seipsam,  66  (Alb.  Mag.,  De  nutrimento). 

Debes  mundare,  61. 

Decem  et  octo  prepositiones,  32  n. 

Declarato  igitur  quod  una  est  sapientia,  10  {Op.  Maj.  iii). 

Deinde  cogitavi  opus  aliquod,  13. 

Deinde  comparo  linguarum  utilitatem,  13. 

Deinde  queritur  an  aliquod  agens,  11  A  (fragment). 

De  libro  claritatis  totius  artis  alchimie,  53. 

Descriptis  his  figuris,  77. 

De  somno  et  vigilia  pertractantes,  41. 

De  speculorum  miraculis  .  .  .  Nichil  ab  oculo,  10  {Op.  Maj.  v.  n. 


ROGER  BACON'S  WORKS  421 

De  sublimiori  quod  geometre,  45. 

Determinata  quarta  parte  philosophic  moralis,  13,  14. 

Determinato  de  parte  mathematice  prima,  35,  II. 

De  utiHtate  arismetrice,  10  {Op.  Maj.  iv). 

Dicto  de  efl&ciente  et  ejus  influentia,  35,  III  {Com.  Nat.  hb.  i, 

pars  2). 
Dictum  est  de  syllogismo,  75. 
Distinctiones  secretorum  sapientum,  21  n. 
Dixit  Salomon  .  .  .  Deus  dedit,  62. 
Domine  mundi  qui   .   .   .  Cogito  et  cogitavi   .   .   .   Senescente 

mundo.  23. 

Et  quoniam  eadem  est  scientia  oppositorum,  10  {Op.  Maj.  v.  2). 

Et  si  astrologi  promittunt,  16. 

Ex  concavis  specuUs  ad  solem,  17a. 

Executis  igitur  duabus  principalibus,  20  n. 

Executo  breviter  tractatu  de  spiritibus  minerahbus,  20  n. 

Expeditis  hiis  que  exiguntur,  35,  II. 

Expletis  quatuor  partibus,  11  (B)  n. 

'  Fusius '  quidem  dictum  est,  10  {Op.  Maj.  iv.  n.). 

Geometria  assecutiva,  17a. 

Habito  de  corporibus  mundi,  35,  III. 

Habito  de  visu  facto,  10  {Op.  Maj.  v.  3). 

Habito  quod  oportet  ponere  quinque  corpora,  35,  III  {De  Coele- 

stibus,  ii). 
Hec  est  doctrina  omnium  experimentorum,  61. 
Hie  aliqua  dicenda  sunt  de  perspectiva,  10  {Op.  Maj.  v.  i). 
Hie   autem   volens   ponere  radicalem  generationem  rerum,   12 

{De  gcnctatione  return). 
Hie   incipit   volumen   verae   Mathematicac,   35,  II  {Communia 

Mathem.). 
Hie  in  fine  perspectivarum  volo  advertere  aliqua  de  motibus 

celestibus,  13. 
Hiis  habitis  volo  descendere,  13. 
Hucusque  (?),  13  n. 
Humana  natura,  68  n. 

In  antiquis  philosophonmi  libris,  49. 

Incipiamus  ergo  generationem  metallorum,  20. 

Incipiamus  in  nomine  dei,  23  n. 

Incipiamus  in  nomine  domini,  24. 

In  debito  regimine  corporis  et  prolongatione,  35  (extract). 


422  APPENDIX 

In  illius  nomine  qui  major  est,  19. 

In  nomine  Domini.    Accipe  sulfur  mundum,  74. 

In  nomine  Domini  ...  ad  instructionem  muitorum,  53, 

In  planis  speculis  rei  vise,  17. 

In  pluribus  antiquorum  codicibus,  49. 

In  principio  dicamus  de  dissolucione  fermenti,  60. 

In  speculo  concavato  concavitate  sectionis,  44. 

Intendo  componere  sermonem  rei  admirabilis,  26. 

Inter  cetera  que  dixi,  49. 

Interrogationi  vestre  de  secretis  naturae,  59. 

Introductio  est  brevis,  37. 

Ista  subscripta  sequerentur  post  capitulum,  62  n. 

Kalendarium  sequens  extractum  est,  69. 

La  distinction  des  secres  des  sages,  21. 

Licet  in  questione  qua  queritur,  56. 

Licet  liber  primus  est  de  consideratione,  62. 

Manifest  ATA  laude  et  declarata  utilitate,  32. 

Manifestato    quod    multae    praeclarae    radices    sapientiae,    10 

{Op.  Maj.  iv). 
Manifestato  quomodo  mathematica  necessarium  est,    10   {Op. 

Maj.  iv,  c.) 
Manifestavi  in  praecedentibus,  10  {Op.  Maj.  vii.  i). 
Mathematica  utitur  tantum  parte,  35,  II  {Communia  Mathem.). 
Mensura  ut  dicitur  est  quicquid,  5. 
Multifariam  multisque  modis,  49. 

Naturalis  philosophic  principales  partes,  16  n. 

Necesse  est  ille  qui  vult  componere  medicinas,  31. 

Nihil  ab  oculo,  10  {Op.  Maj.  v.  n.). 

Non  quidem  necessarium,  20. 

Notandum  quod  in  omni  judicio  quatuor,  15. 

Notandum  quod  quia  omnes  axes,  176. 

Now    that    I   have    set    forth   the    rotes    of    the  science,    10 

{Op.  Maj.  vi). 
Numerus   spherarum    continentium    omnes    motus    stellarum, 

35,  ni  n. 
Nunc  igitur  ad  instanciam  tuam,  10  {Op.  Maj.  v,  i  n.). 
Nunc  investigandus  est  numerus  celorum,  35,  III  {tte  Coelesii- 

bus,  iv). 
Nunc  iuvandum  [mirandum  ?]  est  quod  in  diversis  scientiis,  5. 


ROGER  BACON'S  WORKS  423 

Nunc  tempus  est  ut  fiat  descensus  ad  species  motus,  35,  III 

{Com.  Nat.,  lib.  i,  pars  4). 
Nunc  videndum  est  quomodo  fiunt  fornelli,  63. 

Obsequiis  mihi  possibilibus,  18  n. 

Occasione  cujusdam  comete,  9. 

Occasione    quorundam    librorum    apud    quos    non    est    radix 

scientiae,  47. 
Omnes   homines,   etc.     Dubitatur  de   ista  scientia  primo  de 

substantive,  3. 
Omnes  homines,  etc.    Queritur  hie  primo  utrum  hec  propositio,  3. 
Omnes  homines  qui  sensibiha,  35,  III  n. 

Omnia  tempus  habent.  .  .  .    Igitur  omnia  sive  sint  producta,  7. 
Omnis  egritudo  de  qua  curatur,  30. 
Omnis  forma  inherens,  27. 

Omnis  rationabihs  opinio  de  velocitate,  10  {Op.  Maj.  v.  n.). 
Omnis  sapientia,  20  n. 
Omnium  corpora  constantium,  55. 
Oratio  grammatica  aut  fit  mediante,  34. 
Ostensum  est  in  principio,  35,  III. 

Partium  orationis  quedam,  38. 

Philosophia  dividitur  in  tres  partes,  i  b  n.,  67. 

Ponatur  ab  oculo  rectas,  lya. 

Positis  radicibus  sapientiae  Latinorum,  10  {Op.  Maj.  vi). 

Post  completum  universahs  scientie  medicacionis,  25. 

Post  haec  sequitur  operatio  mathematicae,  13. 

Post  hanc  scientiam  experimentalem,  16. 

Post  locorum  descriptionem,  10  {Op.  Maj.  iv,  /).     Cf.  12  (ii). 

Postquam  declaratum  est  quomodo  mathematica,  10  {Op.  Maj. 

iv,  e). 
Postquam  habitum  est  de  principiis  rerum  naturaUum,  11  (A), 
Postquam  in  prima  parte  huius  Hbri  primi  de  communibus 

naturahum,  35,  III  {Com.  Nat.,  hb.  i,  pars  3). 
Postquam  manifesta  est  necessitas,  10  {Op.  Maj.  iv,  b). 
Postquam  manifesta  vi  mathematice  potestatem,  13. 
Postquam    tradidi    grammaticam   secundum    linguas,    35,    III 

{Com.  Nat.). 
Potest  queri  de  difiicultatibus  accidentibus,  4. 
Prima  igitur  Veritas  circa  corpora  mundi,  35,  III  {De  Coelestibus). 
Primo  igitur  sciendum  quod  nullus  circulus,  35,  III  {De Coelestibus). 
Primum  igitur  capitulum  circa  influentiam  agentis,  ir  (A). 
Primus  hie  Uber  voluminis  grammatici,  32. 
Propositis  radicibus  sapientiae,  10  {Op.  Maj.  v.  i). 


424  APPENDIX 

Propter  multa  in  hoc  libro  contenta  <iui  liber  dicitur  secretum 

secrctorum,  6. 
[Protraxi  hanc  partem  tertiam,  lo  {Op.  Maj.  vii.  4).] 

QuAERiTUR,  etc.     Vide  Queritur. 

Quarta  vcro  scientia  non  nKxlicum  habet,  35,  III. 

Quatuor  sunt  consideranda,  35,  I. 

Quatuor  sunt  sapicntie  inimica,  74. 

Queritur  circa  influmtiam  causarum  utrum  causa  (?)  agat,  40. 

Queritur  de  forma  rcsultante,  76. 

Queritur  primo  utrum  dc  naturalihus  possit,  i  b. 

Quesivisti  fili  carissimc  de  incantatione,  22  n. 

Quesivisti  quis  trium  lapidum  nobilior,  54  n. 

Quia  diximus  in  spcculo  secretorum,  53. 

Quia  omnes  axes,  lyb. 

Quia  univcrsorum  [divcrsorunij  quos  de  speculis,  44. 

Quinque  igitur  corporibus  mundi,  35,  III  {De  Coelestibus,  iii). 

Quoniam  autem  in  omnibus  causis  auctoritas,  36. 

Quoniam  circa  tempus  et  aevum,  13. 

Quoniam  ignoratis  communibus,  65. 

Quoniam  intclligere  et  scire.  .  .  .     Iste  liber  cuius  substantivum 

est  corpus  mobile,  16. 
Quoniam  intentio  principalis  est  innuere,  35,  IV  {Metaph.). 
Quoniam  inter  gradus  sapientiae,  10  {Op.  Maj.  v). 
Quoniam  occasione  cuiusdam  sermonis,  48. 
Quoniam  precipua  delectatio,  10  {Op.  Maj.  v.  i). 
Quoniam  quedam  glose  mentionem  faciunt,  33  n. 
Quoniam  quidem  intelligere,  etc.     Hie  primo  queritur  utrum 

de  corpore  mobili,  la. 
Quoniam  vero  non  expressi,  14. 

Relegatis  igitur  [in  infemum]  quatuor  causis,  10  {Op.  Maj.  ii). 
Rimatus  sum  moderno  tempore  omnia  fere  armaria,  23  n. 

Salutem  [quam]  tibi  amice  karissime,  52. 
Sanctissimo  patri.  .  .  .     Cum  tantae  reverentiae,  12. 
Sanctissimo  patri.   .   .   .     Vestrae  sapientiae  magnitudini  duo 

transmisi,  13. 
Sapientiae  perfecta  consideratio,  10  {Op.  Maj.  i). 
Sciendum  est  quia  philosophi  per  4'"'  verba,  51. 
Sciendum  vero  quod  visio,  10  {Op.  Maj.  v). 
Scito  enim  quod  omne  corpus  aut  est  elementimi,  28  n. 
Scribo  vobis  qui  vultis,  46. 

Secretum  secretonmi  naturae  audiant  secreti,  54. 
[Secunda  pars  descendit  ad  leges,  10  {Op.  Maj.  vii,  2).] 
Secundum  Boethiimi,  71  n. 


ROGER  BACON'S  WORKS  425 

Secundum  quod  sunt  quatuor  elementa,  12  n. 

Secundum  rev.  mag.  Rogerii  Baconis,  74. 

Sed  haec  hactenus.     Nunc   vero  inferam  secundum,   10   {Op. 

Maj.  iv,  d). 
Sed  hoc  est  intelligendum,  11  (A  fragment). 
Senescente  mundo  senescunt  homines,  23. 
Senes  sunt  balneandi,  24. 
Sequitur  de  scientia  e.xperimentali,  13. 
Sicut  ab  antiquis  habemus  auctoribus,  68. 
[Sicut  a  principio  istius  operis,  66  (Alb.  Mag.,  De  Intellectu).] 
Signum  est  in  predicamento,  39. 
Si  locatis  aliquibus,  7. 
Somnus  ergo^t  vigiha  describuntur,  41. 
Species  multiphcata  in  medio,  11  (A). 
Speculum  alchemic  quod  in  corde  meo,  50. 
Stibium  secundum  philosophos,  64. 

Substantia  igitur  alia  est.  .  .  .     Item  omnc  genus,  35,  III. 
Sume  argentum  vivum,  21. 
Summa  regiminis  senum  universalis,  24. 
Superius  quidem  dictum  est,  10  {Op.  Maj.  iv,/). 
Supponatur  ab  oculo,  17a. 

Talentum  mihi  creditum,  63. 

Terminata  parte  in  qua  investigavimus,  35,  III  {De  Coelestibus,  v). 
[Tertia  vero  pars  scientiae  moralis,  13  {Op.  Maj.  vii.  3).] 
Testatur  Gebar  .  .  .  quod  tres  sunt  ordines,  57. 
The  bodies  of  all  things  being,  55. 
Titulus  autem  istius  libri,  35,  II. 
Tres  sunt  ordines  medicinarum,  57. 

Tria  ut  ait  Empedocles. . .  .  Supposito  quod  hec  scientia  de  corpore 
mobili,  2. 

Ut  facilius  fiant  corpora  quinque,  45. 
Utrum  scientia  naturalis.  Addenda. 

Verbum  abbreviatum  verissimum,  21. 

Veri  mathematici  considerans  (?)  scitus  et  loca,  10  {Op.  Maj. 

iv  (?)). 
Veritates  de  magnitudine,  35,  III. 

Vestrae  petitioni  respondeo  diligenter.    Nam  licet  naturae,  18, 
Vestrae  sapientiae  magnitudini  duo  transmisi,  13. 
Visu[m]  rectum  esse  [est],  17a. 
Vulgus  medicorum  non  cognoscit  suam  simplicem  medicinam,  28. 


ADDENDA 

i«   (p    37^>)     ^^^-  BoncompriKTii    152   (sec.   xv),  in   Narducci's 

Catalogue,    p.    60,    now    in    p<)ss<«»sion    of   Messrs.    W. 

Wesley  &  Son,  entitled  in  a  late  hand  Rogeri  Baconis 

Comment  aria,  contains  Quaestioncs  in  tibros  viii  Physi- 

corum  (inc.  '  Utrum  naturalis  sit  scientia  dc  omnibus 

rebus    considerans  '),    by    Johannes    Buridanus.      Cf. 

ed.  Paris,  1509. 
1 1  {A)  (p.  387).  Add  :  Rome  :  Vatican,  Ottob.  Lat.  1870  (sec.  xv), 

ff.   1-48,  anon.  :  ends  '  ut  in  luna  et  stellis ',  Bridges, 

ii-   550   (this  and  other  Vatican   additions  have  been 

kindly  sent  by  Dr.  Pelzer). 
^7'i   (P-   304)-    ^^^ :     Rome:    Vat.  Ottob.   1870,   ff.    yo^-jy", 

Tractatus  de  specnlis,  anon.    Inc.  '  Visum  rectum  esse  '  ; 

cxpi.  stupa  '  apposita  accenditur  '. 
20,  n.  I  (p.  307)-    f'^or  '  seems  to  be  ',  &c.,  read  :    '  i>  Brr,  r  hrrvia- 

rium  '  ;   inc.  '  Ars  alchimie  duo  '. 
-I    (p.  397)-    Add  :    Arezzo  :    Bibl.  Communalc  232   (sec.  xv), 

f.  75^   Vcrbum   Abbrcviatum  ;    inc.  '  Recipe  acetum  '  : 

ff.   yy^-yS',  Tabula  vocabitlorum  Rogerii  Baconis  :    inc. 

'  Argentum  viviim  congelatum  '. — Cambrai,  920,  f.  115 

(sec.  xv). 
29  (p.  401).   Add  :   Oxford  :   E.xeter  Coll.  35,  f.  46*  (sec.  xiv  in.), 

anon . 
(13  (p.  416).  Add  :  Rome  :  Vat.  Lat.  4091,  f.  42  :  inc.  '  Talentum 

mihi  crcditur  '  (Alb.  Magnus). 
76   (p.  419).    Add:    MS.    Vatican,    Borgh.    114,    ff.    119^-120' 

C'Albertus  '). 

Cf.  Weiss,  Primordia  novae  bibliographiae  B.  Albetti 
Magni,  no.  127  (2nd  cd.,  p.  34). 


Oxford  :  Horace  Hart  M.A.  Printer  to  the  University 


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