An inquiry into the human mind [electronic resource], on the principles of common sense. By Thomas Reid, D.D

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A N

I NCLU I R Y

INTO THE

HUMAN MIND,

ON THE PRINCIPLES OF

COMMON SENSE.

BY

THOMAS REID, D. D.

PROFESSOR OF MORAL PHILOSOPHY IN THE UNIVERSITY
OF GLASGOW.

The Infpiration of the Almighty giveth them Underjlanding.

Jo,

THE FIFTH EDITION.

EDINBURGH:

PRINTED FOR EELL & BRADFUTE,
AND WILLIAM CREECH;
AND FOR T. CADELL JUN. & W. DAVIES,
LONDON :

£Y AD. NFTLL & CO.
l80I.

344 74
7-6 - 1924

TO
THE RIGHT HONOURABLE

JAMES, Earl of FINDLATER
and SEAFIELD,

CHANCELLOR OF THE UNIVERSITY OF OLD ABERDEEN.

My Lord,

•TPHough I apprehend that there are things
"*• new, and of fome importance, in the
following inquiry, it is not without timidity
that I have confented to the publication of
it. The fubjecl: has been canvafTed by men
of very great penetration and genius : for
who does not acknowledge Des Cartes, Ma-

LEBRANCHE, L.OCKE, BERKELEY, and HUME,

to be fuch ? A: view of the human under-
Handing, fo different from that which they
have exhibited, will, no doubt, be condemn-
ed by many without examination, as proceed-
ing from temerity and vanity.

a 2* But

iv DEDICATION.

But I hope the candid and difcerning Few,
who are capable of attending to the opera-
tions of their own minds, will weigh delibe-
rately what is here advanced, before they pafs
fentence upon it. To fuch I appeal, as the
only competent judges. If they difapprove,
I am probably in the wrong, and fhall be rea-
dy to change my opinion upon conviction.
If they approve, the Many will at laft yield
to their authority, as they always do.

However contrary my notions are to thofe
of the writers I have mentioned, their fpecu-
lations have been of great ufe to me, and
feem even to point out the road which I have
taken ; and your Lordfhip knows, that the
merit of ufeful difcoveries is fometimes not
more juftly due to thofe that have hit upon
them, than to ethers who have ripened them,
and brought them to the birth.

I acknowledge, my Lord, that I never
thought of calling in queftion the principles
commonly received with regard to the hu-
man

DEDICATION. r

man underftanding, until the Treatife of Ra-
man Nature was published, in the year 1739.
The ingenious author of that treatife, upon
the principles of Locke, who was no fceptic,
hath built a fyftem of fcepticifm, which leaves
no ground to believe any one thing rather
than its contrary. His reafoning appeared to
me to be juft : there was therefore a necef- ,
fity to call in queftion the principles upon
which it was founded, or to admit the con-
clufion.

But can any ingenious mind admit this
fceptical fyftem without reluctance ? I truly
could not, my Lord : for I am perfuaded, that
abfolute fcepticifm is not more - deftructive of
the faith of a Chriftian, than of the fcience of
a philofbpher, and of the prudence of a man of
common underftanding. I am perfuaded, that
the unjuft live by faith as well as the juft ;
that, if all belief could be laid afide, piety,
patriotifm, friendfhip, parental affection, and
private virtue, wTould appear as ridiculous as
fl 3 knight-

vi DEDICATION4.

knight-errantry ; and that the purfuits of
pleafure, of ambition, and of avarice, muft be
grounded upon belief, as well as thofe that are
honourable or virtuous.

The day-labourer toils at his work, in the
belief that he fhall receive his wages at night ;
and if he had not this belief, he would not
toil. We may venture to fay, that even the
author of this fceptical fyftem, wrote it in the
oelief that it mould be read and regarded. I
hope he wrote it in the belief alfo, that it
would be ufeful to mankind : and perhaps it
may prove fo at laft. For I conceive the fcep-
tical writers to be a fet of men, whofe bufinefs
it is, to pick holes in the fabrick of know-
ledge wherever it is wTeak and faulty ; and
when thefe places are properly repaired, the
whole building becomes more firm and folid
than it was formerly.

For my own fat is fact ion, I entered into a
ierious examination of the principles upon
which this fceptical fyftem is built ; and was

not

DEDICATION. vii

hot a little furprifed to find, that, it leans with
its whole weight upon a hypothefis, which is
ancient indeed, and hath been very generally
received by philofophers, but of which I could
find no folid proof. The hypothefis I mean
is, That nothing is perceived but .what is in
the mind which perceives it : That we do not
really perceive things that are external, but
only certain images and pictures of them im-
printed, upon the mind, which are called im-
prejjions and ideas.

If this be true ; fuppofing certain impref-
fions and ideas to exift in my mind, I cannot,
from their exiftence, infer the exiftence of
any thing elfe ; my impreffions and ideas are
the only exiftences of which I can have any
knowledge or conception ; and they are fuch
fleeting and tranlitory beings, that they can
have no exiftence at all, any longer than I
am confcious of them. So that, upon this
hypothefis, the whole univerfe about me, bo-
dies and fpirits, fun, moon, liars, and earth,
friends and relations, ail things without ex-
ception,

viii DEDICATION,

ccption, which I imagined to have a perma-
nent exiftence, whether I thought of them or
not, vanifh at once ;

And, like the hafelefs fahric of a vifion,
Leave not a track behind.

I thought it unreafonable, my Lord, upon
the authority of philofophers, to admit a hy-
pothetic, which, in my opinion, overturns all
philofophy, all religion and virtue, and all
common fenfe : and finding that all the fy-
Hems concerning the human underflanding
which I was acquainted with, were built up-
on this hypothefis, I refolved to inquire into
this fubject anew, without regard to any hy-
pothefis.

What I now humbly prefent to your Lord-
ihip, is the fruit of this inquiry, fo far only
as it regards the five fenfes ; in which I
claim no other merit, than that of having gi-
ven great attention to the operations of my
own mind, and of having exprefied, with all

the

DEDICATION. ir

the perfpicuity I was able, what I conceive
every man, who gives the fame attention, will
feel and perceive. The productions of ima-
gination, require a genius which foars above
the common rank ; but the treafures of know-
ledge are commonly buried deep, and may
be reached by thofe drudges who can dig
with labour and patience, though they have
not wings to fly. The experiments that were
to be made in this inveftigation fuited me, as
they required no other expence, but that of
time and attention, which I could beftow.
The leifure of an academical life, difengaged
from the purfuits of intereft and ambition ;
the duty of my profeffion, which obliged me
to give prelections on thefe fubjects to the
youth ; and an early inclination to fpecula-
tions of this kind, — have enabled me, as I flat-
ter myfelf, to give a more minute attention to
the fubjecl: of this inquiry, than has been gi-
ven before.

My thoughts upon this fubjecl were, a
good many years ago, put together in another

form,

* DEDICATION

form, for the ufe of my pupils ; and after-
wards were fubmitted to the judgment of a
private philofophical fociety, of which I have
the honour to be a member. A great part of
this inquiry was honoured even by yoilr Lord-
fhip's perufal. And the encouragement which
you, my Lord, and others, whofe friendfhip
is my boaft, and whofe judgment I reverence,
were pleafed to give me, counterbalanced my
timidity and diffidence, and determined me
to offer it to the public.

If it appears to your Lordfhip to juftify
the common fenfe and reafon of mankind,
againft the fceptical fubtilties which, in this
age, have 'endeavoured to put them out of
countenance ; if it appears to throw any new
light upon one of the nobleft parts of the di-
vine workmanfhip ; your Lordfhip's refped
for the arts and fciences, and your attention
to every thing which tends to the improve-
ment of them, as well as to every thing elfe
that contributes to the felicity of your coun-
try, leave me no room to doubt of your fa-
vourable

DEDICATION. si

vourable acceptance of this effay, as the fruit
of my induftry in a profeffion wherein I was
accountable to your Lordfhip ; and as a tefti-
mony of the great efteem and refpecl: where-
with I have the honour to be,

My Lord,

Your Lordship's

moll obliged, and

moft devoted fervant,

THO. REID.

CONTENTS.

CHAPTER I.

INTRODUCTION.
Se&. Page,

i. The importance ofthejubjefl, and the means

of prof e curing it, - I

2. The impediments to our knowledge of the

mind, - - - 5

3. The prefent flat e of this part of philofophy.

Of Des Cartes, Malebranche and Locke, 12

4. Apology for thofe philofophers, - 18

5. Of Bijhop Berkeley ; the Treatife of Human

Nature; and of fcepticifm, - 21

6. Of the Treatife of Human Nature, - 26

7. The fyflem of all thefe authors is the fame,

and leads to fcepticifm, - 29

8. We ought not to defpair of a better, - 31

CHAP. II.
OF SMELLING.

Se6l.

1. The order of proceeding. Of the medium

and organ offmell, , - 34

2. The fenfation confidered abflraflly, - 37

3. Senfation and remembrance, natural prin-

ciples of belief, - ~ - 39

4. judgment and belief in fome cafes precede

fimple apprehenjion, - 44

S« Two

*iv CONTENTS.

Sett. Page,

5. Two theories of the nature of belief refuted.

Conclufions from what hath been J aid, 45

6. Apology for met aphyfical abfurdities. Sen-

fation without a fentient, a confequence
of the theory of ideas. Confequences of
this fir ange opinion, - 50

7. The conception and belief of a fentient being

or mind, is fuggejled by our conflitution.
The notion of relations not always got by
comparing the related ideas, - 60

8. There is a quality or virtue in bodies, which

we call their f me II. How this is connebl-
ed in the imagination with the fenfation, 65

9. That there is a principle in human nature,

from which the notion of this, as well
as all other natural virtues or caufes, is
derived, 69

ic. Whether in fenfation the mind is aclive or
pajfive? 77

CHAP. III.
OF TASTING, - 8i

CHAP. IV.
OF HEARING.

Sefl.

1. Variety of founds. Their place and diflance

learned by cujlom, without reafoning, 88

2. Of natural language, - - 92

CHAP.

CONTENTS. Xv

CHAP. V.

OF TOUCH.

Se£, Page.

1. Of heat and cold, - 99

2. Of hardnefs and foftnefs, - - 102

3. Of natural Jigns, - - - no

4. Q/* hardnefs, and other primary qualities, 116

5. Of extenfion, - - - 119

6. Of extenfion, - - - 125

7. Of the exiflence of a material world, 130
g. Of the fyflems of philofophers concerning

thefenfes, - - 143

CHAP. VI. .

OF SEEING.

Sea.

1. The excellence and dignity of this faculty, 152

2. *S^Ztf difcovers almqft nothing which the

blind may not comprehend. The reafon

of this, - 156

3. Of the vifible appearances of ohjetls, 164

4. fk? colour is a quality of bodies, not a

fenfation of the mind, - - 171

5. An inference from the preceding, - 176

6. 27wtf flow? of our fenfations are refemblances

of any of the qualities of bodies, - 183

7. Of vifible figure and extenfion, - 193

8. «SW/£ queries concerning vifible figure an-

fweredy - - 200

9. 0/

xvi CONTENTS.

Seft. Page.

9. Of the geometry of vifibles, - - 212

IQ. Of the parallel motion of the eyes, 232

11. Of our feeing objects erect by inverted

images, - - - - 238

12. The fame fubjeft continued, - 250
!3# Of feeing objects jingle with two eyes, 277
j*. Of the laws of vifionin brute animals, 291

15. Squinting confidered hypothetic ally, 296

16. Facls relating to fquinting, - 316

17. Of the effect of cuflom in feeing objects

fingle, - - . - - 322

18. Of Br Forterfield^s account of fingle and

double 'vijion, - 335

19. Of Dr Briggs's .theory, and Sir Ifaac

Newton's conjecture on this fubjecl, 342

20. Of perception in general, - - 360
21.O/ the procefs of Nature in perception, 375

22. Of the figns by which we learn to per- •

ceive di/lancefrom the eye,^ - 385

23. Of the figns ufed in other acquired per-

ceptions, "."'"" 4°7

24. Of the" analogy between perception, and

the credit we give to human teflimo?iy, 413

CHAP. VII.
CONCLUSION.

Containing Reflections upon the opinions of
Fhtlofophers on this fubjecl, - - 443

A N

INQUIRY

INTO THE

HUMAN M I N D,

CHAP. I.

INTRODUCTION.

SECT. I.

The importance of the fuhjecl, and the means of
profecuting it,

THE fabric of the human mind is curi-
ous and wonderful, as well as that of
the human body. The faculties of the one
are with no lefs wifdom adapted to their
feveral ends, than the organs of the other.
Nay, it is reafonable to think, that as the
mind is a nobler work, and of a higher or-

A der

2 OF THE HUMAN MIND. [CHAP. I.

der than the body, even more of the wifdom
and fkill of the Divine Architect hath been
employed in its ftru&ure. It is therefore
a fubjed highly worthy of inquiry on its
own account, but ftill more worthy on ac-
count of the extenfive influence which' the
knowledge of it hath over every other branch
of fcience.

In the arts and fciences which have leafl
connection with the mind, its faculties are
the engines which we muft employ ; and
the better we understand their nature and
ufe, their defects and diforders, the more
fkilfully we fhall apply them, and with the
greater fuccefs. But in the noblefl arts,
the mind is alfo the fubjecl: upon which we
operate. The painter, the poet, the aclor,
the orator, the moralift, and the ftatefman,
attempt to operate upon the mind in dif-
ferent ways, and for different ends ; and
they fucceed, according as they touch pro-
perly the firings of the human frame. Nor
can their feveral arts ever (land on a folid
foundation, or rife to the dignity of fcience,
until they are built on the principles of the
human conflitution.

Wife men now agree, or ought to agree
in this, that there is but one way to the

knowledge

SECT. I.] INTRODUCTION. 3

knowledge of Nature's works ; the way of
obfervation and experiment. By our confuta-
tion, we have a ftrong propenfity to trace par-
ticular facts and obfervations to general rules,
and to apply fuch general rules to account for
other effects, or to direct us in the production
of them. This procedure of the understanding
is familiar to every human creature in the
common affairs of life, and it is the only one by
which any real difcovery in philofophy can
be made.

The man who firft difcovered that cold
freezes water, and that heat turns it into
vapour, proceeded on the fame general prin-
ciples, and in the fame method, by which
Newton difcovered the law of gravitation,
and the properties of light. His regulcz phi-
lofophandi are maxims of common fenfe, and
are practifed every day in common life ; and
he who philofophizes by other rules, either
concerning the material fyftem, or concern-
ing the mind, miftakes his aim.

Conjectures and theories are the creatures
of men, and will always be found very un-
like the creatures of God. If we would know
the works of God, we mufl confult themfelves
with attention and humility, without daring
to add any thing of ours to what they de-
clare. A juft interpretation of nature is the
A 2 only

4 OF THE HUMAN MIND. [CHAP. I.

only found and orthodox philofophy : what-
ever we add of our own, is apocryphal, and
of no authority.

All our curious theories of the formation
of the earth, of the generation of animals, of
the origin of natural and moral evil, fo far
as they go beyond a juft induction from facts,
are vanity and folly, no lefs than the vortices of
Dks Cartes, or the Archaeus of Paracelsus.
Perhaps the philofophy of the mind hath been
no lefs adulterated by theories, than that of
the material fyftem. The theory of ideas
is indeed very ancient, and hath been very
univerfally received ; but as neither of thefe
titles can give it authenticity, they ought
not to fcreen it from a free and candid exa-
mination ; efpecially in this age, when it
hath produced a fyftem of fcepticifm, that
feems to triumph over all fcience, and even
over the dictates of common fenfe.

All that we know of the body, is owing
to anatomical dirTeclion and obfervation, and
it muft be by an anatomy of the mind that
we can diicover its powers and principles.

SECT.

sect. 2.] introduction; S

SECT. Hi

The impediments to our knowledge of the mind,

BUT it muft be acknowledged, that this
kind of anatomy is* much more diffi-
cult than the other ; and therefore it needs
not feem ftrange, that mankind have made
lefs progrefs in it. To attend accurately to
the operations of our minds, and make them
an object of thought, is no eafy matter even
to the contemplative, and to the bulk of
mankind is next to impoflible.

An anatomift who hath happy opportuni-
ties, may have accefs to examine with his
own eyes, and with equal accuracy, bodies
of all different ages, fexes, and conditions ;
fo that what is defective, obfeure, or preter-
natural in one, may be difcerned clearly, and
in its mod perfect ftate, in another. But
the anatomift of the mind cannot have the
fame advantage. It is his own mind only
that he can examine, with any degree of ac-
curacy and diftinctnefs. This is the only
fubject he can look into. He may, from
outward ligns, collect the operations of other
minds \ but thefe ligns are for the mod part
A 3 ambiguous,

6 OF THE IfUMAN MIND. [CHAP. I.

ambiguous, and muft be interpreted by what
he perceives within himfelf.

So that if a philofopher could delineate
to us, diftinclly and methodically, all the
operations of the thinking principle within
him, which no man was ever able to do,
this would be only the anatomy of one par-
ticular fubjed ; which would be both defi-
cient and erroneous, if applied to human na-
ture in general. For a little reflection may
fatisfy us, that the difference of minds is
greater than that of any other beings which
we confider as of the fame fpecies.

Of the various powers and faculties we
pofTefs, there are fome which nature feems
both to have planted and reared, fo as to
have left nothing to human induftry. Such
are the powers which we have in common
with the brutes, and which are neceflary to
the prefervation of the individual, or the
continuance of the kind. There are other
powers, of which nature hath only planted
the feeds in our minds, but hath left the rear-
ing of them to human culture. It is by the
proper culture of thefe that we are capable
of all thofe improvements in intellectuals, in
tafte, and in morals, which exalt and dignify
human nature ; while, on the other hand, the

negledl

SECT. 2.] INTRODUCTION. J

neglect or perverfion of them makes its dege-
neracy and corruption.

The two-legged animal that eats of na-
ture's dainties, what his tafte or appetite
craves, and fatisfies his third at the cryftal
fountain, who propagates his kind as occalion
and luft prompt, repels injuries, and takes al-
ternate labour and repofe, is, like a tree in
the foreft, purely of nature's growth. But
this fame favage hath within him the feeds' of
the logician, the man of tafte and breeding,
the orator, the ftatefmari, the man of virtue,
and the faint ; which feeds, though planted
in his mind by nature, yet, through want of
culture and exercife, muft lie for ever bu-
ried, and be hardly perceivable by himfelf or
by others.

The lowed degree of focial life will bring
to light fome of thofe principles which lay
hid in the favage ftate : and according to his
training, and company, and manner of life,
fome of theiii, either by their native vigour,
or by the force of culture, will thrive and
grow up to great perfection ; others will be
ftrangely perverted from their natural form ;
and others checked, or perhaps quite eradi-
cated.

A 4 This

8 OF THE HUMAN MIND. [CHAP. I,

This makes human nature fo various and
multiform in the individuals that partake of
it, that, in point of morals, and intellectual
endowments, it fills up all that gap which we
conceive to be between brutes and devils be-
low, and the celeftial orders above ; and fuch
a prodigious diverfity of minds muft make it
extremely difficult to difcover the common
principles of the fpecies.

The language of philofophers, with regard
to the original faculties of the mind, is fo
adapted to the prevailing fyftem, that it can-
not fit any other ; like a coat that fits the
man for whom it was made, and mows him to
advantage, which yet will lit very awkward
Upon one of a different make, although per-
haps as handfome and as well proportioned*
It is hardly poilible to make any innovation
in our philofophy concerning the mind and
its operations, without uling new words and
phrafcs, or giving a different meaning to thofe
that are received ; a liberty which, even when
neceffary, creates prejudice and mifconft ruc-
tion, and which rauft wait the fandrion of
time to authorife it. For innovations in lan-
guage, like thofe in religion and government,
are always fufpecled and dilliked by the ma-
ny*

SECT. 2.] INTRODUCTION. t)

ny, till ufe hath made them familiar, and pre*
fcription hath given them a title.

If the original perceptions and notions of
the mind were to make their appearance
lingle and unmixed, as we firft received them
from the hand of nature, one accuftomed to
reflection would have lefs difficulty in tracing
them ; but before we are capable of reflec-
tion, they are fo mixed, compounded and de-
compounded, by habits, affociations, and ab-
ftradtions, that it is hard to know what they
were originally. The mind may in this re-
fpect be compared to an apothecary or a che-
mift, whofe materials indeed are furnifhed by
nature \ but for the purpofes of his art, he
mixes, compounds, diffolves, evaporates, and
fublimes them, till they put on a quite diffe-
rent appearance ; fo that it is very difficult to
know what they were at firft, and much more
to bring them back to their original and na-
tural form. And this work of the mind is
not carried on by deliberate acts of mature
reafon, which we might recoiled, but by
means of inftincts, habits, aflbciations, and
other principles, which operate before we
come to the ufe of reafon ; fo that it is ex-
tremely difficult for the mind to return upon
its own footfteps, and trace back thofe opera-
tions

tO OF THE HUMAN MIND. [CHAP. I.

tions which have employed it fince it firft be-
gan to think and to a<ft.

Could we obtain a diftintt and full hiftory
of all that hath patted in the mind of a child,
from the beginning of life and ienfation, till
it grows up to the ufe of reafon ; how its in-
fant faculties began to work, and how they
brought forth and ripened all the various no-
tions, opinions, and fentiments, which we find
in ourfelves when we come to be capable of
reflection ; this would be a treafure of-natu*
ral hiftory, which would probably give more
light into the human faculties, than all the
fyfteras of philofophers about them fince the
beginning of the world. But it is in vain to
wi(h for what nature has not put within the
reach of our power. Refle&ion, the only in-
ftrument by which we can difcern the powers
of the mind, comes too late to obferve the
progrefs of nature, in railing them from their
infancy to perfe&ion.

It muft therefore require great caution,
and great application of mind, for a man that
is grown up in all the prejudices of educal
tion, faihion, and philofophy, to unravel his
notions and opinions, till he finds out the Am-
ple and original principles of his conftitution,
of which no account can be given but the

will

SECT. 2.] INTRODUCTION. H

will of our Maker. This may be truly called
an analyjis of the human faculties ; and till
this is performed, it is in vain we expect any
]\ift.fyftem of the mind ; that is, an enumera-
tion of the original powers and laws of our
contlitution, and an explication from them of
the various phenomena of human nature.

Succefs in an inquiry of this kind, it is not
in human power to command ; but perhaps
it is poffible, by caution and humility, to
avoid error and delufion. The labyrinth may
be too intricate, and the thread too fine, to be
traced through all its windings ; but if we
flop where we can trace it no further, and fe-
cure the ground we have gained, there is no
harm done ; a quicker eye may in time trace
it further.

It is genius, and not the want of it, that
adulterates philofophy, and fills it with error
and falfe theory. A creative imagination
difdains the mean offices of digging for a
foundation, of removing rubbifh, and carry-
ing materials : leaving thefe fervile employ-
ments to the drudges in fcience, it plans a de-
fign, and raifes a fabric. Invention fupplies
materials where they are wanting, and fancy
adds colouring, and every befitting ornament.
The work pleafes the eye, and wants nothing

but

ia OF THE HUMAN MIND. [CHAP. I.

but folidity and a good foundation. It feems
even to vie with the works or nature; till fome
fucceeding architect blows it into rubbifh,
and builds as goodly a fabric of his own in its
place. Happily for the prefent age, the caf-
tle-builders employ themfelves more in ro-
mance than in philofophy. That is undoubt-
edly their province, and in thofe regions the
offspring of fancy is legitimate ; but in philo-
fophy it is all fpurious.

SECT; III.

The prefent Jlate of this part of philofophy.—
OfDes Cartes, Malehranche, and Locke.

THAT our philofophy concerning the
mind and its faculties, is but in a very
low ftate, may be reafonably conjectured,
even by thofe who never have narrowly ex-
amined it. Are there any principles with re-
gard to the mind, fettled with that perfpicui-
ty and evidence, which attends the principles
of mechanics, aflronomy, and optics ? Thefe
are really fciences built upon laws of nature
which univerfally obtain. What is difcover-
ed in them, is no longer matter of difpute :
future ages may add to it, but till the courfe

of

SECT. 3.] INTRODUCTION. 13

of nature be changed, what is already efta-
blifhed can never be overturned. But when
we turn our attention inward, and confider
the phenomena of human thoughts, opi-
nions, and perceptions, and endeavour to
trace them to the general laws and the firfl
principles of our conflitution, we are imme-
diately involved in darknefs and perplexity.
And if common fenfe, or the principles of
education, happen not to be ftubborn, it is
odds but we end in abfolute fcepticifm.

Des Cartes finding nothing eftablifhed in
this part of philofophy, in order to lay the
foundation of it deep, refolved not to believe
his own exiftence till he fhould be able to
give a good reafon for it. He was, perhaps,
the firft that took up fuch a refolution : but
if he could indeed have effected his pur-
pofe, and really become diffident of his exift-
ence, his cafe would have been deplorable,
and without any remedy from reafon or phi-
lofophy. A man that difbelieves his own
exiftence, is furely as unfit to be reafoned
with, as a man that believes he is made of
glafs. There may be diforders in the human
frame that may produce fuch extravagancies ;
but they will never be cured by reafoning.
Des Cartes indeed would make us believe,

that

J4 OF THE HUMAN MIND. [CHAP. I.

that he got out of this delirium by this logi-
cal argument, Cogito, ergo fum. But it is
evident he was in his fenfes all the time, and
never ferioufly doubted of his exiftence. For
he takes it for granted in this argument, and
proves nothing at all. I am thinking, fays
he, therefore I am : and is it not as good
reafoning to fay, I am fleeping, therefore I
am ? or, I am doing nothing, therefore I am ?
If a body moves, it muft exift, no doubt ; but
if it is at reft, it muft exift likewife.

Perhaps Des Cartes meant not to aflume
his own exiftence in this enthymeme, but the
exiftence of thought ; and to infer from that
the exiftence of a mind, or fubjecl of thought.
But why did he not prove the exiftence of
his thought ? Confcioufnefs, it may be faid,
vouches that. But who is voucher for con-
fcioufnefs ? Can any man prove that his con-
fcioufnefs may not deceive him ? No man
can : nor can we give a. better reafon for
trufting to it, than that every man, while his
mind is found, is determined, by the conftitu-
tion of his nature, to give implicit belief to
it, and to laugh at, or pity, the man who
doubts its teftimony. And is not every man,
in his wits, as much determined to take his
exiftence upon truft as his confcioufnefs ?

The

oECT. 3.] INTRODUCTION. 15

The other proportion aflumed in this ar-
gument, That thought cannot be without a
mind or fubjecl:, is liable to the fame objec-
tion : not that it wants evidence ; but that
its evidence is no clearer, nor more immedi-
ate, than that of the proportion to be proved
by it. And taking all thefe proportions to-
gether,— I think, — I am confcious, — Every
thing that thinks, exifls, — I exift, — -would
not every fober man form the fame opinion of
the man who ferioufly doubted any one of
them ? And if he was his friend, would he
not hope for his cure from phyfic and good
regimen, rather than from metaphyfic and
logic ?

But fuppofing it proved, that my thought
and my confcioufnefs muft have a fubject,
and confequently that I exift, how do I know
that all that train and fucceflion of thoughts
which 1 remember, belong to one fubjecl:, and
that the I of this moment, is the very indivi-
dual I of yefterday, and of times paft ?

Des Cartes did not think proper to Hart
thjs doubt* but Locke has done it ; and, in
order to refoive it, gravely determines, that
perfonal identity confifts in confcioufnefs ;
that is, if you are confcious that you did fuch
a thing a twelvemonth ago, this confcioufnefs

makes

l6 OF THE HUMAN MIND. [CHAP. I.

makes you to be the very perfon that did it.
Now, confcioufnefs of what is paft, can figni-
fy nothing elfe but the remembrance that I
did it. So that Lockil's principle mud be,
That identity confifts in remembrance ; and
confequently a man muft lofe his perfonal
identity with regard to every thing he for-
gets.

Nor are thefe the only inflances whereby
our philofophy concerning the mind appears
to be very fruitful in creating doubts, but
very unhappy in refolving them.

Des Cartes, Malebranche, and Locke,
have all employed their genius and fkill, to
prove the exiftence of a material world ; and
with very bad fuccefs. Poor untaught mortals
believe undoubtedly, that there is a fun, moon,
and liars ; an earth, which we inhabit ; coun-
try, friends, and relations, which we enjoy ;
land, houfes, and moveables, which we pof-
fefs. But philofophers, pitying the credulity
of the vulgar, refolve to have no faith but
what is founded upon reafon. They apply to
philofophy to furnifti them with reafons for
the belief of thofe things, which all mankind
have believed without being able to give any
reafon for it. And furely one would expecl,
jthat, in matters of fuch importance, the proof

would

SECT. 3.] INTRODUCTION. 17

would not be difficult : but it is the moil dif-
^ficult thing in the world. For thefe three
great men, with the belt good will, have not
been able, from all the treafures of philofo-
phy, to draw one argument, that is fit to con-
vince a man that can reafon, of the exiftence
of any one thing without him. Admired Phi-
lofophy ! daughter of light ! parent of wif-
dom and knowledge ! if thou art (he ! furely
thou haft not yet arifen upon the human
mind, nor blefTed us with more of thy rays,
than are fufficient to fhed a " darknefs vifible"
upon the human faculties, and to diflurb that
repofe and fecurity which happier mortals en-
joy, who never approached thine altar, nor
felt thine influence ! But if indeed thou haft
not power to difpel thofe clouds and phantoms
which thou haft difcovered or created, with-
draw this penurious and malignant ray : I def-
pife Philofophy, and renounce its guidance ;
let my foul dwell with Common Senfe.

B SECT.

j8 OF THE HUMAN MIND. [CHAP. I

SECT. IV.

Apology for thofe philofophcrs.

BUT inftead of defpifing the dawn of light,
we ought rather to hope for its increafe :
inftead of blaming the philofophers I have
mentioned, for the defects and blemilhes of
their fyftem, we ought rather to honour their
memories, as the firft difcoverers of a region in
philofophy formerly unknown ; and, however
lame and imperfect the fyftem may be, they
have opened the way to future difcoveries,
and are juftly entitled to a great fhare in the
merit of them. They have removed an infi-
nite deal of ruft and rubbifh, collected in the
ages of fcholaftic fophiftry, which had ob-
it rutted the way. They have put us in the
right road, that of experience and accurate
reflection. They have taught us to avoid the
fnares of ambiguous and ill-defined words,
and have fpoken and thought upon this fub-
ject with a diftinctnefs and perfpicuity for-
merly unknown. They have made many
openings that may lead to the diicovery of
truths which thfcy did not reach, or to the de-
tection

SECT. 4.] INTRODUCTION* 19

tection of errors in which they were involun-
tarily entangled.

It may be obferved, that the defects and
blemifhes in the received philofophy concern-
ing the mind, which have moil expofed it to
the contempt and ridicule of fenfible men,
have chiefly been owing to this ; — thvit the
votaries of this philofophy, from a natural
prejudice in her favour, have endeavoured to
extend her jurifdiction beyond its juft limits,
and to call to her bar the dictates of Common
Senfe, But thefe decline this jurifdidlion ;
they difdain the trial of reaioning, and difown
its authority ; they neither claim its aid, nor
dread its attacks.

In this unequal conteft betwixt Common
Senfe and Philofophy, the latter will always
come off both with difhonour and lofs ; nor
can (he ever thrive till this rivalfhip is dropt,
thefe encroachments given up, and a cordial
friendfhip reftored : for, in reality, Common
Senfe holds nothing of Philofophy, nor needs
her aid. But, on the other hand, Philofophy
(if I may be permitted to change the meta-
phor) has no other root but the principles of
Common Senfe ; it grows out of them, and
draws its nouriftimcnt from them : fevered
B 2 from

20 OF THE HUMAN MIND. [CHAP. I.

from this root, its honours wither, its fap
is dried up, it dies and rots.

The philofophers of the laft age, whom I
have mentioned, did not attend to the prefer-
ving this union and fubordination fo carefully
as the honour and intereft of philofophy re-
quired : but thofe of the prefent have waged
open war with Common Senfe, and hope to
make a complete conqueft of it by the fubtil-
ties of Philofophy ; an attempt no lefs auda-
cious and vain, than that of the giants to de-
throne almighty Jove.

SECT.

SECT. 5.] INTRODUCTION. 21

SECT. V.

Of Bi/hop Berkeley ; the Treatife of Human
Nature; and of fcepticifm.

THE prefent age, I apprehend, has not
produced two more acute or more prac-
tifed in this part of philofophy, than the Bi-
fhop of Cloyne, and the author of the Treatife
of Human Nature. The firft was no friend to
fcepticifm, but had that warm concern for re-
ligious and moral principles which became
his order : yet the refult of his inquiry was, a
ferious conviction, that there is no fuch thing
as a material world ; nothing in nature but
fpirits and ideas ; and that the belief of mate-
rial fubftances, and of abftracl: ideas, are the
chief caufes of all our errors in philofophy,
and of all infidelity and herefy in religion.
His arguments are founded upon the princi-
ples which were formerly laid down by Des
Cartes, Malebranche, and Locke, and
which have been very generally received.

And the opinion of the ableft judges feems

to be, that they neither have been, nor can be

confuted ; and that he hath proved, by unan-

B 3 fwerable

22 OF THE HUMAN MIND. [CHAP. I.

fwerable arguments, what no man in his fcnfes
can believe.

The fecond proceeds upon the fame princi-
ples, but carries them to their full length *,
and as the Bifhop undid the whole material
world, this author, upon the fame grounds,
undoes the world of fpirits, and leaves nothing
in nature but ideas and impreffions, without
any fubjecl on which they may be impref-
fed.

It feems to be a peculiar ftrain of humour
in this author, to fet out in his introduction,
by promifing, with a grave face, no lefs than
a complete fyftem of the fciences, upon a
foundation entirely new, to wit, that of hu-
man nature ; when the intention of the whole
work is to ihew, that there is neither human
nature nor fcience in the world. It may per-
haps be unreafonable to complain of this con-
duct in an author, who neither believes his
own exiftence, nor that of his reader ; and
therefore could not mean to difappoint him,
or to laugh at his credulity. Yet I cannot
imagine, that the author of the Treatife of Hu-
man Nature is fo fceptical as to plead this apo-
logy. He believed, againft his principles,
that he fhould be read, and that he fhould re-
tain his perfonal identity, till he reaped the

honour

SECT. 5.] INTRODUCTION- £j

honour and reputation juflly due to his meta-
phyfical acumen. Indeed, he ingenuoufly ac-
knowledges, that it was only in folitude and
retirement that he could yield any affent to
his own philofophy ; fociety, like day- light,
difpelled the darknefs and fogs of fcepticifm,
and made him yield to the dominion of Com-
mon Senfe. Nor did I ever hear him charged
with doing any thing, even in folitude, that
argued fuch a degree of fcepticifm as his prin-
ciples maintain. Surely if his friends appre-
hended this, they would have the charity ne-
ver to leave him alone.

Pyrrho the Elean, the father of this philo-
fophy, feems to have carried it to greater per-
fection than any of his fucceflbrs : for if we
may believe Antigonus the Caryftian, quoted
by Diogenes Laertius, his life correfponded
to his doctrine. And therefore, if a cart run
againfl him, or a dog attacked him, or if he
came upon a precipice, he wrould not ftir a
foot to avoid the danger, giving no credit to
his fenfes. But his attendants, who, happily
for him, were not fo great fceptics, took care
to keep him out of harm's way \ fo that he
lived till he was ninety years of age. , Nor is
it to be doubted, but this authors friends
would have been equally careful to keep him
B 4 from

24 OF THE HUMAN MIND. [CHAP. I.

from harm, if ever his principles had taken
too itrong a hold of him.

It is probable the Treatife of Human Nature
was not written in company ; yet it contains
manifeft indications, that the author every
now and then relapfed into the faith of the
vulgar, and could hardly, for half a dozen pa-
ges, keep up the fceptical character.

In like manner, the great Pyrrho himfelf
forgot his principles on fome occaiions ; and
is faid once to have been in fuch a paffion
with his cook, who probably had not roafted
his dinner to his mind, that with the fpit in
his hand, and the meat upon it, he purfued
him even into the market-place.

It is a bold philofophy that rejects, without
ceremony, principles which irrefiftibly govern
the belief and the conduct of all mankind in
the common concerns of life ; and to which
the philofopher himfelf mull yield, after he
imagines he hath confuted them. Such prin-
ciples are older, and of more authority, than
Philofophy : fhe refts upon them as her balls,
not they upon her. If ihe could overturn
them, fhe muft be buried in their ruins ; but
all the engines of philofophical fubtilty are
too weak for this purpofe ; and the attempt is
no lefs ridiculous, than if a mechanic mould

contrive

SECT. 5.] INTRODUCTION. 25

contrive an axis in peritrochio to remove the
earth out of its place ; or if a mathematician
mould pretend to demonftrate, that things
equal to the fame thing are not equal to one
another.

Zeno endeavoured to demonftrate the im-
poffibility of motion ; Hobbes, that there was
no difference between right and wrong ; and
this author, that no credit is to be given to our
fenfes, to our memory, or even to demonftra-
tion. Such philofophy is juftly ridiculous,
even to thofe who cannot detect the fallacy of
it. It can have no other tendency, than to
fhew the acutenefs of the fophift, at the ex-
pence of difgracing reafon and human nature,
and making mankind Yahoos.

SECT-

26 OF THE HUMAN MIND. [CHAP. t.

SECT. VI.

Of the Treatife of Human Nature.

THERE are other prejudices againft this
fyftem of human nature, which, even
upon a general view, may make one diffident
of it.

Des Cartes, Hobbes, and this author, have
each of them given us a fyftem of human na*
ture ; an undertaking too vaft for any one man,
how great foever his genius and abilities may
he. There mud furely be reafon to appre-
hend, that many parts of human nature never
came under their obfervation ; and that others
have been ftretched and diftorted, to fill up
blanks, and complete the fyftem. Christo-
pher Columbus, or Sebastian Cabot, might
almoft as reafonably have undertaken to give
us a complete map of America.

There is a certain character and ftyle in
nature's works, which is never attained in
the mod perfect imitation of them. This
feems to be wanting in the fyftems of human
nature I have mentioned, and particularly in
the laft. One may fee a puppet make varie-
ty of motions and gefliculations, which ftrike

much

SECT. 6.] INTRODUCTION. 27

much at firft view ; but when it is accurate-
ly obferved, and taken to pieces, our admira-
tion ceafes ; we comprehend the whole art of
the maker. How unlike is it to that which
it reprcfents ! what a poor piece of work
compared with the body of a man, whofe
ftructure the more we know, the more won-
ders we difcover in it, and the more feniible
we are of our ignorance ! Is the mechanifm
of the mind fo eahly comprehended, when
that of the body is fo difficult ? Yet, by this
fyflem, three laws of aflbciation, joined to a
few original feelings, explain the whole me-
chanifm of fenfe, imagination, memory, be-
lief, and of all the actions and pafTions of the
mind. Is this the man that nature made?
I fufpect it is not fo eafy to look behind the
fcenes in nature's work. This is a puppet
furely, contrived by too bold an apprentice
of nature, to mimic her work. It fhews to-
lerably by candle-light, but brought into
clear day, and taken to pieces, it will appear
to be a man made with mortar and a trowel.
The more we know of other parts of nature,
the more we like and approve them. The
little I know of the planetary fyflem ; of the
earth which we inhabit ; of minerals, vegeta-
bles, and animals ; of my own body, and of the

laws

28 OF THE HUMAN MIND. [CHAP. I.

laws which obtain in thefe parts of nature ;
opens to my mind grand and beautiful fcenes,
and contributes equally to my happinefs and
power. But when I look within, and confi-
der the mind itfelf, which makes me capable
of all thefe profpecls and enjoyments ; if it
is indeed what the Treatife of Human Nature
makes it, I find I have been only in an in-
chanted caftle, impofed upon by fpeclres and
apparitions. I blufli inwardly to think how
I have been deluded ; I am afliamed of my
frame, and can hardly forbear expoftulating
with my deftiny : Is this thy paftime, O Na-
ture, to put fuch tricks upon a filly creature,
and then to take off the mafk, and fhew him
how he hath been befooled ? If this is the
philofophy of human nature, my foul enter
thou not into her fecrets. It is furely the for-
bidden tree of knowledge \ I no fooner tafte
of it, than I perceive myfelf naked, and flript
of all things, yea even of my very felf. I fee
myfelf, and the whole frame of nature; fhrink
into fleeting ideas, which, like Epicurus's a-
toms, dance about in emptinefs.

SECT.

SECT. 7.] INTRODUCTION. 29

SECT. VII.

The fyjlem of all thefe authors is the fame, and
leads to fcepticifm.

BUT what if thefe profound difquifitions
into the firft principles of human nature,
do naturally and necefTarily plunge a man in-
to this abyfs of fcepticifm ? May we not rea-
fonably judge fo from what hath happened ?
Des Cartes no fooner began to dig in this
mine, than fcepticifm was ready to break in
upon him. He did what he could to fhut it
out. Malebranche and Locke, who dug
deeper, found the difficulty of keeping out
this enemy ftill to increafe ; but they laboured
honeftly in the defign. Then Berkeley, who
carried on the work, defpairing of fecuring all,
bethought himfelf of an expedient : By giving
up the material world, which he thought
might be fpared without lofs, and even with
advantage, he hoped, by an impregnable par-
tition, to fecure the world of fpirits. But,
alas ! the Treatife of Human Nature wantonly
fapped the foundation of this partition, and
drowned all in one univerfal deluge.

Thefe

30 OF THE HUMAN MIND. [CIIAP. I.

Thefe fads, which are undeniable, do in-
deed give reafon to apprehend, that Des
Cartes's fyftem of the human underftanding,
which I (hall beg leave to call the ideal fyftem,
and which, with fome improvements made
by later writers, is now generally received,
hath fome original defect ; that this fcepti-
cifm is inlaid in it, and reared along with it ;
and, therefore, that we mud lay it open to
the foundation, and examine the materials,
before we can expect to raife any folid and
ufeful fabric of knowledge on this fubject.

SECT.

SECT. 8.] INTRODUCTION. 31

SECT. VIII.

We ought not to dcfpair of a better.

BUT is this to be defpaired of, becaufe
Des Cartes and his followers have fail-
ed ? By no means. This pusillanimity would
be injurious to ourfelves, and injurious to
truth. Ufeful difcoveries are fomctimes in-
deed the erlecl: of fuperior genius, but more
frequently they are the birth of time and of
accidents. A traveller of good judgment may
miflake his way, and be unawares led into a
wrong track \ and while the road is fair be-
fore him, he may go on without fufpicion and
be followed by others ; but when it ends in
a coal-pit, it requires no great judgment to
know that he hath gone wrong, nor perhaps
to find out what milled him.

In the mean time, the unprofperous ftate
of this part of philofophy hath produced an
efFect, fomewhat difcouraging indeed to any
attempt of this nature, but an effecl: which
might be expected, and which time only and
better fuccefs can remedy. Senlible men,
who never will be fceptics in matters of com-
mon life, are apt to treat with fovereign con-
tempt

32 OF THE HUMAN MIND. [CHAP. I.

tempt every thing that hath been faid, or is
to be faid, upon this fubjecl. — It is metaphy-
fic, fay they : Who minds it ? Let fcholaflic
fophifters entangle themfelves in their own
cobwebs ; I am refolved to take my own ex-
iftence, and the exiftence of other things, up-
on truft ; and to believe that fnow is cold,
and honey fweet, whatever they may fay to
the contrary. He mult either be a fool, or
want tO( make a fool of me, that would rea-
fon me out of my reafon and fenfes.

I confefs I know not what a fceptic can an-
fwer to this, nor by what good argument he
can plead even for a hearing ; for either his
reafoning is fophiftry, and fo deferves con-
tempt ; or there is no truth in the human fa-
culties, and then why mould we reafon ?

If therefore a man find himfelf entangled
in thefe metaphyfical toils, and can find no
other way to efcape, let him bravely cut the
knot which he cannot loofe, curfe metaphyfic,
and dhTuade every man from meddling with
it. For if I have been led into bogs and
quagmires by following an ignis fatuus, what
can I do better, than to warn others to be-
ware of it ? If Philofophy contradicts herfelf,
befools her votaries, and deprives them of
every objecl: worthy to be purfued or enjoyed,

let

SECT. 8.] INTRODUCTION. 33

let her be fent back to the infernal regions
from which fhe mud have had her origi-
nal.

But is it abfolutely certain that this fair
lady is of the party? Is it not poffible fhe
may have been mifreprefented ? Have not
men of genius in former ages often made their
own dreams to pafs for her oracles ? Ought
fhe then to be condemned without any fur-
ther hearing ? This would be unreafonable.
I have found her in all other matters an
agreeable companion, a faithful counsellor, a
friend to Common Senfe, and to the happinefs
of mankind. This juftly entitles her to my
correfpondence and confidence, till I find in-
fallible proofs of her infidelity.

CHAP.

34 OF THE HUMAN MIND. [CHA*. %.

CHAP. II.
OF SMELLING,

SECT. I.

The order of proceeding. Of the medium and
organ offmell.

IT is fo difficult to unravel the operations
of the human underftanding, and to re-
duce them to their firft principles, that we
cannot expect to fucceed in the attempt, but
by beginning with the fimpleft, and proceed-
ing by very cautious fteps to the more com-
plex. The five external fenfes may, for this
reafon, claim to be firft confidered in an ana-
lyfis of the human faculties. And the fame
reafon ought to determine us to make a choice
even among the fenfes, and to give the prece-
dence, not to the nobleft, or mod ufeful, but
to the fimpleft, and that whofe objects are
lead in danger of being miftaken for other
things.

In this view, an analyfis of our fenfations
may be carried on, perhaps with moft eafe

and

SECT. I.] OF SMELLING. 35

and diftindlnefs, by taking them in this or-
der : Smelling, Tailing, Hearing, Touch, and,
lalt of all, Seeing.

Natural philofophy informs us, that all ani-
mal and vegetable bodies, and probably all or
moll other bodies, while expofed to the air,
are continually fending forth effluvia of vail
fubtilty, not only in their Hate of life and
growth, but in the dates of fermentation
and putrefaction. Thefe volatile particles
do probably repel each other, and fo fcat-
ter themfelves in the air, until they meet
with other bodies to which they have fome
chemical affinity, and with which they unite,
and form new concretes. All the fmell of
plants, and of other bodies, is caufed by thefe
volatile parts, and is fmelled wherever they
are fcattered in the air : And the acutenefs
of fmell in fome animals, fhews us, that thefe
effluvia fpread far, and mull be inconceivably
fubtile.

Whether, as fome chemills conceive, eve-
ry fpecies of bodies hath a fpiritus reftor, a
kind of foul, which caufes the fmell, and all
the fpecific virtues of that body, and which,
being extremely volatile, flies about in the
air in quell of a proper receptacle, I do not
inquire. This, like moll other theories, is
C 2 perhaps

36 OF THE HUM AN MIND. [CHAP. 2.

perhaps rather the product of imagination
than of juft induction. But that all bodies
are fmelled by means of effluvia which they
emit, and which are drawn into the noftrils
along with the air, there is no reafon to
doubt. So that there is manifeft appearance
of defign in placing the organ of fmell in the
infide of that canal, through which the air is
continually pafling in infpiration and expira-
tion.

Anatomy informs us, that the membrana
pituitaria, and the olfactory nerves, which are
diftributed to the villous parts of this mem-
brane, are the organs deftined by the wifdom
of nature to this fenfe ; fo that when a body
emits no effluvia, or when they do not enter
into the nofe, or when the pituitary mem-
brane or olfactory nerves are rendered unfit
to perform their office, it cannot be fmelled.

Yet notwithstanding this, it is evident that
neither the organ of fmell, nor the medium,
nor any motions we can conceive excited in
the membrane above mentioned, or in the
nerve or animal fpirits, do in the lead refem-
ble the fenfation of fmelling ; nor could that
fenfation of itfelf ever have led us to think of
nerves, animal fpirits, or effluvia.

SECT.

SECT. 2.] OF SMELLING. 37

SECT. II.

The fenfation conjidered abflradtly.

HAVING premifed thefe things, with re-
gard to the medium and organ of this
fenfe, let us now attend carefully to what the
mind is confcious of when we fmell a rofe or
a lily ; and fince our language affords no
other name for this fenfation, we (hall call it
a fmell or odour, carefully excluding from the
meaning of thofe names every thing but the
fenfation itfelf, at lead till we have exami-
ned it.

Suppofe a peifon who never had this fenfe
before, to receive it all at once, and to fmell a
rofe \ can he perceive any fimilitude or agree-
ment between the fmell and the rofe ? or in-
deed between it and any other objecl whatfo-
ever ? Certainly he cannot. He finds himfelf
affedled in a new way, he knows not why or
from what caufe; Like a man that feels fotne
pain or pleafure formerly unknown to him,
he is confcious that he is not the caufe of it
himfelf; but cannot, from the nature of the
thing, determine whether it is caufed by body
G 3 or

3B OF THE HUMAN MIND. [CHAP. 2.

or fpirit, by fomething near, or by fomething
at a diftance. It has no fimilitude to any thing
elfc, fo as to admit of a comparifon ; and there-
fore he can conclude nothing from it, linlefs
perhaps that there mud be fome unknown
caufe of it.

It is evidently ridiculous, to afcribe to it
figure, colour, extenfion, or any other quali-
ty of bodies. He cannot give it a place, any
more than he can give a place to melancholy
or joy : nor can he conceive it to have any
exiftence, but when it is fmelled. So that it
appears to be a fimple and .original affection
or feeling of the mind, altogether inexplica-
ble and unaccountable. It is indeed impof-
fible that it can be in any body : It is a fenfa-
tion ; and a fenfation can only be in a fentient
thing.

The various odours have each their differ-
ent degrees of ftrength or weaknefs. Moil
of them are agreeable or difagreeable ; and
frequently thofe that are agreeable when
weak, are difagreeable when ftronger. When
we compare different fmells together, we can
perceive very few refemblances or contrarie-
ties, or indeed relations of any kind between
them. They are all fo fimple in themfelves,
and fo different from each other, that it is

hardly

SECT. 2.] OF SMELLING. 39

hardly Jpoffible to divide them into genera and
/pedes. Mod of the names we give them are
particular ; as the fmell of a rofe, of zjeffa-
mine, and the like. Yet there are fome gene-
ral names ; 2&fweet,flinking, mujly, putrid, ca-
daverous, aromatic. Some of them feem to
refrefh and animate the mind, others to dead-
en and deprefs it.

SECT. III.

Senfation and remembrance, natural principles
of belief.

SO far we have confidered this fenfation
abftractly. Let us next compare it with
other things to which it bears fome relation.
And fir ft I (hall compare this fenfation with
the remembrance, and the imagination of it.

I can think of the fmell of a rofe when I
do not fmell it ; and it is poflible that when
I think of it, there is neither rofe nor fmell
any where exifting. But when I fmell it, I
am neceflarily determined to believe tha^the
fenfation really exifts. This is common to
all fenfations, that as they cannot exift but in

C 4 being

40 OF THE HUMAN MIND. [CHAP. 2.

being perceived ; fo they cannot be perceived,
but they muft exift. I could as eafily doubt
of my own exiftence, as of the exigence of
my fenfations. Even thofe profound philofo-
phers who have endeavoured to difprove their
own exiftence, have yet left their fenfations
to (land upon their own bottom, ftript of a
fubjedt, rather than call in queftion the reality
of their exiftence.

Here then a fenfation, a fmell for inftance,
may be prefented to the mind three different
ways : it may be fmelled, it may be remem-
bered, it may be imagined or thought of. In
the firft cafe, it is neceflarily accompanied
with a belief of its prefent exiftence ; in the
fecond, it is neceftarily accompanied with a
belief of its paft exiftence ; and in the laft, it
is not accompanied with belief at all, but is
what the logicians call ajimple apprebenjion.

Why fenfation fhould compel our belief
of the prefent exiftence of the thing, memo-
ry a belief of its paft exiftence, and imagina-
tion no belief at all, I believe no philofopher
can give a fhadow of reafon, but that fuch is
the nature of thefe operations : They are all
fimple and original, and therefore inexplica-
ble acts of the mind.

Suppofe

SECT. 3.] OF SMELLING. 41

Suppofe that once, and only once, I fmell-
ed a tuberofe in a certain room where it grew
in a pot, and gave a very grateful perfume.
Next day I relate what I faw and fmelled.
When I attend as carefully as 1 can to what
paffes in my mind in this cafe, it appears evi-
dent, that the very thing I faw yefterday, and
the fragrance I fmelled, are now the imme-
diate objects of my mind when I remember
it. Further, I can imagine this pot and flower
tranfported to the room where I now fit, and
yielding the fame perfume. Here likewife it
appears, that the individual thing which I
faw and fmelled, is the object of my imagina-
tion.

Philofophers indeed tell me, that the im-
mediate object of my memory and imagina-
tion in this cafe, is not the pail fenfation, but
an idea of it, an image, phantafm, or fpecies
of the odour I fmelled : that this idea now
exifts in my mind, or in my fenforium ; and
the mind contemplating this prefent idea,
finds it a reprefentation of what is paft, or of
what may exift \ and accordingly calls it me-
mory, or imagination. This is the doctrine
of the ideal philofophy ; which we (hall not
now examine, that we may not interrupt;
the thread of the prefent inve (ligation. Up-
on

42 OF THE HUMAN MIND. [CHAP. 2,

on the ftricteft attention, memory appears to
me to have things that are paft, and not pre-
fent ideas, for its objeft. We fhall after-
wards examine this fyftem of ideas, and en-
deavour to make it appear, that no folid proof
has ever been advanced of the exiftence of
ideas ; that they are a mere fiction and hypo-
thecs, contrived to folve the phenomena of
the human underftanding ; that they do not
at all anfwer this end ; and that this hypo-
thecs of ideas or images of things in the
mind, or in the fenforium, is the parent of
thofe many paradoxes fo mocking to common
fenfe, and of that fcepticifm, which difgrace
our philofophy of the mind, and have brought
upon it the ridicule and contempt of fenfible
men.

In the mean time, I beg leave to think
with the vulgar, that when I remember the
fmell of the tuberofe, that very fenfation
which I had yefterday, and which has now
no more any exiftence, is the immediate ob-
ject of my memory ; and when 1 imagine it
prefent, the fenfation itfelf, and not any idea
of it, is the object of my imagination. But
though the object of my fenfation, memory,
and imagination, be in this cafe the fame, yet
thefe acts or operations of the mind are as

different,

SECT. 3.] OF SMELLING. 43

different, and as eafily diftinguifhable, as fmell,
tafte, and found. I am confcious of a differ-
ence in kind between fenfation and memory,
and between both and imagination. I find
this alfo, that the fenfation compels my be-
lief of the prefent exiftence of the fmell,
and memory my belief of its paft exiftence.
There is a fmell, is the immediate teflimony
of fenfe ; there was a fmell, is the immediate
teflimony of memory. If you afk me, why I
believe that the fmell exifts ? I can give no
other reafon, nor fhall ever be able to give any
other, than that I fmell it. If you afk, why I
believe that it exifled yeflerday ? I can give
no other reafon but that I remember it.

Senfation and memory therefore are fimple,
original, and perfectly diftindl operations of
the mind, and both of them are original prin-
ciples of belief. Imagination is diftinct from
both, but is no principle of belief. Senfation
implies the prefent exiftence of its object ;
memory its paft exiftence ; but. imagination
views its object naked, and without any belief
of its exiftence or non-exiftence, and is there-
fore what the fchools call Jimple apprehenjion.

SECT.

44 OP THE HUMAN MIND. [CHAP. 1.

SECT. IV.

judgment and belief in fome cafes precede Jimple
apprehenfion,

BUT here again the ideal fyftem comes in
our way ; it teaches us, that the firft
operation of the mind about its ideas, is fimple
apprehenfion ; that is, the bare conception of
a thing without any belief about it ; and that
after we have got fimple apprehenfions, by
comparing them together, we perceive agree-
ments or difagreements between them ; and
that this perception of the agreement or difa-
greement of ideas, is all that we call belief,
judgment, or knowledge. Now, this appears
to me to be all fiction, without any foundation
in nature : for it is acknowledged by all, that
fenfation itiuft go before memory arid imagi-
nation ; and hence it necefiarily follows, that
apprehenfion accompanied with belief and
knowledge, mull go before fimple apprehen-
fion, at leaft in the matters we are now fpeak-
ing of. So that here, inftead of faying, that
the belief or knowledge is got by putting to-
gether and comparing the fimple apprehen-
fions, we ought rather to fay, that the fimple

apprehenfion

6ECT. 4«] OT SMELLING. 45

apprehenfion is performed by refolving and
analyfing a natural and original judgment.
And it is with the operations of the mind, in
this cafe, as with natural bodies, which are in-
deed compounded of fimple principles or ele-
ments. Nature does not exhibit thefe ele-
ments feparate, to be compounded by us ; me
exhibits them mixed and compounded in con-
crete bodies, and it is only by art and chemi-
cal analylis that they can be feparated.

SECT. V.

Two theories of the nature of belief refuted,
Conclujions from what hath been J aid.

BUT what is this belief or knowledge
which accompanies fenfation and memo-
ry ? Every man knows what it is, but no man
can define it. Does any man pretend to define
fenfation, or to define confcioufnefs ? It is
happy indeed that no man does. And if no
philofopher had attempted to define and ex-
plain belief, fome paradoxes in philofophy,
more incredible than ever were brought forth
by the moll abjecl: fuperflition, or the molt

frantic

46 OF THE HUMAN MIND. [CHAP. 2.

frantic enthufiafm, had never feen the light.
Of this kind furely is that modern difcovery
of the ideal philofophy, that fenfation, memo-
ry, belief and imagination, when they have
the fame object, are only different degrees of
ftrength and vivacity in the idea. Suppofe
the idea to be that of a future ftate after
death ; one man believes it firmly; this means
no more than that he hath a ftrong and lively
idea of it : Another neither believes nor dis-
believes ; that is, he has a weak and faint
jdea. Suppofe now a third perfon believes
firmly that there is no fuch thing ; J am at a
lofs to know whether his idea be faint or live-
ly : If it is faint, then there may be a firm
belief where the idea is faint ; if the idea is
lively, then the belief of a future ftate and the
belief of no future ftate muft be one and the
fame. The fame arguments that are ufed to
prove that belief implies only a ftronger idea
of the object than fimple apprehenfion, might
as well be ufed to prove that love implies only
a ftronger idea of the object than indifference.
And then what fhall we fay of hatred, which
muft upon this hypothefis be a degree of love,
or a degree of indifference ? If it fhould be
faid, that in love there is fomething more
than an idea, to wit, an affection of the mind ;

may

SECT. 5.} OF SMELLING. 47

may it not be faid with equal reafon, .that in
belief there is Ibmething more than an idea,
to wit, an aflent or perfuafion of the mind ?

But perhaps it may be thought as ridicu-
lous to argue againft this ftrange opinion, as
to maintain it. Indeed, if a man mould main-
tain, that a circle, a fquare, and a triangle,
differ only in magnitude, and not in figure, I
believe he would find nobody difpofed either
to believe him or to argue againft him ; and
yet I do not think it lefs fhocking to common
fenfe, to maintain, that fenfation, memory,
and imagination, differ only in degree, and
not in kind. I know it is faid, that in a deli-
rium, or in dreaming, men are apt to miflake
one for the other. But does it follow from
this, that men who are neither dreaming,
nor in a delirium, cannot diftinguifh them ?
But how does a man know, that he is not in
a delirium ? I cannot tell : neither can I tell
how a man knows that he exifts : But if any
man ferioufly doubts whether he is in a deli-
rium, I think it highly probable that he is,
and that it is time to feek for a cure, which I
am perfuaded he will not find in the whole
fyflem of logic.

I mentioned before, Locke's notion of belief
or knowledge : he holds that it confifts in a

perception

4$ OF THE HUMAN MIND. [CHAP. %,

perception of the agreement or difagreement
of ideas ; and this he values himfelf upon as a
very important difcovery.

We mall have occafion afterwards to exa-
mine more particularly this grand principle of
Locke's philofophy, and to fhewthat it is one
of the main pillars of modern fcepticifm, al-
though he had no intention to make that ufe
of it. At prefent let us only confider how it
agrees with the inftances of belief now under
confederation ; and whether it gives any light
to them. I believe that the fenfation I have,
exifls ; and that the fenfation I remember,
does not now exift, but did exift yefterday.
Here, according to Locke's fyftem, I compare
the idea of a fenfation with the ideas of pad
and prefent exiftence : at one time that this
idea agrees with that of prefent exiftence, but
difagrees with that of pall exiftence ; but at
another time it agrees with the idea of paft
exiftence, and difagrees with that of prefent
exiftence. Truly thefe ideas feem to be very
capricious in their agreements and difagree-
ments. Befides, I cannot for my heart con-
ceive what is meant by either. I fay a fen-
fation exifts, and 1 think I underftand clearly
what I mean. But you want to make the
thing clearer, and for that end tell me, that

there

SECT. 5.] OF SMELLING. 49

there is an agreement between the idea of
that fenfation and the idea of exiftence. To
fpeak freely, this conveys to me no light, but
darknefs ; I can conceive no otherwife of it,
than as an odd and obfcure circumlocution.
I conclude, then, that the belief which accom-
panies fenfation and memory, is a fimpie act of
the mind, which cannot be defined. It is in
this refpect like feeing and hearing, which can
never be fo defined as to be underilood by
thofe who have not thefe faculties : and to
fuch as have them, no definition can make
thefe operations more clear than they are al-
ready. In like manner, every man that has
any belief, and he muft be a curiofity that has
none, knows perfectly what belief is, but can
never define or explain it. I conclude alfo,
that fenfation, memory, and imagination, even
where they have the fame object, are opera-
tions of a quite difFerent nature, and perfectly
diftinguifhable by thofe who are found and
fober. A man that is in danger of confound-
ing them, is indeed to be pitied \ but whatever
relief he may find from another art, he can
find none from logic or metaphyfic. I con-
clude further, that it is no lefs a part of the
. human conftitution, to believe the prefent ex-
iftence of our fenfations, and to believe the

D paft

50 OF THE HUMAN MIND. [CHAJ\ 2.

paft exiftence of what we remember, than it
is to believe that twice two make four. The
evidence of fenfe, the evidence of memory,
and the evidence of the neceftary relations of
things, are all diftincl: and original kinds of
evidence, equally grounded on our conftitu-
tion : none of them depends upon, or can be
refolved into another. To reafon againft any
of thefe kinds of evidence^ is abfurd ; nay to
reafon for them, is abfurd. They are firft
principles ; and fuch fall not within the pro-
vince of Reafon, but of Common Senfe.

SECT. VI.

Apology for metaphyseal abfurdities. Sen/a-
tion without afentient, a confequence of the
theory of ideas. Confequenees of this fir an ge
opinion.

HAVING confidered the relation which
the fenfation of fmelling bears to the re-
membrance and imagination of it, I proceed
to confider, what relation it bears to a mind,
or fentient principle. It is certain, no man
can conceive or believe fmelling to exift of it-

felf,

SECT. 6.] OF SMELLING. 51

felf, without a mind, or fomething that has the
power of fmelling, of which it is called a fen-
fation, an operation or feeling. Yet if any
man mould demand a proof, that fenfation
cannot be without a mind or fentient being,
I confefs that I can give none ; and that to
pretend to prove it, feems to me almoft as ab-
furd as to deny it.

This might have been faid without any apo-
logy before the Treatife of Human Nature ap-
peared in the world. For till that time, no
man, as far as I know, ever thought either of
calling in queftion that principle, or of giving
a reafon for his belief of it. Whether thinking
beings were of an ethereal or igneous nature,
whether material or immaterial, was variouf-
]y difputed ; but that thinking is an opera-
tion of fome kind of being or other, was al-
ways taken for granted, as a principle that
could not pofiibly admit of doubt.

However, fince the author above mention-
ed, who is undoubtedly one of the mod acute
metaphyficians that this or any age hath pro-
duced, hath treated it as a vulgar prejudice,
and maintained, that the mind is only a fuc-
ceffion of ideas and impreflions without any
fubjeel: ; his opinion, however contrary to the
common apprehenfions of mankind, deferves
D 2 refpect.

C2, OF THE HUMAN MIND. [CHAP. 2r

refpett. I beg therefore, once for all, that
no offence may be taken at charging this or
other metaphyfical notions with abfurdity, or
with being contrary to the common fenfe of
mankind. No difparagement is meant to the
understandings of the authors or maintainers
of fuch opinions. Indeed they, commonly
proceed not from defecl: of underftanding, but
from an excefs of refinement : the reafoning
that leads to them, often gives new light to
the fubjedl, and fhews real genius and deep
penetration in the author ; and the premifes
do more than atone for the conclufion.
' If there are certain principles, as I think
there are, which the conftitution of our na-
ture leads us to believe, and which we are
under a neceflity to take for granted in the
common concerns of life, without being able
to give a reafon for them ; thefe are what
we call the principles of common fenfe ; and
what is manifeftly contrary to them, is what
we call abiurd.

Indeed, if it is true, and to be received as
a principle of philofophy, That fenfation and
thought may be without a thinking being ; it
mull be acknowledged to be the mod wonder-
ful difcovery that this or any other age hath
produced. The received doclrine of ideas is
?' the

SECT. 6.] OF SMELLING. $ j

the principle from which it is deduced, and
of which indeed it feems to be a juft and na-
tural confequence. And it is probable, that
it would not have been fo late a difcovery,
but that it is fo (hocking and repugnant to the
common apprehenfions of mankind, that it re-
quired an uncommon degree of philofophical
intrepidity to ufher it into the world. It is a
fundamental principle of the ideal fyftem,
That every object of thought mull be an im-
preffion, or ail idea, that is, a faint copy of
fome preceding impreffion. This is a princi-
ple fo commonly received, that the author
above mentioned, although his whole fyftem
is built upon it, never offers the leaft proof of
it. It is upon this principle, as a fixed point,
that he erects his metaphyfical engines, to
overturn heaven and earth, body and fpirit.
And indeed, in my apprehenfion, it is alto-
gether fufficient for the purpofe. For if im-
preffions and ideas are the only objects of
thought, then heaven and earth, and body
and fpirit, and every thing you pleafe, muft
fignify only impreffions and ideas, or they
mud be words without any meaning. It
feems, therefore, that this notion, however
ftrange, is clofely connected with the received
doctrine of ideas, and we rauft either admit
D 3 the

54 OF THE HUMAN MIND. [CHAP. 2,

the conclufion, or call in queftion the pre-
mifes. •

Ideas feem to have fomething in their na-
ture unfriendly to other exigences. They
were firft introduced into philofophy, in the
humble character of images or reprefentatives
of things \ and in this character they feemed
not only to be incfFenfive, but to ferve admi-
rably well for explaining the operation of the
human underflanding. But fince men began
to reafon clearly and diftinctly about them,
they have by degrees fupplanted their confti-
tuents, and undermined the exiftence of every
thing but themfelves. Firft, they difcarded
all fecondary qualities of bodies ; and it was
found out by their means, that fire is not hot,
nor fnow cold, nor honey fweet ; and, in a
word, that heat and cold, found, colour, tafte,
and fmell, are nothing but ideas or impref-
fioris. Bifhop Berkeley advanced them a ftep
higher, and found out, by juft reafoning, from
the fame principles, that extenfion, folidity,
fpace, figure, and body, are ideas, and that
there is nothing in nature but ideas and fpi-
rits. But the triumph of ideas was completed
by the Treatife of Human Nature, which dif-
cards fpirits alfo, and leaves ideas and impref-
fions as the fole exigences in the univerfe.

What

SECT. 6.] OF SMELLING. 55

What if at laft, having nothing elfe to contend
with, they fhould fall foul of one another, and
leave no exiftence in nature at all ? This
would furely bring philofophy into danger ;
for what fhould we have left to talk or to dif-
pute about ?

However, hitherto thefe philofophers ac-
knowledge the exiftence of impreflions and
ideas ; they acknowledge certain laws of at-
traction, or rules of precedence, according to
which ideas and impreflions range themfelves
iri various forms, and fucceed one another :
but that they fhould belong to a mind, as its
proper goods and chattels, this they have
found to be a vulgar error. Thefe ideas are
as free and independent as the birds of the air,
or as Epicurus's atoms when they purfued
their journey in the vaft inane. Shall we con-
ceive them like the films of things in the Epi-
curean fyftem ?

Principio hoc dico, rerumjimulacra vagari,
Multa modi's mnltis, in cunclas undique parteis
Tenuia, qua facile inter fe junguntur in auris,
Obvia cum veniunt.

Lucr.

Or do they rather refemble Aristotle's in-
telligible fpecies after they are fhot forth from
D 4 the

56 OF THE HUMAN MIND. [CHAP. 2.

the object., and before they have yet ftruck up-
on the pafiive intellect ? But why mould we
feek to compare them with any thing, lince
there is nothing in nature but themfelves?
They make the whole furniture of the uni-
verfe ; flatting into exiftence, or out of it,
without any caufe ; combining into parcels,
which the vulgar call minds ; and fucceeding
one another by fixed laws, without time, place,
or author of thofe laws.

Yet, after all, thefe felf exiftent and inde-
pendent ideas look pitifully naked and defti-
tute, when left thus alone in the univerfe, and
feem, upon the whole, to be in a worfe condi-
tion than they were before. Des Cartes,
Malebranche, and Locke, as they made
much ufe of ideas, treated them handfomely,
and provided them in decent accommodation -,
lodging them either in the pineal gland, or in
the pure intellect, or even in the divine mind.
They moreover clothed them with a commif-
lion, and made them reprefentatives of things,
which gave them lome dignity and character.
But the Treatife of Human Nature, though no
lefs indebted to them, feems to have made but
a bad return, by bellowing upon them this in-
dependent exiflence ; fince thereby they are
turned out of houfe'and home, and fet adrift

in

SECT. 6.] OF SMELLING. 57

in the world, without friend or connexion,
without a rag to cover their nakednefs ; and
who knows but the whole fyftem of ideas may
perifh by the indifcreet zeal of their friends
to exalt them ?

However this may be, it is certainly a moil
amazing difcovery that thought and ideas may
be without any thinking being : — a difcovery
big with confequences which cannot eafily be
traced by thofe deluded mortals who think and
reafon in the common track. We were al-
ways apt to imagine, that thought fuppofed a
thinker, and love a lover, and treafon a traitor :
but this, it feems, was all a miftake ; and it is
found out, that there may be treafon without a
traitor, and love without a lover, laws without
a legiflator, and punifhment without a fufferer,
fucceffion without time, and motion without
any thing moved, or fpace in which it may
move : or if, in thefe cafes, ideas are the lover,
the fufferer, the traitor, it were to be wifhed
that the author of this difcovery had further
condefcended to acquaint us, whether ideas
can converfe together, and be under obliga-
tions of duty or gratitude to each other ;
whether they can make promifes, and enter
into leagues and covenants, and fulfil or break
them, and be puniilied for the breach ? If one

fet

58 OF THE HUMAN MIN0. [CHAP. 2.

fet of ideas makes a covenant, another breaks
it, and a third is punifhed for it, there is rea-
fon to think that juftice is no natural virtue in
this fyftem.

It feemed very natural to think, that the
Treatife of Human Nature required an Author,
and a very ingenious one too ; but now we
learn, that it js only a fet of ideas which came
together, and arranged themfelves by certain
affociations and attractions.

After all, this curious fyftem appears not to
be fitted to the prefent ftate of human nature.
How far it may fuit fome choice fpirits,
who are refined from the dregs of common
fenfe, I cannot fay. It is acknowledged, I
think, that even thefe can enter into this fyf-
tem only in their molt fpeculative hours, when
they foar fo high in purfuit of thofe felf-ex-
iftent ideas, as to lofe fight of all other things.
But when they condefcend to mingle again
with the human race, and to converfe with a
friend, a companion, or a fellow citizen, the
ideal fyftem vanifhes ; common fenfe, like an
irreliftible torrent, carries them along ; and, in
fpitc of all their reafoning and philofophy,
they believe their own exiftence, and the exift-
ence of other things.

Indeed,

SECT. 6.] OF SMELLING. 59

Indeed, it is happy they do fo ; for if they
fhould carry their clofet belief into the world,
the relt of mankind would confider thtm as
difeafed, and fend them to an infirmary.
Therefore, as Plato required certain previous
qualifications of thofe who entered his fchool,
I think it would be prudent for the doctors of
this ideal philofophy to do the fame, and to
refufe admittance to every man who is fo
weak, as to imagine that he ought to have the
fame belief in folitude and in company, or that
his principles ought to have any influence up-
on his practice : for this philofophy is like a
hobby-horfe, which a man in bad health may
ride in his clofet, without hurting his reputa-
tion ; but if he fhould take him abroad with
him to church, or to the exchange, or to the
play-houfe, his heir would immediately call a
jury, and feize his eftate.

SECT.

6o OF THE iuMAN MlND. [CHA?. 2,

SECT. VII.

Tbe conception and belief of afentient being or
mind, is fuggejled by our conjlitution. Tbe
notion of relations not always got by compa-
ring tbe related ideas.

LEAVING this philofophy, therefore, to
thofe who have occalion for it, and can
ufe it difcreetly as a chamber-exercife, we may
Hill inquire, how the reft of mankind, and
even the adepts themfelves, except in fome fo-
litary moments, have got fo ftrong and irrefifti-
ble a belief, that thought muft have a fubjecl:,
and be the acl of fome thinking being : how
every man believes himfelf to be fomething
diftincl: from his ideas and impreffions ; fome-
thing which continues the fame identical
felf when all his ideas and impreffions are
changed. It is impoffible to trace the origin
of this opinion in hiflory : for all languages
have it interwoven in their original conftruc-
tion. All nations have always believed it.
The conftitution of all laws and governments,
as well as the common tranfaclions of life, fup-
pofe it.

It

S£CT, 7.] OF SMELLING. 6l

It is no lefs impoflible for any man to re->
colled when he himfelf came by this notion ;
for, as far back as we can remember, we were
already in pofleflion of it, and as fully per-
fuaded of our own exiftence, and the exiftence
of other things, as that one and one make two.
It feems, therefore, that this opinion preceded
all reafoning, and experience, and inftruction ;
and this is the more probable, becaufe we
could not get it by any of thefe means. It
appears then to be an undeniable fact, that
from thought or fenfation, all mankind, con-
ftantly and invariably, from the firft dawning
of reflection, do infer a power or faculty of
thinking, and a permanent being or mind to
which that faculty belongs ; and that we as
invariably afcribe all the various kinds of fen-
fation and thought we are confcious of, to one
individual mind or felf.

But by what rules of logic we make thefe
inferences, it is impoflible to fhow ; nay, it
is impoflible to fhow how our fenfations and
thoughts can give us the very notion and con-
ception either of a mind or of a faculty. The
faculty of fmelling is fomething very different
from the actual fenfation of fmelling ; for the
faculty may remain when we have no fenfa-
tion. And the mind is no lefs different from

the

62 OF THE HUMAN MIND. [CHAP. 2.

the faculty ; for it continues the fame indivi-
dual being when that faculty is loft. Yet this
fenfation fuggefts to us both a faculty and a
mind ; and not only fuggefts the notion of
them, but creates a belief of their exiftence ;
although it is impoffible to difcover, by rea-
fon, any tie or connexion between one and
the other.

What {hall we fay then ? Either thofe infe-
rences which we draw from our fenfations,
namely, the exiftence of a mind, and of powers
or faculties belonging to it, are prejudices
of philofophy or education, mere fictions of
the mind, which a wife man mould throw
off as he does the belief of fairies ; or they are
judgments of nature, judgments not got by
comparing ideas, and perceiving agreements
and difagreements, but immediately infpired
by our conftitution.

If this laft is the cafe, as I apprehend it is,
it will be impoffible to fhake off thofe- opi-
nions, and we muft yield to them at laft,
though we ftruggle hard to get rid of them.
And if we could, by a determined obftinacy,
fhake off the principles of our nature, this is
not to a6r the philofopher, but the fool or the ,
madman. It is incumbent upon thofe who
think that thefe are not natural principles, to

fhow,

SECT. 7.] OF SMELLING. 63

fhow, in the firft place, how we can otherwife
get the notion of a mind and its faculties ; and
then to ihow, how we come to deceive ourfelves
into the opinion that fenfation cannot be
without a fentient being.

It is the received doctrine of philofophers,
that our notions of relations can only be got
by comparing the related ideas : but, in the
prefent cafe, there feems to be an inftance to
the contrary. It is not by having firft the no-
tions of mind and fenfation, and then com-
paring them together, that we perceive the
one to have the relation of a fubjecl or fub-
ftratum, and the other that of an act: or opera-
tion : on the contrary, one of the related
things, to wit, fenfation, fuggefts to us both
the correlate and the relation.

I beg leave to make ufe of the word fug-
geftion, becaufe I know not one more proper,
to exprefs a power of tjje mind, which feems
entirely to have efcaped the notice of philofo-
phers, and to which we owe many of our fim-
ple notions which are neither impreflions nor
ideas, as well as many original principles of
belief. INfhall endeavour to illuftrate, by an
example, what I underfland by this word.
We all know, that a certain kind of found
fuggefts immediately to the mind, a coach

palling

64 OF THE HUMAN MIND. [CHAP. 2.

palling in the flreet ; and not only produces
the imagination, but the belief, that a coach is
palling. Yet there is here no comparing of
ideas, no perception of agreements or difagree-
ments, to produce this belief; nor is there the
lealt fimilitude between the found we hear, and
the coach we imagine and believe to be paf-
fing.

It is true that this fuggeftion s not natural
and orginal ; it is the refult of experience and
habit. But I think it appears, from what
hath been faid, that there are natural fuggef-
tions ; particularly, that fenfation fuggeils the
notion of prefent exiftence, and the belief
that what we perceive or feel, does now exift ;
that memory fuggeils the notion of pad exift-
ence, and the belief that what we remember
did exift in time pail ; and that our fenfa-
tions and thoughts do alfo fuggeft the notion
of a mind, and the belief of its exiftence, and
of its relation to our thoughts. By a like na-
tural pinciple it is, that a beginning of exift-
ence, or any change in nature, fuggefts to us
the notion of a caufe, and compels our belief
of its exiftence. And in like manner, as fhali
be fhewn when we come to the fenfe of touch,
certain fenfations of touch, by the conftitu-
tion of our nature, fugged to us extenfion, fo-

lidity,

SECT. 8.] OF SMELLING. 65

lidity, and motion, which are no wife like to
fenfations, although they have been hitherto
confounded with them.

SECT. VIII.

There is a quality or virtue in bodies, which we
call their fmelL How this is connected in the
imagination with the fenfation.

WE have coniidered fmell as fignifying
a fenfation, feeling, or impreffion up^
on the mind ; and in this fenfe, it can only be
in a mind, or fentient being : but it is evi-
dent, that mankind give the name of f me 11
much more frequently to fomething which
they conceive to be external, and to be a qua-
lity of body : they underiland fomething by
it which does not at all infer a mind ; and
have not the leaft difficulty in conceiving the
air perfumed with aromatic odours in the de-
farts of Arabia, or in fome uninhabited ifland,
where the human foot never trod. Every
fenlible day-labourer hath as clear a notion of
this, and as full a conviction of the poflibility

E of

66 OF THE HUMAN MIND. [CHAP. 2.

of it, as he hath of his own exigence; and
can no more doubt of the one than of the
other.

Suppofe that fuch a man meets with a mo-
dern philofopher, and wants to be informed,
what fmell in plants is. The philofopher tells
him, that there is no fmell in plants, nor in
any thing, but in the mind ; that it is impof-
iible there can be fmell but in a mind ; and
that all this hath been demonftrated by mo-
dern philofophy. The plain man will, no
doubt, be apt to think him merry : but if he
finds that he is ferious, his next conclufion
will be, that he is mad ; or that philofophy,
like magic, puts men into a new world, and
gives them different faculties from common
men. And thus philofophy and common
fenfe are fet at variance. Hut who is to blame
for it ? In my opinion the philofopher is to
blame. For if he means by fmell what the
reft of mankind mod commonly mean, he is
certainly mad. But if he puts a different
meaning upon the word, without obferving it
himfelf, or giving warning to others, he abu-
fes language, and difgraces philofophy, with-
out doing any fervice to truth : as if a man
mould exchange the meaning of the words
daughter and cow, and then endeavour to

prove

SECT. 8.] OF SMELLING. 6j

prove to his plain neighbour, that his cow
is his daughter, and his daughter his cow.

I believe there is not much more wifdom in
many of thofe paradoxes of the ideal philofo-
phy, which to plain fenfible men appear to be
palpable abfurdities, but with the adepts pafs
for profound difcoveries. I refolve, for my
own part, always to pay a great regard to the
dictates of common fenfe, and not to depart
from them without abfolute neceffity ; and
therefore I am apt to think, that there is real-
ly fomething in the rofe or lily, which is by
the vulgar called Jmell, and which continues
to exift when it is not fmelled : and fhall pro-
ceed to inquire what this is ; how we come
by the notion of it ; and what relation this
quality or virtue of fmell hath to the fenfation,
which we have been obliged to call by the
fame name, for want of another.

Let us therefore fuppofe, as before, a per-
fon beginning to exercife the fenfe of fmell-
ing : a little experience will difcover to him,
that the nofe is the organ of this fenfe, and
that the air, or fomething in the air, is a me-
dium of it. And finding by further experi-
ence, that when a role is near, he has a cer-
tain fenfation ; when it is removed, the fenfa-
tion is gone ; he finds a connection in nature
Ea betwixt

68 OF THE HUMAN MIND. [CHAP. 2.

betwixt the rofe and this fenfation. The rofe
is coniidered as a caufe, occafion, or antece-
dent, of the fenfation ; the fenfation as ah ef-
fect or confequent of the prefence of the
rofe : they are aftbciated in the mind, and
conftantly found conjoined in the imagina-
tion.

But here it deferves our notice, that al-
though the fenfation may feem more clofely
related to the mind its fubject., or to the nofe
its organ ; yet neither of thefe connections
operate fo powerfully upon the imagination,
ns its connection with the rofe its concomi-
tant. The reafon of this feems to be, that its
connection with the mind is more general,
and noway diftinguiftieth it from other fmells,
or even from taftes, founds, and other kinds
of fenfations. The relation it hath to the or-
gan, is likewife general, and doth not diftin-
guifh it from other fmells : but the connec-
tion it hath with the rofe is fpecial, and
conflant ; by which means they become al-
moft infeparable in the imagination, in like-
manner as thunder and lightning, freezing
* and cold.

SECT.

SECT. 9.] OF SMELLING. 6p

SECT. IX.

That there is a principle in human nature,
from which the notion of this, as well as
all other natural virtues or caufes, is deri-
ved.

IN order to illuftrate further how we come
to conceive a quality or virtue in the rofe
which we call fmell, and what this fmell is, it
is proper to obferve, that the mind begins ve-
ry early to third after principles, which may
direct it in the exertion of its powers. The
fmell of a rofe is a certain affection or feeling
of the mind ; and as it is not conftant, but
comes and goes, we want to know when and
where we may expect it, and are uneafy till
we find fomething, which being prefent,
brings this feeling along with it, and being
removed, removes it. This, when found, we
call the caufe of it ; not in a drier and philo-
fophical fenfe : as if the feeling were really
effected or produced by that caufe, but in a
popular fenfe : for the mind is fatisfied, if
E 3 there

yO OP THE HUMAN MIND. [CHAP. 3.

there is a conftant conjunction between them;
and fuch caufes are in reality nothing elfe but
laws of nature. Having found the fmell thus
conftantly conjoined with the rofe, the mind
is at reft, without inquiring whether this con-
junction is owing to a real efficiency or not ;
that being a philofophical inquiry, which
does not concern human life. But every dif-
covery of fuch a conftant conjunction is of
real importance in life, and makes a ftrong
impreflion upon the mind.

So ardently do we defire to find every
thing that happens within our obfervation,
thus connected with fomething elfe, as its
caufe or occafion, that we are apt to fancy
connections upon the flighteft grounds : and
this weaknefs is mod remarkable in the igno-
rant, who know lead of the real connections
eftablifhed in nature. A man meets with an
unlucky accident on a certain day of the
year ; and knowing no other caufe of his mif-
fortune, he is apt to conceive fomething un-
lucky in that day of the calendar ; and if he
finds the fame connection hold a fecond time,
is ftrongly confirmed in his fuperftition. I
remember, many years ago, a white ox was
brought into this country, of fo enormous a
fize, that people oame many miles to fee him.

There

SECT. 9.] OF SMELLING. JI

There happened, fome months after, an un-
common fatality among women in child-
bearing. Two fuch uncommon events fol-
lowing one another, gave a fufpicion of
their connection, and occafioned a com-
mon opinion among the country-people, that
the white ox was the caufe of this fatali-
ty-

However filly and ridiculous this opinion
was, it fprung from the fame root in human
nature, on which all natural philofophy
grows ; namely, an eager defire to find out
connections in things, and a natural, original,
and unaccountable propenfity to believe, that
the connections which we have obferved in
times paft, will continue in time to dome.
Omens, portents, good and bad luck, palmi-
ftry, aftrology, all the numerous arts of divi-
nation, and of interpreting dreams, falfe hy-
pothefes and fyflems, and true principles in
the philofophy of nature, are all built upon
the fame foundation in the human conftitu-
tion \ and are diftinguifhed only according
as we conclude ralhly from too few in-
ftances, or cautioufly from a fufficient indue-
tion.

As it is experience only that difcovers thefe

connections between natural caufes and their

E 4 effects ;

Jt OF THE HUMAN MIND. [CHAP. 2.

effects ; without inquiring further, we attri-
bute to the caufe fome vague and indiftinct
notion of power or virtue to produce the ef-
fect. And in many cafes, the purpofes of
life do not make it neceffary to give diftinct
names to the caufe and the effect. Whence
it happens, that being clofely connected in
the imagination, although very uniike to each
other, one name ferves for both ; and, in com-
mon difcourfe, is moil frequently applied to
that which, of the two, is moft the object of
our attention. This occafions an ambiguity
in many words, which having the fame caufes
in all languages, is common to all, and is apt
to be overlooked even by philofophers. Some
inflances will ferve both to illuftrate and con-
firm what we have faid.

Magnetifm fignifies both the tendency of
the iron towards the magnet, and the power
of the magnet to produce that tendency ; and
if it was afked, whether it is a quality of the
iron or of the magnet? one would perhaps be
puzzled at firft ; but a little attention would
difcover, that we conceive a power or virtue
in the magnet as the caufe, and a motion in
the iron as the effect ; and although thefe are
things quite unlike, they are fo united in the
imagination, that we give the common name

of

SECT. 9.] OF SMELLING. 73

of magnetifm to both. The fame thing may
be faid of gravitation, which fometimes figni-
fies the tendency of bodies towards the earth,
fometimes the attractive power of the earth,
which we conceive as the caufe of that ten-
dency. We may obferve the fame ambigui-
ty in fome of Sir Ifaac Newton's definitions ;
and that even in words of his own making.
In three of his definitions, he explains very
diftinctly what he underftands by the abfolute
quantity, what by the accelerative quanti-
ty, and what by the motive quantity, of a
centripetal force. In the firft of thefe three
definitions, centripetal force is put for thp
caufe, which we conceive to be fome power
or virtue in the centre or central body : in
the two laft, the fame word is put for the
effect of this caufe, in producing velocity,
or in producing motion towards that centre.

Heat fignifies a fenfation, and cold a contra-
ry one. But heat likewife fignifies a quality
or flate of bodies, which hath no contrary,
but different degrees. When a man feels the
fame water hot to one hand, and cold to the
other, this gives him occafion to diftinguifh
between the feeling, and the heat of the bo-
dy 5 and although he knows that the fenfa-
tions are contrary, he does not imagine that

the

74 OF THE HUMAN MINTD. [CHAF. 2.

the body can have contrary qualities at the
fame time. And when he finds a different
talte in the fame body in ficknefs and in
health, he is eafily convinced, that the quali-
ty in the body called tajle is the fame as be-
fore, although the fenfations he has from it
are perhaps oppofite.

The vulgar are commonly charged by phi-
lofophers, with the abfurdity of imagining
the fmeli in the rofe to be fomething like to
the fenfation of fmelling : but I think, un-
juftly ; for they neither give the fame epithets
to both, nor do they reafon in the fame man-
ner from them. What is fmell in the rofe ?
It is a quality or virtue of the rofe, or of
fomething proceeding from it, which we per-
ceive by the fenfe of fmelling ; and this is all
we know of the matter. But what is fmell-
ing ? It is an act of the mind, but is never
imagined to be a quality of the mind. Again,
the fenfation of fmelling is conceived to infer
necefTarily a mind or fentient being ; but
fmell in the rofe infers no fuch thing. We
fay, This body fmells fweet, that ftinks ; but
we do not fay, This mind fmells fweet, and that
ftinks. Therefore, fmell in the rofe, and the
fenfation which it caufes, are not conceived,
even by the vulgar, to be things of the

fame

SECT. 9.] 1 OF SMELLING. 75

fame kind, although they have the fame
name.

From what hath been faid, we may learn,
that the fmell of a rofe fignifies two things.
Firjiy A fenfation, which can have no exiltence
but when it is perceived, and can only be in
a fentient being or mind. Secondly, It figni-
fies fome power, quality, or virtue, in the
rofe, or in effluvia proceeding from it, which
hath a permanent exiftence, independent of
the mind, and which by the conflitution of
nature, produces the fenfation in us. By the
original conflitution of our nature, we are
both led to believe, that there is a permanent
caufe of the fenfation, and prompted to feek
after it ; and experience determines us to
place it in the rofe. The names of all fmells,
taftes, founds, as well as heat and cold, have
a like ambiguity in all languages ; but it de-
fences our attention, that thefe names are but
rarely, in common language, ufed to fignify
the fenfations ; for the moil part, they fignify
the external qualities which are indicated by
the fenfations. The caufe of which pheno-
menon I take to be this : Our fenfations have
very different degrees of flrength. Some of
them are fo quick and lively, as to give us a
great deal either of pleafure or of uneafinefs :

When

yd OF THE HUMAN MIND. [CHAP. 2.

When this is the cafe, we are compelled to
attend to the fenfation itfelf, and to make it
an object of thought and difcourfe ; we give
it a name, which fignifies nothing but the fen-
fation ; and in this cafe we readily acknow-
ledge, that the thing meant by that name is
in the mind only, and not in any thing exter-
nal. Such are the various kinds of pain, fick-
nefs, and the fenfations of hunger and other
appetites. But where the fenfation is not fo
interefting as to require to be made an object
of thought, our conftitution leads us to confi-
der it as a fign of fomething external, which
hath a conftant conjunction w7ith it ; and
having found what it indicates, we give a
name to that : the fenfation, having no proper
name, falls in as an acceflbry to the thing fig-
nified by it, and is confounded under the
fame name. So that the name may indeed
be applied to the fenfation, but moft proper-
ly andcommonly is applied to the thing in-
dicated by that fenfation. The fenfations of
fmell, tafte, found, and colour, are of infi-
nitely more importance as figns or indica-
tions, than they are upon their own ac-
count ; like the words of a language, where-
in we do not attend to the found, but to the
fenfe.

SECT.

SECT. 10.] OF SMELLING. 77

SECT. X.

Whether infenfation the mind is atlive or paf-
Jive P

THERE is one inquiry remains, Whether
in fmelling, and in other fenfations,
the mind is active or paflive ? This pofllbly
may feem to be a queftion about words, or at
leaft of very fmall importance \ however, if it
lead us to attend more accurately to the ope-
rations of our minds, than we are accuflomed
to do, it is upon that very account not alto-
gether unprofitable. I think the opinion of
modern philofophers is, that in fenfation the
mind is altogether paflive. And this un-
doubtedly is fo far true, that we cannot raife
any fenfation in cur minds by willing it ;
and, on the other hand, it feems hardly pof-
fiblc to avoid having the fenfation, when the
object is prefented. Yet it feems likewife
to be true, that in proportion as the attention
is more or lefs turned to a fenfation, or di-
verted from it, that fenfation is more or lefs

perceived

jf8 OF THE HUMAN MINI). [cHAP* 1<

perceived and remembered. Every one
knows, that very intenfe pain may be divert-
ed by a furprife, or by any thing that entirely
occupies the mind. When we are engaged in
earned converfation, the clock may ftrike by
us without being heard ; at leaft we remem-
ber not the next moment that we did hear it.
The noife and tumult of a great trading city,
is not heard by them who have lived in it all
their days ; but it ftuns thofe flrangers who
have lived in the peaceful retirement of the
country. Whether therefore there can be
any fenfation where the mind is purely paf-
five, I will not fay ; but I think we are con-
fcious of having given fome attention to eve-
ry fenfation which we remember, though ever
fo recent.

No doubt, where the impulfe is ftrong and
uncommon, it is as difficult to withhold at-
tention, as it is to forbear crying out in rack-
ing pain, or darting in a fudden fright : but
how far both might be attained by ftrong re-
folution and practice, is not eafy to deter-
mine. So that, although the Peripatetics
had no good reafon to fuppofe an active and
a paflive intellect, fince attention may be well

enough

SECT. IO.] OF SMELLING. 79

enough accounted an act of the will ; yet I
think they came nearer to the truth, in hold-
ing the mind to be in fenfation partly paffive
and partly a&ive, than the moderns, in af-
firming it to be purely paffive. Senfation,
imagination, memory, and judgment, have,
by the vulgar, in all ages, been confidered as
acls of the mind. The manner in which they
are exprefTed, in all languages, fhews this.
When the mind is much employe4 in them,
we fay it is very a&ive ; whereas, if they were
imprefiions only, as the ideal philofophy
would lead us to conceive, we ought in fuch
a cafe rather to fay, that the mind is very
palfive : for I fuppofe no man would attri-
bute great activity to the paper I write
upon, becaufe it receives variety of charac-
ters.

The relation which the fenfation of fmell
bears to the memory and imagination of it,
and to a mind or iubject, is common to all
our fenfations, and indeed to all the opera-
tions of the mind : the relation it bears to the
will, is common to it with all the powers of
underftanding : and the relation it bears to
that quality or virtue of bodies which it in-
dicates, is common to it with the fenfations

of

80 OF THE HUMAN MIND. [CHAP. 2.

of tafte, hearing, colour, heat, and cold : fo
that what hath been faid of this fenfe, may
eafily be applied to feveral of our fenfes, and
to other operations of the mind ; and this, I
hope, will apologize for our infilling fo long
upon it.

CHAP.

CHAP. 3.] OF TASTING. 8l

CHAP. III.

OF TASTING.

A GREAT part of what hath been faid of
the fenfe of fmelling, is fo eafily applied
to thofe of tailing and hearing, that we (hall
leave the application entirely to the reader's
judgment, and fave ourfelves the trouble of a
tedious repetition.

It is probable that every thing that afFe&s
the tafte, is in fome degree foluble in the fa-
Uva. It is not conceivable how any thing
fhould enter readily, and of its own accord,
as it were, into the pores of the tongue, pa-
late, and fauces, unlefs it had fome chemical
affinity to that liquor with which thefe pores
are always replete. It is therefore an admi-
rable contrivance of nature, that the organs
of tafte mould always be moift with a liquor
which is founiverfal a menftruum, and which
deferves to be examined more than it hath been
hitherto, both in that capacity, and as a me-
dical unguent. Nature teaches dogs, and
F other

82 OF THE HUMAN MIND. [CHAP. 3.

other animals, to ufe it in this laft way ; and
its fubferviency both to tafte and digeftion,
fhews its efficacy in the former.

It is with manifeft defign and propriety,
that the organ of this fenfe guards the en-
trance of the alimentary canal, as that of
fmell, the entrance of the canal for refpira-
tion. And from thefe organs being placed
in fuch manner, that every thjng that enters
into the ftomach mull undergo the fcrutiny
of both fenfes, it is plain, that they were in-
tended by nature to diftinguifh wholefome
food from that which is noxious. The brutes
have no other means of chooling their food ;
nor would mankind, in the favage ftate. And
it is very probable, that the fmell and tafte,
no way vitiated by luxury or bad habits,
would rarely, if ever, lead us to a wrong
choice of food among the productions of na-
ture ; although the artificial compofitions of
a refined and luxurious cookery, or of che-
miftry and pharmacy, may often impofe up-
on both, and produce things agreeable to the
tafte and fmell, which are noxious to health.
And it is probable, that both fmell and tafte are
vitiated, and rendered lefs fit to perform their
natural offices, by the unnatural kind of life
men commonly lead in fociety.
«s Thefe

CHAP. 3.] OF TASTING. 83

Thefe fenfes are likewife of great ufe to
diftinguifh bodies that cannot be diftinguifh-
ed by our other fenfes, and to difcern the
changes which the fame body undergoes,
which in many cafes are fooner perceived by
tafte and fmell than by any other means.
How many things are there in the market,
the eating-houfe, and the tavern, as well as in
the apothecary and chemift's (hops, which
are known to be what they are given out to
be, and are perceived to be good or bad in
their kind, only by tafte or fmell ? And how
far our judgment of things, by means of our
fenfes, might be improved by accurate atten-
tion to the fmall differences of tafte and fmell,
and other fenfible qualities, is not eafy to de-
termine. Sir Isaac Newton, by a noble ef-
fort of his great genius, attempted from the
colour of opaque bodies, to difcover the mag-
nitude of the minute pellucid parts, of which
they are compounded : and who knows what
new lights natural philofophy may yet receive
from other fecondary qualities duly exami-
ned ?

Some taftes and fmells ftimulate the nerves,
and raife the fpirits : but fuch an artificial
elevation of the fpirits is, by the laws of na-
ture, followed by a depreffion, which can on-
F2 ly

84 OF THE HUMAN MIND. [CHAP. 3.

ly be relieved by time, or by the repeated
ufe of the like Jlimulus. By the ufe of fuch
things we create an appetite for them, which
very much refembles, and hath all the force
of a natural one. It is in this manner that
men acquire an appetite for fnuff, tobacco,
ftrong liquors, laudanum, and the like.

Nature indeed feems ftudioufly to have
fet bounds to the pleafures and pains we have
by thefe two fenfes, and to have confined them
within very narrow limits, that we might
not place any part of our happinefs in them ;
there being hardly any fmell or tafte fo difa-
greeable that ufe will not make it tolerable,
and at laft perhaps agreeable; nor any fo agree-
able as not to lofe its relifh by conftant ufe.
Neither is there any pleafure or pain of thefe
fenfes which is not introduced, or followed,
by fome degree of its contrary, which nearly
balances it. So that we may here apply the
beautiful allegory of the divine Socrates ;
That although pleafure and pain are con-
trary in their nature, and their faces look dif-
ferent ways, yet Jupiter hath tied them fo
together, that he that lays hold of the one,
draws the other along with it.

As there is a great variety of fraells, feem-
ingly fimple and uncompounded, not only al-
together

CHAP. 3.] OF TASTING. 85

together unlike, but fome of them contrary
to others ; and as the fame thing may be faid
of taftes ; it would feem that one tafte is not
lefs different from another than it is from a
fmell : and therefore it may be a queftion, how
all fmells come to be considered as one genus,
and all taftes as another ? What is the gene-
rical diftinction? Is it only that the nofe is
the organ of the one, and the palate of the
other ? or, abftracting from the organ, is
there not in the fenfations themfelves fome-
thing common to fmells, and fomething elfe
common to taftes, whereby the one is dif-
tinguifhed from the other ? It feems moil
probable that the latter is the cafe ; and that
under the appearance of the greateft iimplici-
ty, there is ftill in thefe fenfations fomething
of compofition.

If one confiders the matter abftra&ly, it

would feem, that a number of fenfations, or

^indeed of any other individual things, which

are perfectly limple and uncompounded, are

incapable of being reduced into genera and

/pedes ; becaufe individuals which belong to

a fpecies, muft have fomething peculiar to

each, by which they are diftinguifhed, and

fomething common to the whole fpecies.

And the fame may be faid of fpecies which be-

F 3 long

86 OF THE HUMAN MIND. [CHAP. 3,

long to one genus. And whether this does
not imply fome kind of compofition, we (ball
leave to metaphyficians to determine.

The fenfations both of fmell and tafte do
undoubtedly admit of an immenfe variety of
modifications, which no language can exprefs.
If a man was to examine five hundred dif-
ferent wines, he would hardly find twoof them
that had precifely the fame tafte : the fame
thing holds in cheefe, and in many other
things. Yet of five hundred different taftes
in cheefe or wine, we can hardly defcribe
twenty, fo as to give a diftincl notion of them
to one who had not tailed them.

Dr Nehemiah Grew, a molt judicious and
laborious naturalift, in a difcourfe read be-
fore the Royal Society, anno 1675, hath en-
deavoured to fhow, that there are at leaft fix-
teen different fimple taftes, which he enu-
merates. How many compound ones may be
made out of all the various combinations of
two, three, four, or more of thefe fimple ones,
they who are acquainted with the theory of
combinations will eafily perceive. All thefe
have various degrees of intenfenefs and weak-
nefs. Many of them have other varieties :
in fome the tafte is more quickly perceived
upon the application of the fapid body, in

others

CHAP. 3.] OF TASTING. 87

others more (lowly ; in fome the fenfation is
mor: permanent, in others more tranfient ;
in fome it feems to undulate, or return after
certain intervals, in others it is conftant : the
various parts of the organ, as the lips, the tip
of the tongue, the root of the tongue, the
fauces, the uvula, and the throat, are fome of
them chiefly affected by one fapid body, and
others by another. All thefe, and other va-
rieties of taftes, that accurate writer illuftrates
by a number of examples. Nor is it to be
doubted, but fmells, if examined with the
fame accuracy, would appear to have as great
variety.

F4 CHAP.

88 OF THE HUMAN MIND. [CHAP. 4.

CHAP. IV.
OF HEARING.

SECT. I.

Variety of founds. Their place and diflance
learned by cujlom, without reafoning*

SOUNDS have probably no lefs variety of
modifications, than either taftes or
odours. For, firft, founds differ in tone.
The ear is capable of perceiving four or five
hundred variations of tone in found, and pro-
bably as many different degrees of ftrength ;
by combining thefe, we have above twenty
thoufand fimple founds that differ either in
tone or ftrength, fuppofing every tone to be
perfect. But it is to be obferved, that to make
a perfect tone, a great many undulations of
elaftic air are required, which muft all be of
equal duration and extent, and follow one
another with perfecl regularity ; and each

undulation

SECT. I.] OF HEARING. 89

undulation muft be made up of the advance
and recoil of innumerable particles of elaftic
air, whofe motions are all uniform in direc-
tion, force, and time. Hence we may eafily
conceive a prodigious variety in the fame
tone, arifing from irregularities of it, occafion-
ed by the conftitution, figure, fituation, or
manner of ftriking the fonorous body : from
the conftitution of the elaftic medium, or its
being difturbed by other motions ; and from
the conftitution of the ear itfelf, upon which
the impreffton is made.

A flute, a violin, a hautboy, and a French
horn, may all found the fame tone, and be
eafily diftinguifhable. Nay, if twenty hu-
man voices found the fame note, and with
equal ftrength, there will (till be fome diffe-
rence. The fame voice, while it retains its
proper difti nations, may yet be varied many
ways, by ficknefs or health, youth or age,
leannefs or fatnefs, good or bad humour. The
fame words fpoken by foreigners and natives,
nay, by perfons of different provinces of the
fame nation, may be diftinguifhed.

Such an immenfe variety of fenfatiops of
fmell, tafte, and found, furely was not given
us in vain. They are figns, by which we
know and diftinguifh things withoutus ; and

it

9^ Of THE HUMAN MIND. [CHAP. 4.

it was fit that the variety of the figns fhould,
in fome degree, correfpond with the variety
of things iignified by them.

It feems to be by cuftom, that we learn to
diftinguifh both the place of things, and their
nature, by means of their found. That fuch
a noife is in the ftreet, fuch another in the
room above me ; that this is a knock at my
door, that, a perfon walking up flairs ; is pro-
bably learnt by experience. I remember,
that once lying abed, and having been put
into a fright, I heard my own heart beat ;
but I took it to be one knocking at the door,
and arofe and opened the door oftener than
once, before I difcovered that the found was
in my own breaft. It is probable, that previ-
ous to all experience, we mould as little
know, whether a found came from the right
or left, from above or below, from a great or
a fmall diftance, as we fhould know whether
it was the found of a drum, or a bell, or a
cart. Nature is frugal in her operations, and
will not be at the expence of a particular in-
ftincl:, to give us that knowledge which expe-
rience will foon produce, by means of a gene-
ral principle of human nature.

For a little experience, by the conftitution
of human nature, ties together, not only in

our

SECT. I.] OF HEARING. gi

our imagination, but in our belief, thofe
things which were in their nature unconnect-
ed. When I hear a certain found, I con-
clude immediately, without reafoning, that a
coach pafles by. There are no premifes from
which this conclusion is inferred by any rules
of logic. It is the effect of a principle of
our nature, common to us with the brutes.

Although it is by hearing, that we are ca-
pable of the perceptions of harmony and me-
lody, and of all charms of mufic ; yet it
would feem, that thefe require a higher fa-
culty, which we call a mujical ear. This
feems to be in very different degrees, in thofe
who have the bare faculty of hearing equally
perfect ; and therefore ought not to be claf-
fed with the external fenfes, but in a higher
order.

SECT.

92 CfT THE HUMAN MIND. [CHAF. 4*

SECT. II.

Of natural language.

ONE of the nobleft purpofes of found un-
doubtedly is language ; without which
mankind would hardly be able to attain any
degree of improvement above the brutes.
Language is commonly confidered as purely
an invention of men, who by nature are no
lefs mute than the brutes, but having a fupe-
rior degree of invention and reafon, have been
able to contrive artificial figns of their
thoughts and purpofes, and to eftablifh them
by common confent. But the origin of lan-
guage deferves to be more carefully inquired
into, not only as this inquiry may be of im-
portance for the improvement of language,
but as it is related to the prefent fubjec~t, and
tends to lay open fome of the firil principles
of human nature. I fhall therefore offer fome
thoughts upon this fubjedt.

By language, I underftand all thofe figns
which mankind ufe in order to communicate

to

*ECT. 2.] OF HEARING. 93

to others their thoughts and intentions, their
purpofes and defires. And fuch ligns may
be conceived to be of two kinds : Firft, fuch
as have no meaning, but what is affixed to
them by compact or agreement among thofe
who ufe them ; thefe are artificial figns : Se-
condly, fuch as, previous to all compact or
agreement, have a meaning which every man
underftands by the principles of his nature.
Language, fo far as it confifts of artificial
ligns, may be called artificial ; fo far as it con-
fifts of natural figns, I call it natural.

Having premifed thefe definitions, I think it
is demonftrable, that if mankind had not a na-
tural language, they could never have invent-
ed an artificial one by their reafon and inge-
nuity. For all artificial language fuppofes
fome compact or ageement to affix a certain
meaning to certain figns ; therefore there
muft be compacts or agreements before the
ufe of artificial figns ; but there can be no
compact or agreement without figns, nor
without language ; and therefore there muft
be a natural language before any artificial
language can be invented : Which was to be
demonftrated.

Had language in general been a human in-
vention, as much as writing or printing, we

mould

94 OF TH£ HUMAN MIND. [CHAP. 4.

ihould find whole nations as mute as the
brutes. Indeed even the brutes have fome
natural figns by which they exprefs their
own thoughts, affections, and defires, and
underftand thofe of others. A chick, as
foon as hatched, understands the different
founds whereby its dam calls it to food, or
gives the alarm of danger. A dog or a horfe
underftands, by nature, when the human
voice careffes, and when it threatens him.
But brutes, as far as we know, have no no-
tion of contracts or covenants, or of moral ob-
ligation to perform them. If nature had gi-
ven them thefe notions, (he would probably
have given them natural figns to exprefs
them. And where nature has denied thefe
notions, it is as impoffible to acquire them by
art, as it is for a blind man to acquire the no-
tion of colours, Some brutes are fenfible of
honour or difgrace ; they have refentment
and gratitude ; but none of them, as far as we
know, can make a promife, or plight their
faith, having no fuch notions from their con-
ftitution. And if mankind had not thefe no-
tions by nature, and natural figns to exprefs
them by, with all their wit and ingenuity
they could never have invented language.

The

SECT. 2.] OF HEARINO. 95

The elements of this natural language of
mankind, or the figns that are naturally ex-
prefiive of our thoughts, may, I think, be re-
duced to thefe three kinds; modulations of
the voice, geftures, and features. By means
of thefe, two lavages who have no common
artificial language, can converfe together ;
can communicate their thoughts in fome to-
lerable manner ; can afk and refufe, affirm
and deny, threaten and fuppiicate ; can traf-
fic, enter into covenants, and plight their
faith. This might be confirmed by hiftori-
cal facts of undoubted credit, if it were ne-
ceflary.

Mankind having thus a common language
by nature, though a fcanty one, adapted only
to the neceffities of nature, there is no great
ingenuity required in improving it by the ad-
dition of artificial figns, to fupply the defici-
ency of the natural. Thefe artificial figns
muit multiply with the arts of life, and the
improvements of knowledge. The articu-
lations of the voice, feem to be, of all figns,
the moft proper for artificial language ; and
as mankind have univerfally ufed them for
that purpofe, we may reafonably judge that
nature intended them for it. But nature pro-
bably does not intend that we mould lay

afidc

g6 of the human mind. [chap. 4.

afide the ufe of the natural figns ; it is
enough that we fupply their defe&s by artifi-
cial ones. A man that rides always in a
chariot, by degrees lofes the ufe of his legs ;
and one who ufes artificial figns only, lofes
both the knowledge and ufe of the natural.
Dumb people retain much more of the natu-
ral language than others, becaufe neceflity ob-
liges them to ufe it. And for the fame rea-
fon, favages have much more of it than civi-
lized nations. It is by natural figns chiefly
that we give force and energy to language;
and the lefs language has of them, it is the
lefs expreflive and perfuafive. Thus, writing
is lefs expreflive than reading, and reading
lefs expreflive than fpeaking without book ;
fpeaking without the proper and natural mo-
dulations, force, and variations of the voice,
is a frigid and dead language, compared with
that which is attended with them ; it is ftill
more expreflive when we add the language
of the eyes and features ; and is then only
in its perfect and natural ftate, and attended
with its proper energy, when to all thefe we
fuperadd the force of action.

Where fpeech is natural, it will be an ex-
ercife, not of the voice and lungs only, but of
all the mufcles of the body •, like that of

dumb

SECT. I.] OT HEARING. 97

dumb people and favages, whofe language, as
it has more of nature, is more exprefiive, and
is more eafily learned.

Is it not pity that the refinements of a civi-
lized life, inftead of fupplying the defects of
natural language, mould root it out, and plant
in its Head dull and lifelefs articulations of un-
meaning founds, or the fcrawling of infigni-
ficant characters ? The perfection of language
•is commonly thought to be, to exprefs hu-
man thoughts and fentiments diftinctly by
thefe dull figns ; but if this is the perfection
of artificial language, it is furely the corrup-
tion of the natural.

Artificial figns fignify, but they do not ex-
prefs ; they fpeak to the understanding, as al-
gebraical characters may do, but the paffions,
the affections, and the will, hear them not :
thefe continue dormant and inactive, till we
fpeak to them in the language of nature, to
which they are all attention and obedience.

It were eafy to mew, that the fine arts of
the mulician, the painter, the actor, and the
orator, fo far as they are exprefiive ; although
the knowledge of them requires in us a deli-
cate tafte, a nice judgment, and much ftudy
and practice ; yet they are nothing elfe but
ihe language of nature, which we brought

G into

98 OF THE HUMAN MIND. [CHAP. 4.

into the world with us, but have unlearned
by difufe, and fo find the greateft difficulty in
recovering it.

Abolifh the ufe of articulate founds and
writing among mankind for a century, and
every man would be a painter, an actor, and
an orator. We mean not to affirm that fuch
an expedient is* practicable ; or, if it were,
that the advantage would counterbalance the
lofs ; but that, as men are led by nature and
neceffity to converfe together, they will ufe
every mean in their power to make themfelves
underftood ; and where they cannot do this
by artificial figns, they wjll do it, as far as
poffible, by natural ones : and he that under-
stands perfectly the ufe of natural figns, muft
be the beft judge in all the expreffive arts.

CHAP,

CHAP. 5.] OF TOUCH. 99

CHAP. V.
OF TOUCH.

SECT. I.

Of heat and cold.

THE fenfes which we have hitherto con-
fidered, are very fimple and uniform,
each of them exhibiting only one kind of fen-
fation, and thereby indicating only one quali-
ty of bodies. By the ear we perceive founds,
and nothing elfe ; by the palate, taftes ; and
by the nofe, odours: Thefe qualities are all
like wife of one order, being all fecondary
qualities : Whereas by touch we perceive not
one quality only, but many, and thofe of very
different kinds. The chief of them are heat
and cold, hardnefs and foftnefs, roughnefs and
fmoothnefs, figure, folidity, motion, and ex-
tenfion. We fhall confider thefe in order.

G ? As

100 OF THE HUMAN MIND. [CHAP. 5,

As to heat and cold, it will eafily be allow-
ed that they are fecondary qualities, of the
fame order with fmell, tafte, and found. And,
therefore, what hath been already faid of
fmell, is eafily applicable to them; that is,
that the words heat and cold have each of
them two nullifications ; they fometimes fig-
nify certain fenfations of the mind, which
can have no exiftence when they are not felt,
nor can exift anywhere but in a mind or fen-
tient being ; but more frequently they figni-
fy a quality in bodies, which, by the laws of
nature, occafions the fenfations of heat and
cold in us : A quality which, though con-
nected by cuftom fo clofely with the fenfa-
tion, that we cannot without difficulty fepa-
rate them ; yet hath not the leaft refemblance
to it, and may continue to exift when there is
no fenfation at all.

The fenfations of heat and cold are perfect-
ly known ; for they neither are, nor can be,
any thing elfe than what we feel them to be ;
but the qualities in bodies which, we call heat
and cold, are unknown. They are only con-
ceived by us, as unknown caufes or occafions
of the fenfations to which we give the fame
names. But though common fenfe fays no-
thing of the nature of thefe qualities, it plain-

Sect, i.] of touch. ioi

ly di&ates the exiftence of them ; and to de-
ny that there can be heat and cold when they
are not felt, is an abfurdity too gro£> to merit
confutation. For what could be more ab-
furd, than to fay, that the thermometer can-
not rife or fall, unlefs fome perfon be prefent,
or that the coaft of Guinea would be as cold
as Nova Zembla, if it had no inhabitants ?

It is the bufinefs of philofophers to invefti-
gate, by proper experiments and inductk n,
what heat and cold are in bodies. And
whether they make heat a particular element
diffufed through nature, and accumulated in
the heated body, or whether they make it a
certain vibration of the parts of the heated
body ; whether they determine that heat and
cold are contrary qualities, as the fenfations
undoubtedly are contrary* or that heat only
is a quality, and cold its privation : thefe que-
itions are within the province of philofophy ;
for common fenfe fays nothing on the one fide
or the other.

But whatever be the nature of that quality
in bodies which we call heat, we certainly
know this, that it cannot in the leaft refemble
the fenfation of heat. It is no lefs abfurd to
fuppofe a likenefs between the fenfation and
the quality, than it would be to fuppofe,, that
G3 the

102 OF THE HUMAN MIND. [CHAP^ gV

the pain of the gout refembles a fquare or *
triangle. The fimpleft man that hath com-
mon fenfe, does not imagine the fenfation of
heat, or any thing that refembles that fenfa-
tion, to be in the fire. He only imagines*
that there is fomething in the fire, which
makes him and other fentient beings feel
heat. Yet as the name of heat, in common
language, more frequently and more pro-
perly iignifies this unknown fomething in
the fire, than the fenfation occafioned by it,
he juftly laughs at the philofopher, who de-
nies that there is any heat in the fire, and
thinks that he fpeaks contrary to common
fenfe.

SECT. II.

Of hardnefs and foftnefs.

LET us next confider hardnefs and foft-
nefs ; by which words we always under-
ftand real properties or qualities of bodies of
which we have a diftinct conception.

When the parts of a body adhere fo firmly
that it cannot eafily be made to change its

figure,

SXCT. 2.] OF TOUCH. IO3

figure, we call it hard ; when its parts are
eafily difplaced, we call it /oft. This is the
notion which all mankind have of hardnefs
and foftnefs : they are neither fenfations, nor
like any fenfation ; they were real qualities
before they were perceived by touch, and con-
tinue to be fo when they are not perceived :
for if any man will affirm, that diamonds
were not hard till they were handled, who
would reafon with him ?

There is, no doubt, a fenfation by which we
perceive a body to be hard or foft. This fen-
fation of hardnefs may eafily be had, by pref-
fing one's hand againft the table, and attend-
ing to the feeling that enfues, fetting alide, as
much as poffible, all thought of the table and
its qualities, or of any external thing. But it
is one thing to have the fenfation, and ano-
ther to attend to it, and make it a diftind: ob-
ject of reflection. The firft is very eafy ; the
laft, in moil cafes, extremely difficult.

We are fo accultomed to ufe the fenfation
as a fign, and to pafs immediately to the hard-
nefs fignified, that, as far as appears, it was
never made an object of thought, either by
the vulgar or by philofophers ; nor has it a
name in any language. There is no fenfation
more diftinct, or more frequent j yet it is ne-
G 4, ver

104 OF THE HUMAN MIND. [CHAF. 5.

ver attended to, but pafTes through the mind
inftantaneoufly, and ferves only to introduce,,
that quality in bodies, which, by a law of our
conftitution, it fuggefts.

There are indeed fome cafes, wherein it is
no difficult matter to attend to the fenfation
occafioned by the hardnefs of a body ; for in-
flance, when it is fo violent as to occafion con-
liderable pain : then nature calls upon us to
attend to it,, and then we acknowledge, that
it is a mere fenfation, and can only be in a
fentient being. If a man runs his head with
violence againfl a pillar, I appeal to him,
whether the pain he feels refembles the hard-
nefs of th^ ftone ; or if he can conceive any
thing like what he feels, to be in an inani-
mate piece of matter.

The attention of the mind is here entirely
turned towards the painful feeling ; and, to
fpeak in the common language of mankind,
he feels nothing in the ftone, but feels a vio-
lent pain in his head. It is quite otherwife
when he leans his head gently againfl the pil-
lar ; for then he will tell you that he feels no-
thing in his head, but feels hardnefs in the
ftone. Hath he not a fenfation in this cafe
as well as in the other ? Undoubtedly he
hath : but k is a fenfation which nature in-
tended

SECT. 2.] OF TOUCK. 105

tended only as a fign of fomething in the
ftone ; and, accordingly, he inftantly fixes
his attention upon the thing fignified ; and
cannot, without great difficulty, attend fo
much to the fenfation, as to be perfuaded that
there is any fuch thing difhinct from the hard-
nefs it iignifies.

But however difficult it may be to attend
to this fugitive fenfation, to flop its rapid pro-
grefs, and to disjoin it from the external qua-
lity of hardnefs, in whofe fhadow it is apt im-
mediately to hide itfelf ; this is what a philo-
fopher by pains and practice mull attain,
otherwife it will be impoffible for him to rea-
fon juflly upon this fubjecl, or even to under -
ftand what is here advanced. For the lall ap-
peal, in fubjecls of this nature, mufl be to
what a man feels and perceives in his own
mind.

It is indeed ftrange, that a fenfation which
we have every time we feel a body hard, and
which, confequently, we can command as of-
ten, and continue as long as we pleafe, a fen-
fation as diftindl and determinate as any
other, fhould yet be fo much unknown, as ne-
ver to have been made an object of thought
and reflection, nor to have been honoured
with a name in any language \ that philofo-

phers,

*®5 OF THE HUMAN MIND. [CHAP. 5.

phers, as well as the vulgar, fhould have en-
tirely overlooked it, or confounded it with
that quality of bodies, which we call hard-
nefs to which it hath not the leaft fimilitude.
May we not hence conclude, That the know-
ledge of the human faculties is but in its in-
fancy ? That we have not yet learned to at-
tend to thofe operations of the mind, of
which we are confcious every hour of our
lives ? That there are habits of inattention
acquired very early, which are as hard to be
overcome as other habits ? For I think it is
probable, that the novelty of this fenfation
will procure fome attention to it in children
at firft ; but being in nowife interefting in it-
felf, as foon as it becomes familiar, it is over-
looked, and the attention turned folely to that
which it lignifies. Thus, when one is learn-
ing a language, he attends to the founds ; but
when he is matter of it, he attends only to the
fenfe of what he would exprefs. If this is
the cafe, we mull become as little children
again, if we will be philofophers : we mud
overcome this habit of inattention which has
been gathering ftrength ever fince we began
to think ; a habit, the ufefulnefs of which, in
common life, atones for the difficulty it-
creates

frECT. 2.} OF TOUCH. I07

creates to the philofopher, in difcovering the
firft principles of the human mind.

The firm cohefion of the parts of a body, is
no more like that fenfation by which I per-
ceive it to be hard, than the vibration of a fo-
norous body is like the found I hear : nor can
I poflibly perceive, by my reafon, any con-
nection between the one and the other. No
man can give a reafon, why the vibration of a
body might not have given the fenlation of
fmelling, and the effluvia of bodies affected
our hearing, if it had fo pleafed our Maker:
In like manner, no man can give a reafon,
why the fenfations of fmell, or tafte, or found*
might not have indicated hardnefs, as well as
that fenfation, which, by our conftitution*
does indicate it. Indeed no man can conceive
any fenfation to reiemble any known quality
of bodies. Nor can any man (hew, by any
good argument, that all our fenfations might
not have been as they are, though no body,
nor quality of body, had ever exifted.

Here, then, is a phenomenon of human na-
ture, which comes to be refolved. Hardnefs
of bodies is a thing that we conceive as di-
ftin&ly, and believe as firmly, as any thing in
nature. We have no way of coming at this
conception and belief, but by means of a cer-
tain

i08 OF THE HUMAN MIND. [CHAP. 5.

tain fenfation of touch, to which hardnefs
hath not the leaft fimilitude $ nor can wc, by
any rules of reafoning, infer the one from the
other. The queftion is, How we come by
this conception and belief?

Firft, as to the conception : Shall we call
it an idea of fenfation, or of renedion ? The
laft will not be affirmed ; and as little can the
firft, unlefs we will call that an idea of fenfa-
tion, which hath no refemblance to any fen-
fation. So that the origin of this idea of
hardnefs, one of the mod common and moll
diftind we have, is not to be found in all our
fyftems of the mind: not even in thofe
which have fo copioufly endeavoured to de-
duce all our notions from fenfations and re-

fle&ion.

But, fecondly, fuppofing we have got the
conception of hardnefs, how come we by the
belief of it ? Is it felf-evident, from compa-
ring the ideas, that fuch a fenfation could not
be felt, unlefs fuch a quality of bodies exift-
ed ? No. Can it be proved by probable or
certain arguments ? No, it cannot. Have
we got this belief, then, by tradition, by edu-
cation, or by experience ? No, it is not got
in any of thefe ways. Shall we then throw
off this belief, as having no foundation in rea-

fon?

SECT. 2.] OF TOUCH. IOO

fon ? Alas ! it is not in our power ; it tri-
umphs over reafon, and laughs at all the ar-
guments of a philofopher. Even the author
of the Treatife of Human Nature, though he
favv no reafon for this belief, but many againft
it, could hardly conquer it in his fpecuiative
and folitary moments ; at other times he fair-
ly yielded to it, and confeffes that he found
himfelf under a neceffity to do fo.

What fhall we fay then of this conception,
and this belief, which are fo unaccountable
and untraceable ? I fee nothing left, but to
conclude, that by an original principle of our
conftitution, a certain fenfation of touch both
fuggefts to the mind the conception of hard-
nefs, and creates the belief of it : or, in other
words, that this fenfation is a natural fign of
hardnefs. \nd this I fhall endeavour more
fully to explain.

SECT.

210 OF THE HUMAN MIND. [CHA** $.

SECT. III.

Of natural Jigns.

AS in artificial figns there is often neithet
, fimilitude between the fign and thing
iignified, nor any connection that arifes ne-
<:effarily from the nature of the things ; fo it
is alfo in natural figns. The word gold has
no fimilitude to the fubftance fignified by it.;
nor is it in its own nature more fit to fignify
this than any other fubftance : yet, by habit
and cuftom, it fuggefts this and no other. In
like manner, a fenfation of touch fuggefts
hardnefs, although it hath neither fimilitude
to hardnefs, nor, as far as we can perceive,
any neceifary connection with it. The dif-
ference betwixt thefe two figns lies only in
this, that, in the firft, the fuggeftion is the ef-
fect of habit and cuftom ; in the fecond, it is
not the effect of habit, but of the original con-
ftitution of our minds.

It appears evident from what hath been
faid on the fubjed of language, that there are
natural figns, as well as artificial ; and parti-
cularly,

SECT. 3.] OF TOUCH. Ill

cularly, That the thoughts, purpofes, and dif-
pofitions of the mind, have their natural figns
in the features of the face, the modulation of
the voice, and the motion and attitude of the
body : That without a natural knowledge of
the connection between thefe figns, and the
things fignified by them, language could ne-
ver have been invented and eftablifhed among
men : and, That the fine arts are all founded
upon this connection, which we may call the
natural language of mankind. It is now pro-
per to obferve, that there are different orders
of natural figns, and to point out the different
claffes into which they may be diftinguifhed,
that we may more diftinctly conceive the re-
lation between our fenfations and the things
they fuggeft, and what we mean by calling
fenfations figns of external things.

The firft clafs of natural figns comprehends
thofe whofe connection with the thing figni-
fied is eftablifhed by nature, but difcovered
only by experience. The whole of genuine
philofophy confifts in difcovering fuch con-
nections, and reducing them to general rules.
The great Lord Verulam had a perfect com-
prehenfion of this, when he called it an inter-
pretation of nature. No man ever more di-
ftinctly underftood, or happily expreffed, the

nature

112 OF THE HUMAN MIND. [CHAP, g.

nature and foundation of the philofophic art.
What is all we know of mechanics, aftrono-
my, and optics, but connections eftablifhed
by nature, and difcovered by experience or
obfervation, and confequences deduced from
them ? All the knowledge we have in agri-
culture, gardening, chemiftry, and medicine,
is built upon the fame foundation. And if
^ver our philofophy concerning the human
mind is carried fo far as to deferve the name
of fcience, which ought never to be defpaired
of, it mud be by obferving fads, reducing
ihem to general rules, and drawing juft con-
clufions from them. What we commonly call
natural caufes, might, with more propriety, be
called natural Jigns, and what we call effects,
the things Jignified. The caufes have no pro-
per efficiency or cafualty, as far as we know ;
and all we can certainly affirm, is, that nature
hath eftablifhed a conftant conjunction be-
tween them and the things called their ef-
fects ; and hath given to mankind a difpofi-
tion to obferve thofe connections, to confide
in their continuance, and to make ufe of them
for the improvement of our knowledge, and
increafe of our power.

A fecond clafs is that wherein the connec-
tion between the fign and thing fignified, is

not

SEdT. 3.] OF TOUCH. II3

not only eftabiifhed by nature, but difcovered
to us by a natural principle, without reafon-
ing or experience. Of this kind are the na-
tural ligns of human thoughts, purpofes, and
defires, which have been already mentioned
as the natural language of mankind. An in-
fant may be put into a fright by an angry
countenance, and foothed again by fmiles and
blandiihments. A child that has a good mu-
fical ear, may be put to fleep or to dance, may
be made merry or forrowful, by the modula-
tion of mulical founds. The principles of all
the fine arts, and of what we call a fine tafte,
may be refolved into connections of this kind.
A fine tafte may be improved by reafoning
and experience ; but if the firft principles of
it were not planted in our minds by nature^ it
could never be acquired. Nay, we have al-
ready made it appear, that a great part of this
knowledge, which we have by nature, is loft
by the difufe of natural figns, and the fubfti-
tution of artificial in their place.

A third clafs of natural figns comprehends
thofe which, though we never before had any
notion or conception of the things flgnined,
do fugged it, or conjure it up, as it were, by
a natural kind of magic, and at once give us
a conception, and create a belief of it. I
H fhewed

114 OF THE HUMAN MIND. [CHAP. J.

mewed formerly, that our fenfations fuggeft
to us a fentient being or mind to which they
belong : a being which hath a permanent ex-
iftence, although the fenfations are tranfient
and of fhort duration : a being which is ftill
the fame, while its fenfations and other ope-
rations are varied ten thoufand ways : a being
which hath the fame relation to all that infi-
nite variety of thoughts, purpofes, actions, af-
fections, enjoyments, and fufferings, which we
are confcious of, or can remember. The con-
ception of a mind is neither an idea of fenfa-
tion nor of reflection \ for it is neither like
any of our fenfations, nor like any thing we
are confcious of. The firft conception of it,
as well as the belief of it, and of the common
relation it bears to all that we are confcious
of, or remember, is fuggefted to every think-
ing being, we do not know how.

The notion of hardnefs in bodies, as well
as the belief of it, are got in a fimilar man-
ner ; being by an original principle of our na-
ture, annexed to that fenfation which we
have when we feel a hard body. And fo na-
turally and neceffarily does the fenfation con-
vey the notion and belief of hardnefs, that hi-
therto they have been confounded by the
mod acute inquirers into the principles of

human

S£CT. 3.] OF TOUCH. II

D

human nature, although they appear, upon
accurate refledion, not only to be different
things, but as unlike as pain is to the point of
a fword.

It may be obferved, that as the firft clafs of
natural figns I have mentioned, is the foun-
dation of true philofophy, and the fecond,
the foundation of the fine arts, or of tafte ; ib
the lad is the foundation of common fenfe ; a
part of human nature which hath never been
explained.

I take it for granted, that the notion of
hardnefs, and the belief of it, is firft got by
means of that particular fenfation, which, as
far back as we can remember, does invariably
fuggeft it ; and that if we had never had fuch
a feeling, we mould never have had any no-
tion of hardnefs. I think it is evident, that
we cannot, by reafoning from our fenfations,
collect the exiftence of bodies at all, far lefs
any of their qualities. This hath been pro-
ved by unanfwerable arguments by the Bi-
fhop of Cloyne, and by the author of the
Treatife of Human Nature. It appears as evi-
dent, that this connection betwTeen our fenfa-
tions and the conception and belief of exter-
nal exiftences, cannot be produced by habit,
experience, education, or any principle of
H 2 human

\l6 of THE HUMAN MIND. [CHAP. 5,

human nature that hath been admitted by
philofophers. At the fame time, it is a fad,
that fuch fenfations are invariably connected
with the conception and belief of external
exiftences. Hence, by all rules of juft rea-
foning, we mull conclude, that this connec-
tion is the effect of our conftitution, and
ought to be conlidered as an original prin-
ciple of human nature, till we find fome
more general principle into which it may be
refolved.

SECT. IV.

Ofbardnefs, and other primary qualities.

FUrther I obferve, that hardnefs is a qua-
lity, of which we have as clear and di-
ftindl a conception as of any thing whatfo-
ever. The cohefion of the parts of a body
with more or lefs force, is perfectly under-
flood, though its caufe is not : we know what
it is, as well as how it affects the touch. It
is therefore a quality of a quite different order
from thofe fecondary qualities we have already
taken notice of, whereof we know no more na-
turally,

SECT. 4.] OF TOUCH. HJ

turally, than that they are adapted to raife
certain fenfations in us. If hardnefs were a
quality of the fame kind, it would be a proper
inquiry for philofophers, What hardnefs in
bodies is ? and we mould have had various
hypothefes about it, as well as about colour
and heat. But it is evident that any fuch
hypothefis would be ridiculous. If any man,
mould fay, that hardnefs in bodies is a certain
vibration of their parts, or that it is certain
effluvia emitted by them which affect our
touch in the manner we feel ; fuch hypothe-
fes would mock common fenfe ; becaufe we
all know, that if the parts of a body adhere
itrongly, it is hard, although it mould neither
emit effluvia, nor vibrate. Yet at the fame
time, no man can fay, but that effluvia, or
the vibration of the parts of a body, might
have affected our touch, in the fame manner
that hardnefs now does, if it had fo pleafed
the Author of our nature : and if either of
thefe hypothefes is applied to explain a fe-
condary quality, fuch as fmell, or tafte, or
found, or colour, or heat, there appears no
manifeft abfurdity in the fuppofition.

The diftin&ion betwixt primary and fe-
condary qualities hath had feveral revolu-
tions. Democritus and Epicurus, and
H 3 their

II? OF THE HUMAN MJND. [pHAB. 5.

their followers, maintained it. Aristotle
and the Peripatetics aboliftied it. Des
Cartes, Malebranche, and Locke, revi-
ved it, and were thought to have put it in a
very clear light. But Bifliop Berkeley
again difcarded this diftin&ion, by fuch
proofs as mud be convincing to thofe that
hold the received doctrine of ideas. Yet, af-
ter all, there appears to be a real foundation
for it in the principles of our nature.

What hath been faid of hardnefs, is fo ea-.
fily applicable, not only to its oppofite, foft-
nefs, but likewife to roughnefs and fmooth-
nefs, to figure and motion, that we may be
excufed from makitig the application, which
would only be a repetition of what hath been
faid. All thefe, by means of certain corre-
fponding fenfations of touch, are prefented to
the mind as real external qualities ; the con-
ception and the belief of them are invariably
connected with the correfponding fenfations,
by an original principle of human nature.
Their fenfations have no name in any lan-
guage ; they have not only been overlooked
by the vulgar, but by philofophers ; or if
they have been at all taken notice of, they
have been confounded with the external qua-
lities which they fugged.

SECT,

SECT. 5.] OF TOUCH. HO,

SECT. V.

Of extenfion.

1

T is further to be obferved, that hardnefs
and foftnefs, roughnefs and fmoothnefs,
figure and motion, do all fuppofe extenfion,
and cannot be conceived without it ; yet I
think it mult, on the other hand, be allowed,
that if we had never felt any thing hard or
foft, rough or fmooth, figured or moved, we
fhould never have had a conception of exten-
fion : fo that as there is good ground to be-
lieve, that the notion of extenfion could not
be prior to that of other primary qualities ; fo
it is certain that it could not be poflerior to
the notion of any of them, being necefTarily
implied in them all.

Extenfion, therefore, feems to be a quality
fuggefted to us, by the very fame fenfations
which fuggeft the other qualities above men-
tioned. When I grafp a ball in my hand, I
perceive it at once hard, figured and extend-
ed. The feeling is very fimple, and hath not
the leafl refemblance to any quality of body.
Yet it fuggefls to us three primary qualities
H 4 perfectly

120 OF THE HUMAN MIND. [CHAP. 5,

perfectly diftind from one another, as well as
from the fenfation which indicates them.
When I move my hand along the table, the
feeling is fo fimple, that I find it difficult to
diftinguifh it into things of different natures ;
yet it immediately fuggefts hardnefs, fmooth-
nefs, extenfion, and motion, things of very dif-
ferent natures, and all of them as diftin&ly
underftood as the feeling which fuggefts
them.

We are commonly told by philofophers, that
we get the idea of extenfion by feeling along
the extremities of a body, as if there was no
manner of difficulty in the matter. I have
fought, with great pains, I confefs, to find out
how this idea can be got by feeling, but I
have fought in vain. Yet it is one of the
clearer!: and mod diftincl: notions we have ;
nor is there any thing whatfoever, about
which the human underftanding can carry on
fo many long and demonftrative trains of rea-
ibning.

The notion of extenfion is fo familiar to us
from infancy, and fo conftantly obtruded by
every thing we fee and feel, that we are apt
to think it obvious how it comes into the
mind ; but upon a narrower examination we
fhali find it utterly inexplicable. It is true

we,

SECT. 5.] OF TOUCH. 121

we have feelings of touch, which every mo-
ment prefent extenfion to the mind ; but how
they come to do fo, is the queftion ; for thofe
feelings do no more refemble extenfion, than
they refemble juftice or courage : nor can the
exiftence of extended things be inferred from
thofe feelings by any rules of reafoning : fo
that the feelings we have by touch, can nei-
ther explain how we get the notion, nor how
we come by the belief of extended things.

What hath impofed upon philofophers in
this matter, is, that the feelings of touch,
which fuggeft primary qualities, have no
names, nor are they ever reflected upon. They
pafs through the mind inftantaneoufly, and
ferve only to introduce the notion and belief
of external things, which by our conftitution
are connected with them. They are natural
figns, and the mind immediately paiTes to the
thing fignified, without making the leaft re-
flection upon the fign, or obferving that there
was any fuch thing. Hence it hath always
been taken for granted, that the ideas of ex-
tenfion, figure, and motion, are ideas of fenfa-
tion, which enter into the mind by the fenfe
of touch, in the fame manner as the fenfations
of found and fmell do by the ear and nofe.
The fenfations of touch are fo connected, by

our

122 OF THE HUMAN MINt). [CHAP. 5.

our conftitution, with the notions of exten-
sion, figure, and motion, that philofophers
have miftaken the one for the other, and ne-
ver have been able to difcern that they were
not only diftincl: things, but altogether unlike.
However, if we will reafon diftinclly upon
this fubjedt, we ought to give names to thofe
feelings of touch ; we muft accuftom ourfeives
to attend to them, and to refled upon them,
that we may be able to disjoin them from,
and to compare them with, the qualities fig-
nified or fuggefted by them.

The habit of doing this is not to be attain-
ed without pains and practice ; and till a man
hath acquired this habit, it will be impoflible
for him to think diftinctly, or to judge right,
upon this fubject.

Let a man prefs his hand againft the table :
he feels it hard. But what is the meaning of
this ? the meaning undoubtedly is, that he
hath a certain feeling of touch, from which
he concludes, without any reaibning, or com-
paring ideas, that there is fomething external
really exifting, whofe parts flick fo firmly to-
gether, that they cannot be difplaced without
confiderable force.

There is here a feeling, and a conclufion
drawn from it, or fome way fuggefted by it.

In

SECT. 5.] OF TOUCH. 123

In order to compare thefe, we muft view them
feparately, and then confider by what tie they
are connected, and wherein they refemble one
another. The hardnefs of the table is the
conclulion, the feeling is the medium by
which we are led to that conclulion. Let a
man attend diftinctly to this medium, and to
the conclulion, and he will perceive them to
be as unlike as any two things in nature. The
one is a fenfation of the mind, which can have
no exiftence but in a fentient being ; nor can
it exift one moment longer than it is felt ;
the other is in the table, and we conclude
without any difficulty,- that it was in the ta-
ble before it was felt, and continues after the
feeling is over. The one implies no kind of
extenfion, nor parts, nor cohefion ; the other
implies all thefe. Both indeed admit of de-
grees ; and the feeling, beyond a certain de-
gree, is a fpecies of pain ; but adamantine
hardnefs does not imply the leaft pain.

And as the feeling hath no fimilitude to
hardnefs, fo neither can our reafon perceive
the leaft tie or connection between them ; nor
will the logician ever be able to fhow a rea-
fon why we mould conclude hardnefs from
this feeling, rather than foftnefs, or any other
quality whatfoever. But in reality all man-
kind

124 OF THE HUMAN MIND. [CHAP. 5.

kind are led by their conftitution to conclude
hardnefs from this feeling.

The fenfation of heat, and the fenfation we
have by prefhng a hard body, are equally
feelings : nor can we by reafoning draw any
conclufion from the one, but what may be
drawn from the other : but, by our conftitu-
tion, we conclude from the firfl an obfcure or
occult quality, of which we have only this re-
lative conception, that it is fomething adapted
to raife in us the fenfation of heat ; from the
fecond, we conclude a quality of which we
have a clear and diftindt conception, to wit,
the hardnefs of the body.

SECT.

SECT. 6.] OF TOUCH. 12$

SECT. VI.

Of extenfion.

TO put this matter in another light, it
may be proper to try, whether from
fenfation alone we can collect any notion of
extenfion, figure, motion, and fpace. I take
it for granted, that a blind man hath the fame
notions of extenfion, figure, and motion, as a
man that fees ; that Dr Saunderson had the
fame notion of a cone, a cylinder, and a
fphere, and of the motions and diftances of
the heavenly bodies, as Sir Isaac Newton.

As fight therefore is not necefTary for our
acquiring thofe notions, we (hall leave it out
altogether in our inquiry into the flrft origin
of them ; and (hall fuppofe a blind man, by
fome flrange diftemper, to have loft all the ex-
perience and habits and notions he had got
by touch ; nor to have the lead conception of
the exiftence, figure, dimenfions, or extenfion,
either of his own body, or of any other ; but
to have all his knowledge of external things
to acquire anew, by means of fenfation, and

the,

Xl6 OF THE HUMAN MIND. [CHAP. 5;

the power of reafon, which we fuppofe to re-
main entire.

We fhall, firft, fuppofe his body fixed im-
moveably in one place, and that he can only
have the feelings of touch, by the application
of other bodies to it. Suppofe him firft to be
pricked with a pin ; this will, no doubt, give
a fmartt fenfation : he feels pain ; but what
can he infer from it ? Nothing furely with re-
gard to the exiftence or figure of a pin. He
can infer nothing from this fpecies of pain,
which he may not as well infer from the gout
or fciatica. Common fenfe may lead him to
think that this pain has a caufe ; but whether
this caufe is body or ipirit, extended or unex-
tended, figured or not figured, he cannot pof-
fibly, from any principles he is fuppofed to
have, form the leaft conjecture. Having had
formerly no notion of body or of extenfion*
the prick of a pin can give him none.

Suppofe, next, a body not pointed, but
blunt, is applied to his body with a force gra-
dually increafed until it bruifes him. What
has he got by this, but another fenfation, or
train of fenfations, from which he is able to
conclude as little as from the former? A
fchirrous tumour in any inward part of the
body,byprefiing upon the adjacent parts, may

give

SECT. 6.] OF TOUCH. I 27

give the fame kind of fenfation as the preflure
of an external body, without conveying any
notion but that of pain, which furely hath no
refemblance to extenfion.

Suppofe, thirdly, that the body applied to
him touches a larger or a lefier part of his
body. Can this give him any notion of its
extenfion or dimenlions ? To me it feems im-
poflible that it fhould, unlefs he had fome
previous notion of the dimenfions and figure
of his own body, to ferve him as a meafure.
When my two hands touch the extremities
of a body ; if I know them to be a foot afun-
der, I eafily collect that the body is a foot
long ; and if I know them to be five feet afun-
der, that it is five feet long : but if I know
not what the diftance of my hands is, I cannot
know the length of the object they grafp ;
and if I have no previous notion of hands at
all, or of diftance between them, I can never
get that notion by their being touched.

Suppofe, again, that a body is drawn along
his hands or face, while they are at reft : Can
this give him any notion of fpace or motion ?
It no doubt gives a new feeling ; but how it
mould convey a notion of fpace or motion, to
one who had none before, I cannot conceive.
The blood moves along the arteries and veins,

and

128 OF THE HUMAN MIND. [CHAP. 5,

and this motion, when violent, is felt : but I
imagine no man, by this feeling, could get the
conception of fpace or motion, if he had it not
before. Such a motion may give a certain
fucceffion of feelings, as the colic may do ;
but no feelings, nor any combination of feel-
ings, can ever refemble fpace or motion.

Let us next fuppofe, that he makes fome
inftin&ive effort to move his head or his
hand ; but that no motion follows, either on
account of external refiftance, or of palfy.
Can this effort convey the notion of fpace and
motion to one who never had it before ? Sure-
ly it cannot.

Laft of all, let us fuppofe, that he moves a-
limb by inftinct, without having had any pre-
vious notion of fpace or motion. He has here
a new fenfation, which accompanies the flex-
ure of joints, and the fwelling of mufcles.
But how this fenfation can convey into his
mind the idea of fpace and motion, is ftill al-
together myfterious and unintelligible. The
motions of the heart and lungs are all per-
formed by the contraction of mufcles, yet give
no conception of fpace or motion. An em-
bryo in the womb has many fuch motions,
and probably the feelings that accompany
them, without any idea of fpace or motion.

Upon

SECT. 6.] 0* TOUCH. I 29

Upon the whole, it appears, that our phi-
lofophers have impofed upon themfelves, and
upon us, in pretending to deduce from fenfa-
tion the firft origin of our notions of external
exiftences, of fpace, motion, and extenfion, and
all the primary qualities of body, that is, the
qualities whereof we have the moft clear and
diftinct conception. Thefe qualities do not
at all tally with any fyftem of the human fa-
culties that hath been advanced. They have
no refemblance to any fenfation, or to any
operation of our minds; and therefore they
cannot be ideas either of fenfation, or of re-
flection. The very conception of them is ir-
reconcilable to the principles of all our phi-
lofophic fyftems of the understanding. The
belief of them is no lefs fo.

SECT-

I30 OF THE HUMAN MIND. [CHAP. 5,

SECT. VII.

Of the exiftence of a material world,

IT is beyond our power to fay, when or in
what order we came by our notions of thefe
qualities. When we trace the operations of
our minds as far back as memory and reflec-
tion can carry us, we find them already in
poffefiion of our imagination and belief, and
quite familiar to the mind: but how they
came firft into its acquaintance, or what has
given them fo ftrong a hold of our belief, an4
what regard they deferve, are no doubt very
important queftions in the philofophy of hu-
man nature.

Shall we, with the Bifhop of Cloyne, ferve
them with a ^vo warranto, and have them
tried at the bar of philofophy, upon the fta-
tute of the ideal fyftem ? Indeed, in this trial
they feem to have come off very pitifully.
For although they had very able counfel,
learned in the law, viz. Des Caktes, Male-
bran che, and Locke, who faid every thing
they could for their clients ; the Bifhop of

Cloyne,

SECT, y.] OF TOUCH. I3I

Clovne, believing them to be aiders and abet-
ters of herefy and fchifm, prosecuted them
with great vigour, fully anfwered all that
had been pleaded in their defence, and filen-
ced their ableft advocates, who feem for half
a century pad to decline the argument, and
to truft to the favour of the jury rather than
to the iirength of their pleadings.

Thus, the wifdom of philofophy is fet in op-
pofition to the common fen fe of mankind. The
firft pretends to demonftrate a priori, that
there can be no fuch thing as a material
world ; that fun, moon, ftars, and earth, ve-
getable and animal bodies, are, and can be no-
thing clfe, but fenfations in the mind, or
images of thofe fenfations in the memory and
imagination ; that, like pain and joy, they can
have no exiftence when they are not thought
of. The laft can conceive no otherwife of
this opinion, than as a kind of metaphyfical#
lunacy ; and concludes, that too much learn-
ing is apt to make men mad ; and that the
man who feriouily entertains this belief,
though in other refpecls he may be a very
good man, as a man may be who believes that
he is made of glafs ; yet furely he hath a foft
place in his underftanding, and hath been
hurt by much thinking.

1 2 This

I32 OF THE HUMAN MIND. [CHAP. 5.

This oppofition betwixt philofophy and
common fenfe, is apt to have a very unhappy
influence upon the philoibpher himfelf. He
fees human nature in an odd, unamiable, and
mortifying light. He confiders himfelf, and
the reft of his fpecies, as born under a necef-
{\\y of believiqg ten thoufand abfurdities and
contradictions, and endowed with fuch a pit-
tance of reafofl, as is juft fufficient to make
this unhappy difcovery : and this is all the
fruit of his profound fpeculations. Such no-
tions of human nature tend to flacken every
nerve of the foul, to put every noble purpofe
and fentiment out of countenance, and fpread
a melancholy gloom, oyer the whole face of
things.

If this is wifdom, let me he deluded with
the vulgar. I find fomething within me that
recoils againft it, and infpires more reverent
fentiments of the human kind, and of the uni-
verfal adminiftration. Common fenfe and
reafon have both one author ; that Almighty
author, in all whpfe other works we obferve
a cpnfiftency, uniformity, and beauty, which
charm and delight the underftanding : there
muft therefore be fome order and confiftency
ip the human faculties, as well as in other
parts of his workmanfhip. A man that thinks

reverently

sfccT. 7.] of Tbucrt. 133

reverently of his own kind, and eftterrts true
wifdom and philofophy, will not be fond, nay,
will be very fufyicious, of fuch ftrartge and
paradoxical opinions. If they are fulie, they
difgrace philofophy ; and if they are true,
they degrade the human fpecies, and make
us juflly afhamed of our frame.

To what purpofe is it for philofophy to de-
cide againft common fenfe in this or any
other matter ? The belief of a material
world is older, and of more authority, than
any principles of philofophy. It declines the
tribunal of reafon, and laughs at all the artil-
lery of the logician. It retains its fovefeign
authority in fpite of all the edicts of philofo-
phy, and reafon itfelf mud ftoop to its orders.
Even thofe philofophers who have difoWned
the authority of our notions of an external
material world, confefs, that they find them-
felves under a neceffity of fubmitting to their
power.

Methinks, therefore, it were better to make
a virtue of neceffity ; and, fince we cannot
get rid of the vulgar notion and belief of an
external world, to reconcile our reafon to it
as well as we can : for if Reafon mould fto-
mach and fret ever fo much at this yoke, fhe
cannot throw it off; if (lie will not be the
1 3 fervant

134 OF THE HUMAN MIND. [CHAP. J.

fervant of Common Senfe, fhe mud be her
Have.

In order, therefore, to reconcile reafon to
common fenfe in this matter, I beg leave to
offer to the confideration of philofophers
thefe two obfervations. Firft, That in all
this debate about the exiftence of a material
world, it hath been taken for granted on both
iides, that this fame material world, if any
fuch there fre, mull be the exprefs image of
our fenfations ; that we can have no concep-
tion of any material thing which is not like
fome fenfation in our minds ; and particular-
ly, that the fenfations of touch are images of
extenfion, hardnefs, figure, and motion. Eve-
ry argument brought againfl the exiftence of
a material world, either by the Bifhop of
Gloyne, or by the author of the Treatife of
Human Nature, fuppofeth this. If this is
true, their arguments are conclufive and un-
anfwerable : but, on the other hand, if it is
not true, there is no fhadow of argument left.
Have thofe philofophers, then, given any fo-
fid proof of this hypotheiis, upon which the
whole weight of fo ftrange a fyftem refts ? No.
They have not fo much as attempted to do
it. But, becaufe ancient and modern philo-
fophers

SECT, 7.] OF TOUCH. 135

ibphcrs have agreed in this opinion, they
have taken it for granted. But let us, as be-
comes philofophers, lay afide authority ; we
need not furely confult Aristotle or
Locke, to know whether pain be like the
point of a fvvord. I have as clear a concep-
tion of extenfion, hardnefs, and motion, as I
have of the point of a fword ; and, with fome
pains and practice, I can form as clear a no-
tion of the other fenfations of touch, as I have
of pain. When I do fo, and compare them
together, it appears to me clear as day-
light, that the former are not of kin to the
latter, nor refemble them in any one feature.
They are as unlike, yea as certainly and ma-
nifestly unlike, as pain is to the point of a
fword. It may be true, that thofe fenfations
lirfl introduced the material world to our ac-
quaintance \ it may be true, that it feldom or
never appears without their company ; but,
for all that, they are as unlike as the paflion
of anger is to thofe features of the counte-
nance which attend it.

So that, in the fentence thofe philofophers
have palled againlt the material world, there
is an error perjona. Their proof touches
not matter, or any of its qualities ; but
ftvikes directly again!! an idol of their own
1 4 imagination,

I36 *" OF THE HUMAN MIND. [CHAP. 5.

imagination, a material world made of ideas
and fenfations, which never had nor can have
an exiftence.

Secondly, The very exiftence of our con-
ceptions of exteniion, figure, and motion,
lince they are neither ideas of fenfation nor
reflection, overturns the whole ideal fyftem,
by which the material world hath been tried
and condemned : fo that there hath been like--
wife in this fentence an error juris.

It is a very fine and a juft obfervation of
Locke, That as no human art can create a
fingle particle of matter, and the whole ex-
tent of our power over the material world,
confifts in compounding, combining, and dif-
joining, the matter made to our hands ; fo in
the world of thought, the materials are all
made by nature, and can only be varioirfly
combined and disjoined by us. So that it is
impoffible for reafon or prejudice, true or
falfe philofophy, to produce one fimple no-
tion or conception, which is not the work of
nature, and the refult of our conftitution.
The conception of extenfion, motion, and the
other attributes of matter, cannot be the ef-
fect of error or prejudice; it muftNbe the
work of nature. And the power or faculty,
by which we acquire thofe conceptions, muft

be

Sect, 7.] or touch. 157

be fomething different from any power of the
human mind that hath been explained, fince
it is neither fenfation nor reflection.

This I would therefore humbly propofe, as
an experimentum cruris, by which the ideal
fyftem muft ftand or fall ; and it brings the
matter to a fhort iffue : Extenflon, figure, mo-
tion, may, any one, or all of them, be taken
for the fubject of this experiment. Either
they are ideas of fenfation, or they are not.
If any one of them can be fhewn to be an
idea of fenfation, or to have the l^aft refem-
blance to any fenfation, I lay my hand up-
on my mouth, and give up all pretence to
reconcile reafon to common fenfe iirthis mat-
ter, and muft furfer the ideal fcepticifm to
triumph, But if, on the other hand, they are
not ideas of fenfation, nor like to any fenfa-
tion, then the ideal fyftem is a rope of fand,
ana* all the laboured arguments of the fcepti-
cal philofophy againft a material world, and
againft the exiftence of every thing but im-
preffions and ideas, proceed upon a falfe hy-
pothefis.

If our philofophy concerning the mind be
fo lame with regard to the origin of our no-
tions of the clearcft, molt (imple, and moft
familiar objects of thought and the powers

from

I38 OF THE HUMAN MIND. [CHAP. 5.

from which they are derived, can we expect
that it mould be more perfect in the account
it gives of the origin of our opinions and be-
lief? We have feen already fome inflances
of its imperfection in this refpect : and per-
haps that fame nature which hath given us
the power to conceive things altogether un-
like to any of our fenfations, or to any opera-
tion of our minds, hath likevvife provided for
our belief of them, by fome part of our con-
flitution hitherto not explained.

Bifhop Berkeley hath proved, beyond the
poflibility of reply, that we cannot by reafon-
ing infer the exiltence of matter from our
fenfations : and the author of the Treatife of
Human Nature hath proved no lefs clearly,
that we cannot by reafoning infer the exift-
ence of our own or other minds from our fen-
fations. But are we to admit nothing but
what can be proved by reafoning ? Then we
muft be fceptics indeed, and believe nothing
at all. The author of the Treatife of Human
Nature appears to me to be, but a half fceptic.
He hath not followed his principles fo far as
they lead him : but after having, with unpa-
ralleled intrepidity and fuccefs, combated
vulgar prejudices ; when he had but one
blow to ftrike, his courage fails him, he fair-

SECT. 7.] OF TOUCH. 1 39

\y lays down his arms, and yields himfelf a
captive to the moft common of all vulgar
prejudices, I mean the belief of the exiftence
of his own impreffions and ideas.

I beg, therefore, to have the honour of ma-
king an addition to the fceptical fyftem, with-
out which, I conceive, it cannot hang toge-
ther. I affirm, that the belief of the exift-
ence of impreflions and ideas, is as little fup-
ported by reafon, as that of the exiftence of
minds and bodies. No man ever did, or
could offer any reafon for this belief. Des
Cartes took it for granted, that he thought,
and had fenfations and ideas ; fo have all his
followers done. Even the hero of fcepticifm
hath yielded this point, I crave leave to fay,
weakly and imprudently. I fay fo, becaufe
I am perfuaded that there is no principle of
his philofophy that obliged him to make this
conceflion. And what is there in impreflions
and ideas fo formidable, that this all-conquer-
ing philofophy, after triumphing over every
other exiftence, fhould pay homage to them ?
Befides, the conceflion is dangerous : for be-
lief is of fuch a nature, that if you leave any
root, it will fpread ; and you may more eailly
pull it up altogether, than fay, Hitherto (halt
fhou go, and no further : the exiftence of im-

' prelfions

I4d OF THE HUMAN MIND. [CHAI\ 5*

preffi ons and ideas I give up to thee ; but fee
thou pretend to nothing more. A thorough
and confiftent fceptic will never, therefore,
yield this point ; and while he holds it,
you can never oblige him to yield any thing
elfe.

To fuch a fceptic I have nothing to fay ;
but of the femi-fceptics, I (hould beg leave
to know, why they believe the exiftence of
their impreffions and ideas. The true reafon
I take to be, becaufe they cannot help it ;
and the fame reafon will lead them to believe
many other things.

All reafoning mufl be from firft principles 3
and for firft principles no other reafon can be
given but this, that, by the conftitution of
our nature, we are under a neceffity of affent-
ing to them. Such principles are parts of our
conftitution, no lefs than the power of think-
ing: reafon can neither make nor deftroy
them ; nor can it do any thing without them :
it is like a telefcope, which may help a man
to fee farther, who hath eyes ; but without
eyes, a telefcope. (lie ws nothing at all. A ma-
thematician cannot prove the truth of his
axioms, nor can he prove any thing, unlefs
he takes them for granted. We cannot prove
the exiftence of our minds, nor even of our

thoughts

3ECT. 7»] OF TOUCH. I4I

thoughts and fenfations. A hiftorian, or a
witneis, can prove nothing, unlefs it is taken
for granted that the memory and fenfes may
be trufted. A natural philofopher can prove
nothing, unlefs it is taken for granted that
the courfe of nature is (leady and uniform.

How or when I got fuch firft principles,
upon which I build all my reafoning, I know
not 5 for 1 had them before I can remember ;
but I am fure they are parts of my conftitu-
tion, and that I cannot throw them off. That
our thoughts and fenfations muft have a fub-
jecl:, which we call ourfelf, is not therefore an
opinion got by reafoning, but a natural prin-
ciple. That our fenfations of touch indicate
fomething external, extended, figured, hard
or foft, is not a deduction of reafon, but a na-
tural principle. The belief of it, and the ve-
ry conception of it, are equally parts of our
qonftitution. If we are deceived in it, we
are deceived by Him that made us, and there
is no remedy.

I do not mean to affirm, that the fenfations
of touch do from the very firft fuggeft the
fame notions of body and its qualities, which
they do when we are grown up. Perhaps
nature is frugal in this, as in her other ope-
rations. The paftion of love, with all its

concomitant

142 OF THE HUMAN MIND. [ctfAP. 5.

concomitant fentiments and defircs, is natu-
rally fuggefted by the perception of beauty
in the other fex. Yet the fame perception
does not fuggeft the tender paffion, till a cer-
tain period of life. A blow given to an in-
fant, raifes grief and lamentation ; but when
he grows up, it as naturally ftirs refentment,
and prompts him to reliftance. Perhaps a
child in the womb, or for fome fhort period
of its exiftence, is merely a fentient being :
the faculties, by which it perceives an exter- (
nal world, by which it refle&s on its own
thoughts, and exiftence, and relation to other
things, as well as its reafoning and moral fa-
culties, unfold themfelves by degrees ; fo that
it is infpired with the various principles of
common fenfe, as with the pafnons of love and
refentment, when it has occafion for them,

SECT.

SECT. 8.] OF TOUCH. I43

SECT. VIII.

Of the fyjlems of pbilofophers concerning the
ftnfes.

ALL the fy items of philofophers^ about
our fenfes and their objects have fplit
upon this rock, of not diftinguifhing proper-
ly fenfations, which can have no exiftence but
when they are felt, from the things fuggefted
by them. Aristotle, with as diftinguifhing
a head as ever applied to philofophical dif-
quifitions, confounds thefe two ; and makes
every fenfation to be the form, without the
matter, of the thing perceived by it : As the
impreflion of a feal upon wax has the form of
the feal, but nothing of the matter of it ; fo
he conceived our fenfations to be imprefTions
upon the mind, which bear the image, like-
nefs, or form of the external thing perceived,
without the matter of it. Colour, found, and
fmell, as well as extenfion, figure, and hard-
nefs, are, according to him, various forms of
matter : our fenfations are the fame forms

imprinted

144 or THE HUMAN MIND. [CHAP. 5.

imprinted on the mind, and perceived in its
own intellect. It is evident from this, that
Aristotle made no diftinftion between pri-
mary and fecondary qualities of bodies, al-
though that diftinction was made by Demo-
critus, Epicurus, and others of the an-
c rents.

Des Cartes, Malebranche, and Locke,
revived the diftinction between primary and
fecondary qualities. But they made the fe-
condary qualities mere fenfations, and the
primary ones refemblances of our fenfations.
They maintained, that colour, found, and
heat, are not any thing in bodies, but fenfa-
tions of the mind : at the fame time, they ac-
knowledged fome particular texture or modi-
fication of the body, to be the caufe or occa-
ilon of thofe fenfations ; but to this modifica-
tion they gave no name. Whereas, by the
vulgar, the names of colour, heat, and found,
are but rarely applied to the fenfations, and
moll commonly to thofe unknown caufes of
them ; as hath been already explained. The
conftitution of our nature leads us rather to
attend to the things fignified by the fenfation,
than to the fenfation itfelf, and to give a
name to the former rather than to the latter.
Thus we fee, that with regard to fecondary

qualities,

SECT. 8.] OF TOUCH. 3 45

qualities, thefe philofophers thought with the
vulgar, and with common fenfe. Their para-
doxes were only an abuie of words. For
when they maintain, as an important modern
difcovery, that there is no heat in the fire,
they mean no more, than that the fire does
not feel heat, which every one knew be-
fore.

With regard to primary qualities, thefe phi-
lofophers erred more grofsly : They indeed
believed the exiftence of thofe qualities ; but
they did not at all attend to the fenfations
that fugged them, which having no names,
have been as little confidered as if they had
no exiftence. They were aware, that figure,
extenfion, and hardnefs, are perceived by
means of fenfations of touch ; whence they
rafhly concluded, that thefe fenfations mud
be images and refemblances of figure, exten-
fion, and hardnefs.

The received hypothefis of ideas naturally
led them to this conclufion ; and indeed can-
not confift with any other ; for, according to
that hypothefis, external things muft be per-
ceived by means of images of them in the
mind ; and what can thofe images of exter-
nal things in the mind be, but the fenfations
by which we perceive them ?

K This

ja6 of the human mind. [chap. 5.

This however was to draw a conclufion
from a hypothecs againft fact. We need not
have recourfe to any hypothecs to know what
our fenfations are, ov what they are like. By
a proper degree of reflection and attention, we
may understand them perfectly, and be as cer-
tain that they are not like any quality of body,
as we can be, that the toothach is not like a
triangle. How a fenfation mould inftantly
make us conceive and believe theexiftence of
an external thing altogether unlike to it, I do
not pretend to know ; and when I fay that
the one fuggefts the other, I mean not to ex-
plain the manner of their connection, but to
exprefs a fact, which every one may be con-
fcious of; namely, that, by a law of our na-
ture, fuch a conception and belief conftantly
and immediately follow the fenfation.

Bifhop Berkeley gave new light to this
fubjeel, by mowing, that the qualities of an
inanimate thing, fuch as matter is conceived
to be, cannot refenible any fenfation ; that it
is impoflible to conceive any thing like the
fenfations of our minds, but the fenfations of
other minds. Every one that attends proper-
ly to his fenfations mull affent to this ; yet it
had efcaped all the philofophers that came be-
fore Berkeley ; it had efcaped even the in-

genirus

SECT. 8.] OF TOUCH. I47

genious Locke, who had fo much praclifed
reflection on the operations of his own mind.
So difficult it is to attend properly even to
our own feelings. They are fo accuftomed
to pafs through the mind unobferved, and in-
ilantly to make way for that which nature
intended them to fignify, that it is extremely
difficult to flop, and furvey them > and when
we think we have acquired this power, per-
haps the mind dill fluctuates between the fen-
fation and its aflbciated quality, fo that they
mix together, and prefent fomething to the
imagination that is compounded of both.
Thus in a globe or cylinder, whofe oppofite
fides are quite unlike in colour, if you turn it
llowly, the colours are perfectly diftinguifh-
able, and their diffimilitude is manifefl ; but
if it is turned faft, they lofe their distinc-
tion, and feem to be of one and the fame co-
lour.

No fucceffion can be more quick, than that
of tangible qualities to the fenfations with
which nature has aflbciated them : But when
one has once acquired the art of making them
feparate and diflinct objects of thought, he will
then clearly perceive, that the maxim of Bi-
fhop Berkeley above mentioned, is felf-cvi-
dent ; and that the features of the face are
K 2 not

I48 OF THE HUMAN MIND. [CHAP. 5.

not more unlike to a paflion of the mind
which they indicate, than the fenfations of
touch are to the primary qualities of bo-

dy.

But let us obferve what ufe the Bifhop
makes of this important difcovery : Why, he
concludes, that we can have no conception of
an inanimate fubftance, fuch as matter is con-
ceived to be, or of any of its qualities ; and
that there is the ftrongeft ground to believe
that there is no exiftence in nature but minds,
fenfations, and ideas : If there is any other
kind of exiftences, it muft be what we neither
have nor can have any conception of. But
how does this follow ? Why thus : We can
have no conception of any thing but what re-
fembles fome fenfation or idea in our minds ;
but the fenfations and ideas in our minds can
refemble nothing but the fenfations and ideas
in other minds ; therefore, the conclufion is
evident. This argument, we fee, leans upon
two propofitions. The laft of them the inge-
nious author hath indeed made evident to all
that underftand his reafoning, and Can at-
tend to their own fenfations : but the firft
propoiition he never attempts to prove ; it
5s taken from the doctrine of ideas, which

hath

SECT. 8.] OF TOUCH. I49

hath been fo univerfally received by phi-
lofophers, that it was thought to need no
proof.

We may here again obferve, that this
acute writer argues from a hypothecs again it
fact, and againft the common fenfe of man-
kind. That we can have no conception of
any thing, unlefs there is fome impreffion,
fenfation, or idea, in our minds which rcfern-
bles it, is indeed an opinion which hath been
very generally received among philofophers ;
but it is neither felf-evident, nor hath it been
clearly proved : and therefore it had been
more reafonable to call in queltion this doc-
trine of philofophers, than to difcard the ma-
terial world, and by that means expofe philo-
fophy to the ridicule of all men, who will
not offer up common fenfe as a faerifice to
metaphyfics;

We ought, however, to do this jultice both,
to the Bifhop of Cloyne and to the author of
the Treatife of Human Nature, to acknow-
ledge, that their conclufions are juftly drawn
from the doctrine of ideas, which has been fo
univerfally received. On the other hand,
from the character of Bilhop Berkeley, and
of his predecefibrs Des Cartes, Locke, and
K 3 Malebrance,

I5C OF THE HUMAN MIND. [CHAP. 5.

Malebranche, we may venture to fay, that
if they had feen all the confequences of this
doctrine, as clearly as the author before men-
tioned did, they would have fufpeded it ve-
hemently, and examined it more carefully
than they appear to have done.

The theory of ideas, like the Trojan horfe,
had a fpecious appearance both of innocence
and beauty; but if thofe philofophers had
known that it carried in its belly death and
deftru&ion to all fcience and common fenfe,
they would not have broken down their walls
to give it admittance.

That we have clear and diftinc~t concep-
tions of extenlion, figure, motion, and other
attributes of body, which are neither fenfa-
tions, nor like any fenfation, is a fad of which
we may be as certain, as that we have fenfa-
tions. And that all mankind have a fixed be-
lief of an external material world, a belief
which is neither got by reafoning nor educa-
tion, and a belief which we cannot fhake off,
even when we feem to have ftrong arguments
againfl it, and no fhadow of argument for it,
is likewife a facl, for which we have all the
evidence that the nature of the thing admits.
Thefe facts are phenomena of human na-
ture,

Sect. 8.] of touch. 151

tare, from which we mny juilly argue againit
any hypothecs, however generally received.
But to argue from a hypothetic againft fads,
is contrary to the rules of true philofo-
phy.

K 4 CHAP.

I52 Or THE HUMAN MIND. [CHAF. 6,

CHAP. VI.

OF SEEING. 53-iixi

■

SECT. I.

The excellence and dignity of this faculty.

THE advances made in the knowledge of
optics in the laft ager and in the prefent,
and chiefly the difcoveries of Sir Isaac New-
ton, do honour, not to philofophy only, but
to human nature. Such difcoveries ought
for ever to put to fhame the ignoble attempts
of our modern fceptics to depreciate the hu-
man underftanding, and to difpirit men in the
fearch of truth, by reprefenting the human
faculties as fit for nothing, but to lead us into
abfurdities and contradictions*

Of the faculties called the five fenfes, fight
is without doubt the nobleft. The rays of
light, which minifter to this fenfe, and of

which,

SECT. I.] OF SEEING. I53;

which, without it, we could never have had
the lead conception, are the mod wonderful
and aftonifhing part of the inanimate creation.
We mud be fatisfied of this, if we conflder
their extreme minutenefs, their inconceivable
velocity, the regular variety of colours which
they exhibit, the invariable laws according to
which they are acted upon by other bodies,
in their reflections, inflections, and refractions,
without the lead change of their original pro-
perties, and the facility with which they per-
vade bodies of great denlity, and of the clo-
feft texture, without reiiftance, without
crowding or difturbing one another, without
giving the leaft fenfible impulfe to the light-
ed bodies.

The dructure of the eye, and of all its ap-
purtenances, the admirable contrivances of
nature for performing all its various external
and internal motions, and the variety in the
eyes of different animals, fuited to their feve-
ral natures and ways of life, clearly demon-
drate this organ to be a maderpiece of Na-
ture's work. And he mud be very ignorant
of what hath been difcovered about it, on
have a very drange cad of underdanding,
who can ferioufly doubt, whether or not the
rays of light and the eye were made for one

another,

154 0F THE HuMAN mind. [chap. 6.

another, with confummate wifdom, and per-
fed fkill in optics.

If we fhall fuppofe an order of beings, en-
dued with every human faculty but that of
light, how incredible would it appear to fuch
beings, accuftomed only to the flow informa-
tions of touch, that, by the addition of an or-
gan, confiding of a ball and focket of an inch
diameter, they might be enabled in an inltant
of tjme, without changing their place, to per-
ceive the difpofition of a whole army, or the
order of a battle, the figure of a magnificent
palace, or all the variety of a landfcape ? If a
man were by feeling to find out the figure of
the peak of Teneriffe, or even of St Peter's
Church at Rome, it would be the work of a
lifetime.

It would appear ft ill more incredible to fuch
beings as we have fuppofed, if they were in-
formed of the difcoveries which may be made
by this little organ in things far beyond the
reach of any other fenfe : That by means of
it we can find our way in the pathlefs ocean ;
that we can traverfe the globe of the earth,
determine its figure and dimenfions, and deli-
neate every region of it : Yea, that we can
meafure the planetary orbs, and make difco-
veries in the fphere of the fixed ftars.

Would

SECT. I.] OF SEEING* I

3D

Would it not appear ftill more aftonifhing
to fuch beings, if they fhould be further in-
formed, That, by means of this fame orga.n,
we can perceive the tempers and difpofitions,
the paffions and affections of our fellow-crea-
tures, even when they want mod to conceal
them ? That when the tongue is taught moft
artfully to lie and diffemble, the hypocrify
fhould appear in the countenance to a discern-
ing eye ? And that by this organ, we can of-
ten perceive what is ftraight and what is
crooked in the mind as well as in the body ?
— How many myfterious things muft a blind
man believe, if he will give credit to the re-
lations of thofe that fee ? Surely he needs as
ftrong a faith as is required of a good Chri-
ftian.

It is not therefore without reafon, that the
faculty of feeing is looked upon, not only as
more noble than the other fenfes, but as ha-
ving fomething in it of a nature fuperior to
fenfation. The evidence of reafon is called
feeing, not feeling, fmelling, or tafiing. Yea,
we are wont to exprefs the manner of the di-
vine knowledge by feeing, as that kind of
knowledge which is moil perfect in us.

SECT.

I56 01? THE HUMAN MIND. [CHAP. Oi

I

• I | f)

SECT. II.

&£$ difcovers ahnoft nothing which the MM
may not comprehend. The reafon of this.

Notwithstanding what hath been faid
pf the dignity and fuperior nature of
this faculty, it is worthy of our obfervation,
that there is very little of the knowledge ac-
quired by fight, that may not be communi-
cated to a man born blind. One who never
faw the light, may be learned arid knowing
in every fcience, even in optics ; and may
make difcoveries in every branch of philofo-
phy. He may underftand as much as an-
other man, not only of the order, diftances,
and motions of the heavenly bodies ; but of
the nature1 of light, and of the laws of the re-
fledion and refraction of its rays. He may
underftand diftinftly, how ttiofe laws produce
the phenomena of the rain-bow, the prifm,
the camera obfcura, and the magic larithorn,
and all the powers of the microfeope and
telefcope. This is a fa& fufficiently attefted

by experience.

In

SECT. l.\ OF SEEING. I57

In order to perceive the reafon of it, we
mud diftinguifh the appearance that obje&s
make to the eye, from the things fuggefted
by that appearance : and again, in the vifible
appearance of objects, we mufl diftinguifh
the appearance of colour from the appearance
of extenfion, figure, and motion. Firfl, then,
as to the vifible appearance of the figure, and
motion, and extenfion of bodies, I conceive
that a man born blind may have a diftinct no-
tion, if not of the very things, at lead of fome-
thing extremely like to them. May not a
blind man be made to conceive, that a body
moving directly from the eye, or directly to-
wards it, may appear to be at reft ? and that
the fame motion may appear quicker or flow-
er, according as it is nearer to the eye or far-
ther off, more direct or more oblique ? May
he not be made to conceive, that a plain fur-
face, in a certain pofition, may appear as a
ftraight line, and vary its vifible figure, as its
pofition, or the pofition of the eye, is varied ?
That a circle feen obliquely will appear an
eliipfe ; and a fquare, a rhombus, or an oblong
rectangle? Dr Saunderson underftood the
projection of the fphere, and the common
rules of perfpective ; and if he did, he muft
have underftood all that I have mentioned.

158 OF THE HUMAN MIND. [CHAP. 6.

If there were any doubt of Dr Saunderson's
underftandrng thefe things, I could mention
my having heard him fay in converfation, that
he found great difficulty in underftanding Dr
Halley's demonftration of that propofition,
That the angles made by the circles of .the
fphere, are equal to the angles made by their
reprefentatives in the ftereographic projec-
tion : But, faid he, when I laid afide that de-
monftration, and confidered the propofition in
my own way, I faw clearly that it mud be
true. Another gentleman, of undoubted cre-
dit and judgment in thefe matters, who had
part in this converfation, remembers it di-
ilindly.

As to the appearance of colour, a blind man
mud be more at a lofs ; becaufe he hath no
perception that refembles it. Yet he may, by
a kind of analogy, in part fupply this defect.
To thofe who fee, a fcarlet colour fignifies an *
unknown quality in bodies, that makes to the
eye an appearance, which they are well ac-
quainted with, and have often obferved : to
a blind man, it fignifies an unknown quality
that makes to the eye an appearance, which
he is unacquainted with. But he can con-
ceive the eye to be varioirfly affected by dif-
ferent colours, as the nofe is by different

fmells,

SECT. 2.] OF SEEING. 159

fmells, or the car by different founds. Thus
he can conceive fcaiiet to differ from blue, as
the found of a trumpet does from that of a
drum j or as the fmell of an orange differs
from that of an apple. It is impoflible to
know whether a fcarlet colour has the fame
appearance to me which it hath to another
man ; and if the appearances of it to differ-
ent perfons differed as much as colour does
from found, they might never be able to dif-
cover this difference. Hence it appears obvi-
ous, that a blind man might talk long about
colours diflinclly and pertinently : and if you
were to examine him in the dark about the
nature, compofition, and beauty of them, he
might be able to anfwer, fo as not to betray
his defect.

We have feen how far a blind man may go
in the knowledge of the appearances which
things make to the eye. As to the things
which are fuggefted by them, or inferred from
them ; although he could never difcover them
of himfelf, yet he may underfland them per-
fectly by the information of others. And
every thing of this kind that enters into our
minds by the eye, may enter into his by the
ear. Thus, for inftance, he could never, if
left to the direction of his own faculties, have

dreamed

2<6o OF THE HUMAN MIND. [CHAP. 6.

dreamed of any fuch thing as light ; but he
can be informed of every thing we know
about it. He can conceive, as diftinctly as
we, the minutenefs and velocity of its rays,
their various degrees of refrangibility and re-
flexibility, and all the magical powers and
virtues of that wonderful element. He could
never of himfelf have found out, that there
are fuch bodies as the fun, moon, and liars ;
but he may be informed of all the noble dif-
coveries of aftronomers about their motions,
and the laws of nature by which they are re-
gulated. Thus it appears, that there is very
little knowledge got by the eye, which may
not be communicated by language to thofe
who have no eyes.

If we mould fuppofe, that it were as uncom-
mon for men to fee, as it is to be born blind \
would not the few who had this rare gift, ap-
pear as prophets and infpired teachers to the
many ? We conceive infpiration to give a
man no new faculty, but to communicate to
him in a new way, and by extraordinary
means, what the faculties common to man-
kind can apprehend, and what he can com*
municate to others by ordinary means. On
the fuppofition we have made, fight would
appear to the blind very limiliar to this ; for

the

SECT. 1.] OF SEEING. l6t

the few who had this gift, could communicate
the knowledge acquired by it to thofe who
had it not. They could not indeed convey to
the blind any diftinct notion of the manner
in which they acquired this knowledge. A
ball and focket would feem, to a blind man,
in this cafe, as improper an inftrument for ac-
quiring fuch a variety and extent of know-
ledge, as a dream or a vifion. The manner in
which a man who fees, difcerns fo many
things by means of the eye, is as unintelligi-
ble to the blind, as the manner in which a
man may be infpired with knowledge by the
Almighty, is to us. Ought the blind man,
therefore, without examination, to treat all
pretences to the gift of feeing as impofture ?
Might he not, if he were candid and trada-
ble, find reafonable evidence of the reality of
this gift in others, and draw great advantages
from it to himfelf ?

The diftinclion we have made between the
vifible appearances of the objects of fight, and
things fuggefted by them, is neceflTary to give
us a juft notion of the intention of nature in
giving us eyes. If we attend duly to the
operation of our mind in the ufe of this facul-
ty, we (hall perceive, that the vifible appear-
ance of objects is hardly ever regarded by us.

L It

l6l OF THE HUMAN MIND. [CHAP. 6.

It is not at all made an objeft of thought or re-
flection, but ferves only as a fign to introduce
to the mind fomething elfe, which may be
diftindtly conceived by thofe who never faw.
Thus, the vifible appearance of things ia
my room varies almoft every hour, according
as the day is clear or cloudy, as the fun is in
the eaft, or fouth, or weft, and as my eye is !
in one part of the room or in another : but I
never think of thefe variations, other wife than
as figns of morning, naon, or night, of a clear
or cloudy fky. A book or a chair has a dif-
ferent appearance to the eye, in every differ-
ent diftance and pofition ; yet we conceive it
to be ftill the fame ; and, overlooking the ap-
pearance, we immediately conceive the real
figure, diftance, and pofition of the body, of
which its vifible or perfpective appearance is
a fign and indication.

When I fee a man at the diftance of ten
. yards, and afterwards fee him at the diftance
of a hundred yards, his vifible appearance in
its length, breadth, and all its linear propor-
tions, is ten times lefs in the laft cafe than it
is in the firft : yet I do not conceive him one
inch diminifhed by this diminution of his vi-
fible figure. Nay, I do not in the leaf! attend
to this diminution, even when 1 draw from it

the

SECT. 2.] OF SEEING. 163

the conclufion of his being at a greater di-
llance. For fuch is the fubtiity of the mind's
operation in this cafe, that we draw the con-
clufion, without perceiving that ever the pre-
mifes entered into the mind. A thoufand
fuch inftances might be produced, in order to
(hew that the vilible appearances of objects
are intended by nature only as flgns or indi-
cations ; and that the mind palTes inftantly
to the things figniried, without making the
leaft reflection upon the fign, or even percei-
ving that there is any fuch thing. It is in a
way fomewhat fimilar, that the founds of a
language, after it is become familiar, are over-
looked, and we attend only to the things fig-
nified by them.

It is therefore a juft and important obfer-
vation of the Bifhop of Cloyne, That the vi-
fible appearance of objects is a kind of lan-
guage ufed by nature, to inform us of their
diftance, magnitude, and figure. And this
obfervation hath been very happily applied
by that ingenious writer, to the folution of
fome phenomena in optics, which had before
perplexed the greateft matters in that fcience.
The fame obfervation is further improved by
the judicious Dr SMrTH, in his Optics, for ex-
plaining the apparent figure of the heavens,
L 2 and

164 OF THE HUMAN MIND. [CHAP. 6.

and the apparent diftances and magnitudes of
objects feen with glafles, or by the naked eye.
Avoiding as much as poffible the repetition
of what hath been faid by thefe excellent wri-
ters, we (hall avail ourfelves of the diftindion
between the figns that nature ufeth in this
vifual language, and the things fignified.by
them ; and in what remains to be faid of
fight, {hall firfl make fome obfervations upon
the iigns.

SECT. III.

Of the vijble appearances of objects.

1

N this fedlion we muft fpeak of things
which are never made the objecl: of reflec-
tion, though almoft every moment prefented
to the mind. Nature intended them only for
jigns ; and in the whole courfe of life they
are put to no other ufe. The mind has ac-
quired a confirmed and inveterate habit of
inattention to them ; for they no fooner ap^
pear, than quick as lightning the thing figni-
fied fucceeds, and engroffes all our regard.
They hav,e no name in language ; and al-
though we are confcious of them when they

pafst

f

SECT. 3.] OF SEEING. J 65

pafs through the mind, yet their paffage is fo
quick, and fo familiar, that it is absolutely
unheeded ; nor do they leave any footfteps
of themfelves, either in the memory or ima-
gination. That this is the cafe with regard
to the fenfations of touch, hath been fhown in
the, lad chapter ; and ft holds no lefs with re-
gard to the vifible appearances of objects.

I cannot therefore entertain the hope of
'being intelligible to thofe readers who have
not, by pains and practice, acquired the habit
of diftinguifhing the appearance of objects to
the eye, from the judgment which we form
by fight, of their colour, diftance, magnitude,
and figure. The only profeffion in life where-
in it is necefiary to make this diflinclion, is
that of painting. The painter hath occafion
for an abstraction, with regard to vifible ob-
jects, fomewhat fimilar to that which we here
require : and this indeed is the molt difficult
part of his art. For it is evident, that if he
could fix in his imagination the vifible ap-
pearance of objects, without confounding it
with the things fignified by that appearance,
it would be as eafy for him to paint from the
life, and to give every figure its proper fha-
ding and relief,- and its perfpective propor-
tions, as it is to paint from a copy. Pcrfpec-
L 3 tive,

l66 OF THE HUMAN MIND. [CHAP. 6.

tive, fliading, giving relief, and colouring, are
nothing elfe but copying the appearance
which things make to the eye. Wc may there-
fore borrow fome light on the fubject of vifi-
ble appearance from this art.

Let one look upon any familiar object, ftich
as a book, at different defiances and in differ-
ent pofitions : is he not able to affirm, upon
the teftimony of his fight, that it is the fame
book, the fame object, whether feen at the
diftance of one foot or of ten, whether in one
pofition or another \ that the colour is the
fame, the dimenfions the fame, and the figure
the fame, as far as the eye can judge ? This
furely m'uft be acknowledged. The fame in-
dividual object is prefented to the mind, only
placed at different diftances, and in different
pofitions. Let me afk, in the next place,
Whether this object has the fame appearance
to the eye in thefe different diftances ? Infalli-
bly it hath not. For,

Firft, However certain our judgment may
be that the colour is the fame, it is as certain
that it hath not the fame appearance at dif-
ferent diftances. TWiere is a certain degrada-
tion of the colour, and a certain confufion and
indiftinctnefs of the minute parts, which is
the natural confequence of the removal of the

obiccl;

SECT. 3.] OF SEEING. 167

object to a greater diftance. Thofe that are
not painters, or critics in painting, overlook
this ; and cannot eaiily be perluaded, that the
colour of the fame objecl hath a different ap-
pearance at the diftance of one foot and of ten,
in the fhade and in the light. But the ma-
ilers in painting know how, by the degrada-
tion of the colour, and the confufion of the
minute parts, figures, which are upon the
fame canvas, and at the fame diftance from the
eye, may be made to reprefent objects which
are at the moft unequal diftances. They
know how to make the objects appear to be of
the fame colour, by making their pictures real-
ly of different colours, according to their di-
flances or fliades.

Secondly, Every one who is acquainted
with the rules of perfpective, knows that the
appearance of the figure of the book mufl va-
ry in every different pofition : yet if you afk
a mart that has no notion of perfpective, whe-
ther the figure of it does not appear to his eye
to be the fame in all its different pofitions ?
he can with a good confeience affirm, that it
does. He hath learned to make allowance
for the variety of vifible figure arifing from the
difference of pofition, and to draw the proper
conclufions from it. But he draws thefe con-
L 4 cluftons

l63 OF THE HUMAN MIND. [CHAP. 6.

clufions fo readily and habitually, as to lofe
fight of the premifes; and, therefore, where he
hath made the fame conclufion, he conceives
the viiible appearance mud have been the
fame.

Thirdly, Let us confider the apparent mag-
nitude Qr dimenfions of the book. Whether
I view it at the diftance of one foot or of ,ten
feet, it feems to be about feven inches long,
five broad, and one thick. J can judge of
thefe dimenfions ve¥y nearly by the eye, and
I judge them to be the fame at both diftances.
But yet it is certain, that at the diftance of one
foot, its vifible length and breadth is about
ten times as great as at the diftance of ten
feet ; and confequently its furface is about a
hundred times as great. This great change
of apparent magnitude is altogether overlook-
ed, and every man is apt to imagine, that it
appears to the eye of the fame fize at both dif-
tances. Further, when I look at the book, it
feems plainly to have three dimenfions, of
length, breadth, and thicknefs : but it is cer-
tain that the viiible appearance hath no more
than two, and can be exactly reprefented up-
on a canvas which hath only length and
breadth.

In the lad place, Does not every man, by

fight,

SECT. 3.] OF SEEING. 169

fight, perceive the diftance of the book from
his eye ? Can he not affirm with certainty,
that in one cafe it is not above one foot diftant,
that in another it is ten ? Neverthelefs it ap-
pears certain, that diftance from the eye, is
no immediate object of fight. There are cer-
tain things in the vifible appearance, which
are figns of diftance from the eye, and from
which, as we fliall afterwards {how, we learn
by experience to judge of that diftance with-
in certain limits ; but it feems beyond doubt,
that a man born blind, and fuddenly made to
fee, could form no judgment at firft of the di-
ftance of the objects which he faw. The
young man couched by Cheseldon, thought,
at firft, that every thing he faw touched his
eye, and learned only by experience to judge
of the diftance of vifible objects.

I have entered into this long detail, in or-
der to ftiew, that the vifible appearance of an
object is extremely different from the notion
of it which experience teaches us to form by
fight ; and to enable the reader to attend to
the vifible appearance of colour, figure, and
cxtenfion, in vifible things, which is no com-
mon object of thought, but muft be carefully
attended to by thofe who would enter into the
philofophy of this fenfe, or would comprehend

what

170 OF THE HUMAN MIND. [CHAP. 6.

what (hall be faid upon it. To a man newly
made to fee, the vilible appearance of objects
would be the fame as to us ; but he would
fee nothing at all of their real dimenlions, as
we do. He could form no conjecture, by
means of his light only, how many inches or
feet they were in length, breadth, or thick-
nefs. He could perceive little or nothing of
their real figure ; nor could he difcern that
this was a cube, that a fpherc ; that this was
a cone, and that a cylinder. His eye could
not inform him, that this object was near, and
that more remote. The habit of a man or of
a woman, which appeared to us of one uniform
colour, varioufly folded and fhaded, would
prefent to his eye neither fold nor fhade, but
variety of colour. In a word, his eyes, though
ever fo perfect, would at firft give him almoft
no information of things without him. They
would indeed prefent the fame appearances to
him as they do to us, and fpeak the fame lan-
guage ; but to him it is an unknown language ;
and therefore he would attend only to the
ligns, without knowing the fignification of
them : whereas to us it is a language perfectly
familiar ; and therefore we take no notice of
the ligns, but attend only to the thing fignifi-
ed by them.

SECT.

SECT. 4.] OF SEEING. I7I

SECT. IV.

■That colour is a quality of bodies, not a fenfa-
tion of the mind.

BY colour, all men, who have not been
tutored by modern philcfophy, under-
hand, not a fenfation of the mind, which can
have no exiftencc when it is not perceived,
but a quality or modification of bodies, which
continues to be the fame, whether it is feen or,
not. The fcarlet-rofe, which is before me, is
Hill a fcarlet-rofe when I fhut my eyes, and was
fo at midnight when no eye faw it. The co-
lour remains when the appearance ceafes : it re-
mains the fame when the appearance changes.
For when I view this fcarlet-rofe through a
pair of green fpe&acles, the appearance is
changed, but I do not conceive the colour of
the rofe changed. To a perfon in the jaun-
dice, it has Hill another appearance ; but he
is eafily convinced, that the change is in his
eye, and not in the colour of the objecl. Eve-
ry different degree of light makes it have a
different appearance, and total darknefs takes

away

XJZ OF THE HUMAN MIND. [CHAP. 6.

away all appearance, but makes not the leaft
change in the colour of the body. We may,
by a variety of optical experiments, change
the appearance of figure and magnitude in a
body, as well as that of colour ; we may make
one body appear to be ten. But all men be-
lieve, that as a multiplying glafs does not real-
ly produce ten guineas out of one, nor a mi-
crofcope turn a guinea into a ten pound piece ;
fo neither does a coloured glafs change the
real colour of the object feen through it,
when it changes the appearance of that co-
lour.

The common language of mankind fhows
evidently, that we ought to diftinguifh be-
tween the colour of a body, which is concei-
ved to be a fixed and permanent quality in
the body, and the appearance of that colour to
the eye, which may be varied a thoufand
ways, by a variation of the light, of the medi-
um, or of the eye itfelf. The permanent co-
lour of the body is the caufe, which, by the
mediation of various kinds or degrees of
light, and of various tranfparent bodies inter-
pofed, produces all this variety of appearan-
ces. When a coloured body is prefented,
there is a certain apparition to the eye, or to
the mind, which we have called the appear-
2 ance

SECT. 4.] Of SEEING. 173

ance of colour. Mr Locke calls it an idea;
and indeed it may be called fo with the great-
eft propriety. This idea can have no exift-
ence bui when it is perceived. It is a kind
of thought, and can only be the act of a per-
cipient or thinking being. By the conftitu-
tion of our nature, we are led to conceive this
idea as a fign of fomething external, and are
impatient till we learn its meaning. A thou-
fand experiments for this purpofe are made
every day by children, even before they come
to the ufe of reafon. They look at things,
they handle them, they put them in various
pofitions, at different diftances, and in differ-
ent lights. The ideas of light, by thefe means,
come to be affociated with, and readily to fug-
ged, things external, and altogether unlike
them. In particular, that idea which we have
called the appearance of colour, fuggefts the
conception and belief of fome unknown qua-
lity in the body, which occalions the idea ;
and it is to this quality, and not to the idea,
that we give the name of colour. The vari-
ous colours, although in their nature equally
unknown, are eafily diftinguifhed when we
think or fpeak of them, by being affociated
with the ideas which they excite. In like
manner, gravity, magnetifm, and electricity,

although

1^4 THK I1UMAN MIND. [CHAP. 6.

although all unknown qualities, arc diftin-
guifhed by their different effects. As we
grow up, the mind acquires a habit of palling
fo rapidly from the ideas of fight to the ex-
ternal things fuggefted by them, that the ideas
are not in the lead attended to, nor have
they names given them in common language.
When we think or fpeak of any particular
colour, however fimple the notion may feem to
be, which is prefented to the imagination, it
is really in fome fort compounded. It in-
volves an unknown caufe, and a known ef-
fect. The name of colour belongs indeed to
the caufe only, and not to the effect. But
as the caufe is unknown, we can form no
difti.nct conception of it, but by its rela-
tion to the known effed. And therefore
both go together in the imagination, and are
fo clofely united, that they are miflaken for
one fimple object of thought. When I would
conceive thofe colours of bodies which we
call fcarlet and blue ; if 1 conceived them on-
ly as unknown qualities, I could perceive no
diftinction between the one and the other. I
muff therefore, for the fake of diftinction, join
.' to each of them, in my imagination, fome ef-
fect or fome relation that is peculiar. And
the mod obvious diftinction is, the appear-
ance which one and the other makes to the

eye. *

SECT. 4.] OF SEEING,

'

eye. Hence the appearance is, in the imagi-
nation, fo clofely united with the quality call-
ed afcarlet-colour, that they are apt to be mif-
taken for one and the fame thing, although
they are in reality fo different and fo unlike,
that one is an idea in the mind, the other is a
quality of body.

I conclude, then, that colour is not a fenfa-
tion, but a fecondary quality of bodies, in the
fenfe we have already explained ; that it is a
certain power or virtue in bodies, that in fair
daylight exhibits to the eye an appearance,
which is very familiar to us, although it hath
no name. Colour differs from other fecond-
ary qualities in this, that whereas the name
of the quality is fometimes given tothefenfa-
tion which indicates it, and is occafioned by
it, we never, as far as I can judge, give the
name of colour to the fenfation, but to the qua-
lity only. Perhaps the reafon of this may be,
that the appearances of the fame colour are fo
various and changeable, according to the dif-
ferent modifications of the light, of the medi-
um, and of the eye, that language could not
afford names for them* And indeed they are
fo little interefting, that they are never at-
tended to, but ferve only as figns to intro-
duce the things iignitled by them. Nor

ought

I76 OF THE HUMAN MIND. [CHAP. 6.

ought it to appear incredible, that appear-
ances fo frequent and fo familiar Ihould have
no names, nor be made objeds of thought ;
fince we have before fhown, that this is true
of many fenfations of touch, which are no lefs
frequent, nor lefs familiar.

SECT. V.

An inference from the preceding.

FROM what hath been faid about colour,
we may infer two things. The firft is,
that one of the moll remarkable paradoxes of
modern philofophy, which hath been univer-
fally efteemed as a great difcovery, is, in real-
ity, when examined to the bottom, nothing
elfe but an abufe of words. The paradox I
mean is, That colour is not a quality of bo-
dies, but only an idea in the mind. We have
fhown, that the word colour, as ufed by the
vulgar, cannot (ignify an idea in the mind,
but a permanent quality of body. We have
fhown, that there is really a permanent quali-
ty of body, to which the common ufe of this
word exactlv agrees. Can any ftronger proof

be

SECT. 5,3 OF SEEING. I77

he defired, that this quality is that to which
the vulgar give the name of colour 9 If it
mould be faid, that this quality, to which we
give the name of colour, is unknown to the
vulgar, and therefore can have no name among
them ; I anfwer, it is indeed known only by
its effects ; that is, by its exciting a certain
idea in us : but are there not numberlefs qua-
lities of bodies, which are known only by
their effects, to which, notwithftanding, we
find it neceflary to give names ? Medicine
alone might furnifh us with a hundred inftan-
ces of this kind. Do not the words q/lrin-
gent, narcotic, cpifpaflic, caujiic, and innume-
rable others, lignify qualities of bodies, which
are known only by their effects upon animal
bodies ? Why then mould :not the vulgar
give a name to a quality, whofe effects are
every moment perceived by their eyes ? We
have all the reafon, therefore, that the nature
of the thing admits, to think that the vulgar
apply the name of colour to that quality of
bodies, which excites in us what the philofo-
phers call the idea of colour. And that there
is fuch a quality in bodies, all philofophers
allow, who allow that there is any fuch thing
as body. Philofophers have thought fit to
leave that quality of bodies, which the vul-
M gar

I78 OF THE HUMAN MIND. [CHAP. 6.

gar call colour, without a name, and to give
the name of colour to the idea or appearance,
to which, as we have (hown, the vulgar give
no name, becaufe they never make it an ob-
ject of thought or reflection. Hence it ap-
pears, that when philofophers affirm that co-
lour is not in bodies, but in the mind ; and
the vulgar affirm, that colour is not in the
mind, but is a quality of bodies ; there is no
difference between them about things, but on-
ly about the meaning of a word.

The vulgar have undoubted right to give
names to things which they are daily con-
verfant about ; and philofophers feem juftly
chargeable with an abufe of language, when
they change the meaning of a common word,
without giving warning.

If it is a good rule, to .think with philofo-
phers, and fpeak with the vulgar, it muft be
right to fpeak with the vulgar, when we think
with them, and not to fhock them by philofo-
phical paradoxes, which, when put into com-
mon language, exprefs only the common fenfe
of mankind.

If you afk a man, that is no philofopher,
what colour is ? or, what makes one body ap-
pear white, another fcarlet ? He cannot tell.
He leaves that inquiry to philofophers, and

can

SECT. 5.3 OF SEEING.

179

can embrace any hypothefis about it, except
that of our modern philosophers, who affirm,
that colour is not in body, but only in the
mind.

Nothing appears more fhocking to his ap-
prehenfion, than that vifible obje&s fhould
have no colour, and that colour Ihould be in
that which he conceives to be invifible.* Yet
this ftrange paradox is not only univerfally re-
ceived, but confidered as one of the nobleft
difcoveries of modern philofophy. The in-
genious Addison, in the Spectator, N° 413.,
fpeaks thus of it. " I have here fuppofed,
44 that my reader is acquainted with that great
4i modern difcovery, which is at prefent uni-
41 verfally acknowledged by all the inquirers
44 into natural philofophy, namely, that light
44 and colours, as apprehended by the imagi-
" nation, are only ideas in the mind, and not
" qualities that have any exiftence in matter.
" As this is a truth, which has been proved
" incontettably by many modern philofophers,
44 and is indeed one of the fined fpeculations
44 in that fcience, if the Englifti reader would
44 fee the notion explained at large, he maf
" find it in the eighth chapter of the fecond
" book of Locke's EJfay on Human Under-
"Jlanding."

M 2 Mr

l8o OF THE HUMAN MIND. [CHAP. 6.

Mr Locke and Mr Addison are writers who
have deferved fo well of mankind, that one
mud feel fome uneafinefs in differing from
them, and would wifh to afcribe all the merit
that is due to a difcovery upon which they
put fo high a value. And indeed it is juft to
acknowledge, that Locke, and other modern
philofophers on the fubjecl: of fecondary qua-
lities, have the merit of diftinguifhing more
accurately than thofe that went before them,
between the fenfation in the mind, and that
conftitution or quality of bodies which gives
occafion to the fenfation. They have fhown
clearly, that thefe two things are not only di-
ftindt, but altogether unlike : that there is no
fimilitude between the effluvia of an odorous,
body, and the fenfation of fmell, or between
the vibrations of a founding body, and the
fenfation of found : that there can be no re-
femblance between the feeling of heat, and
the conftitution of the heated body which
occafions it j or between the appearance
which a,coloured body makes to the eye, and
the texture of the body which caufes that
appearance.

Nor was the merit fmall of diftinguifhing;
thefe things accurately ; becaufe, however
different and unlike in their nature, they have

been

&ECT. 5.] OF SEEING,. l£l

been always fo aflbciated in the imagination,
as to coalefce as it were into one two-faced
form, which, from its amphibious nature,
could not juftly be appropriated either to bo-
dy or mind ; and, until it was properly di-
itinguifhed into its different conftituent parts,
it was impoffible to aflign to either their juft
fhares in it. None of the ancient philofo-
phers had made this diftinction. The fol-
lowers of Democritus and Epicurus con-
ceived the forms of heat, and found, and co-
lour, to be in the mind only, but that our
fenfes fallacioufly reprefented them as being
in bodies. The Peripatetics imagined, that
thofe forms are really in bodies ; and that
the images of them are conveyed to the mind
by our fenfes.

The one fyftem made the fenfes naturally
fallacious and deceitful ; the other made the
qualities of body to refemble the fenfations
of the mind. Nor was it polfible to find a
third, without ' making the diftinclion we
have mentioned \ by which indeed the errors
of both thefe ancient fyftems are avoided, and
we are not left under the hard neceffity of be-
lieving, either, on the one hand, that our
fenfations are like to the qualities of body, or,
on the other, that God hath given us one fa-,
-M 3 $ulty

t82 OF THE HUMAN MIND, [cttAP. 6.

culty to deceive us> and another to detect the
cheat.

We defire, therefore, with pleafure, to do
juftice to the doctrine of Locke, and other
modern philosophers, with regard to colour,
and other fecondary qualities, and to afcribe
to it its due merit, while we beg leave to cen-
fure the language in which they have expref-
fed their doctrine. When they had explain-
ed and eftablifhed the diftinclion between the
appearance which colour makes to the eyer
and the modification of the coloured body,
which, by the laws of Nature, caufes that ap-
pearance ; the queftion was, Whether to give
the name of colour to the caufe, or to the ef-
fect ? By giving it, as they have done, to* the
effect, they fet philofophy apparently in oppo-
fition to common fenfe, and expofe it to the
ridicule of the vulgar. But, had they given
the name of colour to ttie caufe, as they ought
to have done, they muft then have affirmed,
with the vulgar, that colour is a quality of
bodies ; and that there is neither colour, nor
any thing like it, in the mind. Their lan-
guage, as well as their fentiments, would have
been perfectly agreeable to the common ap-
prehenfions of mankind, and true philofophy
would have joined hands with Common Senfe-.

As

SECT. 6.] OF SEEING. J 83

As Locke was no enemy to common fenfe, it
may be prefumed, that, in this inftance, as in
fome others, he was feduced by fome received
hypothecs : and, that this was actually the
cafe, will appear in the following fe&ion.

SECT. VI.

That none of our fenfaiions are refanblances of
any of the qualities of bodies.

A Second inference is, That although co-
lour is really a quality of body, yet it
is not reprefented to the mind by an -dea or
fenfation that refembles it ; on the contrary,
it is fuggefted by an idea which does not iii
the leaft refemble it. And this inference is
applicable, not to colour only, but to all the
qualities of body which we have examined.

It deferves to be remarked, that, in the
analyfis we have hitherto given of the opera-
tions of the five fenfes, and of the qualities of
bodies difcovered by them, no inftance hath
occurred, either of any fenfation which re-
fembles any quality of body, or of any quali-
ty of body whofe image or refcrnblance is
conveyed to the mind by means of the fenfes.*
M 4 There

184 OF THE HUMAN MIND. [cHAF. 6.

There is no phenomeno'. in nature more
unaccountable, than the intercourfe that is
carried on between the mind and the exter-
nal world : there is no phenomenon which
philofophical fpirits have mown greater avi-
dity to pry into and to refolve. It is agreed
by all, that this intercourfe is carried on by
means of the fenfes : and this fatisfies the
vulgar curiofity, but not the philofophic.
Philofophers muft have fome fyftem, fome hy-
pothefis, that mews the manner in which
our fenfes make us acquainted with external
things. All the fertility of human invention
feems to have produced only one hypothefis
for this purpofe, which therefore hath been
univerfally received \ and that is, that the
mind, like a mirror, receives the images of
things from without, by means of the fenfes \
fo that their ufe muft be to convey thefe ima-
ges into the mind.

Whether to thefe images of external things
in the mind, we give the name of fenjibls
forms, or fenjible /pedes, with the Peripatetics*
or the name of ideas of fenfation, with Locke ^
or whether, with later philofophers, we di-
ftinguifh fenfutionsy which are immediately
conveyed by the fenfes, from ideas of fenfa-
tion, which are faint copies of our fenfations

retained

SECT. 6.] OF SEEING. I&5

retained in the memory and imagination ;
thefe are only differences about words. The
hypothefis I have mentioned is common to all
thefe different fy (terns.

The neceffary and allowed confequence of
this hypothefis is, That no material thing, nor
any quality of material things, can be con-
ceived by us, or made an object of thought,
until its image is conveyed to the mind by
means of the fenfes. We fhall examine this
hypothefis particularly afterwards, and at this
time only obferve, that, in confequence of it,
one would naturally expect, that to every
quality and attribute of body we know or can
conceive, there mould be a fenfation corre-
fponding, which is the image and refemblance
of that quality ; and that the fenfations which
have no fimilitude or refemblance to body,
or to any of its qualities, mould give us no
conception of a material world, or of any
thing belonging to it. Thefe things might
be expected as the natural confequences of
the hypothefis we have mentioned.

Now, we have coniidered, in this and the
preceding chapters, extenfion, figure, folidity,
motion, hardnefs, rough nefs, as Well as colour,
heat and cold, found, talte, and fmell. We
Jjave endeavoured to fhew, that our nature

and

1 86 OF THE HUMAN MIND. [CHAP. 6.

and conftitutioti lead us to conceive thefe as
qualities of body, as all mankind have always
conceived them to be. Wfe have likewife
examined, with great attention, the various
fenfations we have by means of the dye fenfes,
and are not able to find among them all, one
iingle image of body, or of any of its quali-
ties* From whence then come thofe images
of body and of its qualities into the mind ?
Let philofophers refolve this queftion. All I
can fay is, that they come not by the fenfes.
I am fure, that, by proper attention and care,
I may know my fenfations, and be able to af-
firm with certainty what they refemble, and
what they do not refemble. I have examined
them one by one, and compared them with
matter and its qualities ; and I cannot find
one of them that confefTes a refembling fea-
ture.

A truth fo evident as this, That our fenfa-
tions are not images of matter, or of any of
its qualities, ought not to yield to a hypothe-
fis fuch as that above mentioned, however
ancient, or however univerfally received by
philofophers ; nor can there be any amicable
union between the two. This will appear
by fome reflections upon the fpirit of the an-
cient

S£CT. 6k] OF SEEING. 187

cient and modern philofophy concerning fen-
fation.

During the reign of the Peripatetic philo-
fophy, our fenfations were not minutely or
accurately examined. The attention of phi-
lofophers, as well as of the vulgar, was turned
fc the things fignified by them : therefore, in
confequence of the common hypothefis, it was
taken for granted, that all the fenfations We
have from external things, are the forms or
images of thefe external things. And thus
the truth we have mentioned, yielded entire!}
to the hypothelis, and was altogether fuppref-
fed by it.

Des Cartes gave a noble example of turn-
ing our attention inward, and fcrutinizing
our fenfations ; and this example hath been
very worthily followed by modern philofo-
phers, particularly by Malebranche, Locke,
Berkeley, and Hume. The effecl: of this
fcrutiny hath been, a gradual difcovery of
the truth above mentioned, to wit, the difli-
militude between the fenfations of our minds,
and the qualities or attributes of an infentient
inert fubflance, fuch as we conceive matter to
be. But this valuable and ufeful difcovery,
in its different ftages, hath ftill been unhap-
pily united to the ancient hypothefis; and,

from

188 OF THE HUMAN MIND. [CHAP. 6*

from this inaufpicious match of opinions, fo
unfriendly and difcordant in their natures,
have arifen thofe monfters of paradox and
fcepticifm with which the modern philofophy
is too juftly chargeable.

Locke faw clearly, and proved incontefta-
bly, that the fenfations we have by tafte,
fmell, and hearing, as well as the fenfations
of colour, heat, and cold, are not refemblan-
ces of any thing in bodies ; and in this he
agrees with Des Cartes and Malebranche.
Joining this opinion with the hypothefis, it
follows necefiarily, that three fenfes of the
five are cut off from giving us any intelli-
gence of the material world, as being altoge-
ther inept for that office. Smell, and tafte,
and found, as well as GQlour and heat, can
have no more relation to body, than anger or
gratitude ; nor ought the former to be called
qualities of body, whether primary or fecond-
ary, any more than the latter. For it was
natural and obvious to argue thus from that
hypothefis : If heat, and colour, and found,
are real qualities of body, the fenfations, by
which we perceive them, muft be refemblan-
ces of thofe qualities ; but thefe fenfations are
not resemblances ; therefore thofe are not
real qualities of body.

We

SECT. 6.] OF SEEING. 189

We fee then, that Locke, having found that
the ideas of fecondary qualities are no refem-
blances, was compelled, by a hypothefis com-
mon to all philofophers, to deny that they are
real qualities of body. It is more difficult to
>afiign a reafon, why, after this, he fhould call
them fecondary qualities ; for this name, if I
miftake not, was of his invention. Surely he
did not mean that they were fecondary qua-
lities of the mind ; and I do not fee with what
propriety, or even by what tolerable licence,
he could call them fecondary qualities of bo-
dy, afjfer finding that they were no qualities
of body at all. In this, he feems to have fa-
crificed to Common Senfe, and to have been
led by her authority, even in oppofition to
his hypothefis. The fame fovereign miftrefs
of our opinions that led this philofopher to
call thofe things fecondary qualities of body,
which, according to his principles and reafon-
ings, were no qualities of body at all, hath
led, not the vulgar of all ages only, but phi-
lofophers alfo, and even the difciples of Locke,
to believe them to be real qualities of body :
(he hath led them to invefligate, by experi-
ments, the nature of colour, and found, and
heat, in bodies. Nor hath this inveftigation
been fruitlefs, as it mull have been, if there

hM

I90 OF THE HUMANKIND. [CHAP. 6.

had been no fuch thing in bodies : on the
contrary, it hath produced very noble and
ufeful difcoveries, which make a very confl-
derable part of natural philofophy. If then
natural philofophy be not a dream, there is
fomething in bodies, which we call colour,
and heat, and found. And if this be fo, the
hypothecs from which the contrary is conclu-
ded, mud be falfe : for the argument, leading
to a falfe conclufion, recoils againft the hy-
pothetic from which it was drawn, and thus
directs its force backward. If the qualities
of body were known5 to Us only by fenfations
that refemble them, then colour, and found,
and heat, could be no qualities of body ; but
thefe are real qualities of body ; and there-
fore the qualities of body are not known on-
ly by means of fenfations that refemble them.
But to proceed : What Locke had proved
with regard to the fenfations we have by fmell,
tafte, and hearing, Bifhop Berkeley proved
no lefs unanfwerably with regard to all our
bther fenfations; to wit, that none of them
can in the leaft refemble the qualities of a
lifelefs and infentient being, fuch as matter is
conceived to be. Mr Hume hath confirmed
this by his authority and reafoning. This
opinion furely looks with a very malign afpecl

upon

SECT. 6,] OF SEEING. If)*

upon the old hypothefis ; yet that hypothefis
hath flill been retained, and conjoined with
it. And what a brood of monfters hath this
produced !

The firft-born of this union, and perhaps
the moil harmlefs, was, That the fecondary
qualities of body were mere fenfations of the
mind. To pafs by Malebranche's notion of
feeing all things in the ideas of the divine
mind, as a foreigner never naturalized in this
ifland ; the next was Berkeley's fyftem, That
extenfion, and figure, and hardnefs, and mo-
tion ; that land, and fea, and houfes, and our
own bodies, as well as thofe of our wives, and
children, and friends, are nothing but ideas
of the mind ; and that there is nothing exifl-
ing in nature, but minds and ideas.

The progeny that followed, is Hill more
frightful ; fo that it is furprifing, that one
could be found who had the courage to act
the midwife, to rear it up, and to ufher it into
the world. No caufes nor effects ; no fub-
ftances, material or fpiritual ; no evidence
even in mathematical demonftration ; no li-
berty nor active power ; nothing exifting in
nature, but impreffions and ideas following
each other, without time, place, or lubjed.
Surely no age ever produced fuch a fyflem of

opinion?,

I92 OF THE HUMAN MIND. [CHAP. 6.

opinions, juftly deduced with great acutenefs,
perfpicuity, and elegance, from a principle
univerfally received. The hypothefis we have
mentioned, is the father of them all. The
diffimilitude of our fenfations and feelings to
external things, is the innocent mother of
moil of them.

As it happens fometimes in an arithmetical
operation, that two errors balance one ano-
ther, fo that the conclulion is little or nothing
afFeded by them ; but when one of them is
corrected, and the other left, we are led far-
ther from the truth, than by both together :
fo itfeems to have happened in the Peripa-
tetic philofophy of fenfation, compared with
the modern. The Peripatetics adopted two
errors ; but the lad ferved as a corrective to
the firft, and rendered it mild and gentle ; fo
that their fyftem had no tendency to fcepti-
cifm. The moderns have retained the firft of
thofe errors, but have gradually detected and
conceded the laft. The confequence hath
been, that the light we have (truck out hath
created darknefs, and fcepticifm hath advan-
ced hand in hand with knowledge, fpreading
its melancholy gloom, firft over the material
world, and at laft over the whole face, of na-
ture. Such a phenomenon as this, is apt to

ftaggev

SECT. 7.] OF SEEING. 1()3

ftagger even the lovers of light and know-
ledge, while its caufe is latent ; but when
that is detected, it may give hopes, that this
darknefs fhall not be everlafting, but that it
ihall be fucceeded by a more permanent
light.

SECT. VII.

Of vi/ible figure and extenjion.

ALthough there is no refemblance, nor,
as far as we know, any neceffary con-
nection, between that quality in a body which
we call its colour, and the appearance which
that colour makes to the eye ; it is quite
other wife with regard to its figure and mag-
nitude. There is certainly a refemblance,
and a necelfary connection, between the vi-
fible figure and magnitude of a body, and its
real figure and magnitude ; no man can give
a reafon why a fcarlet colour affects the eye
in the manner it does ; no man can be fure
that it affects his eye in the fame manner as

N it

194 OF THE HUMAN MIND. [CHAP. G.

it affects the eye of another, and that it has
the fame appearance to him as it has to ano-
ther man ; but we can affign a reafon why a
circle placed obliquely to the eye, mould ap-
pear in the form of an ellipfe. The vifible
figure, magnitude, -^nd polition, may, by ma-
thematical reafoning, be deduced from the
real ; and it may be demonftrated, that every
eye that fees diftinctly and perfectly, mull,
in the fame fituation, fee it under this form,
and no other. Nay, we may venture to affirm,
that a man born blind, if he were inftructed
in mathematics, would be able to determine
the vifible figure of a body, when its real fi-
gure, diftance, and pofition, are given. Dr
Saunderson underftood the projection of the
fphere, and perfpective. Now, I require no
more knowledge in a blind man, in order to
his being able to determine the vifible figure
oi bodies, than that he can project the outline
of a given body, upon the furface of a hollow
fphere, whofe centre is in the eye. This pro-
jection is the vifible figure he wants ; for it
is the fame figure with that which is project-
ed upon the tunica retina in vifion.

A blind man can conceive lines drawn from
every point of the object to the centre of the
eye, making angles. He can conceive, that

the

SECT. 7.] OF SEEING. IO5

the length of the object will appear greater
or lefs, in proportion to the angle which it
fubtends at the eye ; and that, in like man-
ner, the breadth, and in general the diltance
of any one point of the object from any other
point, will appear greater or lefs, in propor-
tion to the angles which thofe diftances fub-
tend. He can eafily be made to conceive,
that the vifible appearance has no thicknefs,
any more than a projection of the fphere, or
a perfpective draught. He may be informed,
that the eye, until it is aided by experience,
does not reprefent one object as nearer or
more remote than another* Indeed he would
probably conjecture this of himfelf, and be
apt to think, that the rays of light mull make
the fame impreflion upon the eye, whether
they come from a greater or a lefs diftance.

Thefe are all the principles which we fup-
pofe our blind mathematician to have ; and
thefe he may certainly acquire by informa-
tion and reflection. It is no lefs certain, that
from thefe principles, having given the real
figure and magnitude of a body, and its po-
iition and diftance with regard to the eye, he
can find out its vifible figure and magnitude.
He can demonftrate in general, from thefe
principles, that the vifible figure of all bodies
N 2 will

Iq6 OF THE HUMAN MIND. [CHAP. 6.

will be the fame with that of their projection
upon the furface of a hollow fphere, when
the eye is placed in the centre. And he can
demonftrate, that their vifible magnitude will
be greater or lefs, according as their projec-
tion occupies a greater or lefs part of the fur-
face of this fphere.

To fet this matter in another light, let us
diftinguifh betwixt the pojition of objects with
regard to the eye, and their dijiance from it.
Objects that lie in the fame right line drawn
from the centre of the eye, have the fame po-
rtion, however different their diftances from
the eye may be : but obje&s which lie in
different right lines drawn from the eye's
centre, have a different pofition; and this
difference of pofition is greater or lefs, in pro-
portion to the angle made at the eye by the
right lines mentioned. Having thus defined
what we mean by the pofition of objects with
regard to the eye, it is evident, that as the
real figure of a body confifts in the fituation
of its feveral parts with regard to one ano-
ther, fo its vifible figure confifts in the pofi-
tion of its feveral parts with regard to the
eye ; and as he that hath a diftinct conception
of the fituation of the parts of the body with
regard to one another, mud have a diftinct

conception

SECT. 7-] OF SEEING. I97

conception of its real figure ; fo he that con-
ceives diftin&ly the pofition of its feveral parts
with regard to the eye, muft have a diftinct
conception of its vifible figure. Now, there
is nothing furely to hinder a blind man from
conceiving the pofition of the feveral parts of
a body with regard to the eye, any more than
from conceiving their fituation with regard to
one another ; and therefore I conclude, that
a blind man may attain a diftinct conception
of the vifible figure of bodies.

Although we think the arguments that
have been offered are fufficient to prove, that
a blind man may conceive the vifible exten-
fion and figure of bodies ; yet, in order to
remove fome prejudices againft this truth, it
will be of ufe to compare the notion which a
blind mathematician might form to himfelf
of vifible figure, with that which is prefented
to the eye in vifion, and to obferve wherein
they differ.

Firft, Vifible figure is never prefented to
the eye but in conjunction with colour; and
although there be no connection between
them from the nature of the things, yet, ha-
ving fo invariably kept company together, we
are hardly able to disjoin them even in our
imagination. What mightily increafes this
N 3 difficulty

I98 OF THE HUMAN MIND. [CHAP. 6T

difficulty is, that we have never been accuf-
tomed to make vifible figure an object of
thought. It is only iifea* as a fign, and, ha-
ving ferved this purpofe, paffes away, without
leaving a trace behind. The drawer or de-
figner, whofe bufinefs it is to hunt this fugi-
tive form, and to take a copy of it, fipds how
diffi ult his talk is, after many years labour
and practice. Happy ! if at laft he can ac-
quire the art of arrefting it in his imagination,
until he can delineate it. For then it is evi-
dent, that he muft be able to draw as accu-
rately from the life as from a copy. But how
few of the profefled matters of defigning are
ever able to arrive at this degree of perfec-
tion ? it is no wonder, then, that we fhould
find fo great difficulty in conceiving this form
apart from its conftant afifociate, when it is fq
difficult to conceive it at all. But our blind
man's notion of viiible figure will not be af-
fociated with colour, of which he hath no con-
ception ; but it will perhaps be aflbciated
with hardnefs or fmoothneis, with, which he
is acquainted by touch. Thefe different af-
fociations are apt to impofe upon us, and to
make things item different, which in reality
are t,he lame.

Secondly,

SECT. 7,] OF SEEING. I99

Secondly, The blind man forms the notion
of vifible figure to himfelf, by thought, and
by mathematical reafoning from principles ; i
whereas the man that fees, has it prefented to
his eye at once, without any labour, without
any reafoning, by a kind of infpiration. A
man may form to himfelf the notion of a pa-
rabola, or a cycloid, from the mathematical
definition of thofe figures, although he had
never feen them drawn or delineated. Ano-
ther, who knows nothing of the mathemati-
cal definition of the figures, may fee them de-
lineated on paper, or feel them cut out in
wood. Each may have a diftinct conception
of the figures, one by mathematical reafon-
ing, the other by fenfe. Now, the blind man
forms his notion of vifible figure in the fame
manner as the firft of thefe formed his notion
of a parabola or a cycloid, which he never
faw. .

Thirdly, Vifible figure leads the man that
fees, directly to the conception of the real fi-
gure, of which it is a fign. But the blind
man's thoughts move in a contrary direction.
For he mull firft know the real figure, dis-
tance, and fituation, of the body, and from
thence he flowly traces out the vifible figi.<e
by mathematical reafoning. Nor does his
N 4 nature

100 OF THE HUMAN MIND. [CHAP. 6.

nature lead him to conceive this vifible figure
as a fign ; it is a creature of his own reafon.
and imagination.

SECT. VIII.

Some queries concerning vifible figure an-
fwered.

i

T may be afked, What kind of thing is this
vifible figure ? Is it a fenfation, or an idea ?
If it is an idea, from what fenfation is it co-
pied? Thefe queftions may feem trivial or
impertinent to one who does not know, that
there is a tribunal of inquifition erected by
certain modern philofophers, before which
every thing in nature muft anfwer. The ar-
ticles of inquifition are few indeed, but very
dreadful in their confequences. They are
only thefe : Is the prifoner an impreflion or
an idea ? If an idea, from what impreflion co-
pied ? Now, if it appears that the prifoner is
neither an impreflion, nor an idea copied from
fome impreflion, immediately, without being

allowed

SECT. 8.] OF SEEING. 201

allowed to offer any thing in arreft of judg-
ment, he is fentenced to pafs out of exiftence,
and to be, in all time to come, an empty un-
meaning found, or the ghoft of a departed
entity.

Before this dreadful tribunal, caufe and ef-
fect, time and place, matter and fpirit, have
been tried and caft : how then fliall fuch a
poor flimfy form as vifible figure Hand before
it ? It mud even plead guilty, and confefs
that it is neither an impreflion nor an idea.
For, alas ! it is notorious, that it is extended
in length and breadth ; it may be long or
ihort, broad or narrow, triangular, quadran-
gular, or circular : and therefore, unlefs ideas
and impreffions are extended and figured, it
cannot belong to that category.

If it mould ftill be alked, To what cate-
gory of beings does vifible figure then be-
long ? I can only, in anfwer, give fome tokens,
by which thofe who are better acquainted with
the categories, may chance to find its place.
It is, as we have faid, the pofition of the feve-
ral parts of a figured body, with regard to the
eye. The different pofitions of the feveral
parts of the body with regard to the eye, when
put together, make a real figure, which is tru-
ly extended in length and breadth, and which

represents

20% OF THE HUMAN MIND. [CHAP. 6.

reprefents a figure that is extended in length,
breadth, and thicknefs. In like manner, a pro-
jection of the fphere is a real figure, and hath
length and breadth, but reprefents the fphere,
which hath three dimenfions. A projection
of the fphere, or a perfpeclive view of a pa-
lace, is a reprefentative in the very fame fenfe
as vifible figure is, and wherever they have
their lodgings in the categories, this will be
found to dwell next door to them.

It may farther be afked, Whether there be
any fenfation proper to viiible figure, by which
it is fuggefted in virion ? Or by what means
it is prefented to the mind ? This is a quef-
tion of fome importance, in order to our ha-
ving a diftinci notion of the faculty of feeing :
and to give all the light to it we can, it is ne-
cefTary to compare this fenfe with other fen-
fes, and to make fome fuppofitions, by which
we may be enabled to diftinguifh things that
are apt to be confounded, although they are
totally different.

There are three of our fenfes which give
us intelligence of things at a diftarice : fmell,
hearing, and fight. In fmelling, and in hear-
ing, we have a fenfation or impreflion upon
the mind, which, by our constitution, we con-
ceive to be a fign of fomething external : but

the

$ECT. 8.] OF SEEING. 203

the pofition of this external thing, with regard
to the organ of fcnfe, is not prefented to the
mind along with the fenfation. When I hear
the found of a coach, I could not, previous to
experience, determine whether the founding
body was above or below, to the right hand
or to the left. So that the fenfation fuggefls
to me fome external object as the caufe or oc-
cafion of it ; but it fuggefts not the pofition of
that object, whether it lies in this direction or
in that. The fame thing may be faid with
regard to fmelling. But the cafe is quite dif-
ferent with regard to feeing. When I fee an
object, the appearance which the colour of it
makes, may be called the fenfation, which
fuggefts to me fame external thing as its caufe ;
but it fuggefls likewife the individual direction
and pofition of this caufe with regard to the
eye. I know it is precifely in fuch a direction,
and in no other. At the fame time, I am not
confeious of any thing that can be called fen-
fation, but the fenfation of colour. The pofi-
tion of the coloured thing is no fenfation, but
it is by the laws of my conftitution prefented
to the mind along with the colour, without
any additional fenfation.

Let us fuppofe, that the eye were fo confti-
tutedj that the rays coming from any one point

of

204 OF THE HUMAN MIND. [CHAP. 6.

of the object were not, as they are in our eyes,
collected in one point of the retina, but diffu-
fed over the whole : It is evident to thofe who
underftand the ftructure of the eye, that fuch
an eye as we have fuppofed, would (hew the
colour of a body as our eyes do, but that it
would neither fhew figure nor poiitiori. The
operation of fuch an eye would be precifely fi-
milar to that of hearing and fmell ; it would
give no perception of figure or extenfion, but
merely of colour. Nor is the fuppofition we
have made altogether imaginary: for it is near-
ly the cafe of moil people who have cataracts,
whofe cryftalline, as Mr Cheselden obferves,
does not altogether exclude the rays of light,
but diffufes them over the retina, fo that fuch
perfons fee things as one does through a glafs
of broken jelly : they perceive the colour,
but nothing of the figure or magnitude of ob-
jects.

Again, if we fhould fuppofe, that fmell and
found were conveyed in right lines from the
objects, and that every fenfation of hearing
and fmell fuggefted the precife direction or
pofition of its object ; in this cafe, the ope-
rations of hearing and fmelling would be fi-
milar to that of feeing : we mould fmell and
hear the figure of objects, in the fame fenfe

as.

SECT. 8.] OF SEEING. 205

as now we fee it ; and every fmell and found
would be affociated with fome figure in the
imagination, as colour is in our prefent ftate.

We have reafon to believe, that the rays of
light make fome impreilion upon the retina;
but we are not confcious of this impreilion $
nor have anatomifts or philofophers been able
to difcover the nature and effe&s of it ; whe-
ther it produces a vibration in the nerve, or
the motion of fome fubtile fluid contained in
the nerve, or fomething different from either,
to which we cannot give a name. Whatever
it is, we fhall call it the material imprejfion ;.
remembering carefully, that it is not an im-
preilion upon the mind, but upon the body ;
and that it is no fenfation, nor can refemble
fenfation, any more than figure or motion can
refemble thought. Now, this*material impref-
fion, made upon a particular point of the
retina, by the laws of our conftitution, fug-
gefts two things to the mind, namely, the co-
lour, and the pofition of fome external object.
No man can give a reafon, "why the fame ma-
terial impreflion might not have fuggefted
found, or fmell, or either of thefe, along with
the pofition of the object. That it mould
fuggefl colour and pofition, and nothing elfe,
we can refolve only into our conftitution, or

the

1Q>6 of the human mind. [chap. 6«

the will of our Maker. And fince there is
no neceffary connection between theie two
things fuggefted by this material impreffion, it
might, if it had fo pleafed our Creator, have
fuggefted one of them without the other. Let
us fuppofe, therefore, fince it plainly appears
to be poffible, that our eyes had been fo fra-
med, as to fuggeft to us the pofition of the ob-
ject, without fuggefting colour, or any other
quality : What is the confequence of this fup-
pofition ? It is evidently this, that the perfon
endued with fuch an eye, would perceive the
vifible figure of bodies, without having any
fenfation or impreilion made upon his mind.
The figure he perceives is altogether exter-
nal ; and therefore cannot be called an impref-
fion upon the mind, without the grofTeft abufe
of language. If it fhould be faid, that it is
impoffible to perceive a figure, unlefs there
be fome impreffion of it upon the mind ; I
beg leave not to admit the impoflibility of
this, without fome proof: and I can find none.
Neither can I conceive what is meant by an
impreffion of figure upon the mind. I can
conceive an impreffion of figure upon wax, or
upon any body that is fit to receive it ; but
an impreffion of it upon the mind, is to me
quite unintelligible ; and although 1 form the

moil

SECT. 8.] OF SEEING. 10J

moil diftinc~t conception of the figure, I can-
not, upon the ftricteit examination, find any
impreflion of it upon my mind.

If we fuppofe, laft of all, that the eye hath
the power reftored of perceiving colour, I ap-
prehend that it will be allowed, that now it
perceives figure in the very fame manner as
before, with this difference only, that colour
is always joined with it.

In anfwer therefore to the queftion propo-
sed, there feems to be no fenfation that is ap-
propriated to vilible figure, or whofe office it
is to fugged it. It feems to be fuggefted im-
mediately by the material impreflion upon the
organ, of which we are not confcious : and
why may not a material impreflion upon the
retina fuggefl vifible figure, as well as the ma-
terial impreflion made upon the hand, when we
grafp a ball, fuggefts real figure ? In the one
cafe, one and the fame material impreflion,
fuggefts both colour and vifible figure ; and
in the other cafe, one and the fame material
impreflion fuggefts hardnefs, heat, or cold,
and real figure, all at the fame time.

We fhall conclude this fection with another
queftion upon this fubjecl. Since the vifible
figure of bodies is a real and external object
to the eye, as their tangible figure is to the

touch ;

208 OF THE HUMAN MIND. [CHAP. 6.

touch; it may be aiked, Whence arifes the
difficulty of attending to the firft, and the faci-
lity of attending to the laft ? It is certain, that
the firft is more frequently prefented to the
eye, than the laft is to the touch ; the firft is
as diftincl and determinate an objedt as the
laft, and feems in its own nature as proper for
fpeculation. Yet fo little hath it been attend-
ed to, that it never had a name in any lan-
guage, until Bifhop Berkeley gave it that
which we have ufed after his example, to di-
ftinguifh it from the figure which is the ob-
ject of touch.

The difficulty of attending to the vifible
figure of bodies, and making it an objedt of
thought, appears fo iimilar to that which we
find in attending to our fenfations, that both
have probably like caufes. Nature intended
the vifible figure as a fign of the tangible
figure and fituation of bodies, and hath taught
us by a kind of inftincl: to put it always to
this ufe. Hence it happens, that the mind
paffes over it with a rapid motion, to attend
to the things fignified by it. It is as unnatu-
ral to the mind to ftop at the vifible figure,
and attend to it, as it is to a fpherical tody to
ftop upon an inclined plane. There is an in-
ward principle, which conftantly carries it for-
ward,

sect. 8.] of seeing* 209

ward, and which cannot be overcome but by
a contrary force.

There are other external things which na-
ture intended for ligns ; and we find this com-
mon to them all, that the mind is difpofed to
overlook them, and to attend only to the
things fignified by them. Thus there are cer-
tain modifications of the human face, which
are natural ligns of the prefent difpofition of
the mind. Every man underftands the mean-
ing of thefe figns, but not one of a hundred
ever attended to the figns themfelves, or knows
any thing about them. Hence you may find
many an excellent practical phyfiognomift,
who knows nothing of the proportions of a
face, nor can delineate or defcribe the expref-
fion of any one paifion.

An excellent painter or ftatuary can tell,
not only what are the proportions of a good
face, but what changes every pafiion makes in
it. This, however, is one of the chief myfte-
ries of his art, to the acquifition ot which, in-
finite labour and attention, as well as a happy
genius, are required. But when he puts his
art in pra&ice, and happily exprefies a pafiion
by its proper figns, every one underftands the
meaning of thefe figns, without art, and with- ^
out reflection.

O What

Z1Q OF THE HUMAN MIND. [CHAP. 6.

What has been faid of painting, might ea-
fily be applied to all the fine arts. The diffi-
culty in them all confifts in knowing and at-
tending to thofe natural figns, whereof every
man underftands the meaning.

We pafs from the fign to the thing figni-
fied, with eafe, and by natural impulfe \ but
to go backward from the thing fignified to
the fign, is a work of labour and difficulty,
Vifible figure, therefore, being intended by
nature to be a fign, we pafs on immediately to
the thing fignified, and cannot eafily return to
give any attention to the fign.

Nothing fhews more clearly our indifpofi-
tion to attend to vifible figure and vifible ex-
tenfion than this, that although mathematical
reafoning is no lefs applicable to them, than
to tangible figure and extenfion, yet they have
entirely efcaped the notice of mathematicians.
While that figure and that extenfion which
are objects of touch, have been tortured tea
thoufand ways for twenty centuries, and a
very noble fyftem of fcience has been drawn-
out of them; not a fingle propofition do we
find with regard to the figure and extenfion
which are the immediate objects of fight !

When the geometrician draws a diagram
with the mod perfect accuracy ; when he

keeps

SECT. 8.] OF SEEING. 2II

keeps his eye fixed upon it, while he goes
through a long procefs of reafoning, and de-
monftrates the relations of the feveral parts of
his figure ; he does not confider, that the vi-
fible figure prefented to his eye, is only the
reprefentative of a tangible figure, upon which
all his attention is fixed ; he does not confider
that thefe two figures have really different
properties ; and that what he (Jemonftrates to
be true of the one, is not true of the other.

This perhaps will feem fo great a paradox,
even to mathematicians, as to require demon-
stration before it can be believed. Nor is the
demonftration at all difficult, if the reader
will have patience to enter but a little into
the mathematical confideration of vifible fi-
gure, which we fhall call the geometry of vi-
Jibles.

O 2 SECT.

212 OF THE HUMAN MIND. [cHAF. 6.

SECT. IX.

Of the geometry of vijibles.

IN this geometry, the definitions of a point -y
of a line, whether ftraight or curve ; of
an angle, whether acute, or right, or obtufe ;
and of a circle, are the fame as in common
geometry. The mathematical reader will ea-
fily enter into the whole myftery of this geo-
metry, if he attends duly to thefe few evident
principles.

i. Suppofmg the eye placed in the centre
of a fphere, every great circle of the fphere
will have the fame appearance to the eye as
if it was a ftraight line. For the curvature
of the circle being turned dire&ly toward the
eye, is not perceived by it. And for the fame
reafon, any line which is drawn in the plane
of a great circle of the fphere, whether it be
in reality ftraight or curve, will appear ftraight
to the eye.

2. Every vifible right line will appear to
coincide with fome great circle of the fphere ;

and

SECT. 9.] OF SEEING. 2I3

and the circumference of that great circle,
•even when it is produced until it returns into
itfelf, will appear to be a continuation of the
fame vtfible right line, all the parts of it being
vifibly in directum. For the eye, perceiving
only the pofition of objects with regard to it-
felf, and not their diftance, will fee thofe
points in the fame viiible place which have
the fame pofition with regard to the eye, how
different foever their diftances from it may be.
Now, fince a plane palling through the eye
and a given viiible right line, will be the plane
of fome great circle of the fphere, every point
of the vifible right line will have the fame po-
fition as fome point of the great circle ; there-
fore they will both have the fame vifible place,
and coincide to the eye : and the whole cir-
cumference of the great circle continued even
until it returns into itfelf, will appear to be a
continuation of the fame vifible right line.
Hence it follows :

3. That every vifible right line, when it is
continued in diredum, as far as it may be con-
tinued, will be reprefented by a great circle
of a fphere, in whofe centre the eye is placed.
It follows,

4. That the vifible angle comprehended
under two vifible right lines, is equal to the

O 3 fpherical

214 0F THE HUMAN MIND. [CHAP. 6.

fpherical angle comprehended under the two
great circles which are the reprefentatives of
thcfe vifible lines. For fince the vifible lines
appear to coincide with the great circles, the
vifible angle comprehended under the former,
mult be equal to the vifible angle compre-
hended under the latter. But the vifible
angle comprehended under the two great
circles, when feen from the centre, is of the
fame magnitude with the fpherical angle which
they really comprehend, as mathematicians
know ; therefore the vifible angle made by
any two vifible lines, is equal to the fpherical
angle made by the two great circles of the
fphere which are their reprefentatives.

5. Hence it is evident, that every vifible
right-lined triangle, will coincide in all its
parts with fome fpherical triangle. The fides
of the one will appear equal to the fides of
the other, and the angles of the one to the
angles of the other, each to each ; and there-
fore the whole of the one triangle will appear
equal to the whole of the other. In a word,
to the eye they will be one and the fame, and
have the fame mathematical properties. The
properties therefore of vifible right-lined tri-
angles, are not the fame with the properties

of

SECT. 9.] OF SEEING. 215

of plain triangles, but are the fame with thofe
of fpherical triangles.

6. Every ltffer circle of the fphere, will ap-
pear a circle to the eye, placed, as we have
fuppofed all along, in the centre of the fphere.
And, on the other hand, every vifible circle
will appear to coincide with fome lefier circle
of the fphere.

7. Moreover, the whole furface of the
fphere will reprefent the whole of vifible
fpace : for fince every vifible point coincides
with fome point of the furface of the fphere,
and has the fame vifible place, it follows, that
all the parts of the fpherical furface taken to-
gether, will reprefent all pofiible vifible places,
that is, the whole of vifible fpace. And from
this it follows, in the laft place, *

8. That every vifible figure will be repre-
fented by that part of the furface of the fphere,
on which it might be projected, the eye be-
ing in the centre. And every fuch vifible
figure will bear the fame ratio to the whole
of vifible fpace, as the part of the fpherical
furface which reprefents it, bears to the whole
fpherical furface.

The mathematical reader, I hope, will en-
ter into thefe principles with perfect facility,
and will as eafily perceive, that the following
O 4 propofitions

2l6 OF THE HUMAN MIND. [CHAP. 6.

propofitions with regard to vifible figure and
fpace, which we offer only as a fpecimen, may
be mathematically demonstrated from them,
and are not lefs true nor lefs evident than the
propofitions of Euclid, with regard to tangi-
ble figures..

Prop. 1. Every right line being produced,
will at laft return into itfelf.

2. A right line returning into itfelf, is the
longeft pouible right line ; and all other right
lines bear a finite ratio to it.

3. A right line returning into itfelf, divides
the whole of vifible fpace into two equal
parts, which will both be comprehended under
this right line.

4. The whole of vifible fpace bears a finite
ratio to any part of it.

5. Any two right lines being produced, will
meet in two points, and mutually bifect each
other.

6. If two lines be parallel, that is, every
where equally diftant from each other, they
cannot both be ftraight.

7. Any right line being given, a point may
be found, which is at the fame diftance from
all the points of the given right line.

8. A circle may be parallel to a right line,

that

SECT. 9.] OF SEEING, 217

that is, may be equally diftant from it in all
its parts.

9. Right-lined triangles that are fimilar, are
alfo equal.

10. Of every right-lined triangle, the three
angles taken together, are greater than two
right angles.

11. The angles of a right-lined triangle,
may all be right angles, or all obtufe angles.

12. Unequal circles are not as the fquares
of their diameters, nor are their circumferences
in the ratio of their diameters.

This fmall fpecimen of the geometry of
vifibles, is intended to lead the reader to a
clear and diftinct conception of the figure and
extenfion which is prefented to the mind by
virion ; and to demonftrate the truth of what
we have affirmed above, namely, That thofe
figures and that extenfion which are the im-
mediate obje&s of fight, are not the figures
and the extenfion about which common geo-
metry is employed ; that the geometrician,
while he looks at his diagram, and demon-
flrates a proportion, hath a figure prefented
to his eye, which is only a fign and reprefen-
tative of a tangible figure ; that he gives not
the leafl attention to the firft, but attends on-
ly

2l8 OF THE HUMAN MIND. [CHAP. 6.

ly to the laft ; and that thefe two figures have
different properties, fo that what he demon-
ftrates of the one, is not true of the other.

It deferves, however, to be remarked, that
as a fmall part of a fpherical furface differs
not fenfibly from a plain furface ; io a fmali
part of vifible extenfion differs very little from
that extenfion in length and breadth, which
is the object of touch. And it is likewife to
be obferved, that the human eye is fo formed,
that an object which is feen diftinctly and at
one view, can occupy but a fmall part of vi-
fible fpace : for we never fee diftinclly what
is at a confiderable diftance from the axis of
the eye ; and therefore, when we would fee a
large object at one view, the eye muft be at
fo great a diftance, that the object occupies
but a fmall part of vifible fpace. From thefe
two obfervations, it follows, that plain figures
which are feen atone view, when their planes
are not oblique, but direct to the eye, differ
little from the vifible figures which they pre-
fent to the eye. The feveral lines in the tan-
gible figure have very nearly the fame pro-
portion to each other as in the vifible ; and
the angles of the one are very nearly, al-
though not ftriclly and mathematically, equal
to thofe of the other. Although therefore

we

SECT. 9.] OF SEEING. 219

we have found many instances of natural figns
which have no limilitude to the things figni-
fied, this is not the cafe with regard to vifible
figure. It hath in all cafes fuch a limilitude
to the thing lignified by it, as a plan or pro-
file hath to that which it reprefents ; and in
fome cafes the fign and thing fignified have
to all fenfe the fame figure and the fame pro-
portions. If we could find a being endued
with fight only, without any other external
fenfe, and capable of reflecting and reafoning
upon what he fees, the notions and philofo-
phical fpeculations of fuch a being, might
aflift us in the difficult talk of diflinguifhing
the perceptions which we have purely by
fight, from thofe which derive their origin
from other fenfes. Let us fuppofe fuch a
being, and conceive, as well as we can, what
notion he would have of vifible objects, and
what conclufions he would deduce from them.
We mull not conceive him difpofed by his
constitution, as we are, to confider the vifible
appearance as a fign of fomething elfe : it is
no fign to him, becaufe there is nothing figni-
fied by it; and therefore we mufl fuppofe
him as much difpofed to attend to the vifible
figure and extenfion of bodies, as we are dif-
pofed

220 OF THE HUMAN MIND. [CHAP. 6.

pofed to attend to their tangible figure and
extenfion.

If various figures were prefcnted to his
fenfe, he might, without doubt, as they grow
familiar, compare them together, and per-
ceive wherein they agree, and wherein they
differ. He might perceive vifible objects to
have length and breadth, but could have no
notion of a third dimenfion, any more than
we can have of a fourth. All vifible objects
would appear to be terminated by lines,
ftraight or curve ; and objects terminated by
the fame vifible lines, would occupy the fame
place, and fill the fame part of vifible fpace.
It would not be poffible for him to conceive
one object to be behind another, or one to be
nearer, another more diftant.

To us, who conceive three dimenfions, a
line may be conceived ftraight ; or it may be
conceived incurvated in one dimenfion, and
ftraight in another ; or, laftly, it may be in-
curvated in two dimenfions. Suppofe a line,
to be drawn upwards and downwards, its
length makes one dimenfion, which we (hall
call upwards and downwards ; and there are
two dimenfions remaining, according to which
it may be ftraight or curve. It may be bent to
the right or to the left \ and if it has no bend-
ing

SECT. 9.] OF SEEING. 221

ing either to right or left, it is ftraight in this
dimenlion. But fuppofing it ftraight in this
dimenfion of right and left, there is ftill ano-
ther dimenfion remaining, in which it may
be curve ; for it may be bent backwards or
forwards. When we conceive a tangible
ftraight line, we exclude curvature in either
of thefe two dimenfions : and as what is con-
ceived to be excluded, muft be conceived, as
well as what is conceived to be included,
it follows, that all the three dimenfions en-
ter into our conception of a ftraight line.
Its length is one dimenfion, its ftraight-
nefs in two other dimenfions is included, or
curvature in thefe two dimenfions excluded,
in the conception of it.

The being we have fuppofed, having no
conception of more than two dimenfions, ^of
which the length of a line is one, cannot pof-
fibly conceive it either ftraight or curve in
more than one dimenfion : fo that in his con-
ception of a right line, curvature to the right
hand or left is excluded ; but curvature back-
wards or forwards cannot be excluded, be-
caufe he neither hath, nor can have any con-
ception of fuch curvature. Hence we fee the
reafon that a line, which is ftraight to the
eye, may return into itfelf: for its being

ftraight

£22 OF THE HUMAN MIND. [CHAP. 6.

flraight to the eye, implies only ftraightnefs
in one dimenfion ; and a line, which is ftraight
inone dimenfion, may notwithstanding be curve
in another dimenfion, and fo may return into
itfelf.

To us, who conceive three dimenfions, a
furface is that which hath length and breadth,
excluding thicknefs : and a furface may be
either plain in this third dimenfion, or it may
be incurvated : fo that the notion of a third
dimenfion enters into our conception of a fur-
face ; for it is only by means of this third di-
menfion, that we can diftinguifh furfaces into
plain and curve furfaces ; and neither one nor
the other can be conceived, without concei-
ving a third dimenfion.

The being we have fuppofed having no con-
ception of a third dimenfion, his vifible figures
have length and breadth indeed ; but thick-
nefs is neither included nor excluded, being a
thing of which he has no conception. And
therefore vifible figures, although they have
length and breadth, as furfaces have, yet they
are neither plain furfaces, nor curve furfaces.
For a curve furface implies curvature in a
third dimenfion, and a plain furface implies
the want of curvature in a third dimenfion ;
and fuch a being can conceive neither of thefe,

becaufe

SECT. 9.] OF SEEING. 223

becaufe he has no conception of a third di-
menfion. Moreover, although he hath a di-
ftinct conception of the inclination of two lines
which make an angle, yet he can neither con-
ceive a plain angle nor a fpherical angle.
Even his notion of a point is fomewhat lefs
determined than ours. In the notion of a
point, we exclude length, breadth, and thick-
nefs ; he excludes length and breadth, but
cannot either exclude or include thicknefs,
becaufe he hath no conception of it.

Having thus fettled the notions which fuch
a being as we have fuppofed might form of
mathematical points, lines, angles, and figures,
it is eafy to fee, that by comparing thefe to-
gether, and reafoning about them, he might
diicover their relations, and form geometrical
conclusions, built upon felf-evident principles.
He might likewise, without doubt, have the
fame notion of numbers as we have, and form
a fyftem of arithmetic. It is not material to
fay in what order he might proceed in fuch
dilcoveries, or how much time and pains he
might employ about them ; but what fuch a
being, by reafon and ingenuity, without any
materials of fenfation but thofe of fight only,
might discover.

As

224 OF THE HUMAN MIND. [CHAP. 6.

As it is more difficult to attend to a detail
of poffibilities, than of fads even of (lender
authority, I fhall beg leave to give an ^extract
from the travels of Johannes Rudolphus
Anepigraphus, a Roficrucian philofopher,
who having, by deep ftudy of the occult fci-
ences, acquired the art of tranfporting him-
felf to various fublunary regions, and of con-
verfing with various orders of intelligences, in
the courfe of his adventures, became acquaint-
ed with an order of beings exactly fuch as I
have fuppofed.

How they communicate their fentiments to
one another, and by what means he became
acquainted with their language, and was ini-
tiated into their philofophy, as well as of many
other particulars, which might have gratified
the curiofity of his readers, and perhaps added
credibility to his relation, he hath not thought
fit to inform us ; thefe being matters proper
for adepts only to know.

His account of their philofophy is as fol-
lows :

" The Idomenians," faith he, " are many
« of them very ingenious, and much given to
" contemplation. In arithmetic, geometry,
" metaphyfics, and phyfics, they have mod
" elaborate fyiiems. In the two latter indeed

" they

SECT. 9.] OF SEEING. 225

" they have had many difputes, carried on
" with great fubtilty, and are divided into va-
" rious feds ; yet in the two former there hath
" been no lefs unanimity than among the hii-
" man fpecies.' Their principles relating to
" numbers and arithmetic, making allowance
" for their notation, differ in nothing from
" ours : but their geometry differs very con-
" fiderably."

As our author's account of the geometry of
the Idomenians agrees in every thing with
the geometry of vifibles, of which we have
already given a fpecimen, we fhall pafs over
it. He goes on thus: " Colour, extenfion,
" and figure, are conceived to be the effen-
*' tial properties of body. A very confider-
M able fed maintains, that colour is the ef-
" fence of body. If there had been no co-
" lour, fay they, there had been no percep-
u tion or fenfation. Colour is all that we
" perceive, or can conceive, that is peculiar
" to body 5 extenfion and figure being modes
" common to body and to empty fpace. And
u if we fhould fuppofe a body to be annihr-
" lated, colour is the only thing in it that can
" be annihilated ; for its place, and confe-
" quently the figure and extenfion of that
" place, muft remain, and cannot be imagi-
P « necl.

226 OF THE HUMAN MIND. [CHAP. 6.

u hed not to exift. Thefe philofophers hold
" fpacc to be the place of all bodies, immove-
" able and indeftruclible, without figure, and
" fimilar in all its parts, incapable of increafe
" or diminution, yet not unmeafurable : for
** every the lead part of fpace bears a finite
" ratio to the whole. So that with them the
" whole extent of fpace is the common and
41 natural meafure of every thing that hath
" length and breadth, and the magnitude of
" every body and of every figure is exprefled
" by its being fuch a part of the univerfe.
" In like manner, the common and natural
" meafure of length, is an infinite right line,
" which, as hath been before obferved, re-
" turns into itfelf, and hath no limits, but
" bears a finite ratio to every other line.

" As to their natural philofophy, it is now
" acknowledged by the wifeft of them to
" have been for many ages in a very low ftate.
" The philofophers obferving, that one body
" can differ from another only in colour, fi-
" gure, or magnitude, it was taken for grant-
" ed, that all their particular qualities muft
** arife from the various combinations of thefc
" their efiential attributes. And therefore it
" was looked upon as the end of natural phi-
" lofophy, to fhew how the various combina-

" tions

SECT. 9-3 or SEEING. 227

" tions of thefe three qualities in different bo-
" dies produced all the phenomena of na-
44 ture. It were endlefs to enumerate the va-
" rious fyftems that were invented with this
" view, and the difputes that were carried on
" for ages ; the followers of every fyftem ex-
" pofing the weak fides of other fyftems, and
" palliating thofe of their own, with great
" art.

" At lad, fome free and facetious fpirits,
" wearied with eternal difputation, and the
" labour of patching and propping weak fy[-
" terns, began to complain of the fubtilty of
" nature ; of the infinite changes that bodies
" undergo in figure, colour, and magnitude ;
" and of the difficulty of accounting for thefe
" appearances, making this a pretence for
" giving up all inquiries into the caufes of
" things, as vain and fruitlefs.

" Thefe wits had ample matter of mirth
" and ridicule in the fyftems of philofophers,
u and finding it an eafier tafk to pull down
" than to build or fupport, and that every
" feet furniflied them with arms and auxili-
** aries^to deftroy another, they began to
" fpread mightily, and went on with great
" fuccefs. Thus phiiofophy gave way to
" fcepticifm and irony, and thofe fyftems
P 2 u which

228 OF THE HUMAN MIND. [CHAP. 6.

" which had been the work of ages, and the
" admiration of the learned, became the jeft
" of the vulgar : for even the vulgar readily
" took part in the triumph over a kind of
" learning which they had long fufpe&ed, be-
" caufe it produced nothing but wrangling
" and altercation. The wits having now
" acquired great reputation, and being flufh-
" ed with fuccefs, began to think the triumph
" incomplete, until every pretence to knowT-
" ledge was overturned ; and accordingly be-
" gan their attacks upon arithmetic, geome-
" try, and even upon the common notions of
" untaught Idomenians. So difficult it hath
a always been (fays our author) for great
" conquerors to know where to flop.

" In the mean time, natural philofophy be-
" gan to rife from its alhes, under the direc-
" tion of a perfon of great genius, who is
" looked upon as having had fomething in
" him above Idomenian nature. He obfer-
" ved, that the Idomenian faculties were cer-
" tainly intended for contemplation, and that
" the works of nature were a nobler fubjecl
" to exercife them upon, than the follies of
" fyftems, or the errors of the learned ; and
" being fenfible of the difficulty of finding
" out the caufes of natural things, he propo-

" fed.

SECT. 9.] OF SEEING. 229

" fed, by accurate obfervatibn of the pheno-
" mena of nature, to find out the rules ac-
" cording to which they happen, without iri-
" quiring into the caufes of thofe rules. In
" this he made confiderable progrefs himfelf,
" and planned out much work for his follow-
M ers, who call themfelves i?ida5live philofo-
" phers. The fceptics look with envy upon
" this rifing feci, as eclipfing their reputation,
" and threatening to limit their empire ; but
" they are at a lofs on what hand to attack
" it. The vulgar begin to reverence it, as
" producing ufeful difcoveries.

" It is to be obferved, that every Idome-
" nian firmly believes, that two or more bo-
" dies may exift in the fame place. For this
" they have the teftimony of fenfe, and they
" can no more doubt of it, than they can
" doubt whether they have any perception
" at all. They often fee two bodies meet,
" and coincide in the fame place, and fepa-
" rate again, without having undergone any
" change in their fenfible qualities by this
" penetration. When two bodies meet, and
" occupy the fame place, commonly one on-
u ly appears in that place, and the other dif-
" appears. That which continues to appear

P 3 "is

2J0 OF THE HUMAN MIND. [CHAP. 6.

" is faid to overcome, the otficr to be over-
" come."

To this quality of bodies they gave a name,
which our author tells us hath no word an-
fwering to it in any human language. And
therefore, after making a long apology, which
I omit, he begs leave to call it the overcoming
quality of bodies. He aflures us, that " the
** fpeculations which had been raifed about
•' this fingle quality of bodies, and the hypo-
" thefes contrived to account for it, were fuf-
" ficient to fill many volumes. Nor have
41 there been fewer hypothefes invented by
44 their philofophers, to account for the chan-
44 ges of magnitude and figure; which, in
44 moft bodies that move, they perceive to be
" in a continual fluctuation. The founder
*' of the inductive feci, believing it to be
*' above the reach of Idomenian faculties,
44 to difcover the real caufes of thefe ph*no-
44 mena, applied himfelf to find from obfer-
" vation, by what laws they are connected
44 together ; and difcovered many mathema-
44 tical ratios and relations concerning the
44 motions, magnitudes, figures, and over-
" coming quality of bodies, which conftant
" experience confirms. But the oppofers of
41 this feci choofe rather to content themfelves

" with

SECT. 9.] OF SEEING. 231

" with feigned caufes of thefe phenomena,
" than to acknowledge the real laws where-
" by they are governed, which humble their
" pride, by being confeffedly unaccount-
" able."

Thus far Johannes Rudolphus Anepi-
graphus. Whether this Anepigraphus be
the fame who is recorded among the Greek al-
chemiftical writers not yet publilhed, by Bor-
richius, Fabricius, and others, I do not pre-
tend to determine. The identity of their
name, and the fimilitude of their ftudies, al-
though no flight arguments, yet are not abfo*
lutely conclufive. Nor will I take upon me
to judge of the narrative of this learned tra-
veller by the external marks of his credibili-
ty ; I fhall confine myfelf to thofe which the
critics call internal. It would even be of
fmall importance to inquire, whether the Ido-
menians have a real, or only an ideal exift-
ence ; fince this is difputed among the learn-
ed with regard to things with which we are
more nearly connected. The important que-
ftion is, Whether the account above given, is
a juft account of their geometry and philofo-
phy ? We have all the faculties which they
have, wTith the addition of others which they
have not ; we may therefore form fome judg-
P 4 ment

232 0,F THE HUMAN MIND. [CHAP. 6,

merit of their philofophy and geometry, by
fcpa rating from all others, the perceptions we
have by fight, and reafoning upon them. As
far as 1 am able to judge in this way, after a
careful exa ination, their geometry muft be
fuch as Anepigraphus hath defcribed. Nor
does his account of their philofophy appear
to contain any evident marks of impofture ;
although here, no doubt, proper allowance is
to be made for liberties which travellers take,
as well as for involuntary miftakes which they
are apt to fall into.

SECT. X.

Of the parallel motion of the eyes.

HAving explained, as diftin&ly as wf
can, vifible figure, and fhewn its con-
nection with the things fignified by it, it will
be proper next to confider fome phenomena
of the eyes, and of vifion, which have com-
monly been referred to cuftom, to anatomical
or to mechanical caufes j but which, as I con-
ceive.

SECT. 10.] OF SEEING. £33

ceive, mud be refolved into original powers
and principles of the human mind ; and there-
fore belong properly to the fubjec~t of this in-
quiry.

The firft is, the parallel motion of the eyes ;
by which, when one eye is turned to the right
or to the left, upwards or downwards, or
ftraight forwards, the other always goes along
with it in the fame direction. We fee plain-
ly, when both eyes are open, that they are
always turned the fame way, as if both were
acted upon by the fame motive force : and
if one eye is fhut, and the hand laid upon it,
while the other turns various ways, we feel
the eye that is fhut turn at the fame time, and
that whether we will or not. What makes
this phenomenon furpriling is, that it is ac-
knowledged by all anatomifts, ,that the muf-
cles which move the two eyes, and the nerves
which ferve thefe mufcles, are entirely diftincr.
and unconnected. It would be thought very
furpriling and unaccountable, to fee a man,
who, from his birth, never moved one arm,
without moving the other precifely in the
fame manner, fo as to keep them always pa-
rallel : y^t it would not be more difficult to
find the phyfical caufe of fuch motion of the
arms, than it is to find the caufe of the pa-
rallel

234 OF THE HUMAN MIND. [CHAP. 6.

rallel motion of the eyes, which is perfectly
fimilar.

The only caufe that hath been afiigned of
this parallel motion of the eyes, is cuftom.
We find by experience, it is faid, when we
begin to look at objecls, that, in order to have
diftindt vifion, it is necefiary to turn both eyes
the fame way ; therefore we foon acquire the
habit of doing it conftantly, and by degrees
lofe the power of doing otherwife.

This account of the matter feems to be in-
fufficient ; becaufe habits are not got at once ;
it takes time to acquire and to confirm them ;
and if this motion of the eyes were got by
habit, we mould fee children, when they are
born, turn their eyes different ways, and
move one without the other, as they do their
hands or legs. I know fome have affirmed
that they are apt to do fo. But I have never
found it true from my own obfervation, al-
though I have taken pains to make obferva-
tions of this kind, and have had good oppor-
tunities. I have Hkewife confulted experien-
ced midwives, mothers and nurfes, and found
them agree, that they had never obferved
diftortions of this kind in the eyes of children,
but when they had reafon to fufpect convul-
fions, or fome preternatural caufe.

It

SECT. 10.] OF SEEING. 235

It feems therefore to be extremely proba-
ble, that, previous to cuftom, there is fome-
thing in the conftitution, fome natural initinct,
which directs us to move both eyes always
the fame way.

We know not how the mind acts upon the
body, nor by what power the mufcles are con-
tracted and relaxed ; but we fee that in fome
of the voluntary, as well as in fome of the
involuntary motions, this power is fo directed,
that many mufcles which have no material tie
or connection, act in concert, each of them
being taught to play its part in exact time
and meafure. Nor doth a company of ex-
pert players in a theatrical performance, or
of excellent muficians in a concert, or of good
dancers in a country-dance, with more regu-
larity and order, confpire and contribute their
feveral parts, to produce one uniform effect,
than a number of mufcles do, in many of the
animal functions, and in many voluntary ac-
tions. Yet we fee fuch actions no lefs fkil-
fully and regularly performed in children,
and in thofe who know not that they have
fuch mufcles, than in the mod fkilful aifato-
mift and phyfiologift.

Who taught all the mufcles that are con-
cerned in fucking, in fwallowing our food, in

breathing,

336 OF THE HUMAN MIND. [CHAP. 6.

breathing, and in the feveral natural expul-
sions, to act their part in fuch regular order
and exact meafure ? It was not cuftomfu re-
ly. It was that fame powerful and wife Be-
ing wko made the fabric of the human body,
and fixed the laws by which the mind ope-
rates upon every part of it, fo that they may
anfwer the purpofes intended by them. And
when we fee,: in fo many other inftances, a
fyftem of unconnected mufcles confpiring fo
wonderfully in their feveral functions, with-
out the aid of habit, it needs not be thought
ftrange, that the mufcles of the eye fhould,
without this aid, confpire to give that direction
to the eyes, without which they could not an-
fwer their end.

We fee a like confpiring action in the muf-
cles which contract the pupils of the two eyes ;
and in thofe mufcles, whatever they be, by
which the conformation of the eyes is varied,
according to the diftance of objects.

It ought however to be obferved, that al-
though it appears to be by natural inftinct
that both eyes are always turned the fame
way, there is (fill fome latitude left for cuf-
tom.

What we have faid of the parallel motion
of the eyes, is not to be underftood fo ftrictly,

as

SECT. 10.] OF SEEING. <2$J

as if nature directed us to keep their axes al-
ways precifely and mathematically parallel to
each other. Indeed, although they are always
nearly parallel, they hardly ever are exactly
fo. When we look at an object, the axes of
the eyes meet in that object ; and therefore,
make an angle, which is always fmall, but
will be greater or lefs, according as the object
is nearer or more remote. Nature hath very
wifely left us the power of varying the pa-
rallelifm of our eyes a little, fo that we can
direct them to the fame point, whether remote
or near. This, no doubt, is learned by cuf-
torn ; and accordingly we fee, that it is a long
time before children get this habit in perfec-
tion.

This power of varying the parallelifm of
the eyes is naturally no more than is fufficient
for the purpofe intended by it ; but by much
practice and (training, it may be increafed.
Accordingly we fee, that fome have acquired
the power of diftorting their eye? into unna-
tural directions, as others have acquired the
power of diftorting their bodies into unnatu-
ral poftures.

Thofe who have loft the fight of an eye,
commonly lofe what they had got by cuftom,
in the direction of their eyes, but retain what

they

238 Or THE HUMAN MIND. [CHAP. 6.

they had by rvature ; that is, although their
eyes turn and move always together ; yet,
when they look upon an objed, the blind eye
will often have a very fmali deviation from
it ; which is not perceived by a flight ob-
ferver, but may be difcemed by one accuf-
tomed to make exact obfervations in thefe mat-
ters.

SECT. XL

Of our feeing objecls erecl by inverted images.

ANother phenomenon which hath per-
plexed philofophers, is, our feeing ob-
jects erect, when it is well known that their
images or pictures upon the tunica retina of
the eye are inverted.

The fagacious Kepler fir ft made the noble
difcovery, That diftinct but' inverted pictures
of vifible objects, are formed upon the retina
by the rays of light coming from the object.
The fame great philofopher demonftrated from
the principles of optics, how thefe pictures are

formed,

SECT. II.] OF SEEING. 239

formed, to- wit, That the rays coming from
any one point of the object, and falling upon
the various parts of the pupil, are, by the
cornea and cryftalline, refracted fo as to meet
again in one point of the retina, and there
paint the colour of that point of the object
from which they come. As the rays from
different points of the object crofs each other
before they come to the retina, the picture
they form mud be inverted ; the upper part
of the object being painted upon the lower
part of the retina, the right fide of the object
upon the left of the retina, and fo of the other
parts.

This philofopher thought that we fee ob-
jects erect by means of thefe inverted pictures,
for this reafon, That as the rays from different
points of the object crofs each other, before
they fall upon the retina, we conclude that
the impulfe which we feel upon the lower
part of the retina, comes from above ; and that
the impulfe which we feel upon the higher
part, comes from below.

Des Cartes afterwards gave the fame fo-
lution of this phenomenon, and illuftrated it
by the judgment which we form of the pofi-
tion of objects which we feel with our arms

crofled.

246 OF THE HUMAN MIND. [CHAP. 6.

croffed, or with two ftfcks that erofs each
other.

Bat we cannot acquiefce in this folatron.
Firft, Becaufe it fuppofes our feeing things
erect, to be a, deduction of reafon, drawn from
certain premifes : whereas it feems to be an
immediate perception. And, fecondly, Be-
caufe the premifes from which all mankind are
fuppofed to draw this conlclufion, never enter-
ed into the minds of the far greater part, but
are abfolutely unknown to them. We have
no feeling or perception of the pictures upon
the retina, and as little furely of the pofition
of them. In order to fee objects erect, ac-
cording to the principles of Kepler or Des
Cartes, we muft previoufly know, that the
rays of light come from the object to the eye
in ftraight lines ; we muft know, that the rays
from different points of the object crofs one
another, before they form the pictures upon
the retina ; and laftly, we muft know, that
thefe pictures are really inverted. Now, al-
though all thefe things are true, and known
to philofophers, yet they are abfolutely un-
known to the far greateft part of mankind :
nor is it pomble that they who are abfolutely
ignorant of them, fhould reafon from them,
and build conclufions upon them. Since

therefore

SECT, II.] OF SEEING. 24I

therefore vifible objects appear erect to the
ignorant as well as to the learned, this cannot
be a conclulion drawn from premifes which
never entered into the minds of the ignorant.
We have indeed had occation to obferve ma-
ny inftances of concluiions drawn, either by
means of original principles, or by habit, from
premifes which pafs through the mind very
quickly, and which are never made the ob-
jects of reflection ; but furely no man will
conceive it poffible to draw concluiions from
premifes which never entered into the mind
at ail.

Bifhop Berkeley having juftly rejected this
folution, gives one founded upon his own prin-
ciples; wherein he is followed by the judicious
Dr Smith in his Optics; and this we {hall next
explain and examine.

That ingenious writer conceives the ideas
of fight to be altogether unlike thofe of touch.
And fince the notions we have of an object by
thefe different fenfes have no fimilitude, we
can learn only by experience how one fenfe
will be affected, by what, in a certain man-
ner, affects the other. Figure, pofition, and
even number, in tangible objects, are ideas of
touch ; and although there is no fimilitude
between thefe and the ideas of light, yet we
Q^ learn

24* 0F THE HUMAN MIND. [CHAP. 6.

learn by experience, that a triangle affects the
fight in fuch a manner, and that a fquare af-
fects it in fuch another manner : hence we
judge that which affe&s it in the firft manner,
to be a triangle, and that which affects it in
the fecond, to be a fquare. In the fame way,
finding from experience, that an object in an
erect pofition, affects the eye in one manner,
and 'the fame object in an inverted pofition,
affects it in another, we learn to judge, by the
manner in which the eye is affected, whether
the object is erect or inverted. In a word, vi-
fible ideas, according to this author, are figns
of the tangible ; and the mind paffeth from
the fign to the thing fignified, not by means
of any fimilitude between the one and the
other, nor by any natural principle; but by
having found them conftantly conjoined in
experience, as the founds of a language are
with the things they fignify. So that if the
images upon the retina had been always erect,
they would have fhewn the objects erect, in
the manner as they do now that they are in-
verted : nay, if the vifible idea which we now
have from an inverted object, had been affo-
piated from the beginning with the erect po-
fition of that object, it would have fignified
an erect pofition* as readily as it now fignifies

an

SECT. II.] OF SEEING. 243

an inverted one. And if the vifible appear-
ance of two (hillings had been found connect-
ed from the beginning with the tangible idea
of one milling, that appearance would as na-
turally and readily have iignified the unity of
the object, as now it fignifies its duplicity.

This opinion is undoubtedly very ingenious ;
and, if it is juft, ferves to refolve, not only
the phenomenon now under confideration, but
likewife that which we fhall next coniider,
our feeing objects iingle with two eyes.

It is evident, that in this folution it is fup-
pofed, that we do not originally, and previous
to acquired habits, fee things either erect or
inverted, of one figure or another, iingle or
double, but learn from experience to judge
of their tangible pofition, figure, and number,
by certain vifible figns.

Indeed, it mult be acknowledged to be ex-
tremely difficult to diftinguifh the immediate
and natural objects of fight, from the conclu-
fions which we have been accuftomed from
infancy to draw from them. Bifhop Berke-
ley was the firft that attempted to diftinguifh
the one from the other, and to trace out the
boundary that divides them. And, if in doing
fo, he hath gone a little to the right- hand or
to the left, this might be expected in a fub-
(^2 ject

244 0F THE HUMAN MIND. [CHAP. 6.

jed: altogether new, and of the greateft fub-
tilty. The nature of vifion hath received
great light from this diftinction ; and many
phenomena in optics, which before. appeared
altogether unaccountable, have been clearly
and diftindly refolved by it. It is natural,
and almoft unavoidable, to one who hath
made an important difcovery in philofophy,
to carry it a little beyond its lphere, and to
apply it to the refolution of phenomena which
do not fall within its province. Even the
great Newtom, when he had difcovered the
univerfal law of gravitation, and obferved how
many of the phenomena of nature depend up-
on this, and other laws of attraction and re-
pulfion, could not help expreffing his conjec-
ture, that all the phenomena of the material
world depend upon attracting and repelling
forces in the particles of matter. And I fu-
fpect. that the ingenious Bifhop of Cloyne,
having found fo many phenomena of vifion
reducible to the conilant afibciation of the
ideas of fight and touch, carried this princi-
ple a little beyond its jufl limits.

In order to judge, as well as we can, whe-
ther it is fo, let us fuppofe fuch a blind man
as Dr SAUiNDERsoN, having all the knowledge
#nd abilities which a blind man may have,

fuddenly

SECT. II.] OF SEEING. 245

fuddenly made to fee perfectly. Let us fup-
pofe him kept from all opportunities of afTo-
dating his ideas of light with thofe of touch,
until the former become a little familiar ; and
the fir ft furprife, occafioned by objects fo new,
being abated, he has time to canvafs them,
and to compare them, in his mind, with the
notions which he formerly had by touch ;
and in particular to compare, in his mind,
that vifible extenlion which his eyes prefent,
with the extenlion in length and breadth with
which he was before acquainted.

We have endeavoured to prove, that a
blind man may form a notion of the vifible
extenfion and figure of bodies, from the rela-
tion which it bears to their tangible extenfion
and figure. Much more, when this vifible
extenfion and figure are prefented to his eye,
will he be able to compare them with tangi-
ble extenlion and figure, and to perceive, that
the one has length and breadth as well as the
other ; that the one may be bounded by lines,
either ftraight or curve, as well as the other.
And therefore, he will perceive, that there
may be vifible as well as tangible circles,
triangles, quadrilateral and multilateral fi-
gures. And although the vifible figure is
coloured, and the tangible is not, they may,
Q^3 notwithstanding,

24^ OF THE HUMAN MIND. [CHAP. 6\

notwithstanding, have the fame figure ; as
two objects of touch may have the fame fi-
gure, although one is hot and the other cold.

We have demonftrated, that the proper-
ties of vifible figures differ from thofe of the
plain figures which they reprefent : but it
was obferved at the fame time, that when the
object is fo fmall as to be feen diftin&ly at
one view, and is placed dire&ly before the
eye, the difference between the vifible and
the tangible figure is too fmall to be perceived
by the fenfes. Thus, it is true, that of every
vifible triangle, the three angles are greater
than two right angles ; whereas, in a plain
triangle, the three angles are equal to two
right angles : but, when the vifible triangle is
fmall, its three angles will be fo nearly equal
to two right angles, that the fenfe cannot dif-
cern the difference. In like manner, the cir-
cumferences of unequal vifible circles are not,
but thofe of plain circles are, in the ratio of
their diameters ; yet in fmall vifible circles,
the circumferences are very nearly in the ratio
of their diameters ; and the diameter bears
. the fame ratio to the circumference, as in a
plain circle, very nearly.

Hence it appears, that fmall vifible figures
(and fuch only can be feen diftinctly at one

view)

sect. Ii.] of seeing* 247

view) have not only a refemblance to the
plain tangible figures which have the fame
name, but are to all fenfe the fame. So that
if Dr Saunderson had been made to fee, and
had attentively viewed the figures of the firft
book of Euclid, he might, by thought and
confideration, without touching them, have
found out that they were the very figures he
was before fo well acquainted with by touch.

When plain figures are feen obliquely, their
vifible figure differs more from the tangible ;
and the reprefentation which is made to the
eye, of folid figures, is ftill more imperfect ;
becaufe vifible extenfion hath not three, but
two dimenfions only. Yet, as it cannot be
faid that an exact picture of a man hath no
refemblance of the man, or that a perfpective
view of a houfe hath no refemblance of the
houfe ; fo it cannot be faid, with any pro-
priety, that the vifible figure of a man, or of
a houfe, hath no refemblance of the objects
which they reprefent.

Bifhop Berkeley therefore proceeds upon
a capital miftake, in fuppofing that there is
no refemblance betwixt the extenfion, figure,
and pofition which we fee, and that which we
perceive by touch.

(^4 We

248 OF THE HUMAN. MIND. [CHAP. 6.

We may further obferve, that Bifhop
Berkeley's fyftem, with regard to material
things, mud have made him fee this queftion,
of the erect appearance of objects, in a very
different light from that in which it appears
to thofe who do not adopt his fyftem.

In his theory of vifion, he feems indeed to
allow, that there is an external material
world : but he believed that this external
world is tangible only, and not vifible ; and
that the vifible world, the proper object of
fight, is not external, but in the mind. If
this is fuppofed, he that affirms that he fees
things erect and not inverted, affirms that
there is a top and a bottom, a right and a left
in the mind. Now, 1 confefs I am not fo
well acquainted with the topography of the
mind, as to be able to affix a meaning to thefe
words when applied to it.

We (hall therefore allow, that if vifible
objects were not external, but exifled only in
the mind, they could have no figure, or pofi-
tion, ox extenfion ; and that it would be ab-
furd to affirm, that they are feen either erect
or inverted ; or that there is any refemblance
between them and the objects of touch. But
when we propofe the queftion, Why objects
are feen erect and not inverted ? we .take it

for

SECT. II.] OF SEEING. 249

for granted, that we are not in Bifliop Berke-
ley's ideal world, but in that world which
men, who yield to the di&ates of common
fenfe, believe themfelves to inhabit. We take
it for granted, that the objects both of fight
and touch, are external, and have a certain
figure, and a certain pofition with regard to
one another, and with regard to our bodies,
whether we perceive it or not.

When I hold my walking-cane upright in
my hand, and look at it, I take it for granted,
that I fee and handle the fame individual ofc-
jedt. When I fay that I feel it erect, my
meaning is, that I feel the head directed from
the horizon, and the point directed towards
it : and when I fay that I fee it erect, I mean
that I fee it with the head directed from the
horizon, and the point towards it. I conceive
the horizon as a fixed object both of light and
touch, with relation to which, objects are faid
to be high or low, erecl or inverted: and
when the qucftion isafkcd, Why I fee the
object erect, and not inverted? it is the fame
as if you mould afk, Why I fee it in that po-
fition which it really hath ? or, Why the eye
fhows the real pofition of objects, and doth
not fhow them in an inverted pofition, as they
are [gqti by a common aftronomical telefcope,

or

35O OF THE HUMAN MIND. [CHAP. 6.

or as their pi&ures are feen upon the retina
of an eye when it is difle&ed.

SECT. XII.

The fame fubjed continued.

IT is impoflible to give a fatisfadtory anfwer
to this queftion, otherwife than by point-
ing out the laws of nature which take place
in vifion ; for by thefe the phenomena of vi-
iion mull be regulated.

Therefore I anfwer, Firft, That by a law
of nature the rays of light proceed from every
point of the object to the pupil of the eye in
ftraight lines. Secondly, That by the laws
of nature, the rays coming from any one point
of the object to the various parts of the pupil,
are fo refracted, as to meet again in one point
of the retinaj and the rays from different
points of the object, firft crofting each other,
and then proceeding to as many different
points of the retina, form an inverted picture
of the object.

So

SECT. 12.] OF SEEING. 2^1

So far the principles of optics carry us 5
and experience further allures us, that if there
is no fuch picture upon the retina, there is no
vifion ; and that fuch as the picture on the
retina is, fuch is the appearance of the object,
in colour and figure, diftindtnefs or indiftinct-
nefs, brightnefs or faintnefs.

It is evident, therefore, that the pictures
upon the retina are, by the laws of nature, a
mean of vifion ; but in what way they ac-
complifli their end, we are totally ignorant.
Philofophers conceive, that the impreflion
made on the retina by the rays of light, is
communicated to the optic nerve, and by the
optic nerve conveyed to fome part of the
brain, by them called the fenforium ; and that
the impreflion thus conveyed to the fenforium
is immediately perceived by the mind, which
is fuppofed to refide there. But we know-
nothing of the feat of the foul : and we are
fo far from perceiving immediately what is
tranfa&ed in the brain, that of all parts of the
human body we know leaft about it. It is
indeed very probable, that the optic nerve is
an inftrument of vifion no lefs neceffary than
the retina ; and that fome impreflion is made
upon it, by means of the pictures on the re-
tina.

2$Z OF THE. HUMAN MIND. [CHAP. 6.

tina. But of what kind this impreffion is, we
know nothing.

There is not the lead probability, that there
is any picture or image of the object either in
the optic nerve or brain. The pictures on
the retina are formed by the rays of light \
and whether we fuppofe, with fome, that their
impulfe upon the retina caufes fome vibration
of the fibres of the optic nerve; or, with
others, that .it. gives motion to fome fubtile
fluid contained in the nerve ; neither that vi-
bration, nor this motion, can refemble the vi-
fible object which is prefented to the mind.
Nor is there any probability, that the rnind
perceives the pictures upon the retina. Thefe
pictures are no more objects of our percep-
tion, than the brain is, or the optic nerve.
No man ever faw the pictures in his own eye,
nor indeed the pictures in the eye of another,
until it was taken out of the head and duly
prepared.

It is very ftrange, that philofophers, of all
ages, mould have agreed in this notion, That
the images of external objecls are conveyed
by the organs of fenfe to the brain, and are
there perceived by the mind. Nothing can
be more unphilolophical. For, firft, This
notion hath no foundation in fad and obser-
vation.

SECT. 12.] OF SEEING. 25 3

vation. Of all the organs of fenfe, the eye
only, as far as, we can difcover, forms any
kind of image of its object ; and the images
formed by the eye are not in the brain, but
only in the bottom of the eye ; nor are they
at all perceived or felt by the mind. Second-
ly, It is as difficult to conceive how the mind
perceives images in the brain, as how it per-
ceives things more diftant. If any man will
mew how the mind may perceive images in
the brain, I will undertake to fhew how it
may perceive the moll diftant objects : for if
we give eyes to the mind, to perceive what
is tranfacted at home in its dark chamber,
why may we not make thefe eyes a little long-
er lighted ? and then we fhall have no occa-
iion for that unphilofophical fiction of images
in the brain. In a word, the manner and
mechanifm of the mind's perception is quite
beyond our comprehenfion : and this way of
explaining it by images in the brain, feems to
be founded upon very grofs notions of the
mind and its operations ; as if the fuppofed
images in the brain, by a kind of contact,
formed fimilar impreffions or images of ob-
jects upon the mind, of which impreffions it
is fuppofed to be confeious.

We

254 °F THE HUMAN MIND. [CHAP. 0.

We have endeavoured to mew, throughout
the courfe of this inquiry, that the impref-
iions made upon the mind by means of the
five fenfes, have not the lead refemblance to
the obje&s of fenfe : and therefore, as we fee
no ftvadow of evidence, that there are any
iiich images in the brain, fo we fee no pur-
pofe, in philofophy, that the fuppofition of
them can anfwer. Since the picture upon the
retina, therefore, is neither itfelf feen by the
mind, nor produces any irnprefTion upon the
brain or fenforinm, which is feen by the mind,
Hor makes any irnprefTion upon the mind that
jefembles the object, it may ftili be afked,
How this picture upon the retina caufes vi-
iion ?

Before we anfwer this queftion, it is proper
to obferve, that in the operations of the mind,
as well as in thofe of bodies, we mull often be
fatisfied with knowing; that certain things are
conne&ed, and invariably follow one another,
without being able to difcover the chain that
goes between them. It is to fuch connections
that we give the name oi laws of nature; and
when we fay that one thing produces another
by a law of nature, this fignifies no more, but
that one thing, which we call in popular lan-
guage the eaufe, is conftantly and invariably

followed

SECT. 12.] OF SEEING. 255

followed by another, which we call the effeft ;
and that we know not how they are connect-
ed. Thus, we fee it is a fact, that bodies gra-
vitate towards bodies ; and that this gravita-
tion is regulated by certain mathematical pro-
portions, according to the diftances of the bo-
dies from each other, and their quantities of
matter. Being unable to difcover the caufe
of this gravitation, and prefuming that it is
the immediate operation, either of the Author
of nature, or of fome fubordinate caufe, which
we have not hitherto been able to reach, we
call it a law of nature. If any philofopher
fhould hereafter be fo happy as to difcover the
caufe of gravitation, this can only be done by
difcovering fome more general law of nature,
of which the gravitation of bodies is a necef*
fary confequence. In every chain of natural
caufes, the highefl link is a primary law of
nature, and the higheft link which we can
trace, by juft induction, is either this primary
law of nature, or a neceffary confequence of
it. To trace out the laws of nature, by in-
duction, from the phenomena of nature, is all
that true philofophy aims at, and all that it can
ever reach.

There are laws of nature by which the ope-
rations of the mind are regulated ; there are

alfo

2$6 OF THE HUMAN MIND. [CHAP. 6.

alfo laws of nature that govern the material
fyftem : and as the latter are the ultimate con-
clusions which the human faculties can reach
in the philofophy of bodies, fo the former are
the ultimate concluuons we can reach in the
philofophy of minds.

To return, therefore, to the queftion above
propofed, we may fee, from what hath been
jtifl now obferved, that it amounts to this, By
what law of nature is a picture upon the re-
tina, the mean or occafion of my feeing an ex-
ternal object of the fame figure and colour, in
a contrary poiition, and in a certain direction
from the eye ?

It will, without doubt, be allowed, that I
fee the whole object in the fame manner and
by the fame law by which I fee any one point
of it. Now, I know it to be a fact, that, in
direct vilion, I fee every point of the object in
the direction of the right line that pallet h
from the centre of the eye to that point of the
object: : and I know likewife, from optics,
that the ray of light that comes to the centre
of my eye, panes on to the retina in the fame
direction'. Hence it appears to be a fact, that
every point of the object is feen in the direc-
tion of a right line palling from the picture of
that point on the retina through the centre of

the

SECT. 12.] OF SEEING. 2^7

the eye. As this is a fact that holds univer-
fally and invariably, it muft either be a law of
nature, or the neceflary confequence of fome
more general law of nature. And according
to the juft rules of philofophizing, we may
hold it for a law of nature, until ibme more
general law be difcovered, whereof it is a ne-
ceflary confequence, which I fufpect can ne-
ver be done.

Thus we fee, that the phenomena of vifion
lead us by the hand to a law of nature, or a
law of our constitution, of which law our fee-
ing objects erect by inverted images, is a ne-
ceflary confequence. For it neceffarily fol-
lows, from the law we have mentioned, that
the object whofe picture is loweft on the re-
tina, muft be feen in the higheft direction
from the eye ; and that the object whofe pic-
ture is on the right of the retina, muft be {gqii
on the left ; fo that if the pictures had been
erect in the retina, we fhould have feen the
object inverted. My chief intention in hand-
ling this queftion, was to point out this law of
nature ; which, as it is a part of the conftitu-
tion of the human mind, belongs properly to
the fubject of this inquiry. For this reafon I
fliall make fome further remarks upon it, af-
ter doing juftice to the ingenious Dr Porter-

R FIELD,

258 OF THE HUMAN MIND. [CHAP. 6.

field, who, long ago in the Medical EfTays,
or more lately in his Treatife of the Eye,
pointed out, as a primary law of our nature,
That a vifible object appears in the direction
of a right line perpendicular to the retina
at that point where its image is painted. If
lines drawn from the centre of the eye to all
parts of the retina be perpendicular to it, as
they mull be very nearly, this coincides with
the law we have mentioned, and is the fame
in other words. In order, therefore, that we
may have a more diftincl: notion of this law of
our conftitution, we may obferve,

1. That we can give no reafon why the re-
tina is, of all parts of the body, the only one
on which pictures made by the rays of light
caufe vilion ; and therefore we mud refolve
this folely into a law of our conftitution. We
may form fuch pidures by means of optical
glafles, upon the hand, or upon any other part
of the body ; but they are not felt, nor do
they produce any thing like vifion. A pic-
ture upon the retina is as little felt as one up-
on the hand ; but it produces vifion \ for no
other reafon that we know, but becaufe it is
deftined by the wifdom of nature to this pur-
pofe. The vibrations of the air ftrike upon
the eye, the palate, and the olfactory mem-
brane,

SECT. 12.] OF SEEING. 259

brane, with the fame .force as upon the mem-
brant tympani of the ear : The impreflion they
make upon the laft, produces the fenfation of
found ; but their impreffions upon any of the
former, produces no fenfation at all. This
may be extended to all the fenfes, whereof
each hath its peculiar laws, according to which,
the impreffions made upon the organ of that
fenfe, produce fenfations or perceptions in the
mind, that cannot be produced by impreffions
made upon any other organ.

2. We may obferve, that the laws of per-
ception, by the different fenfes, are very dif-
ferent, not only in refpect of the nature of the
objects perceived by them, but likewife in re-
fpecl of the notices they give us of the di-
ftance and fituation of the object. In all of
them the object is conceived to be external,
and to have real exiftence, independent of our
perception : but in one, the diftance, figure
and lituation of the object, are all prefented to
the mind ; in another, the figure and litua-
tion, but not the diftance ; and in others, nei-
ther figure, fituation, nor diftance. In vain
do we attempt to account for thefe varieties
in the manner of perception by the different
fenfes, from principles of anatomy or natural
philofophy. They muft at laft be refolved Hi-
ll 2 to

l6o OF THE HUMAN MIND. [CHAP. 6.

to the will of our Maker, who intended that
our powers of perception fhould have certain
limits, and adapted the organs of perception,
and the laws of nature by which they operate,
to his wife purpofes.

When we hear an unufual found, the fen-
fation indeed is in the mind, but we know
that there is fomething external that produ-
ced this found. At the fame time, our hear-
ing does not inform us, whether the founding-
body is near or at a diftance, in this direction
or that ; and therefore we look round to dif-
cover it.

If any new phenomenon appears in the hea-
vens, we fee exactly its colour, its apparent
place, magnitude, and figure, but we fee not
' its diftance. It may be in the atmofphere, it
may be among the planets, or it may be in
the fphere of the fixed ftars, for any thing the
eye can determine.

The teftimony of the fenfe of touch reaches
only to objects that are contiguous to the or-
gan, but with regard to them, is more precife
and determinate. When we feel a body with
our hand, we know the figure, diftance, and
pofition of it, as well as whether it is rough or
fmooth, hard or foft, hot or cold.

The

SECT. 12.] OF SEEING. l6t

The fenfations of touch, of feeing, and hear-
ing, are all in the mind, and can have no
exiftence but when they are perceived. How
do they all conftantly and invariably fugged
the conception and belief of external objects,
which exift whether they are perceived or
not ? No philofopher can give any other an-
fwer to this, but that fuch is the conftitution
of our nature. How do we know, that the
object of touch is at the fingers end, and no
where elfe ? That the object of light is in
fuch a direction from the eye, and in no other,
but may be at any diflance ? and that the ob-
ject of hearing may be at any diftance, and in
any direction ? Not by cuftom furely ; not
by reafoning, or comparing ideas, but by the
conftitution of our nature. How do we per-
ceive vilible objects in the direction of right
lines perpendicular to that part of the retina
on which the rays ftrike, while we do not per-
ceive the objects of hearing in lines perpendi-
cular to the membrana tympani, upon which
the vibrations of the air ftrike ? Becaufe fuch
are the laws of our nature. How do we know
the parts of our bodies affected by particular
pains ? Not by experience or by reafoning,
but by the conftitution of nature. The fen-
fation of pain is, no doubt, in the mind, and
R 3 cannot

<2,6l OF THE HUMAN MIND. [CHAP. 6;

cannot be faid to have any relation, from its
own nature, to any part of the body : but this
fenfation, by our confiitution, gives a percep-
tion of fome particular part of the body, whofe
diforder caufes the uneafy fenfation. If it
were not fo, a man who never before' felt ei-
ther the gout or the toothach, when he is firft
feized with the gout in his toe, might miftake
it for the toothach.

Every fenfe, therefore, hath its peculiar laws
and limits, by the confiitution of our nature ;
and one of the laws of fight is, that we always
fee an object in the direction of a right line
pairing from its image on the retina through
the centre of the eye.

3. Perhaps fome readers will imagine, that
it is eafier, and will anfwer the purpofe as
well, to conceive a law of nature, by which
we mall always fee objects in the place in
which they are, and in their true pofition,
without having recourfe to images on the re-
tina, or to the optical centre of the eye.

To this I anfwer, that nothing can be a law
of nature which is contrary to fact. The laws
of nature are the molt general fads we can dif-
cover in the operations of nature. Like other
facts, they are not to be hit upon by a happy
conjecture, but juftly deduced from obferva-

tion ;

SECT. 12.] OF SEEING. 263

tion : Like other general fads, they are not to
be drawn from a few particulars, but from a co-
pious, patient, and cautious induction. That
we fee thing always in their true place and
pofition, is not fact ; and therefore it can be
no law of nature. In a plain mirror, I fee
myfelf, and other things, in places very diffe-
rent from thofe they really occupy. And fo
it happens in every inftance, wherein the rays
coming from the object are either reflected or
refracted before falling upon the eye. Thofe
who know any thing of optics, know that, in
all fuch cafes, the object is feen in the direc-
tion of a line pairing from the centre of the
eye, to the point where the rays were laft re-
flected or refracted ; and that upon this all
the powers of the telefcope and microfcope
depend.

Shall we fay, then, that it is a law of na-
ture, that the object is feen in the direction
which the rays have when they fall on the
eye, or rather in the direction contrary to that
of the rays when they fall upon the eye ? No.
This is not true, and therefore it is no law of
nature. For the rays, from any one point of
the object, come to all parts of the pupil ; and
therefore mult have different directions : but
we fee the object only in one of thefe direc-
R 4 tions,

264 • OF THE HUMAN MIND. [CHAP. 6,

tions, to wit, in the direction of the rays that
come to the centre of the eye. And this holds
true, even when the rays that mould pafs
through the centre are ftopt, and the object is
feen by rays that pafs at a diftance from the
centre.

Perhaps it may Hill be imagined, that al-
though we are not made fo as to fee objects
slvvays in their true place, nor fo as to fee
them precifely in the direction of the rays
when they fall upon the cornea ; yet we may
be fo made, as to fee the object in the direc-
tion which the rays have when they fall up-
on the retina, after they have undergone all
their refractions in the eye, that is, in the di-
rection in whicli the rays pafs from the cry-
ftalline to the retina. But neither is this
true ; and confequently it is no law of our
conftitution. In order to fee that it is not
true, we muft conceive all the rays that pafs
from the cryftalline to one point of the re-
tina, as forming a fmall cone, whofe bafe is
upon the back of the cryftalline, and whofe
vertex is a point of the retina. It is evident
that the rays which form the picture in this
point, have various directions, even after they
pafs the cryftalline ; yet the object is feen on-
ly in one of thefe directions, to- wit, in the

direction

SECT. 12.] OF SEEING. 265

direction of the rays that come from the cen-
tre of the eye. Nor is this owing to any
particular virtue in the central rays, or in the
centre itfelf ; for the central rays may be ftopt.
When they are ftopt, the image will be form-
ed upon the fame point of the retina as be-
fore, by rays that are not central, nor have
the fame direction which the central rays
had : and in this cafe the object is feen in
the fame direction as before, although there
are now no rays coming in that direction.

From this induction we conclude, That our
feeing an objecl: in that particular direction in
which we do fee it, is not owing to any law
of nature by which we are made to fee it in
the direction of the rays, either before their
refractions in the eye, or after, but to a law
of our nature, by which we fee the object in
the direction of the right line that paifeth from
the picture of the object upon the retina to the
centre of the eye.

The facts upon which I ground this induc-
tion, are taken from fome curious experiments
of Scheiner, in his Fundament. Optic., quo-
ted by Dr Porterfield, and confirmed by
his experience. I have alfo repeated thefe
experiments, and found them to anfwer. As
Jthey are eafily made, and tend to illuftrate

and

l66 OF THE HUMAN MIND. [CHAP. 6.

and confirm the law of nature I have mention-
ed, I fhall recite them as briefly and diftinclly
as I can.

Experiment i. Let a very fmall objecl, fuch
as the head of a pin, well illuminated, be fix-
ed at fuch a diftance from the eye, as to be
beyond the neareft limit, and within the far-
theft limit of diftincl virion : For a young
eye, not near-lighted, the objecl: may be pla-
ced at the diftance of eighteen inches. Let the
eye be kept fteadily in one place, and take a
diftincl view of the objecl:. We know from
the principles of optics, that the rays from
any one point of this objecl, whether they
pafs through the centre of the eye, or at any
diftance from the centre which the breadth
of the pupil will permit, do all unite again
in one point of the retina. We know alfo,
that thefe rays have different directions, both
before they fall upon the eye, and after they
pafs through the cryftalline.

Now, we can fee the objecl by any one
fmall parcel of thefe rays, excluding the reft,
by looking though a fmall pin-hole in a card.
Moving this pin-hole over the various parts
of the pupil, we can fee the objecl, firft by
the rays that pafs above the centre of the eye,
then by the central rays, then by the rays that

pafs

SECT. 12.] OF SEEING. l6j

pafs below the centre, and in like manner by
the rays that pafs on the right and left of the
centre. Thus, we view this object, fuccef-
fively, by rays that are central, and by rays
that are not central ; by rays that have differ-
ent directions, and are varioufly inclined to
each other, both when they fall upon the
cornea, and when they fall upon the retina ;
but always, by rays which fall upon the fame
point of the retina. And what is the event ?
It is this, that the object is feen in the fame
individual direction, whether feen by all
thefe rays together, or by any one parcel of
them.

Experiment 2. Let the object above men-
tioned be now placed within the nearer! limit
of diftinct vifion, that is, for an eye that is
not near-fighted, at the diflance of four or
five inches. We know, that in this cafe, the
rays coming from one point of the object, do
not meet in one point of the retina, but fpread
over a fmall circular fpot of it ; the central
rays occupying the centre of this circle, the
rays that pafs above the centre occupying the
upper part of the circular fpot, and fo of the
reft. And we know that the object is in this
cafe feen confufed, every point of it being
feen, not in one, but in various directions.

To

268 OF THE HUMAN MIND. [CHAP. 6.

To remedy this confufion, we look at the ob-
ject through the pin-hole, and while we move
the pin hole over the various parts of the pu-
pil, the object does not keep its place, but
feems to move in a contrary direction.

It is here to be obferved, that when the
pin-hole is carried upwards over the pupil,
the picture of the object is carried upwards
upon the retina, and the object at the fame
time feems to move downwards, fo as to be
always in the right line palling from the pic-
ture through the centre of the eye. It is
likewife to be obferved, that the rays which
form the upper and the lower pi&ures upon
the retina, do not crofs each other as in ordi-
nary vifion ; yet ftill the higher picture fhews
the object lower, and the lower picture fhews
the object higher, in the fame manner as when
the rays crofs each other. Whence we may
obferve, by the way, that this phenomenon of
our feeing objects in a pofition contrary to
that of their pictures upon the retina, does not
depend upon the eroding of the rays, as Kep-
ler and Des Cartes conceived.

Experiment 3. Other things remaining as in
the laft experiment, make three pin-holes in
a ftraight line, fo near, that the rays coming
from the object through all the holes, may

enter

SECT. 12.] OF SEEING. 269

enter the pupil at the fame time. In this cafe
we have a very curious phenomenon ; for the
object is feen triple with one eye. And if
you make more holes within the breadth of
the pupil, you will fee as many objects as
there are holes. However, we fhali fuppofe
them only three ; one on the right, one in the
middle, and one on the left ; in which cafe,
you fee three objects {landing in a line from
right to left.

It is here to be obferved, that there are
three pictures on the retina ; that on the left
being formed by the rays which pafs on the
left of the eye's centre ; the middle picture
being formed by the central rays, and the
right-hand picture by the rays which pafs on
the right of the eye's centre. It is farther to
be obferved, that the object which appears
on the right, is not that which is feen through
the hole on the right, but that which is feen
through the hole on the left ; and in like
manner, the left-hand object is feen through
the hole on the right, as is eafily proved by
covering the holes fuccefiively. So that, what-
ever is the direction of the rays which form
the right-hand and left-hand pictures, ftill
the right-hand picture (hows a left-hand

object,

27O Of THE HUMAN MIND, [CHAP. 6.

objea, and the left-hand picture fhows a right-
hand objed.

Experiment 4. It is eafy to fee how the two
laft experiments may be varied, by placing
the objed beyond the fartheft limit of diftind
vifion. In order to make this experiment,
1 looked at a candle at the diftance of ten
feet, and put the eye of my fpedacles behind
the card, that the rays from the fame point
of the objed might meet, and crofs each
other, before they reached the retina. In this
cafe, as in the former, the candle was feen tri-
ple through the three pin-holes ; but the can^
die on the right, was feen through the hole on
the right ; and, on the contrary, the left-hand
candle was feen through the hole oo*the left.
In this experiment, it is evident from the
principles of optics, that the rays forming
the feveral pidures on the retina, crofs each
other a little before they reach the retina ; and
therefore the left-hand pidure is formed by
the rays which pafs through the hole on the
right : fo that the pofition of the pidures is
contrary to that of the holes by which they
are formed ; and therefore is alfo contrary to
that of their objeds, as we have found it to
be in the former experiments,

Thefe

SECT. 12.] OF SEEING. V]l

Thefe experiments exhibit feveral uncom-
mon phenomena, that regard the apparent
place, and the direction of vifible objects from
the eye ; phenomena that feem to be moil
contrary to the common rules of virion. When
we look at the fame time through three holes
that are in a right line, and at certain diftan-
ces from each other, we expect, that the ob-
jects feen through them fhould really be, and
fhould appear to be, at a diftance from each
other : Yet, by the firft experiment, we may,
through three fuch holes, fee the fame object,
and the fame point of that object ; and through
all the three it appears in the fame individual
place and direction.

When the rays of light come from the ob-
ject in right lines to the eye, without any re-
flection, inflection, or refraction, we expect,
that the object fhould appear in its real and
proper direction from the eye ; and fo it com-
monly does : But in the fecond, third, and
fourth experiments, we fee the object in a di-
rection which is not its true and real direction
from the eye, although the rays come from the
object to the eye, without any inflection, re-
flection, or refraction.

When both the object and the eye are fix-
ed without the leaft motion, and the medium

unchanged,

272 OF THE HUMAN MIND. [cHAP. 6i

unchanged, we expect, that the objeft mould
appear to reft, and keep the fame place : Yet
in the fecond and fourth experiments, when
both the eye and the object are at reft, and
the medium unchanged, we make the object
appear to move upwards or downwards, or in
any direction we pleafe.

When we look at the fame time, and with
the fame eye, through holes that ftand in a
line from right to left, we expect, that the ob-
ject feen through the left-hand hole Ihould
appear on the left, and the object feen through
the right-hand hole, mould appear on the
right : Yet in the third experiment, we find
the direct contrary.

Although many inftances occur in feeing
the fame object double with two eyes, we al-
ways exped, that it mould appear fingle when
feen only by one eye : Yet in the fecond and
fourth experiments, we have inftances where-
in the fame object may appear double, triple,
or quadruple to one eye, without the help of
a polyhedron or multiplying glafs.

All thefe extraordinary phenomena, regard-
ing the direction of vifible objects from the
eye, as well as thofe that are common and or-
dinary, lead us to that law of nature which I
have mentioned, and are the necefTary confe-

quences*

SECT. 12.] OF SEEING. 273

quences of it. And, as there is no probabi-
lity that we fhall ever be able to give a reafon
why pictures upon the retina make us fee ex-
ternal objects, any more than pictures upon
the hand or upon the cheek ; or, that we fhall
ever be able to give a reafon, why we fee the
object in the direction of a line palling from
its picture through the centre of the eye, ra-
ther than in any other direction : I am there-
fore apt to look upon this law as a primary
law of our conflitution.

To prevent being mifunderftood, I beg the
reader to obferve, that I do not mean to affirm,
that the picture upon the retina will make us
fee an object in the direction mentioned, or in
any direction, unlefs the optic nerve, and the
other more immediate inflruments of vifion,
be found, and perform their function. We
know not well what is the office of the optic
nerve, nor in what manner it performs that
office ; but that it hath fome part in the fa-
culty of feeing, feems to be certain ; becaufe
in an amaurojis, which is believed to be a dif-
order of the optic nerve, the pictures on the
retina are clear and diilinct, and yet there is
no vifion.

We know (till lefs of the ufe and function
pf the choroid membrane ; but it feems like-

S wife

2^4 0F THE HUMAN MIND. [CHAP. 6.

wife to be neceflary to vifion : for it is well
known, that pictures upon that part of the
retina where it is not covered by the choroid,
I mean at the entrance of the optic nerve,
produce no virion, any more than a picture
upon the hand. We acknowledge, therefore,
that the retina is not the lad and moft imme-
diate inftrument of the mind in vifion. There
are other material organs, whofe operation is
neceflary to feeing, even after the pictures
upon the retina are formed. If ever we come
to know the ftruclure and ufe of the choroid
membrane, the optic nerve, and the brain,
and what impreflions are made upon them by
means of the pictures on the retina, fome
more links of the chain may be brought with-
in our view, and a more general law of vifion
difcovered : but while we know fo little of
the nature and office of thefe more immediate
inftruments of vifion, it feems to be impoflible
to trace its laws beyond the pictures upon the
retina.

Neither do I pretend to fay, that there may
not be difeafes of the eye, or accidents, which
may occafion our feeing objects in a direction
fomewhat different from that mentioned a-
bove. I fhall beg leave to mention one i li-
ft ance of this kind that concerns myfelf.

SECT. 12.] OF SEEING. 275

In May 176J, being occupied in making
an exact meridian, in order to obferve the
tranfit of Venus, I rafhly directed to the fun,
by my right eye, the crofs hairs of a fmall te-
lefcope. I had often done the like in my
younger days with impunity ; but I fufFered
by it at laft, which I mention as a warning to
others.

I foon obferved a remarkable dimnefs in
that eye ; and for many weeks, when I was
in the dark, or fhut my eyes, there appeared
before the right eye a lucid fpot, which trem-
bled much like the image of the fun feen by
reflection from water. This appearance grew
fainter, and lefs frequent by degrees ; fo that
now there are feldom any remains of it. Bat
fome other very fenfible effects of this hurt
ftill remain. For, firft, The light of the right
eye continues to be more dim than that of the
left. Secondly, The neareft limit of diftinct
vifion is more remote in the right eye than in
the other ; although, before the time men-
tioned, they were equal in both thefe refpects,
as I had found by mauy trials. But, thirdly,
what I chiefly intended to mention, is, That
a ftraight line, in fome circumftances, appears
to the right eye to have a curvature in it.
Thus, when I look upon a mufic-book, and,
S 2 fhutting

Zj6 OF THE HUMAN MIND. [CHA1\ (J.

fhutting my left eye, dired the right to a
point of the middle line of the five which
compofe the ftaffof mufic ; the middle lino
appears dim, indeed, at the point to which
the eye is directed, but ftraight ; at the fame
time the two lines above it, and the two be-
low it, appear to be bent outwards, and to be
more diflant from each other, and from the
middle line, than at other parts of the ftarT, to
which the eye is not directed. Fourthly, Al-
though I have repeated this experiment times
innumerable, within thefe fixteen months, I
do not find that cuftom and experience takes
away this appearance of curvature in flraight
lines. Laftly, This appearance of curvature
is perceptible when I look with the right eye
only, but not when I look with both eyes ;
yet I fee better with both eyes together, than
even with the left eye alone.

I have related this fact minutely as it is,
without regard to any hypothefis ; bccaufe I
think fuch uncommon fads deferve to be re-
corded. I fhall leave it to others to conjec-
ture the caufe of this appearance. To me it
fecms mod probable, that a fmall part of the
retina towards the centre is fhrunk, and that
thereby the contiguous parts are drawn near-
er to the centre, and to one another, than they

were

SECT. 12.] OF SEEING. 277

were before ; and that objects whofe images
fall on thefe parts, appear at that diftance
from each other which correfponds, not to the
interval of the parts in their prefent preterna-
tural contraction, but to their interval in their
natural and found ftate.

SECT. XIII.

Of feeing obj eels fingle with two eyes.

ANother phenomenon of vifion which
deferves attention, is our feeing objects
fingle with two eyes. There are two pictures
of the object, one on each retina ; and each
picture by itfelf makes us fee an object in a
certain direction from the eye : yet both to-
gether commonly make us fee only one object.
All the accounts or folutiorts of this pheno-
menon given by anatomifts and philofophers,
feem to be unfatisfactory. I fhall pafs over
the opinions of Galen, of Gassendus, of Bap-
tista Porta, and of Rohault. The reader
may fee thefe examined and refuted by Dr

S 3 PORTERFIELD.

2J$ OF THE HUMAN MIND. [CHAP. 6v

Porterfield. I fliall examine Dr Porter-
field's own opinion, Bifhop Berkeley's, and
fome others. But it will be neceflary firft to
afcertain the facls ; for if we miftake the phe-
nomena of lingle and double vifion, it is ten
to one but this miftake will lead us wrong in
nfligning the caufes. This likewiie we ought
carefully to attend to, which is acknowledged
in theory by all who have any true judgment
or juft tafte in inquiries of this nature, but is
very often overlooked in pra&ice, namely,
That in the folution of natural phenomena, all
the lengtft that the human faculties can carry
us, is only this, that from particular pheno-
mena, we may, by induction, trace out gene-
ral phenomena, of which all the particular
ones are neceffary confequences. And when
we have arrived at the mod general phe-
nomena we can reach, there we muft flop.
If it is afked, Why fuch a body gravitates
towards the earth ? all the anfwer that can be
given, is, Becaufe all bodies gravitate towards
the earth. This is refolving a particular phe-
nomenon into a general one. If it fhould
again be alked, Why do all bodies gravitate
towards the* earth ? we can give no other fo-
lution of this phenomenon, but that all bodies
whatfoever gravitate towards each other.

This

SECT. 13.] OF SEEING. 279

This is refolving a general phenomenon into
a more general one. If it mould be afked,
Why all bodies gravitate to one another ? we
cannot tell ; but if we could tell, it could on-
ly be by refolving this univerial gravitation of
bodies into fome other phenomenon (till more
general, and of which the gravitation of all
bodies is a particular inflance. The moil ge-
neral phenomena we can reach, are what we
call laws of nature. So that the laws of nature
are nothing elfe but the moil general facts re-
lating to the operations of nature, which in-
clude a great many particular facts under
them. And if in any cafe we fhould give the
name of a law of nature to a general pheno-
menon, which human induftry (hall after*
wards trace to one more general, there is no
great harm done. The molt general aiTumes
the name of a law of nature when it is difco-
vered ; and the lefs general is contained and
comprehended in it. Having premifed thefe
things, we proceed to conlider the phenome-
na of (ingle and double virion, in order to dis-
cover fome general principle to which they all
lead, and of which they are the necelfary con-
fequences. If we can difcover any fuch ge*
neral principle, it mud either be a law of na-
ture, or the neceiTary confequcncc of fome
* S 4 law

2&0 OF THE HUMAN MIND. [CHAP. 6.

law of nature ; and its authority will be equal,
whether it is the firft or the laft.

I. We find, that when the eyes are found
and perfect, and the axes of both directed to
one point, an object placed in that point is
feen fingle ; and here we obferve, that in this
cafe the two pictures which fhow the object
fingle, are in the centres of the retina. When
two pictures of a fmall object arc formed up-
on points of the retina, if they (how the ob-
ject fingle, we fhall, for the fake of perfpi-
cuity, call fuch two points of the retina, cor-
re/ponding points s and where the object is
feen double, we mall call the points of the
retina on which the pictures are formed, points
that do not correfpond. Now, in this firft phe-
nomenon it is evident, that the two centres
of the retina are correfponding points.

2. Suppofing the fame things a9 in the laft
phenomenon, other objects at the fame d*f-
tance from the eyes as that to which their
axes are directed, do alfo appear fingle. Thus*
if I direct my eyes to a candle placed at the
diftance of ten feet ; and, while 1 look at this
candle, another Hands at the fame diftance
from my eyes, within the field of vifion ; I
can, while I look at the firft candle, attend to
the appearance which the fecond makes to

the

SECT. 13.] OF SEEING. 2$I

the eye ; and I find that in this cafe it always
appears (ingle. It is here to be obferved, that
the pictures of the fecond candle do not fall
upon the centres of the retina; but they both
fall upon the fame fide of the centres, that is,
both to the right, or both to the left, and both
are at the fame diflance from the centres.
This might eafily be demonfirated from the
principles of optics. Hence it appears, that
in this fecond phenomenon of fingle virion,
the correfponding points are points of the two
retina, which are fimiiarly fituate with refpe.ct
to the two centres, being both upon the fame
fide of the centre, and at the fame diftance
from it. It appears likewife from this pheno-
menon, that every point in one retina corre-
fponds with that which is fimiiarly fituate in
the other.

3. Suppofing ftill the fame things, objects
which are much nearer to the eyes, or much
more diftant from them, than that to which
the two eyes are directed, appear double.
Thus, if the candle is placed at the diftance
of ten feet, and I hold my finger at arms-
length between my eyes and the candle ; wheu
I look at the candle, I fee my finger double ;
and when I look at my finger, I fee the can-
dle double : And the fame thing happens

with

^82 Ot THE HUMAN MIND. [CHAP. 6.

With regard to all other objects at like diftan-
ces, which fall within the fphere of vilion.
In this phenomenon, it is evident to thofe who
underftand the principles of optics, that the
pictures of the objects which are feen double,
do not fall upon points of the retina which
are fimilarly fituate, but that the pictures of
the objects feen lingle do fall upon points fi-
milarly fituate. Whence we infer, that as
the points of the two reduce, which are fimi-
larly fituate with regard to the centres, do
correfpond, fo thofe which are dimmilarly
iituate do not correfpond.

4. It is to be obferved, that although, in
fuch cafes as are mentioned in the laft pheno-
menon, we have been accuflomed from infan-
cy to fee objects double which we know to be
fingle ; yet cuflom, and experience of the
unity of the object, never take away this ap-
pearance of duplicity.

5. It may however be remarked, that the
cuflom of attending to vifible appearances has
a conliderable effect, and makes the phenome-
non of double vifion to be more or lefs ob-
ferved and remembered. Thus you may find
a man that can fay with a good confcience,
that he never faw things double all his life;
yet this very man, put in the lituation above

mentioned,

SECT. I3.] OF SEEING. 283

mentioned, with his finger between him and
the candle, and defired to attend to the ap-
pearance of the object which he does not look
at, will, upon the firft trial, fee the candle
double, when he looks at his finger ; and his
finger double, when he looks at the candle.
Does he now fee othervvife than he faw be-
fore ? No, furely ; but he now attends to what
he never attended to before. The fame dou-
ble appearance of an object hath been a thou-
fand times prefented to his eye before now ;
but he did not attend to it ; and fo it is as
little an object of his reflection and memory,
as if it had never happened.

When we look at an object, the circumja-
cent objects may be feen at the fame time, al-
though more obfcurely and indiftinctly : for
the eye hath a confiderable field of virion,
which it takes in at once. But we attend
only to the object we look at. The other ob-
jects which fall within, the field of vifion, are
not attended to : and therefore are as if thev
were not feen. If any of them draws our
attention, it naturally draws the eyes at the
fame time : for in the common courfe of life,
the eyes always follow the attention : or if, at
any time, in a reverie, they are fepa rated from
it, we hardly at that time fee what is directly

before

284 OF THE H0MAN MIND. tCHAP' &

before us. Hence we may fee the reafon,
why the man we are fpeaking of thinks that
he never before faw an objed double. When
he looks at any objed, he fees it fmgle, and
takes no notice of other vifible objeds at that
time, whether they appear fmgle or double.
If any of them draws his attention, it draws
his eyes at the fame time ; and as foon as the
eyes are turned towards it, it appears fmgle.
But in order to fee things double, at lead in
order to have any reflection or remembrance
that he did fo, it is neceflary that he mould
look at one objed, and at the fame time at-
tend to the faint appearance of other objeds
which are within the field of vifion. This is
a pradice which perhaps he never ufed, nor
attempted ; and therefore he does not recoi-
led that ever he faW an objed double. But
when he is put upon giving this attention, he
immediately fees objeds double in the fame
manner, and with the very fame circumftan-
ces, as they who have been accuftomed, for
the greateft part of their lives, to give this at-
tention.

There are many phenomena of a fimilar
nature, which mew, that the mind may not
attend to, and thereby, in fome fort, not per-
ceive, objeds that ftrike the fenfes. I had

occafion

SECT. 13.] OF SEEING. 285

occafion to mention feveral inftances of this
in the fecond chapter ; and I have been af-
fured, by perfons of the beft ikill in mufic,
that in hearing a tune upon the harpfichord,
when they give attention to the treble, they
do not hear the bafs ; and when they attend
to the bafs, they do not perceive the air of
the treble. Some perfons are fo near-fighted,
that, in reading, they hold the book to one
eye, while the other is directed to other ob-
jects. Such perfons acquire the habit of at-
tending, in this cafe, to the objects of one eye,
while they give no attention to thofe of the
other.

6. It is obfervable, that in all cafes where-
in we fee an object double, the two appear-
ances have a certain pofition with regard to
one another, and a certain apparent or angu-
lar diftance. This apparent diftance is great-
er or lefs in different circumflances ; but in
the fame circumflances, it is always the fame,
not only to the fame, bur to different perfons.

Thus, in the experiment above mentioned,
if twenty different perfons, who fee perfectly
with both eyes, fhall place their finger and
the candle at the di (lances above expreffed,
and hold their heads upright ; looking at the
finger, they will fee two candles, one on the

right,

1%6 OF THE HUMAN MIND. [CHAP. 6.

right, another on the left. That which is feen
on the right, is feen by the right eye, and that
which is feen on the left, by the left eye ;
and they will fee them at the fame apparent
diftance from each other. If again they look
at the candle, they will fee two fingers, one
on the right, and the other on the left ; and
all will fee them at the fame apparent dif-
tance *, the finger towards the left being feen
by the right eye, and the other by the left.
If the head is laid horizontally to one fide,
other circumftances remaining the fame, one
appearance of the object feen double, will be
directly above the other. In a word, vary
the circumftances as you pleafe, and the ap-
pearances are varied to all the fpectators in
one and the fame manner.

7. Having made many experiments in ou-
der to afcertain the apparent diftance of the
two appearances of an object feen double, I
have found that in all cafes this apparent dif-
tance is proportioned to the diftance between
the point of the retina, where the picture is
made in one eye, and the point which is fi-
tuated fimilarly to that on which the picture
is made on the other eye. So that as the ap-
parent diftance of two objects feen with one
eye, is proportioned to the arch of the retina,

which

SECT. 13.] OF SEEING. 287

which lies between their pictures : in like
manner, when an object is feen double with
the two eyes, the apparent diftance of the two
appearances is proportioned to the arch of
either retina, which lies between the picture
in that retina, and the point correfponding to
that of the picture in the other retina.

8. As in certain circumilances we invaria-
bly fee one object appear double, fo in others
we as invariably fee two objects unite into
one ; and, in appearance, lofe their duplicity.
This is evident in the appearance of the bi-
nocular telefcope. And the fame thing hap-
pens when any two fimilar tubes are applied
to the two eyes in a parallel direction ; for in
this cafe w7e fee only one tube. And if two
ihiilings are placed at the extremities of the
two tubes, one exactly in the axis of one eye,
and the other in the axis of the other eye, we
-{hall fee but one milling. If two pieces of
coin, or other bodies, of different colour, and
of different figure, be properly placed in the
two axes of the eyes, and at the extremities
of the tubes, we fhall fee both the bodies in
one and the fame place, each as it were fpread
over the other, without hiding it ; and the
colour will be that which is compounded of
the two colours.

9. Frpm

28S OF THE HUMAN MIND. [CHAP. 6.

9. From thefe phenomena, and from all the
trials I have been able to make, it appears
evidently, that in perfect human eyes, the
centres of the two retina correfpond and har-
monize with one another ; and that every
other point in one retina, doth correfpond and
harmonize with the point which is fimilarly
fituate in the other; in fuch manner, that
pictures falling on the correfponding points of
the two retina:, fhew only one object, even
when there are really two : and pictures fall-
ing upon points of the retina which do not
correfpond, fhew us two vifible appearances,
although there be but one object. So that
pictures, upon correfponding points of the
two retime, prefent the fame appearance to
the mind as if they had both fallen upon the
fame point of one retina ; and pictures upon
points of the two retina, which do not corre-
fpond, prefent to the mind the fame apparent
diftance and pofition of two objects, as if one
of thofe pictures was carried to the point cor-
refponding to it in the other retina. This re-
lation and fympathy between correfponding
points of the two retina, I do not advance as
an hypothefis, but as a general fad or pheno-
menon of vifion. All the phenomena before
'mentioned, of fingle or double vifion, lead to

it,

SECT. 13.] OF SEEING. 289

it, and are neceflary confequences of it. It
holds true invariably in all perfect human
eyes, as far as I am able to collect from innu-
merable trials of various kinds made upon my
own eyes, and many made by others at my
defire. Moft of the hypothefes that have
been contrived to refolve the phenomena of
iingle and double vifion, fuppofe this general
fact, while their authors were not aware of
it. Sir Isaac Newton, who was too judi-
cious a philofopher, and too accurate an ob-
ferver, to have offered even a conjecture which
did not tally with the facts that had fallen
under his obfervation, propofes a query with
refpect to the caufe of it, Optics, quer. 15.
The judicious Dr Smith, in his Optics, lib. 1.
§ 137. hath confirmed the truth of this gene-
ral phenomenon from his own experience,
not only as to the apparent unity of objects
whofe pictures fall upon the correiponding
points cf the retinae, but alfo as to the appa-
rent diftance of the two appearances of the
fame object when feen double.

This general phenomenon appears there-
fore to be founded upon a very full induction,
which is all the evidence we can have for a
fact of this nature. Before we make an end
of this fubject, it will be proper to inquire,

T firft,

2QO OF THE HUMAN MIND. [CHAP. 6.

firft, Whether thofe animals whofe eyes have
an adverfe pofition in their heads, and look
contrary ways, have fuch correfponding points
in their retina P Secondly, What is the pofi-
tion of the correfponding points in imperfect
human eyes, I mean in thofe that fquint ?
And, in the laft place, Whether this harmony
of the correfponding points in the retina, be
natural and original, or the effecT: of cuftom ?
And if it is original, Whether it can be ac-
counted for by any of the laws of nature al-
ready difcovered ? or whether it is itfelf tp
be looked upon as a law of nature, and a part
of the human conftitution ?

SECT.

SECT. 14.] OF SEEING. 29I

SECT. XIV.

Of the laws of vijion in brute animals.

IT is the intention of nature, in giving eyes
to animals, that they may perceive the (i-
tuation of vifible objects, or the direction in
which they are placed : it is probable, there-
fore, that, in ordinary cafes, every animal,
whether it has many eyes or few; whether of
one ftructure or of another, fees objects fin-
gle, and in their true and proper direction.
And fince there is a prodigious variety in the
ftructure, the motions, and the number of
eyes in different animals and infects, it is pro-
bable that the laws by which vifion is regu-
lated, are not the fame in all, but various,
adapted to the eyes which nature hath given
them.

Mankind naturally turn their eyes always
the fame way, fo that the axes of the two eyes
meet in one point. They naturally attend to,
or look at that object: only which is placed in
the point where the axes meet. And whe-
T 2 ther

302 OF THE HUMAN MIND. [CHAP. 6.

the i the object be more or lefs diftant, the
configuration of the eye is adapted to the dif-
tance of the object, fp as to form a diftinct
pidtu e of it.

When we ufe our eyes in this natural way,
the two pictures of the object we look at, are
formed upon the centres of the two retina ;
and the two pictures of any contiguous object
are formed upon the points of the retina which
are fimilarly fituate with regard to the centres.
Therefore, in order to our feeing objects fingle,
and in their proper direction, with two eyes,
it is fufficient that we be fo conftituted, that
objects whofe pictures are formed upon the
centres of the two retina, or upon points fi-
milarly fituate with regard to thefe centres,
lb all be feen in the fame vifible place. And
this is the conftitution which nature hath ac-
tually given to human eyes.

When we diftort our eyes from their .paral-
lel direction, which is an unnatural motion,
but may be learned by practice ; or when we
direct the axes of the two eyes to one point,
and at the fame time direct our attention to
fome vilible object much nearer or murh more
diftant than that point, which is alio unnatu-
ral, yet mav be learned ; in thefe cafes, and
in thefe only, we lee one object double, or

two

SECT. 14.] OF SEEING. 293

two objeds confounded in one. In theie
cafes, the two pictures of the fame object are
formed upon points of the retina which are
not fimilarly fituate, and fo the object is fccn
double ; or the two pictures of different ob-
jects are formed upon points of the retina;
which are fimilarly fituate, and fo the two ob-
jects are feen confounded in one place.

Thus it appears, that the laws of vifion in
the human conftitution are wifely adapted to
the natural ufe of human eyes, but not to that
ufe of them which is unnatural. We fee ob-
jects truly when w7e ufe our eyes in the natu-
ral way ; but have falfe appearances prefented
to us when we ufe them in a way that is un-
natural. We may reafonably think, that the
cafe is the fame with other animals. But is
it not unreafonable to think, that thofe ani-
mals which naturally turn one eye towards
one object, and another eye towards another
object, mult thereby have fuch falfe appear-
ances prefented to them, as we have when we
do fo againft nature ?

Many animals have their eyes by nature
placed adverfe and immoveable, the axes of
the two eyes being always directed to oppofite
points. Do objects painted on the centres of
the twro retina appear to fuch animals as they
T3 do

^94 0F TH£ HUMAN MIND. [CHAP. 6.

do to human eyes, in one and the fame vifible
place ? I think it is highly probable that they
do not ; and that they appear, as they really
are, in oppofite places.

If we judge from analogy in this cafe, it
will lead us to think that there is a certain
correfpondence between points of the two re-
tina in fuch animals, but of a different kind
from that which we have found in human
eyes. The centre of one retina will corre-
fpond with the centre of the other, in fuch
manner, that the obje&s whofe pictures are
formed upon thefe correfponding points, (hall
appear not to be in the fame place, as in hu-
man eyes, but in oppofite places. And in the
fame manner will the fuperior part of one re-
tina correfpond with the inferior part of the
other, and the anterior part of one with the
pofterior part of the other.

Some animals, by nature, turn their eyes
with equal facility, either the fame way, or
different ways, as we turn our hands and arms.
Have fuch animals correfponding points in
their retina, and points which do not corre-
fpond, as the human kind has ? I think it is
probable that they have not ; becaufe fuch a
conflitution in them could ferve no other pur-
pofe but to exhibit falfe appearances.

If

SECT. 14.] OF SEEING. 195

If we judge from analogy, it will lead us to
think, that as fuch animals move their eyes in
a manner fimilar to that in which we move
our arms, they have an immediate and natu-
ral perception of the direction they give to
their eyes, as we have of the direction we give
to our arms ; and perceive the fituation of vi-
able objects by their eyes, in a manner fimi-
lar to that in which we perceive the fituation
of tangible objects with our hands.

We cannot teach brute animals to ufe their
eyes in any other way than in that which
nature hath taught them ; nor can we teach
them to communicate to us the appearances
which vifible objects make to them, either in
ordinary or in extraordinary cafes. We have
not therefore the fame means of difcovering
the laws of virion in them, as in our own kind,
but mult fatisfy ourfelves with probable con-
jectures : and what we have faid upon this fub-
ject, is chiefly intended to fhew^ that animals
to which nature hath given eyes differing in
their number, in their pofition, and in their
natural motions, may very probably be fub-
jected to different laws of vifion, adapted to
the peculiarities of their organs of vifion.

*

T 4 SECT.

296 OF THE HUMAN MIND. [CHAP. 6.

SECT. XV.

Squinting conjidered hypothetic ally.

WHether there be correfponding points
in the retina, of thofe who- have an
involuntary fquint ? and if there are,- whether
they be fituate in the fame manner as in thofe
who have no fquint ? are not queftions of
mere curiolity. They are of real importance
to the phyfician who attempts the cure of a
fquint, and to the patient who fubmits to the
cure. After fo much has been faid of the
Jlrabifmus, or fquint, both by medical and by
optical writers, one might expect to find a-
bundance of facts for determining thefe que-
ftions. Yet 1 confefs I have been difappoint-
ed in this expectation, after taking fome pains
both to make obfervations, and to collect thofe
which have been made by others.

Nor will this appear very ftrange, if we
confider, that, to make the obfervations which
are neceffary for determining thefe queftions,
knowledge of the principles of optics, and of

the

SECT. 15.] OF SEEING. 297

the laws of vifion, muft concur with opportu-
nities rarely to be met with.

Of thofe who fquint, the far greater part
have no diftinct vifion with one eye. When
thi9 is the cafe, it is impoffible, and indeed of
no importance, to determine the fituation of
the correfponding points. When both eyes
are good, they commonly differ fo much in
their direction, that the fame object cannot be
feen by both at the fame time ; and in this
cafe it will be very difficult to determine the
fituation of the correfponding points ; for fuch
perfons will probably attend only to the ob-
jects of one eye, and the objects of the other
will be as little regarded as if they were not
feen.

We have before obferved, that when we
look at a near object, and attend to it, we do
not perceive the double appearances of more
diftant objects, even when they are in the
fame direction, and are prefented to the eye
at the fame time. It is probable that a fquint-
ing perfon, when he attends to the objects of
one eye, will, in like manner, have his atten-
tion totally diverted from the objects of the
other : and that he will perceive them as little
as we perceive the double appearances of ob-
jects when we ufe our eyes in the natural

way.

498 of the Human mind. [cha£. 6.

way. Such a perfon, therefore, unlefs he is
fo much a philofopher as to have acquired the
habit of attending very accurately to the vi-
iible appearances of objects, and even of ob-
jects which he does not look at, will not be
able to give any light to the queftions now
under coniideration.

It is very probable that hares, fabbits, birds,
and fifties, whofe eyes are fixed in an adverfe
pofition, have the natural faculty of attending
at the fame tinie to vifible objects placed in
different, and even in contrary directions ;
becaufe, without this faculty, they could not
have thofe advantages from the contrary di*
rection of their eyes, which nature feems to
have intended. But it is not probable that
thofe who fquint have any fuch natural facul-
ty ; becaufe we find no fuch faculty in the
reft of the fpecies. We naturally attend to
objects placed in the point where the axes of
the two eyes meet, and to them only. To
give attention to an object in a different di-
rection is unnatural, and not to be learned
without pains and practice.

A very convincing proof of this may be
drawn from a fact now well known to philo-
fophers : when one eye is fhut, there is a cer-
tain fpace within the field of virion, where we

can

sect. 15.] Of seeing. 299

can fee nothing at all ; the fpace which is di-
rectly oppofed to that part of the bottom of
the eye where the optic nerve enters. This
defect of fight, in one part of the eye, is com-
mon to all human eyes, and hath been fo from
the beginning of the world ; yet it was never
known, until the fagacity of the Abbe Ma-
riotte difcovered it in the lad century. And
now when it is known, it cannot be percei-
ved, but by means of fome particular experi-
ments, which require care .and attention to
make them fucceed.

What is the reafon that fo remarkable a de-
fect of fight, common to all mankind, was fo
long unknown, and is now perceived with fo
much difficulty ? It is furely this, That the
defect is at fome diftance from the axis of the
eye, and confequently in a part of the field of
vifion to which we never attend naturally,
and to which we cannot attend at all, without
the aid of fome particular circumftances.

From what we have faid, it appears, that,
to determine the fituation of the correfpond-
ing points in the eyes of thofe who fquint, is
impoffible, if they do not fee diitinctly with
both eyes ; and that it will be very difficult,
unlefs the two eyes differ fo little in their di-
rection, that the fame object may be feen with

both

300 OF THE HUMAN MIND. [CHAP. 6.

both at the fame time. Such patients I ap-
prehend are rare ; at leaft there are very few
of them with whom I have had the fortune to
meet : and therefore, for the affiflance of thofe
who may have happier opportunities, and in-
clination to make the proper ufe of them, we
fhall confider the cafe of fquinting hypotheti-
cally, pointing out the proper articles of in-
quiry, the observations that are wanted, and
the conclufions that may be drawn from them.
i. It ought to be inquired, Whether the
fquinting perfon fees equally well with both
eyes ? and, if there be a defect in one, the
nature and degree of that defecl ought to be
remarked. The experiments by which this
may be done, are fo obvious, that I need not
mention them. But I would advife the ob-
ferver to make the proper experiments, and
not to rely upon the teftimony of the patient ;
becaufe 1 have found many inftances, both of
perfons that fquinted, and others, who were
found, upon trial, to have a great defect in
the fight of one eye, although they were ne-
ver aware of it before. In all the following
articles, it is fuppofed that thic patient fees
with both eyes fo well, as to be able to read
with either, when the other is covered.

2. It

SECT. 15.] OF SEEING. 30I

2. It ought to be inquired, Whether, when
one eye is covered, the other is turned direct-
ly to the object ? This ought to be tried in
both eyes fucceffively. By this obfervation,
as a touch- itone, we may try the hypothelis
concerning fquinting, invented by M. de la
Hire, and adopted by Boerhaave, and ma-
ny others of the medical faculty.

The hypothecs is, That in one eye of a
fquinting peribn, the greateft feniibility and
the molt diftin£t vifion is not, as in other
men, in the centre of the retina, but upon
one iide of the centre ; and that he turns the
axis of this eye alide from the object, in or-
der that the picture of the object may fall up-
on the moft fenfible part of the retina, and
thereby give the moft diftinct vifion. If this
is the caufe of fquinting, the fquinting eye
will be turned afide from the object, when
the other eye is covered, as well as when it
is not.

A trial fo eafy to be made, never was made
for more than forty years ; but the hypothelis
was very generally received. So prone are
men to invent hypothefes, and fo backward to
examine them by facts. At laft Dr Jurin
having made the trial, found that perfons who
(quint, turn the axis of the fquinting eye di-
rectly

302 0? THE HUMAN MIND. [CHAP. 6.

redly to the object, when the other eye is co-
vered. This facl is confirmed by Dr Por-
terfield ; and I have found it verified in all
the inftances that have fallen under my ob-
servation.

3. It ought to be inquired, Whether the
axes of the two eyes follow one another, fo
as to have always the fame inclination, or
make the fame angle, when the perfon looks
to the right or to the left, upward or down-
ward, or ftraight forward. By this observa-
tion we may judge, whether a fquint is ow-
ing to any defect in the mufcles which move
the eye, as fome have fuppofed. In the fol-
lowing articles we fuppofe that the inclination
of the axes of the eyes is found to be always
the fame.

4. It ought to be inquired, Whether the
perfon that fquints fees an object iingle or
double ?

If he fees the object double ; and if the
two appearances have an angular diftance e-
qual to the angle which the axes of his eyes
make with each other, it may be concluded
that he hath correfponding points in the
retina of his eyes, and that they have the fame
fituation as in thofe who have no fquint. If
the two appearances mould have an angular;

diftance,

SECT. 15.] OF SEEING. 303

diftance, which is always the fame, but ma-
nifeftly greater or lefs than the angle con-
tained under the optic axes, this would in-
dicate correfponding points in the retina,
whofe fituation is not the fame as in thofe
who have no fquint ; but it is difficult to
judge accurately of the angle which the optic
axes make.

A fquint, too fmall to be perceived, may
occafion double vifion of objects : for if we
fpeak ftrictly, every perfon fquints more or
lefs, whofe optic axes do not meet exactly in
the object which he looks at. Thus, if a man
can only bring the axes of his eyes to be pa^
rallel, but cannot make them converge in the
Jeaft, he mull have a fmall fquint in looking
at near objects, and will fee them double,
while he fees very diftant objects fingle. A-
gain, if the optic axes always converge, fo as
to meet eight or ten feet before the face at
fartheft, fuch a perfon will fee near objects
iingle ; but when he looks at very diftant
objects, he will fquint a little, and fee them
double.

An inftance of this kind is related by A-
guilonius in his Optics ; who fays, that he
had feen a young man to whom near objects

appeared

304 OF THE HUMAN MIND. [CHAP. 6.

appeared lingle, but diftant obje&s appeared
doable.

Dr Briggs, in his Nova vijionis theoria, ha-
ving colleded from authors feveral inftances
of double vifion, quotes this from Aguilo-
nius, as the moll wonderful and unaccount-
able of all, in fo much that he fufpe&s fome
impofition on the part of the young man :
but to thofe who underftand the laws by
which (ingle and double vifion are regulated,
it appears to be the natural effect of a very
fmall fquint.

Double vifion may always be owing to
a fmall fquint, when the two appearances are
feen at a fmall angular diftance, although no
fquint was obferved : and 1 do not remember
any inftances of double vifion recorded by
authors, wherein any account is given of the
angular diflance of the appearances.

In almoft all the inftances of double vifion,
there is reafon to fufpedt a fquint or diftor-
tion of the eyes, from the concomitant cir-
cumftances, which we find to be one or other
of the following, the approach of death," or
of a deliqaium, exceffive drinking, or other
intemperance, violent headach, bliftering the
head, fmoking tobacco, blows or wounds in
the head. In all thefe cafes, it is reasonable

to

Sect. 15.] of seeing. 305

to fufpect a diftoKion of the eyes, either from
fpafm, or paralyfis in the mufcles that move
them. But although it be probable that there
is always a fquint greater or lefs where there
is double vifion ; yet it is certain that there is
not double vifion always where there is a
fquint. I know no inflance of double vifion
that continued for life, or even for a great
number of years. We fhall therefore fup-
pofe, in the following articles, that the fquint-
ing perfon fees objecls fingle.

5. The next inquiry then ought to be,
Whether the object is feen with both eyes at
the fame time, or only with the eye whofe
axis is directed to it ? It hath been taken
for granted, by the writers upon the Jlrabif-
mus, before Dr Jurin, that thofe who fquint^
commonly fee objects fingle with both eyes
at the fame time ; but I know not one fact
advanced by any writer which proves it. Dr
Jurin is of a contrary opinion ; and as it is
of confequence, fo it is very eafy to determine
this point in particular inftances, by this ob-
vious experiment. While the perfon that
fquints looks fteadily at an object, let the ob-
ferver carefully remark the direction of both
his eyes, and obferve their motions ; and let
an opaque body be interpofed between the

U object

tcfo OF THE HUMAN WIND. [CRAP. 6w

object and the two eyes fucceffively. If the
patient, notwithftandirig this interpofition, and
without changing the direction of the eyes,
continues to fee the object all the time, it
may be concluded that he faw it with both
eyes at once. But if the interpofition of the
body between one eye and the object makes
it difappear, then we may be certain, that it
was feen by that eye only. In the two foU
lowing articles, we mail fuppofe the firft
to happen, according to the common hypo-
thelis.

6. Upon this fuppofition, it ought to be in-
quired, Whether the patient fees an object
double in thofe circumftances wherein it ap-
pears double to them who have no fquint?
Let him, for inftance, place a candle at the
diftance of ten feet ; and holding his finger
at arm's length between him and the candle,
let him obferve, when he looks at the candle,
whether he fees his finger with both eyes, and
whether he fees it fingle or double ; and when-
he looks at his finger, let him obferve whe-
ther he fees the candle with both eyes, and
whether fingle or double.

By this obfervation, it may be determined,
whether to this patient, the phenomena of
double as well as of fingle vifion axe the fame

as

SECT. 15.] CfF SEEING. S°7

as to them who have no fquint. If they are
not the fame ; if he fees objects iingle with
two eyes, not only in the cafes wherein they
appear iingle, but in thofe alfo wherein they
appear double to other men ; the conclufion
to be drawn from this fuppofition is, thai his
fingle virion does not arife from correfpond-
ing points in the retina of his eyes ; and that
the laws of virion are not the fame in him as
in the reft of mankind.

7. If, on the other hand, he fees objecls
double in thofe cafes wherein they appear
double to others, the conclufion muft be, that
he hath correfponding points in the retina of
his eyes, but unnaturally fituate \ and their fi-
tuation may be thus determined.

When he looks at an object, having the
axis of one eye directed to it, and the axis of
the other turned alide from it ; let us fuppofe
a right line to pals from the object through
the centre of the diverging eye. We fhall,
for the fake of perfpicuity, call this right line
the natural axis of the eye : and it will make
an angle with the real axis, greater or lefs,
according as his fquint is greater or lefs. Wc
fhall alfo call that point of the retina in which
the natural axis cuts it, the natural centre of
the retina; which will be more or lefs diftant
U 2 from

3p8 i OF THE HUMAN MIND. [CHAP, 6.

from the real centre, according as the fquint
is greater or lefs.

Having premifed thefe definitions, it will
be evident to thofe who underftand the prin-
ciples of optics, that in this perfon the natu-
ral centre of one retina correfponds with the
real centre of the other, in the very fame
manner as the two real centres correfpond in
perfeft eyes ; and that the points fimilarly fi-
tuate with regard to the real centre in one
retina, and the natural centre in the other, do
likewife correfpond, in the very fame manner
as the points fimilarly fituate with regard to
the two real centres correfpond in perfect

eyes.

If it is true, as has been commonly affirm-
ed, that one who fquints fees an object with
both eyes at the fame time, and yet fees it
fingle, the fquint will mod probably be fuch
as we have defcribed in this article. And
we may further conclude, that if a perfon af-
fected with fuch a fquint as we have fuppo-
fed, could be brought to the habit of looking
ftraight, his fight would thereby be greatly
hurt. For he would then fee every thing
double which he faw with both eyes at the
fame time ; and objeds diftant from one ano-
ther, would appear to be confounded toge-
ther*

SECT. 15.] • OF SEEING. 309

ther. His eyes are made for fquinting, as
much as thofe of other men are made for look-
ing ftraight ; and his fight would be no lefs
injured by looking ftraight, than that of ano-
ther man by fquinting. He can never fee
perfectly when he does not fquint, unlefs the
correfponding points of his eyes fhould by
cuftom change their place ; but how fmall the
probability of this is, will appear in the 17th
fedion.

Thofe of the medical faculty who attempt
the cure of a fquint, would do well to confi-
der whether it is attended with fuch fymp-
toms as are above defcribed. If it is, the cure
would be worfe than the malady : for every
one will readily acknowledge, that it is better
to put up with the deformity of a fquint, than
to purchafe the cure by the lofs of perfed and
diftind vifion.

8. We fhall now return to Dr Jurin's hy-
pothefis, and fuppofe, that our patient, when
he faw objects Angle notwithftanding his
fquint, was found, upon trial, to have feen them
only with one eye.

We would advife fuch a patient, to endea-
vour, by repeated efforts, to lelfen his fquint,
and to bring the axes of his eyes nearer to a
parallel diredion. We have naturally the
U 3 power

JIO Of THE HUMAN MIND, [CHAP. 6.

power of making fmall variations in the in-
clination of the optic axes ; and this power
may be greatly increafed by exercife.

In the ordinary and natural ufe of our eyes,
we can direct their axes to a fixed ftar ; in
this cafe they mud be parallel : we can direct
them alfo to an object fix inches diftant from
the eye ; and in this cafe the axes mud make,
an angle of fifteen or twenty degrees. We
fee young people in their frolics learn to fquint,
making their eyes either converge or diverge,
when they will, to a very confiderable degree.
Why mould it be more difficult for a fquint-
ing perfon to learn to look ftraight when he
pleafes ? If once, by an effort of his will, he
can but leffen his fquint, frequent practice
will make it eafy to leffen it, and will daily
increafe his power. So that if he begins this
practice in youth, and perfeveres in it, he may
probably, after fome time, learn to direct both
his eyes to one object.

When he hath acquired this power, it will
be no difficult matter to determine, by proper
oblervations, whether the centres of the reti-
na, and other points fimilarly fituate with re-
gard to the centres, correfpond, as in other

men.

9. Let

SECT. IS-] OF SEEING. 3II

9. Let us now fuppofe that he finds this to
be the cafe ; and that he fees an object {ingle
with both eyes, when the axes of both are di-
rected to it. It will then concern him to ac-
quire the habit of looking ftraight, as he hath
got the power, becaufe he will thereby not
only remove a deformity, but improve his
light : and I conceive this habit, like all others,
may be got by frequent exercife. He may
praclife before a mirror when alone, and in
company he ought to have thofe about him,
who will obferve and admonifh him when he
f quints.

10. What is fuppofed in the 9th article, is
not merely imaginary ; it is really the cafe of
fome fquinting perfons, as will appear in the
next fection. Therefore it ought further to
be inquired, How it comes to pafs, that fuch
a perfon fees an object which he looks at, on-
ly with one eye, when both are open ? In
order to anfwef this queftion, it may be ob-
ferved, firft, Whether, when he looks at an
object, the diverging eye is not drawn fo clofe
to the nofe, that it can have no diflinct ima-
ges ? Or, fecondly, Whether the pupil of
the diverging eye is not covered wholly, or
in part, by the upper eyelid ? Dr Juiun ob-
ferved inftances of thefe cafes in perfons that

U 4 fquinted,

312 OF THE HUMAN MIND. [CHAP. 6«

fqtiintcd, and ailigns them as caufes of their
feeing the object only with one eye. Third-
ly, it may be obferved, Whether the diver-
ging eye is not fo directed, that the picture of
the objeel: falls upon that part of the retina
where the optic nerve enters, and where there
is no virion ? This will probably happen in
a fquint wherein the axes of the eyes con-
verge, fo as to meet about fix inches before the
nofe.

ii. In the laft place, it ought to be inqui-
red, Whether fuch a perfon hath any diftincl:
vifion at all with the diverging eye, at the
time he is looking at an objeel: with the
other ?

It may feem very improbable, that he
fhould be able to read with the diverging eye
when the other is covered, and yet, when both
are open, have no diftincl viiion with it at all.
But this perhaps will not appear fo improba-
ble, if the following confiderations are duly
attended to.

Let us fuppofe that one who faw perfectly,
gets, by a blow on the head, or fome other
accident, a permanent and involuntary fquint.
According to the laws of virion, he will fee
objects double, ^nd will fee objects diftant
from one another confounded together : but

fuch

SECT. 15.] OF SEEING. 313

fuch vifion being very difagreeable, as well as
inconvenient, he will do every thing in his
power to remedy it. For alleviating fuch
diftreffes, nature often teaches men wonder-
ful experiments, which the fagacity of a phi-
Jofopher would be unable to difcover. Every
accidental motion, every direction or confor-
mation of his eyes, which leffens the evil, will
be agreeable ; it will be repeated, until it be
learned to perfection, and become habitual,
even without thought or deiign. Now, in
this cafe, what diflurbs the fight of one eye,
is the light of the other ; and all the difa-
greeable appearances in vifion would ceafe,
if the light of one eye was extinct : The
fight of one eye wrill become more diftinct
and more agreeable, in the fame proportion
as that of the other becomes faint and indif-
tinct. It may therefore be expected, that
every habit will, by degrees, be acquired,
which tends to deftroy diftinct vifion in one
eye, while it is preferved in the other. Thefe
habits will be greatly facilitated, if one eye
was at fir ft better than the other ; for in that
cafe the belt eye will always be directed to
the object which he intends to look at, and
every habit will be acquired which tends to

hinder

314 °* THE HUMAN MIND. [CHAP. 6,

hinder his feeing it at all, or feeing it diAincV
ly by the other at the fame time.

I (hall mention one or two habits that may
probably be acquired in fuch a cafe ; perhaps
there are others which we cannot fo. ealily
conjecture. Firft, By a fmall increafe or di-
minution of his fquint, he may bring it to cor-
refpood with one or other of the cafes men-
tioned in the lad article. Secondly, The di-
verging eye may be brought to fuch a con-
formation as to be extremely mort-fighted,
and confequcntly to have no diAinct vifion of
objects at a diAance. I knew this to be the
cafe of one perfon that fquinted ; but cannot
fay whether the Ihort-fightednefs of the di-
verging eye was original, or acquired by ha-
bit.

We fee, therefore, that one who fquints,
and originally faw objects double by reafon
of that fquint, may acquire fuch habits, that
when he looks at an object, he Avail fee it only
with one eye : nay, he may acquire fuch ha-
bits, that when he looks at an object with his
belt eye, he mall have no diAinct vifion with
the other at all. Whether this is really the
cafe, being unable to determine in the inftan-
ces that have fallen under my obfervation, I
mail leave to future inquiry.

I

SECT. 15.] OF SEEING. 3I5

I have endeavoured, in the foregoing arti-
cles, to delineate fuch a procefs as is proper
in obferving the phenomena of fquinting. I
know well by experience, that this procefs
appears more eafy in theory, than it will be
found to be in practice ; and that in order to
carry it on with fuccefs, fome qualifications
of mind are neceflary in the patient, which
are not always to be met with. But if thofe
who have proper opportunities, and inclina-
tion, to obferve fuch phenomena, attend duly
to this procefs, they may be able to furnifh
fa&s lefs vague and uninftrudlive than thofe
we meet with, even in authors of reputation.
By {uch fads, vain theories may be exploded,
and our knowledge of the laws of nature,
which regard the nobleft of our fenfes, enlar-
ged.

SECT-

316 OF THE HUMAN MIND. [CHAP. 6.

SECT. XVI.

Fa6ls relating to fquinting.

HAving confidered the phenomena of
fquinting hypothetically, and their con-
nection with correfponding points in the re-
tina, I mall now mention the fads I have had
occafion to obferve myfelf, or have met with
in authors, that can give any light to this fub-
jeft.

Having examined above twenty perfons
that fquinted, I found in all of them a defect
in the fight of one eye. Four only had fo
much of diftincl vifion in the weak eye, as to
be able to read with it when the other was
covered. The reft faw nothing at all diftincl-
ly with one eye.

Dr Porterfield fays, that this is general-
ly the cafe of people that fquint : and I fu-
fpedt it is fo more generally than is commonly
imagined. Dr Jurin, in a very judicious
dhTertation upon fquinting, printed in Dr

Smith's

SECT. l6.] OF SEEING, 317

Smith's Optics, obferves, that thofe who fquint,
and fee objects with both eyes, never fee the
fame object with both at the fame time ; that
when one eye is directed ilraight forward to
an object, the other is drawn fo clofe-to the
nofe, that the object cannot at all be feen by
it, the images being too oblique and too iri-
diflinct to affect the eye. In fome fquinting
perfons, he obferved the diverging eye drawn
under the upper eyelid, while the other was
' directed to the object. From thefe obferva-
tions he concludes, that " the eye is thus di-
" ftorted, not for the fake of feeing better
" with it, but rather to avoid feeing at all
" with it as much as poliible." From all the
obfervations he had made, he was fatisfied,
that there is nothing peculiar in the ftructure
of a fquinting eye ; that the fault is only in
its wrong direction ; and that this wrong di-
rection is got by habit. Therefore he pro-
pofes that method of cure which we have de-
fcribed in the 8th and 9th articles of the lad
fection. He tells us, that he had attempted a
cure after this method, upon a young Gentle-
man, with promiiing hopes of fuccefs ; but
was interrupted by his falling ill of the fmall-
pox, of which he died.

It

$l8 OF THE HUMAN MIND. [CHAP. 6\

It were to be wifhed that Dr Jurin had ac-
quainted us, whether he ever brought the
young man to direct the axes of both eyes to
the fame object, and whether, in that cafe,
he faw the object fingle, and faw it with both
eyes ; and that he had like wife acquainted
us, whether he faw objects double when bis
fquint was diminifhed. But as to thefe fads
he is filent.

I wifhed long for an opportunity of trying
Dr Jurin's method of curing a fquint, with-
out finding one \ having always, upon exami-
nation, difcovered fo great a defect in the
fight of one eye of the patient as difcouraged
the attempt.

But I have lately found three young Gen-
tlemen, with whom I am hopeful this method
may have fuccefs, if they have patience and
perfeverance in uiing it. Two of them are
brothers, and, before I had accefs to examine
them, had been practicing this method by the
direction of their tutor, with fuch fuccefs, that
the elder looks ftraight when he is upon his
guard : the vounger can direct both his eyes
to one object ; but they foon return to their
uiaal fquint.

A third young Gentleman, who had never
heard of this method before, by a few days

practice,.

SECT.' 1 6.] OF SEEING. 310

practice, was able to direct both his eyes to
orie object, but could not keep them long in
that direction. All the three agree in this,
that when both eyes are directed to one ob-
ject, they fee it arid the adjacent objects fin-
gle ; but when they fquint, they fee objects
fometimes lingle and fometimes double. I
obferved of all the three, that when they
fquinted moil, that is, in the way they had
been accuftomed to, the axes of their eyes
converged, fo as to meet five or fix inches be-
fore the nofe. It is probable that in this cafe
the picture of the object in the diverging eye,
mud fall upon that part of the retina where
the optic nerve enters ; and therefore the ob-
ject could not be feen by that eye.

All the three have fome defect in the fight
of one eye, which none of them knew until I
put them upon making trials ; and when they
fquint, the beft eye is always directed to the
object, and the weak eye is that which di-
verges from it. But when the beft eye is co-
vered, the weak eye is turned directly to the
object. Whether this defect of fight in one
eye, be the effect of its having been long dif-
ufed, as it rauft have been when they fquint-
ed ; or whether fome original defect in one
eye might be the occafion of their fqutnting,

time

giO OF THE HUMAN MIND. [crtAt. 6*

time may difcover. The two brothers have
found the light of the weak eye improved by
ufing to read with it while the other is cover-
ed. The elder can read an ordinary print
with the weak eye ; the other, as well as the
third Gentleman, can only read a large print
with the weak eye. I have met with one
other perfon only who fquinted, and yet could
read a large print with the weak eye. He is
a young man, whofe eyes are both tender and
weak-fighted, but the left much weaker than
the right. When he looks at any object, he
always directs the right eye to it, and then
the left is turned towards the nofe fo much,
that it is impoffible for him to fee the fame
objed with both eyes at the fame time.
When the right eye is covered, he turns the
left direftly to the objecl: ; but he fees it in-
diftinaiy, and as if it had a mill about it.

I made feveral experiments, fome of them
in the company and with the affiftance of an
ingenious phyfician, in order to difcover, whe-
ther objecls that were in the axes of the two
eyes, were feen in one place confounded to-
gether, as in thofe who have no involuntary
fquint. The objed placed in the axis of the
weak eye was a lighted candle, at the diltance
of eight or ten feet. Before the other eye

was

SEtT. l6.] OF SEEING. 3II

Was placed a printed book, at fuch a diflance
as that he could read upon it. He faid, that
while he read upon the book, he faw the can-
dle but very faintly. And from what we
could learn, thefe two objects did not appear
in one place, but had all that angular diftanc^
in appearance which they had in reality.

If this was really the cafe, the conclusion
to be drawn from it is, that the correfponding
points in his eyes are not iituate in the fame
manner as in other men ; and that if he could
be brought to direct both eyes to one object,
he would fee it double. But confidering that
the young man had never been accuftomed to
obfervations of this kind, and that the fight
of one eye was fo imperfect, I do not pretend
to draw this concluiion with certainty from
this fingle inflance.

All that can be inferred from thefe fads is,
that of four perfons who fquint, three appear
to have nothing preternatural in the flructure
of their eyes. Jlhe centres of the retina 9 and
the points limilarly fituate with regard to the
centres, do certainly correfpond in the fame
manner as in other men. So that if they can
be brought to the habit of directing their
eyes right to an object, they will not only re-
move a deformity ^ but improve their fight.

X With

322 OF THE HUMAN MIND. [cHAP. 6,

With regard to the fourth, the cafe is dubious,
with fome probability of a deviation from the
ufual courfe of nature in the fituation of the
correfponding points of his eyes.

SECT. XVII.

Of the effecl of cujlom in feeing obj eels fugle.

IT appears from the phenomena of fingle
and double vinon, recited in Seel. 13. that
our feeing an object fingle with two eyes, de-
pends upon thefe two things. Firft, Upon
that mutual correfpondence of certain points
of the retina which we have often defcribed.
Secondly, Upon the two eyes being directed
to the object fo accurately, that the two ima-
ges of it fall upon correfponding points.
Thefe two things mull concur in order to our
feeing an object fingle with two eyes ; and
as far as they depend upon cuftom, fo far on-
ly can lingle vifion depend upon cuftom.

With regard to the fecond, that is, the ac-
curate direction of both eyes to the object, I

think

SECT. I^.] OF SEEING. 3*3

think it muft be acknowledged that this is
only learned by cuftom. Nature hath wifely
ordained the eyes to move in fuch a manner,
that their axes fhall always be nearly parallel ;
but hath left it in out power to vary their in-
clination a little* according to the diftance of
the object we look at. Without this power,
objects would appear fingle at one particular
diftance only ; and, at diflances much lefs, or
much greater* would always appear double.
The wifdom of nature is confpicuous in gi-
ving us this power, and no lefs confpicuous in
making the extent of it exactly adequate to
the end*

The parallelifm of the eyes, in general, is
therefore the work of nature-; but that pre-
cife and accurate direction, which muft be
varied according to the diftance of the objecl,
is the effect of cuftom. The power wThich
nature hath left us of varying the inclination
of the optic axes a little, is turned into a ha-
bit of giving them always that inclination
which is adapted to the diftance of the object.

But it may be afked, What gives rife to
this habit ? The only anfwer that can be given
to this queftion is, that it is found necefTary
to perfect and diftinct vifion. A man who
hath loft the light of one eye, very often lofes

X 2 the

324 OF THE HUMAN MIND. [CHAP. 6,

thfr habit of dire&ing it exactly to the object:
he looks at, becaufe that habit is no longer of
ufe to him. And if he fhould recover the
light of his eye, he would recover this habit,
by finding it ufeful. No part of the human
conftitution is more admirable than that
whereby we acquire habits which are found
ufeful, without any defign or intention. Chil-
dren muft fee imperfectly at firft ; but, by
ufing their eyes, they learn to ufe them in the
bed manner, and acquire, without intending
it, the habits neceflary for that purpofe. E-
very man becomes moft expert in that kind
of vifion which is moft ufeful to him in his
particular profeffion and manner of life. A
miniature painter, or an engraver, fees very
near objects better than a failor ; but the fail-
or fees very diftant objecls much better than
they. A perfon that is (hort-fighted, in look-
ing at diftant objects, gets the habit of con-
trading the aperture of his eyes, by almoft
doling his eyelids. Why? For no other
reafon, but becaufe this makes him fee the ob-
je& more diftinct. In like manner, the rea-
fon why every man acquires the habit of
directing both eyes accurately to the object,
muft be, becaufe thereby he fees it more per-

fedly and diftinctly.

It

SECT. 17.] OF SEEING. 325

It remains to be confidered, whether that
correfpondence between certain points of the
retina, which is likewife neceflary to fingle
vifion, be the effect of cuftom, or an original
property of human eyes.

A flrong argument for its being an original
property, may be drawn from the habit juft
now mentioned, of directing the eyes accu-
rately to an object. This habit is got by our
finding it neceflary to perfect and diftinct vi-
fion. But why is it neceflary ? For no other
reafon but this, becaufe thereby the two ima-
ges of the object: falling upon correfponding
points, the eyes aflift each other in vifion, and
the object is feen better by both together,
than it could be by one ; but when the eyes
are not accurately directed, the two images
of an object fall upon points that do not cor-
refpond, whereby the fight of one eye difturbs
the fight of the other, and the object is feen
more indiftinctly with both eyes than it would
be with one. Whence it is rcafonable to con-
clude, that this correfpondence of certain
points of the retina, is prior to the habits we
acquire in vifion, and confequently is natural
and original. We have all acquired the ha-
bit of directing our eyes always in a particu-
lar manner, which caufes fingle vifion. Now,
X3 if

326 OF THE HUMAN MIND. [CHAP. 6.

if nature hath ordained that we fhould have
ijngle vifion only, when our eyes are thus- di-
rected, there is an obvious reafon why all
mankind fhould agree in the habit of direct-
ing them in this manner. But if fingle vifion
is the effect of cuftom, any other habit of di-
recting the eyes would have anfvvered the
purpofe ; and no account can be given why
this particular habit fhould be fo univerfal ;
and it muft appear very ftrange, that no one
inftance hath been found of a perfon who had
acquired the habit of feeing objects {ingle with
both eyes, while they were directed in any
other manner.

The judicious Dr Smith, in his excellent
Syftem of Optics, maintains the contrary opi-
nion, and offers fome reafonings and facts in
proof of it. He agrees with Bifhop Berkeley
in attributing it entirely to cuftom, that we
fee objects fingle with two eyes, as well as that
we fee objects erect by inverted images. Ha-
ving confidered Bifhop Berkeley's reafon-
ings in the nth lection, we fhall now beg
leave to make fome remarks on what Dr
Smith hath faid upon this fubject, wij:h the
refpect due to an author to whom the world
owes, not only many valuable difcoveries of
bis own, but thofe of the brighteit mathema-
tical

SECT. 17.] OF SEEING. 327

tical genius of this age, which, with great la-
bour, he generoufly redeemed from oblivion.

He obferves, that the queflion, Why we fee
objects fingle with two eyes? is of the fame
fort with this, Why we hear founds iingle
with two ears ? and that the fame anfwer muft
ferve both. The inference intended to be
drawn from this obfervation is, that as the fe-
cond of thefe phenomena is the effect of cuf-
tom, fo likewife is the firft.

Now I humbly conceive that the queftions
are not fo much of the fame fort, that the
fame anfwer mull ferve for both ; and more-
over, that our hearing fingle with two ears, is
not the 'effect of cuftom.

Two or more vifible objects, although per-
fectly flmilar, and feen at the very fame time,
may be diflinguiihed by their vifible places ;
but two founds perfectly fimilar, and heard
at the fame time, cannot be diftinguifhed ;
for, from the nature of found, the fenfations
they occafion muft coalefce into one, and lofe
all diflinction. If therefore it is afked, Why
we hear founds fingle with two ears ? I an-
fwer, Not from cuftom ; but becaufe two
founds which are perfectly like and fynchro-
nous, have nothing by which they can be di-
X 4 ftingiiifhed.

328 OF THE HUMAN MIND. [CHAP. 6.

ftinguifhed. But will this anfwer fit the other
queftion ? I think not.

The object makes an appearance to each
eye, as the found makes an impreffion upon
each ear ; fo far the two fenfes agree. But
the vifible appearances may be diftinguifhed
by place, when perfectly like in other re-
fpects ; the founds cannot be thus diftinguifh-
ed ; and herein the two fenfes differ. Indeed,
if the two appearances have the fame vifible
place, they are, in that cafe, as incapable of
diftinction as the founds were, and we fee the
object fingle. But when they have not the
fame vifible place, they are perfectly diftin-
guifhable, and we fee the object double. We
fee the object fingle only, when the eyes are
directed in one particular manner ; while
there are many other ways of directing them
within the fphere of our power, by which we
fee the object double.

Dr Smith juftly attributes to cuftom that
well-known fallacy in feeling, whereby a but-
ton preiTed with two oppofite fides of two
contiguous fingers laid acrofs is felt double.
I agree with him, that the caufe of this ap-
pearance is, that thofe oppofite fides of the
fingers have never been ufed to feel the fame
object, but two different objects, at the fame

time.

SECT. 17.] OF SEEING. 329

time. And I beg leave to add, that as cuf-
tom produces this phenomenon, fo a contrary
cuftom deftroys it : for if a man frequently
accuftoms himfelf to feel the button with his
fingers acrofs, it will at lad be felt fingle ; as
I have found by experience.

It may be taken for a general rule, That
things which are produced by cuftom, may
be undone or changed by difufe, or by a con-
trary cuftom. On the other hand, it is a ftrong
argument, that an effect is not owing to cuf-
tom, but to the conftitution of nature, when
a contrary cuftom, long continued, is found
neither to change nor weaken it, I take this
to be the beft rule by which we can deter-
mine the queftion prefently under confidera-
tion. I fliall therefore mention two facts
brought by Dr Smith, to prove that the cor-
refponding points of the retina have been
changed by cuftom ; and then I (hall mention
fome facts tending to prove, that there are
correfponding points of the retina of the eyes
originally, and that cuftom produces no change
in them.

" One fact is related upon the authority of
" Martin Folkes, Efq; who was informed by
" Dr Hepburn of Lynn, that the Reverend
" Mr Foster of Clinchwharton, in that neigh.

" bourhood,

030 0*" THE HUMAN MIND. [CHAP. 6.

*« bourhood, having been blind for fome years
•' of a gutta ferena, was reltored to fight by
" falivation : and that, upon his firft begin-
" ning to fee, all objects appeared to him
" double ; but afterwards the two appear-
" ances approaching by degrees, he came at
" laft to fee fingle, and as diftinctly as he did
" before he was blind."

Upon this cafe I obferve, firft, That it does
not prove any change of the corresponding
points of the eyes, unlefs we fuppofe, what is
not affirmed, that Mr Foster directed his eyes
to the objed at firft, when he faw double,
with the fame accuracy, and in the fame man-
ner, that he did afterwards when he faw An-
gle. 2dly, If we fhould fuppofe this, no ac-
count can be given, why at firft the two ap-
pearances fhould be feen at one certain angu-
lar diftance rather than another ; or why this
angular diftance mould gradually decreafe,
until at laft the appearances coincided. How
could this effect be produced by cuftom?
But, thirdly, Every circumftance of this cafe
may be accounted for, on the fuppofition that
Mr Foster had correfponding points in the
retina of his eyes from the time he began to
fee, and that cuftom made no change with
regard to them. We need only further fup-
pofe,

SECT. 17.] 0* SEEING. 33!

pofe, what is common in fuch cafes, that by
ibme years blindnefs he had loft the habit of
directing his eyes accurately to an object, and
that he gradually recovered this habit when
he came to fee.

The fecond fact mentioned by Dr Smith,
is taken from Mr Cheselden's Anatomy ; and
is this : " A gentleman who, from a blow on
" the head, had one eye diflorted, found eve-
" ry object appear double \ but by degrees
" the moll familiar ones became lingle ; and
" in time all objects became fo, without any
" amendment of the diftortion."

I obferve here, that it is not faid that the
two appearances gradually approached, and
at lad united, without any amendment of the
diftortion. This would indeed have been a
decifive proof of a change in the correfpond-
ing points of the retina : and yet of fuch a
change as could not be accounted for from
cuftom. But this is not faid ; and if it had
been obferved, a circumftance fo remarkable
would have been mentioned by Mr Chesel-
den, as it was in the other cafe by Dr Hep-
burn. We may therefore take it for granted,
that one of the appearances vanifhed by de-
grees, without approaching to the other.
£nd this I conceive might happen feveral

ways.

332 OF THE HUMAN MIND. [CHAP. 6.

ways. Firft, The light of the diftorted eye
might gradually decay by the hurt ; fo the
appearances prefented by that eye would gra-
dually vanifh. Secondly, A fmall and unper-
ceived change in the manner of directing the
eyes, might occafion his not feeing the object
with the diftorted eye, as appears from
Seel. 15. Art. 10. Thirdly, By acquiring the
habit of directing one and the fame eye always
to the object, the faint and oblique appear-
ance, prefented by the other eye, might be
fo little attended to when it became familiar,
as not to be perceived. One of thefe caufes,
or more of them concurring, might produce
the effect mentioned, without any change of
the correfponding points of the eyes.

For thefe reafons, the facts mentioned by
Dr Smith, although curious, feem not to be
decilive.

The following facts ought to be put in the
oppoiite fcale. Firft, In the famous cafe of
the young gentleman couched by Mr Che-
selden, after having had cataracts on both
eyes until he was thirteen years of age, it ap-
pears, that he faw objects lingle from the time
he began to fee with both eyes. Mr Chesel-
den's words are : " And now being lately
" couched of his other eye, he fays, that ob-

" jects,

SECT. 17.] OF SEEING, 333

44 jects, at firft appeared large to this eye, but
41 not fo large as they did at firft to the other;
" and looking upon the fame objed with
" both eyes, he thought it looked about twice
" as large as with the firft couched eye only,
" but not double, that we can anywife dif-
44 cover."

Secondly, The three young gentlemen men-
tioned in the laft fection, who had fquinted,
as far as I know, from infancy ; as foon as
they learned to direct both eyes to an object,
faw it {ingle. In thefe four cafes, it appears
evident, that the centres of the retina corre-
fponded originally, and before cuftom could
produce any fuch effect : for Mr Chesel*
den's young gentleman had never been ac-
cuftomed to fee at all before he was couched ;
and the other three had never been accuftom-
ed to direct the axes of both eyes to the ob-
ject.

Thirdly, From the facts recited in Sect. 13.
it appears, That from the time we are capable
of obferving the phenomena of (ingle and
double vifion, cuftom makes no change in
them.

I have amufed myfelf with fuch obferva-
tions for more than thirty years ; and in every
cafe wherein I faw the object double at firft,

I

334 0F THE HUMAN MIND. [CHAP. 6„

I fee it fo to this day, not with (landing the
conftant experience of its being fingle. . In
other cafes where I know there are two ob-
jects, there appears only one, after thoufands
of experiments.

Let a man look at a familiar object through
a polyhedron or multiplying-glafs every hour
of his life, the number of vifible appearances
will be the fame at lad as at firft : nor does
any number of experiments, or length of time,
make the leaft change.

Effects produced by habit, muft vary ac-
cording as the ads by which the habit is ac-
quired are more or lefs frequent : but the
phenomena of fingle and double vifion are fo
invariable and uniform in all men, are fo -ex-
actly regulated by mathematical rules, that I
think we have good reafon to conclude, that
they are not the effect of cuftom, but of fixed
and immutable laws of nature.

SECT.

SECT. l8.] OF SEEING. 335

SECT. XVIII.

Of Dr Porterfield's account of Jingle and
double vijion.

BIshop Berkeley and Dr Smith fecin to
attribute too much to cuftom in vifion ;
Dr Porterfield too little.

This ingenious writer thinks, that, by an
original law of our nature, antecedent to cuf-
tom and experience, we perceive vifible ob-
jects in their true place, not only as to their
direction, but likewife as to their diftance from
the eye: and therefore he accounts for our
feeing objects liiigle, with two eyes, in. this
manner. Having the faculty of perceiving
the object; with each eye in its true place, we
mult perceive it with both eyes in the fame
place ; and confequently mull perceive it
lingle.

He is aware, that this principle, although
it accounts for our feeing objects fingle with
two eyes, yet does not at all account for our

feeing

336 Of THE HUiMAN MIND. [CHAP. 60

feeing objects double : and whereas other
writers on this fubject take it to be a fufficient
caufe for double vifion that we have two eyes,
and only find it difficult to affign a caufe for
fingle vifion ; on the contrary, Dr Porter-
field's principle throws all the difficulty oh
the other fide.

Therefore, in order to account for the phe-
nomena of double vifion, he advances another
principle, without fignifying whether he con-
ceives it to be an original law of our nature,
or the effect of cuftom. It is, That our na-
tural perception of the diftance of objects
from the eye, is not extended to all the ob-
jects that fall within the field of vifion, but
limited to that which we directly look at ;
and that the circumjacent objects, whatever
be their real diftance, are feen at the fame
diftance with the object we look at; as if
they were all in the furface of a fphere where-
of the eye is the centre.

Thus, fingle vifion is accounted for by our
feeing the true diftance of an object which
we look at ; and double vifion, by a falfe ap-
pearance of diftance in objects which we do
not directly look at.

We agree with this learned and ingenious
author, that it is by a natural and original

principle

SECT. 18.] OF SEEING. • 33jf

principle that we fee vifible objeds in a cer-
tain direction from the eye, and honour him
as the author of this difcovery : but we can-
not afient to either of thofe principles by which
he explains fingle and double vifion, for the
following reafons :

i. Our having a natural and original per-
ception of the diftance of objeds from the
eye, appears contrary to a well-attefted fad :
for the young gentleman couched by Mr Che-
selden, imagined at firft, that whatever he
faw, touched his eye, as what he felt touched
his hand.

2. The perception we have of the diftance
of objeds from the eye, whether it be from
nature or cuftom, is not fo accurate and de-
terminate as is neceflary to produce fingle vi-
fion. A miftake of the twentieth or thirtieth
part of the diftance of a fmall objed, fuch as
a pin, ought, according to Dr Porterfield's
hypothefis, to make it appear double. Very
few can judge of the diftance of a vifible ob-
jed with fuch accuracy. Yet we never find
double vifion produced by miftaking the dif-
ftance of the objed* There are many cafes
in vifion, even with the naked eye, wherein
we miftake the diftance of an objed by one
half or more : why do we fee fuch objeds
Y fingle ?

3.38 O* THE fiUMAN MtND. E[?frA>. 6.

jingle ? When I move my fpectacles From ray
eyes toward a fmaU object, two or three feet
diftant, the object feems to approach, fo as to
be feeh 'at 1 aft at about half its real diftance ;
but it is feenfingle at that apparent diftance,
as well as when we fee it with the naked eye
at its real diftance. And when we look at an
obj^cl with a binocular telefcope, properly
fitted to the eyes, we fee it iingle, while it ap-
pears fifteen or twenty times nearer than it is.
There are then few cafes wherein the diftance
of an objecl from the eye is feen fo accurately
as is neceflary for tingle vifion, upon this hy-
p -thefts : This feems to be a conclufive argu-
ment againft the account given of fingle vi-
fion. We find, likewife, that falfe judgments
or fallacious appearances of the diftance of
an object, do not produce double vifion. This
feems to be a conclufive argument againft the
account given of double vifion.

V The perception we have of the linear
diftance of objects, feems to be wholly the ef-
fect of experience. This I think -hath been
proved by Bifhop Berkeley arid by Dr
Smith :;' and when we come to point out the
riieans of- judging of diftance by fight, it will
appear that they are all furnifhed by expe-
rience.

4. Suppofing

SECT. 1 8:] OP SEEING. 339

4. Supposing that by a law of our nature,
the diflance of objects from the eye were per-
ceived mod accurately, as well as their direc-
tion, it will not follow that we raufl fee the
object iingle. Let us confider what means
fuch a law of nature would furnifh for rc-
folving the queflion, Whether the. objects of
the two eyes are in one and the fame place,
and confequently are not two, but one ?

Suppofe then two right lines, one drawn
from the centre of one eye to its object, the.
other drawn, in like manner, from the centre
of the other eye to its object. This law of
nature gives us the direction or pofition of
each of thefe right lines, and the length of
each ; and this is all that it gives. Thefe are
geometrical data, and we may learn from
geometry what is determined by their means.
Is it then determined by thefe data, Whether
the two right lines terminate in one and the
fame point, or not ? No truly. In order to
determine this, we mull have three other data.
We muft know whether the two right lines
are in one plane : we muft know what angle
they make, and we muft know the diftance
between the centres of the eyes. And, when
thefe things are known, we muft apply the
rules of trigonometry, before we can refolve

Y2 the

340 OF THE HUMAN MIND. [CHAP. 6.

the queflion, Whether the objects of the two
eyes are in one and the fame place \ and con-
fequently whether they are two or one ?

5. That falfe appearance of diftance into
which double virion is refolved, cannot be the
effect of cuftom ; for conftant experience
contradicts it: Neither hath it the features
of a law of nature ; becaufe it does not anfwer
any good purpofe, nor indeed any purpofe at
all but to deceive us. But why fhould we
feek for arguments, in a queflion concerning
what appears to us, or does not appear ? The
queftion is, At what diftance do the objects
now in my eye appear ? Do they all appear
at one diftance, as if placed in the concave
furface of a fphere, the eye being in the cen-
tre ? Every man furely may know this with
certainty ; and, if he will but give attention
to the teftimony of his eyes, needs not afk a
philofopher, how vifible objects appear to
him. Now, it is very true, that if I look up
to a ftar in the heavens, the other ftars that
appear at the fame time, do appear in this
manner : Yet this phenomenon does not fa-
vour Dr Porte kjeteld's hypothefis ; for the
liars and 'heavenly bodies, do not appear at
their true diftances when we look directly to
them, any more than when they are feen ob-
liquely :

SECT. l8.] OF SEEING. 341

liquely : and if this phenomenon be an argu-
ment for Dr Porterfield's fecond principle,
it m uft deftroy the firft.

The true caufe of this phenomenon will be
given afterwards ; therefore, fetting it afide
for the prefent, let us put another cafe. I fit
in my room, and direct my eyes to the door,
which appears to be about fixteen feet dis-
tant : at the fame time I fee many other ob-
jects faintly and obliquely ; the floor, floor-
cloth, the table which I write upon, papers,
ftandifti, candle, &c. Now, do all thefe ob-
jects appear at the fame diftance of fixteen
feet? Upon the clofeft attention, I find they
do not.

Y 3 SECT.

34^ OP THE HUMAN MIND. [CHAP. 6.

.

•

.

SECT. XIX.

;

.

.

Of Br Briggs's theory, and Sir Isaac New-
ton's conjedlure on ihisfubjett.

.

I AM afraid the reader, as well as the wri-
ter, is already tired of the fubjecl of fingle
and double vifion. The multitude of theo-
ries advanced by authors of great name, and
the multitude of fads, obferved without fuffi-
cient fkill in optics, or related without atten-
tion to the mod material and decifive cir-
cumftances, have equally contributed to per-
plex it.

In order to bring it to fome ifTue, I have,
in the 13th feclion, given a more full and re-
gular deduction than had been given hereto-
fore, of the phenomena of fingle and double
vifion, in thofe whofe fight is perfect ; and
have traced them up to one general principle,
which appears to be a law of vifion in human
eyes that are perfect and in their natural

ftate.

In

sfct; 19.] or seeing. 343

In the 14th fe&ion 1 have mnde it appear,
that this law of virion, although excellently
adapted to the fabric of human eyes, cannot
anfvver the purpofes of vifion in fome other
animals ; and therefore, very probably, is not
common to all animals. The purpofe of the
15th and i6th fedtions is, to inquire, whether
there be any deviation from this law of vifion
in thofe who fquint ?. a queftion which is of
real importance in ;the medical, art, as Well as
in the philofophy of vifion ; but which, after-
all that hath been obferved and written on
the fubj'ect, feems not to be ripe for a de-
termination, for want of proper observations.
Thofe who have had ikill to make proper ob-
servations, have wanted opportunities ; and
thofe who have had opportunities, have want-
ed ikill or attention. I have therefore thought
it worth while to give a diftinct account of
the observations neceflary for the determina-
tion of this queftion, and what conclufions
may be. drawn from the facts obferved. I
have like wife collected, and fet in one view,
the mod concluiive facts that have occurred
in authors, or have fallen under my own ob-
fervation<

It mud be confeffed, that thefe fads, when

applied to the queftion in hand, make a very

Y 4 poor

344 0F THE HUMAN mind. [chap. 6.

poor figure ; and the Gentlemen of the me-
dical faculty are called upon, for the honour
of ttreir profeflion, and for the benefit of man-
kind, to add to them.

All the medical, and all the optical wri-
ters, upon the Jirabifntus, that I have met
with, except Dr Jurin, either affirm, or take
it for granted, that fquinting perfons fee the
objecl with both eyes, and yet fee it fingle.
Dr Jurin affirms, that fquinting perfons ne-
ver fee the object with both eyes ; and that
if they did, they would fee it double. If the
common opinion be true, the cure of a fquint
would be as pernicious to the light of the
patient, as the caufing of a permanent fquint
would be to one who naturally had no fquint :
and therefore no phyiician ought to attempt
fuch a cure ; no patient ought to fubmit to
it. But if Dr Jurin's opinion be true, moil
young people that fquint may cure them-
felves, by taking fome pains ; and may not
only remove the deformity, but at the fame
time improve their fight. If the common
opinion be true, the centres and other points
of the two retina in fquinting perfons do not
correfpond as in other men, and nature in
them deviates from her common rule. But
if Dr Jurin's opinion be true, there is rea-

fou

SECT. I9.] OF SEEING. 345

fon to think, that the fame general law of
vifion which we have found in perfect human
eyes, extends alfo to thofe which fquint.

It is impoffible to determine, by rcafoning,
which of thefe opinions is true ; or whether
one may not be found true in fome patients,
and the other in others. Here, experience
and obfervation are our only guides ; and a
deduction of inftances, is the only rational ar-
gument. It might therefore have been ex-
pected, that the patrons of the contrary opi-
nions fhould have given inftances, in fupport
of them, that are clear and indifputable : but
I have not found one fuch inftance on either
lide of the queftion, in all the authors I have
met with. I have given three inftances from
my own obfervation, in confirmation of Dr
Jurin's opinion, which admit of no doubt ;
and one, which leans rather to the other opi-
nion, but is dubious. And here I muft leave
the matter to further obfervation.

In the 17th fection, 1 have endeavoured to
flicw, that the correfpondence and fympathy
of certain points of the two retinte, into which
we have refolved all the phenomena of fingle
and double vifion, is not, as Dr Smith con-
ceived, the effect of cuftom, nor can be chan-
ged by cuftom, but is a natural and original

property

346 OF THE HUMAN MIND. [CHAP. 6,

.property of human eyes : and in the lad fec-
tion, that it is not owing to an original and
natural perception of the true diftance of ob-
jects from the eye, as Dr Porterfield ima-
gined. After this recapitulation, which is
intended to relieve the attention of the reader,
fhall we enter into more theories upon this
fubject?

That of Dr Briggs, firfl publifhed in Eng-
lish, in the Philofophical Tranfadions, after
wards in Latin, under the title of Nova vU
fionis theoria, with a prefatory epiftle of Sir
Isaac Newton to the author, amounts to
this, That the fibres of the optic nerves paf-
iing from correfponding points of the retime
to the thalami nervorum opticorum, having the
fame length, the fame tenfion, and a fimilar
fituation, will have the fame tone ; and there-
fore their vibrations, excited by the impref-
fion of the rays of light, will be like unifons
in mufic, and will prefent one and the fame
image to the mind : but the fibres palling
from parts of the retina, which do not cor-
refpond, having different tenfions and tones,
will have difcordant vibrations ; and therefore
prefent different images to the mind.

I fhall not enter upon a particular exami-
nation of this theory. It is enough to ob-

ferve,

SECT. 19.] OF SEEING. 347

ferve, in general, that it is .a. fyftem of con-
jectures concerning things of which we ,are
entirely ignorant ; and that all fuch theories
in philofophy dc ferve rather to be laughed at,
than to he ferioufly refuted.

From the firft dawn of philofophy to thi,
day, it hath been believed that the optic
nerves are intended to carry the images of
vifible objects from the bottom of the eye to
the mind; and that the nerves belonging to
the organs of the other fenfes have a like of-
fice. But how do we know this ? We, con-
jecture it : and taking this conjecture for a.
truth, we confider how the nerves may bed
anfvver this purpofe. The fyftem of the nerves,
for many ages, was taken to be a hydraulic
engine, confifting of a bundle of pipes, which
carry to and fro a liquor called animal fpU
rits. About the time of Dr Briggs, it was
thought rather to be a ftringed inftrument,
compofed of vibrating chords, each of which
had its proper tenfion and tone. But fome,
with as great probability, conceived it to be a
wind inftrument, which played its part by the
vibrations of an elaftic ether in the nervous
fibrils.

Thefe, I think, are all the engines into
which the nervous fyftem hath been mould-
ed

348 OF THE HUMAN MIND. [CHAP. 6.

ed by philofophers, for Conveying the images
of feniible things from the organ to the fen-
foriwn. And for all that we know of the mat-
ter, every man may freely choofe which he
thinks fitted for the purpofe \ for, from fad
ami experiment, no one of them can claim
preference to another. Indeed, they all ieem
fo unhandy engines for carrying images, that
a man would be tempted' to invent a new
one.

Since, therefore, a blind man may guefs as
well in the dark as one that fees, I beg leave
to offer another conjedure touching the ner-
vous fyftem, which I hope will anfwer the
purpofe as well as thofe we have mentioned,
and which recommends itfelf by its fimplL
city. Why may not the optic nerves, for in-
ftance, be made up of empty tubes, opening
their mouths wide enough to receive the rays
of light which form the image upon the re-
tina, and gently conveying them fafe, and in
their proper order, to the very feat of the foul,
until they flafh in her face ? It is eafy for an
ingenious philofopher to fit the caliber of
thefe empty tubes to the diameter of the par-
ticles of light, fo as they fhall receive no grof-
fer kind of matter. And if thefe rays fhould
be in danger of miftaking their way, an ex-
pedient

SECT. Ip.] OF SEEING. 349

pedient may alfo be found to prevent this.
For it requires no more than to bcftow upon
the tubes of the nervous fyftem a periftaltie
motion, like that of the alimentary tube.

It is a peculiar advantage of this hypothe-
cs, that, although all philofophers believe that
the fpecies or images of things are conveyed
by the nerves to the foul, yet none of their
hypothefes ihew how this may be done. For
how can the images of found, tafte, fmell, co-
lour, figure, and all fenfible qualities, be made
out of the vibrations of mufical chords, or the
undulations of animal fpirits, or of ether?
We ought not to fuppofe means inadequate
to the end. Is it not as philofophical, and
more intelligible, to conceive, that as the fto-
mach receives its food, fo the foul receives her
images by a kind of nervous deglutition ? I
might add, that we need only continue this
periftaltie motion of the nervous tubes from
the fenforium to the extremities of the nerves
that ferve the muicles, in order to account for
inufcular motion.

Thus nature will be confonant to herfelf ;
and as fenfation will be the conveyance of the
ideal aliment to the mind, fo mutcular motion
will be the expulfion of the recrementitious
part of it. For who can deny, that the ima:

ges

35^ OF THE HUMAN MIND. [CHAP. 6.

ges of things conveyed by ferifation, may, af-
ter due concoction, become fit to be thrown
off by mufculai1 motion ? I only give hints
of the'fe things to the ingenious, hoping that
in time this hypothefis may be vvrcught up
into a fyfteni as truly philosophical, as that of
animal fpirits, or the vibration of nervous
fibres.

To be ferious : In the operations of na-
ture, T hold the theories of a phiiofopher,
which are unfupported by fa cV in the fame
eftimation with the dreams of a man aileep,
or the ravings of a madman. We laugh at
the Indian philofopher, who, to account for
the'fupport of the earth, contrived the hypo-
thefis of a huge elephant, and tofupport the
elephant, a huge tortoife. If we will candid-
ly corifefs the truth, we know as little of the
operation of the nerves, as he did of the man-
ner in which the earth is fuppoited ; and" our
hypothcfes about animal fpirits, or about the
teniion and vibrations of the nerves, are as
like to be true, as his about the fu ppbrt of
the earth. His elephant' was a hypothelis,
and our hypothcfes are elephants, livery the-
ory in phirofophy, which is built on pure
conjecture, is an elephant ; and every theory
that is fupportcd partly by fact, and part-

SECT. IOi] OF SEEING. 351

ly by conjecture, is like Nebuchadnezzar's
image, vvhofe feet were partly of iron, and
partly of clay.

The great Newton fir ft gave an example
to philofophers, which always ought to be,
but rarely hath been followed, by diftinguifh-
ing his conjectures from his conclufiohs, and
putting the former by themfelves, in the mo-
deft form of queries. This is fair and legal ;
but all other philofophical traffic in conjec-
ture, ought to be held contraband and illicit.
Indeed his conjectures have commonly more
foundation in fact, and more verifimilitude,
than the dogmatical theories of mod other
philofophers ; and therefore we ought not to
omit that which he hath offered concern-
ing the caufe of our feeing objects lingle with
two eyes, in the 15th query annexed to his
Optics.

" Are not the fpecies of objects feen with
& both eyes, united where the Optic nerves
w meet before they come into the brain, the
*' fibres on the right fide of both nerves uni-
* ting there, and after union going thence
" into the brain in the nerve which is on the
" right fide of the head, and the fibres on the
|M left iide of both nerves uniting in the fame
W place, and after union going into the brain

" in

35^ OF THE HUMAN MINfc. [CHAP. 6.

" in the nerve- which is on the left fide of the
f* head ; and thefe two nerves meeting in the
" brain in fuch a manner that their fibres
" make but one entire fpecies or picture, half
" of which on the right fide of the fenforium
"comes from the right fide of both eyes
" through the right fide of both optic nerves,
" to the place where the nerves meet, and
" from thence on the right fide of the head
" into the brain, and the other half on the
" left fide of the fenforium comes, in like
" manner, from the left fide of both eyes ?
" For the optic nerves of fuch animals as
" look the fame w7ay with both eyes, (as men,
" dogs, fheep, oxen, &c), meet before they
" come into the brain ; but the optic nerves
" of fuch animals as do not look the fame way
" with; both eyes, (as of fifhcs and of the cha-
" meleon), do not meet, if I am rightly in-
" formed."

I beg leave to difiinguifh this query into
two, which are of very different natures ; one
being purely anatomical, the other relating to
the carrying fpecies or pictures of vifible ob-
jects to the fenforium.

The firft queftion is, Whether the fibres
coming from correfponding points of the two
r£t'u\ay do not unite at the place where the

optic

SECT. 19.] CT SEEING. 353

optic nerves meet, and continue united from
thence to the brain ; fo that the right optic
nerve, after the meeting of the two nerves, is
compofed of the fibres coming from the right
fide of both retina, and the left, of the fibres
coming from the left fide of both retina?

This is undoubtedly a curious and rational
queftion ; becaufe, if we could find ground
from anatomy to anfwer it in the affirmative,
it would lead us a ftep forward in difcovering
the caufe of the correfpondence and fympathy
which there is between certain points of the
two retina. For although we know not what
is the particular function of the optic nerves,
yet it is probable, that fome impreffion made
upon them, and communicated along their
fibres, is necefTary to vifion : And whatever be
the nature of this impreffion, if two fibres are
united into one, an impreffion made upon one
of them, or upon both, may probably produce
the fame erTed. Anatomifls think it a fuffi-
cient account of a fympathy between two parts
of the body, when they are ferved by branch-..
es of the fame nerve : we fhould therefore
look upon it as an important difcovery in ana-
tomy, if it were found that the fame nerve
fent branches to the correfponding points of
the retina.

Z But

354 OF THE HUMAN MIND. [CHAf.&

But hath any fuch difcovery been made I
No, not fo much as in one fubjed, as far as I
can learn. But in feveral fubjeas, the con-
trary feems to have been difcovered. Dr
Porterfield hath given us two cafes at length
from Vesalius, and one fem Oesalpinus,
tvherein the optic nerves, after touching one
another as ufual, appeared to be reflected back
to the fame fide whence they came, without
any mixture of their fibres. Each of thefe
perfons had loft an eye fome time before his
death, and the optic nerve belonging to that
eye was fbrunk, fo that it could be diftinguifh-
ed from the other at the place where they
met. Another cafe which the fame author
gives from Vesalius, is ftill mare remark-
able ; for in it the optic nerves did not touch
at all ; and yet, upon inquiry, thofe who were
moft familiar with the perfon in his lifetime,
declared that he never complained of any de-
fed of fight, or of his feeing objeds double.
Diemerbkceck tells us, that Aquapendens
and Valverda likewife affirm, that they have
met with fubjeas wherein the optic nerves
did not touch.

- As, thefe obfervations were made before Sir
Isaac Newton put this query, it is uncertain
whether he was ignorant of them, or whether

he

SECT. I9.] OF SEEING. 355

he fufpedted fome inaccuracy in them, and de-
ll red that the matter might be more carefully
examined. But from the following pafiage
of the moft accurate Win slow, it does not
appear, that later obfervations have been more
favourable to his conjecture. " The union of
V thefe [optic] nerves, by the (mall curva-
" tures of their cornua, is very difficult to be
" unfolded in human bodies. This union is
" commonly found to be very clofe, but in
" fome fubjects it feems to be no more than a
"" ftrong adhefion, in others to be partly made
" by an interferon or crolfing of fibres.
" They have been found quite feparate; and
" in other fubjects, one of them has been
" found to be very much altered both in fize
" and colour, through its whole paflage, the
" othe/ remaining in its natural ftate."

When we confider this conjecture of Sir
Isaac Newton by itielf, it appears more inge-
nious, and to have more verifimilitude, than
any thing that has been offered upon the fub-
ject. ; and we admire the caution and modefty
of the author, in propollngit only as a fubjecl:
of inquiry : but when we compare it with the
obfervations of anatomifts which contradict it,
we are naturally led to this reflection, That if
we trufl to the conjectures of men of the
X 2 greateft

356 OF THE HUMAN MIND. [CHAP. 6.

greatcft genius in the operations of nature, we
have only the chance of going wrong in an
ingenious manner.

The fecond part of the query is, Whether
the two fpecies of objects from the two eyes
are not, at the place where the optic nerves
meet, united into one fpecies or pidure, half
of which is carried thence to the fenforium in
the right optic nerve, and the other half in
the left ? and whether thefe two halves are
not fo put together again at the fenforium, as
to make one fpecies or piclure ?

Here it feems natural to put the previous
queftion, What reafon have we to believe,
that pi&ures of -objects are at all carried to the
fenforium, either by the optic nerves, or by
any other nerves ? Is it not poilible, that thi*
great philofopher, as well as many of a lower
form, having been led into this opinion at firfi
by education, may have continued in it, be-*
caufe he nevar thought of calling it in que-
ftion ? I confefs this was my own cafe for a
confiderable part of my life. But fince I was
led by accident to think feriouily what reafon
I had to believe it, I could find none at all.
It feems to be a mere hypothecs, as much as
the Indian philofopher's elephant. I am not
confeious of any pictures of external objects

in

SECT. 19.] OF SEEING. 357

in my fenforium, any more than in my fto-
mach : the things which I perceive by my
fenfes, appear to be external, and not in any
part of the brain ; and my fenfations, pro-
perly fo called, have no refemblance of ex-
ternal objects.

The conclufion from all that hath been
(aid, in no lefs than feven fections, upon our
feeing objects iingle with two eyes, is this,
That, by an original property of human eyes,
objects painted upon the centres of the two
retina, or upon points fimilarly fituate with
regard to the centres, appear in the fame
vifible place ; that the molt plaulible attempts
to account for this property of the eyes, have
been unfuccefsful ; and therefore, that it muft
be either a primary law of our constitution,
or the confequence of fome more general law
which is not yet difcovered.

We have now finifhed what we intended to
fay, both of the vilibie appearances of things
to the eye, and of the laws of our conftitu-
tion by which thofe appearances are exhibit-
ed. But it was obferved, in the beginning of
this chapter, that the vifible appearances of
objects ferve only as figns of their diftance,
magnitude, figure, and other tangible quali-
ties. The vifible appearance, is that which is
Z 3 prefented,

35& OF THI- HUMAN MIND. [CHAP. 6*

preferred to the mind by nature, according to
thofe laws of our conftitution, which have been
explained. But the thing fignified by that
appearance, is that which is prcfented to the
mind by cuftom.

When one fpeaks to us in a language that
is familiar, we hear certain founds, and this is
all the effeel: that his difcourie has upon us
by nature : but by cuftom we underftand the
meaning of thefe founds ; and therefore we
fix our attention, not upon the founds, but
upon the things fignified by them/ In like
manner, we fee only the vifible appearance of
objects by nature ; but we learn by cuftom to
interpret thefe appearances, and to underftand
their meaning. And when this vifual lan-
guage is learned, and becomes familiar, we at-
tend only to the things fignified ; and cannot,
without great difficulty, attend to the figns by
which they are prefented. The mind pafles
from one to the other fo rapidly, and fo fami-
liarly, that no trace of the iign is left in the
memory, and we feem immediately, and with-
out the intervention of any fign, to perceive
the thing fignified.

When I'look at the apple-tree, which ftands
before my window, I perceive, at the firft
glance, its diftance and magnitude, the rough-

nefs

SECT. I9.] OF SEEINC 359

nefs of its trunk, the difpofition of its branches,
the figure of its leaves and fruit. I fcem to
perceive all thefe things immediately. The
vifible appearance which prefented them all
to the mind, has entirely efcaped me ; I can-
not, without great difficulty, and painful ab-
ftra&ion, attend to it, even when it Hands be-
fore me. Yet it is certain, that this vifible
appearance only, is prefented to my eye by
nature, and that I learned by cuftom to col-
lect all the reft from it. If I had never feen
before now, I fhould not perceive either the
diftance or tangible figure of the tree, and it
would have required the practice of feeing for
many months, to change that original per-
ception which nature gave me by my eyes, in-
to that which I now have by cultom.

The objects which we fee naturally and ori-
ginally, as hath been before obferved, have
length and breadth, but no thicknefs, nor dif-
tance from the eve. Cuftom, by a kind of
legerdemain, withdraws gradually thefe origi-
nal and proper objects of fight, and fubftitute?
in their place objects of touch, which have
length, breadth, and thicknefs, and a deter-
minate diftance from the eye. By what means
tiis change is brought about, and what prin-
X 4 ciple^

360 ^ OF THE HUMAN MIND. [CHAP. 6.

ciples of the human mind concur in it, we
are next to inquire.

SECT. XX.

Of perception in general.

SEnsation, and the perception of exter-
nal objeds by the fenfes, though very
different in thejr nature, have commonly been
confidered as one and the fame thing. The
purpofes of common life do not make it ne-
ceffary to diftinguifh them, and the received
opinions of philofophers tend rather to con^
found them : but, without attending careful-
ly to this diftinction, it is impoflible to have
any juft conception of the operations of our
fenfes. The moil fimple operations of the
mind, admit not of a logical definition : all
we can do is to defer i be them, fo as to lead
thofe who are confeious of them in themfelves,
to attend to them, and reflect, upon them : and
it is often very difficult to defcribe them fo as
to anfwer this intention.

The

SECT. 20.] OF SEEING. 361

The fame mode of expreflion is ufed to de-
note fenfation and perception ; and therefore
we are apt to look upon them as things of the
fame nature. Thus, I feel a pain ; I fee a
tree : the firft denoteth a fenfation, the laft a
perception. The grammatical analyfis of both
expreffions is the fame : for both confift of an
active verb and an object. But, if we attend
to the things fignified by thefe expreffions, we
fhall find, that in the firft, the diftinction be-
tween the act and the object is not real but
grammatical ; in the fecond, the diftinction
is not only grammatical but real.

The form of the expreflion, I feel pain,
might feem to imply, that the feeling is fome-
thing diftinct from the pain felt ; yet in rea-
lity, there is no diftinction. As thinking a
thought is an expreflion which could fignify
no more than thinking, fo feeling a pain figni-
lies no more than being pained. What we
have faid of pain is applicable to every other
mere fenfation. It is difficult to give inftan-
ces, very few of our fenfations having names ;
and where they have, the name being com-
mon to the fenfation, and to fomething elfe
which is aflbciated with it. But when we at-
tend to the fenfation by itfelf, and feparate it
from other things which are conjoined with

it

362 OF THE HUMAN MIND, [CHAP. 6\

it in the imagination, it appears to be fome-
thing which can have no exiftence but in a
fenti.ent mind, no diftinclion from the act of
the mind by which it is felt.

Perception, as we here underftand it, hath
always an object diftinct from the ad by which
it is perceived; an object which may exift
whether it be perceived or not. I perceive a
tree that grows before my window ; there is
here an object which is perceived, and. an aft
of. the mind by which it is perceived ; and
thefe two are not only diitioguilhable, but
they are extremely unlike in their natures.
The object is made up. of a. trunk, branches,
and leaves ; but the act of the mind, by which
it is perceived, hath neither trunk, branches,
nor leaves. I am confcious of this act of my
mind, and I can reflect upon it ; but it is too
Ample to admit of' an analyfis, and I cannot
find proper words to defcribe it. I find no-
thing that refembles it lb much as the remem-
brance of the tree, or the imagination of it.
Yet both thefe diirer efTential'ly from percep-
tion • they differ likewife one from another.
It is in vainthat a philofopher afiures me, that
the imagination of the tree, the remembrance
of it, and the perception of it, are all one, and
differ only in degree of vivacity. I know the

contrary :

SECT. 20.] OF SEEING. 363

contrary ; for I am as well acquainted with all
the three, as I am with the apartments of my
own houfe. I know this alfo, that the percep-
tion of an objed implies both a conception of
its form, and a belief of its prefent exiftence.
I know, moreover, that this belief is not the
effect of argumentation and reafoning ; it is
the immediate effect of my constitution.

I am aware, that this belief which I have
in perception, Hands expofed to the ftrongeft
batteries of fcepticifm. But they make no
great impreflion upon it. The fceptic afks
me, Why do you believe the exiftence of the
external object which you perceive ? This
belief, Sir, is none of my manufacture ; it
came from the mint of nature ; it bears her
image and fuperfcription ; and, if it is not
right, the fault is not mine : I even took it
upon trull, and without fufpicion. Reafon,
fays the fceptic, is the only judge of truth,
and you ought to throw off every opinion and
every belief that is not grounded on reafon.
Why, Sir, mould I believe the faculty of rea-
fon more than that of perception ; they came
both out of the fame fhop, and were made by
the fame artift ; and if he puts one piece of
falfe ware into my hands, what mould hin-
der him from putting another ?

Perhaps

364 OF THE HUMAN MIND. [CHAP. 6.

v Perhaps the fceptic will agree to diftruft
reafon, rather than give any credit to percep-
tion. For, fays he, fince, by your own con-
ceflion, the objed which you perceive, and
that act of your mind, by which you per-
ceive it, are quite different things, the one
may exiit without the other ; and as the ob-
ject may exift without being perceived, fo
the perception may exift without an object.
There is nothing fo fhameful in a philofopher
as to be deceived and deluded ; and therefore
you ought to refolve firmly to withhold af-
fent, and to throw off this belief of external
objects, which may be all delufion. For my*
part, 1 will never attempt to throw it off;
and although the fober part of mankind will
not be very anxious to know my reafons, yet
if they can be of ufe to any fceptic, they are
thefe.

Firft, Becaufe it is not in my power : why
then ftiould 1 make a vain attempt ? It would
be agreeable to fly to the moon, and to make
a vifit to Jupiter and Saturn ; but when I
know that nature has bound me down by
the law of gravitation to this planet which I
inhabit, 1 reft contented, and quietly fuffer
myielf to be carried along in its orbit. My be-
lief is carried along by perception, as irrefiili-

bly

SECT. 20.] OF SEEING. 365

bly as my body by the earth. And the great-
eft fceptic will find himfelf to be in the fame
condition. He may druggie hard to difbe-
lieve the informations of his fenfes, as a man
does to fwim again ft a torrent ; but ah ! it is
in vain. It is in vain that he drains every
nerve, and wreftles with nature, and with
every object that ftrikes upon his fenfes. For
after all, when his ftrength is fpent in the
fruitlefs attempt, he will be carried down
the torrent with the common herd of belie-
vers.

Secondly, I think it would not be prudent
to throw off this belief, if it were in my power.
If nature intended to deceive me, and im-
pofe upon me by falfe appearances, and I, by
my great cunning and profound logic, have
difcovered the impofture ; prudence would
dictate to me in this cafe, even to put up this
indignity done me, as quietly as I could, and
not to call her an impoftor to her face, left fhe
fhould be even with me in another way. For
what do I gain by refenting this injury ? You
ought at leaft not to believe what (he fays.
This indeed feems reasonable, if fhe intends
to impofe upon me. But what is the confe-
quence ? I refolve not to believe my fenfes.
I break my nofe againft a poll that comes in

my

366 OF THE HUMAN MIND. [cHAPi 6.

my way ; I ftep into a dirty kennel ; and, af-
ter twenty fuch wife and rational actions, I
am taken up and clapt into a mad-houfe. Now,
I confefs I would rather make one of the cre-
dulous fools whom nature impofes upon, than
of thofe wife and rational philofophers who
refolve to withhold aflent at all this expence.
If a man pretends to be a fceptic with regard
to the informations of fenfe, and yet prudent-
ly keeps out of harm's way as other men do,
he muft excufe my fufpicion, that he either
ads the hypocrite, or impofes upon himfelf.
For if the fcale of his belief were fo evenly
poifed, as to lean no more to one fide than to
the contrary, it is impoffible that his actions
could be directed by any rules of common
prudence.

Thirdly, Although the two reafons already
mentioned are perhaps two more than enough,
I {hall offer a third. I gave implicit belief
to the informations of nature by my fenfes,
for a confiderable part of my life, before I
had learned fo much logic as to be able to
Hart a doubt concerning them. And now,
when I reflect upon what is paft, I do not find
that I have been impofed upon by this belief.
I find, that without it 1 mult have perifhed
by a thoufand accidents. I find, that with-

out

SECT. 20.] OF SEEING. 367

out it I fhould have been no wifer now than
when I was born. I fhould not even have
been able to acquire that logic which fuggefts
thefe fceptical doubts with regard to my fen -
ies. Therefore, I confider this inilructive be-
lief as one of the befl gifts of nature. I
thank the Author of my being who bellowed
it upon me, before the- eyes of my reafon were
opened, and flill bellows it upon me to be my
guide, where: reafon leaves me in the dark.
And now I yield to the direction of my fen-
fes, not from inflincl only, but from confi-
dence and truft.in a faithful and beneficent
Monitor, grounded upon the experience of
his paternal care and goodnefs.

In all this, I deal with the Author of my
being, no otherwife than I thought it reason-
able to deal with my parents and tutors. I
believed by inflincl: whatever they told me,
long before I had the idea of a lie, or thought
of the poffibility of their deceiving me. Af-
terwards, upon reflection, I found they had
acted like fair and honeil people who wifhed
me well. I found, that if I had not believed
what they told me, before I could give a rea-
fon of my belief, I had to this day been little
better than a changeling. And although this,
natural credulity hath ibmetimes occafioned

my

368 OF THE HUMAN MIND. [CHAP. 6.

my being impofed upon by deceivers, yet it
hath been of infinite advantage to me upon
the whole ; therefore I confider it as another:
good gift of nature. And I continue to give
that credit, from reflection, to thofe of whofe
integrity and veracity I have had experience,
which before I gave from inftindt.

There is a much greater fimilitude than is
commonly imagined, between the teftimony
x)f nature given by our fenfes, and the tefti-
mony of men given by language. The ere-
dit we give to both is at firft the effect of in-
ftincl only. When we grow up, and begin
to reafon about them, the credit given to hu-
man teftimony is reftrained, and weakened,
by the experience we have of deceit. But
the credit given to the teftimony of our fen-
fes, is eftablifhed and confirmed by the uni-
formity and conftancy of the laws of na-
ture.

Our perceptions are of two kinds : fome
are natural and original, others acquired, and
the fruit of experience. When 1 perceive
that this is the tafle of cyder, that of bran-
dy ; that this is the fmell of an apple, that of
an orange ; that this is the noife of thunder,
that the ringing of bells ; this the found of a
coach palling, that the voice of fuch a friend ;

thefe

SECT. 20. j OF SEEING. 369

thefe perceptions, and others of the fame kind,
are not original, they are acquired. But the
perception which I have by touch, of the hard-
nefs and foftnefs of bodies, of their extenfion,
figure, and motion, is not acquired ; it is ori-
ginal.

In all our fenfes, the acquired perceptions
are many more than the original, especially
in light. By this fenfe we perceive originally
the vilible figure and colour of bodies only,
and their vifible place : but we learn to per-
ceive by the eye, almoft every thing which
we can perceive by touch. The original per-
ceptions of this fenfe, ferve only as figns to in-
troduce the acquired.

The figns by which objects are prefenfced to
us in perception, are the language of nature
to man \ and as, in many refpecls, it hath great
affinity with the language of man to man \ fo
particularly in this, that both are partly na-
tural and original, partly acquired by cuftom.
Our original or natural perceptions are analo-
gous to the natural language of man to man,
of which we took notice in the 4th chapter ;
and our acquired perceptions are analogous to
artificial language, which, in our mother-
tongue, is got very much in the fame manner
A a with

37*0 OF THE flUMAN ftlND. [fc'HAI*. ft

with our acquired perceptions, as we fhall af-
terwards more fully explain.

Not only men, but children, Miots, and
brutes, acquire by habit many perceptions
which they had not originally. Almoft every
employment in life, hath perceptions of this
kind that are peculiar to it. The fhepherd
knows' every fheep of his flock, as we do our
acquaintance, and can pick them out of ano-
ther flock one by one. The butcher knows
by fight the weight and quality of his beeves
and fheep before they are killed. The farmer
perceives by his eye, very nearly, the quan-
tity of hay in a rick, or of corn in a heap.
The failor fees the burden, the built, and the
diftance of a fhip at fea, while fhe is a great
way off. Every man accuflomed to writing,
diftinguifhes his acquaintance by their hand-
writing, as he does by their faces. And the
painter diftinguiihes in the works of his art,
the ftyle of all the great mafters. In a word,
acquired perception is very different in dif-
ferent perfons, according to the diverfity of
objects about which they are employed, and
the application they bellow in obferving them.

Perception ought not only to be diftinguifh-
ed from fenfation, but likewife from that know-
ledge

SECT. 20.} 6£*SEEIn6. ffli

ledge of the objects of lenfe which is got by
reafoning. There is no reafoning in percep-
tion, as hath been obferved. The belief which
is implied in it, is the effect of inftinct. But
there are many things, with regard to fenfible
objects, which we can infer from what we
perceive ; and fuch conclufions of reafon
ought to be diflinguifhed from what is mere-
ly perceived. When I look at the moon, I
perceive her to be fometimes circular, fome-
times horned, and fometimes gibbous. This
is fimple perception, and is the fame in the
philofopher, and in the clown : but from thefe
various appearances of her enlightened part,
I infer that fhe is really of a fpherical figure;
This conclufion is not obtained by fimple per-
ception, but by reafoning. Simple percep-
tion has the fame relation to the conclufions
of reafon drawn from our perceptions, as the
axioms in mathematics have to the propo-
fitions. I cannot demonftrate, that two quan-
tities which are equal to the fame quantity,
are equal to each other ; neither can 1 de-
monftrate, that the tree which I perceive, ex-
ifts. But, by the constitution of my nature,
fny belief is irrefiftibly carried along by my
apprehenflon of the axiom ; and by the con-
ftitution of mv nature, my belief is no lefs
A a 2 irrefiftibly

372 OF THE HUMAN MIND. [CHAP. 6.

irrefiftibly carried along by my perception of
the tree. All reafoning is from principles.
The firft principles of mathematical reafon-
ing are mathematical axioms and definitions \
and. the firft principles of all our reafoning
about exiftences, are our perceptions. The
firft principles of every kind of reafoning are
given us by nature, and are of equal autho-
rity with the faculty of reafon itfelf, which
is alfo the gift of nature. The conclufions
of reafon are all built upon firft principles,
and can have no other foundation. Moft juft-
ly, therefore, do fuch principles difdain to
be tried by reafon, and laugh at all the artil-
lery of the logician, when it is direfted againft

them.

When a long train of reafoning is necef-
fary in demonftrating a mathematical propo-
fition, it is eafily diftinguiftied from an axiom*
and they feem to be things of a very differ-
ent nature. But there are fome propofitions
which lie fo near to axioms, that it. is diffi-
cult to fay, whether they ought to be held as
axioms, or demonftrated as proportions. The
fame thing holds with regard to perception,
and the conclufions drawn, from it. Some
of thefe conclufions follow our perceptions fo
eafily, and are fo immediately connecled with

them,

%ECT. 20.] OF SEEING. 373

them, that it is difficult to fix the limit which
divides the one from the other.

Perception, whether original or acquired,
implies no exercife of reafon ; and is com-
mon to men, children, idiots, and brutes. The
more obvious conclufions drawn from our per-
ceptions, by reafon, make what we call com-
mon under Jlanding ; by which men conduct
themfelves in the common affairs of life, and
by which they are diftinguiflied from idiots.
The more remote conclufions which are drawn
from our perceptions, by reafon, make what
we commonly call Jcience in the various parts
of nature, wThether in agriculture, medicine,
mechanics, or in any part of natural philofo-
phy. When I fee a garden in good order,
containing a great variety of things of the
belt kinds, and in the mofl flourifhing condi-
tion, I immediately conclude from thefe figns,
the fkill and induftry of the gardener. A
farmer, when he rifes in the morning, and
perceives that the neighbouring brook over-
flows his field, concludes that a great deal of
rain hath fallen in the night. Perceiving his
fence broken, and his corn trodden down, he
concludes that fome of his own or his neigh-
bours cattle have broke loofe. Perceiving that
his liable- door is broke open, and fome of his
A a 3 horfe*

374 0F THE HUMAN MIND. t [CHAP. ^

Jiorfes gone, he concludes that a thief has car-
ried them off. He traces the prints of his,
horfes feet in the foft ground, and by them
difcovers whict* road the thief hath taken,
Thefe are inflances of common underfland-
ing, which dwells fo near to perception, that
it is difficult to trace the line which divides
the one from t{ie other. In like manner, this
fcience of nature dwells fo near to common
underflanding, that we cannot difcern where
the latter ends and the former begins. I per-
ceive that bodies, lighter than water, fwim in
water, and that thofe which are heavier fink.
Hence I conclude, that if a body remains
wherever it is put under water, whether at
the top or bottom, it is precifely of the fame
weight with water. If it will reft only when
part of it is above water, it is lighter than,
water. And the greater the part above water
is, compared with the whole, the lighter is the
body. If it had no gravity at all, it would
make no impreffion upon the water, but (land
wholly above it. Thus, every man, by com-
mon underflanding, has a rule by which he
judges of the fpecific gravity of bodies whic}i
fwim in water : and a Hep or two more leads
him into the fcience of hydroflatics.

AH

SECT. 21.] OF SEEING. 375

All that we know of nature, or of exiften-
ces, may be compared to a tree, which hath
its root, trunk, and branches. In this tree of
knowledge, perception is the root, common
underftanding is the trunk, and the fciences
are the branches.

SECT. XXI.

Of the procefs of Nature in perception.

ALthough there is no reafoning in per-
ception, yet there are certain means
and inftruments, which, by the appointment
or* nature, mud intervene between the object
and our perception of it \ and, by thefe pur
perceptions are limited and regulated, Firft,
if the object is not in contact with the organ
of fenfe, there muft be fome medium which
pafTes between them. Thus, in virion, the
rays of light ; in hearing, the vibrations of
elaftic air ; in fmelling, the effluvia of the bo-
dy fmelled, muft pafs from the object to the
prgan ; otherwife we have no perception. Se-
A a 4 co^ly>

/

376 OF THE HUMAN MIND. [CHAP. 6.

condly, There mud be fome action or impref-
lion upon the organ of fenfe, either by the
immediate application of the object, or by the
medium that goes between them. Thirdly r
The nerves which go from the brain to the
organ, mud receive fome impreflion by means
of that which was made upon the organ ; and
probably, by means of the nerves, fome im-
preflion muft be made upon the brain. Fourth-
ly, The impreflion made upon the organ,
nerves, and brain, is followed by a fenfation.
And, lad of all, This fenfation is followed by
the perception of the object.

Thus our perception of objects is the refult
of a train of operations ; fome of which af-
fect the body only, others affect the mind.
We know very little of the nature of fome
of thefe operations ; we .know not at all how
they are connected together, or in what way
they contribute to that perception which is
the refult of the whole : but, by the laws of
our constitution, we perceive objects in this,
and in no other way.

There may be other beings, who can per-
ceive external objects without rays of light,
or vibrations of air, or effluvia of bodies, with-
out imprcflions on bodily organs, or even
without fenfations : but we are fo framed by
the Author of Nature, that even when we are

furroundcd

SECT- 21.] OF SEEING. 377

furrounded by external objects, we may per-
ceive none of them. Our faculty of percei-
ving an object lies dormant, until it is roufed
and ftimulated by a certain correfponding
fenfation. Nor is this fenfation always at
hand to perform its office ; for it enters into
the mind only in corifequence of a certain cor-
refponding impreffion made on the organ of
fenfe by the object.

Let us trace this correspondence of impref-
lions, fenfations, and perceptions, as far as we
can ; beginning with that which is firft in
order, the impreffion made upon the bodily
organ. But, alas ! we know not of what na-
ture thefe impreffions are, far lefs how they
excite fenfations in the mind.

We know that one body may act upon a-
nother by preffure, by percuflion, by attrac-
tion, by repulfion, and probably in many other
ways, which we neither know, nor have names
to exprefs. But in which of thefe ways ob-
jects, when perceived by us, act upon the or-
gans of fenfe, thefe organs upon the nerves,
and the nerves upon the brain, we know not.
Can any man tell me how, in virion, the rays
of light act upon the retina, how the retina
acts upon the optic nerve, and how the optic
nerve acts upon the brain ? No man can.

When

J7§ OF THE flUMAN MIND. [CHAP, 6,

When I feel the. pain of the gout in my toe,
I know that there is fpme unufual impreflion
made upon that part of my body. ( But of
\vhat kind is it ? Are the fmall veflels dif-
tended with fome redundant elaftic, or une-
laftic fluid ? Are the fibres unufually ftretch-.
ed ? Are they torn afunder by force, or gnaw-
ed and corroded by fome acrid humour ? I
can anfwer none of thefe queftions. All that
I feel, is pain, which is not an impreflion up-
on the body, but upon the mind ; and all that
I perceive by this fenfation is, that fome dif-
temper in my toe pccafions this pain. But as
I know pot the natural temper and texture
of my toe when it is at eafe, I know as little
what change or diforder of its parts occafions
this uneafy fenfation. In like manner, in
every other fenfation, there is, without doubt,
fome impreflion made upon the organ of fenfe ;
but an impreflion of which we know not the
nature. It is too fubtile to be difcovered by
our fenfes, and we may make a thoufand con-
jectures without coming near the truth. If
we underftood the ftructure of our organs of
fenfe fo minutely, as to difcover what effects
are produced upon them by external obj edits,
this knowledge would contribute nothing to
our perception of the object ; for they per-
ceive,

SECT. 21.] OF SEEING. 379

ceive as diftin&ly who know leaft about the
manner of perception, as the greateft adepts.
It is necefTary that the impreffion be made up-
on our organs, but not that it be Jcnown. Na-
ture carries on this part of the procefs of per-
ception, without our confcioufnefs or concur-
rence.

But we cannot be unconfcious of the next
ftep in this procefs, the fenfation of the mind,
which always immediately follows the im-
preffipn made upon the body. It is eflTential
to a fenfation to be felt, and it can be nothing
more than we feel it to be. If we can only
acquire the habit of attending to our fenfa-
tions, we may know them perfectly. But how
are the fenfations of the mind produced by
impreffions upon the body ? Of this we are
absolutely ignorant, having no means of know-
ing how the bocly acts upon the mind, or the
mind upon the body. When we confider the
riature and attributes of both, they feem to be
fo different, and fo unlike, that we can find
no handle by which the one rqay lay hold of
the other. There is a deep and dark gulf be-
tween them, which our underftanding cannot
pafs ; and the manner of their correfpondencc
and intercou^rfe is abfolutely unknown.

Experience

380 OF THE HUMAN MIND. [CHAP. 6.

Experience teaches us,' that certain impref-
iions upon the body are conftantly followed
by certain fenfations of the mind; and that,
on the other hand, certain determinations of
the mind are conftantly followed by certain
motions in the body : but we fee not the chain
that ties thefe things together. Who knows
but their connection may be arbitrary, and
owing to the will of our Maker ? Perhaps
the fame fenfations might have been connect-
ed with other impreffions, or other bodily or-
gans. Perhaps we might have been fo made,
as to tafte with our fingers, to fmell with our
ears, and to hear by the nofe. Perhaps we
might have been fo made, as to have all the
fenfations and perceptions which we have,
without any impreflion made upon our bodily
organs at all.

However thefe things may be, if nature
had given us nothing more than impreffions
made upon the body, and fenfations in our
minds correfponding to them, we mould in
that cafe have been merely fentient, but not
percipient beings. We mould never have been
able to form a conception of any external ob-
ject, far lefs a belief of its exiftence. Our fen-
- fations have no refemblance to external ob-
jects ; nor can we difcover, by our reafon, any

neceflary

SECT. 21.] OF SEEING. 381

neceffary connection between the exigence of
the former, and that of the latter.

We might perhaps have been made of fuch
a conftitution, as to have our prefent percep-
tions connected with other fenfations. We
might perhaps have had the perception of ex-
ternal objects, without either impreflions upon
the organs of fenfe, or fenfations. Or, laftly,
The perceptions we have, might have been
immediately connected with the impreflions
upon our organs, without any intervention of
fenfations. This laft feems really to be the
cafe in one inftance, to wit, in our perception
of the vifible figure of bodies, as was obferved
in the 8th fection of this chapter.

The procefs of nature in perception by the
fenfes, may therefore be conceived as a kind
of drama, wherein fome things are performed
behind the fcencs, others are reprefented to
the mind in different fcenes, one fucceeding
another. The impreflion made by the object
upon the organ, either by immediate contact,
or by fome intervening medium, as well as
the impreflion made upon the nerves and
brain, is performed behind the fcenes, and the
rnind fees nothing of it. But every fuch im-
preflion, by thelaws of the drama, is followed
by a fcnfation, which is the firft fcene exhibi-

ted

$§i OF THlf HUMAN 1VIIND. [c&A$. 6-.

ted to the mind ; and this fcene is quickly
fucceeded by another, which is the perception
of the object.

In this drama, nature is the actor* we are-
the fpectatorS. We know nothing of the ma-
chinery by means of which every different
impreffion upon the organ, nerves, and brain,
exhibits its correfponding fenfation ; or of the
machinery by means of which each fenfation
exhibits its correfponding perception. We are
infpired with the fenfation, and we are infpi-
fed with the correfponding perception, by
means unknown. And becaufe the mind paf-
fes immediately from the fenfation to that
conception and belief of the object which we
have in perception, in the fame manner as it
paffes from figris to the things fignified by
them, we have therefore called our fenfations
figris of external objeEis ; finding no word more
proper to exprefs the function which nature
hath afligned them in perception, and the re-
lation which they bear to their correfponding
objects.

There is no neceflity of a refemblance be-
tween the fign and the thing fignified : and
indeed no fenfation can refemble any exter-
nal object. But there are two things neceflary
to eur knowing things by means of ligns. Firfly

That

SECT, lis] OF SEEING. $$$

That a real connection between the fign and
thing fignified be eftablifhed, either by the
Courfe of nature, or by the will and appoint-
ment of men. When they are connected by
the courfe of nature, it is a natural fign ; when
by human appointment, it is an artificial fign.
Thus, fmoke is a natural fign of fire ; certain
features are natural figns of anger : but our
words, whether expreiled by articulate founds
or by writing, are artificial figns of our thoughts
and purpofes.

Another requifite to our knowing things
by figns is, that the appearance of the fign to
the mind, be followed by the conception and
belief of the thing fignified. Without this,
the fign is not underftood or interpreted ; and
therefore is no fign to us, however fit in its
own nature for that purpofe.

Now, there are three ways in which the
mind pafles from the appearance of a natural
fign to the conception and belief of the thing
fignified ; by original principles of our con-
ftitution, by caftbm, and by reafoning.

Our original perceptions are got in the firft
of thefe ways, our acquired perceptions in the
fecond, and all that reafon difcovers of the
courfe of nature, in the third. In the firft of
thefe ways, nature, by means of the fenfations

of

384 OF THE HUMAN MIND. [CHAP. 6.

of touch, informs. hs of the hardnefs and foft-
nefs of bodies ; of their extenflon, figure, and
motion ; and of that fpace in which they
move and are placed, as, hath been already
explained in the fifth chapter of this inquiry.
And in the fecond of thefe ways (lie informs
us, by means of our eyes^ of almoft all the
fame things which originally we could per-
ceive only by touch.

In order, therefore, to under ft and more par-
ticularly how we learn* to perceive fo many
things by the eye, which originally could be
perceived only by touch, it will be proper,
firft, To point out the figns by which thofe
things are exhibited to the eye, and their con-
nection with the things fignified by them ;
and, teeondly, To confider how the expe-
rience of this connection produces that habit
by which the mind, without any reafoning or
reflection, pafTes from the fign to the concep-
tion and belief of the thing, fignified.

Of all the acquired perceptions which we
have by fight, the mod remarkable is the per-
ception of the diftance of objects from the
eye ; we mail therefore particularly confider
the figns by which this perception is exhibi-
ted, and only make fome general remarks with

regard

SECT. 22.] OF SEEING;, 385

regard to the ligns which are ufed in other ac-
quired perceptions.

SECT. XXII.

Of the figns by which we learn to perceive di-
Jlancefrom the eye.

IT was before obferved in general, That the
original perceptions of fight are ligns which
ferve to introduce thofe that are acquired :
but this is not to be underftood as if no other
ligns were employed for that purpofe.. There
are feveral motions of the eyes, which, in or-
der to diftinc~t vilion, muft be varied, accord-
ing as the object is more or lefs diftant ; and
fuch motions being by habit connected with
the correfponding diftances of the object, be-
come ligns of thofe diftances. Thefe motions
were at firft voluntary and unconfined ; but
as the intention of nature was, to produce
perfect and diftinct vifion by their means, we
foon learn by experience to regulate them ac-
B b cording

386 OF THE HUMAN MIND, [CHAP. 6.

cording to that intention only, without the
lead reflection.

A fhip requires a different trim for every
variation of the direction and flrength of the
wind : and, if we may be allowed to borrow
that word, the eyes require a different trim
for every degree of light, and for every varia-
tion of the diftance of the object, while it is
within certain limits. The eyes are trimmed
for a particular object, by contracting certain
mufcles, and relaxing others ; as the fhip is
trimmed for a particular wind, by drawing
certain ropes and flackening others. The fai-
lor learn^ the trim of his fhip, as we learn the
trim of our eyes, by experience. A fhip, al-
though the noblefl machine that human art
can boaft, is far interior to the eye in this re-
fpedt, that it requires art and ingenuity to na-
vigate her ; and a failor mufl know what
ropes he mufl pall, and what he mufl flacken,
to fit her to a particular wind: but with fuch
funenor wifdom is the fabnc of the eye, and
the principles of its motion contrived, that it
requires no art nor ingenuity to fee by it.
Even that part of virion which is got by ex-
perience, is attained by idiots. We need not
know what mufcles we are to contract, and

what

SECT. 22.] OF SEEING. 3&7

what we are to relax, in order to {it the eye
to a particular diftance of the object.

But although we are not confcious of the
motions we perform, in order to fit the eyes to
the di fiance of the object, we are confcious of
the effort employed in producing thefe mo-
tions ; and probably have fome fenfation
which accompanies them, to which we give
as little attention as to other fenfations. And
thus, an effort confcioufly exerted, or a fenfa-
tion confequent upon that effort, comes to be
conjoined with the diftance of the object
which gave occafion to it, and by this con-
junction becomes a lign of that diftance. Some
inftances of this will appear in confidering
the means or figns by which we learn to fee
the diftance of objects from the eye. In the
enumeration of thefe, we agree with Dr Por-
xerfield, notwithstanding that diftance from
the eye, in his opinion, is perceived original-
ly, but in our opinion, by experience only.

In general, when a near object affects the
eye in one manner, and the fame object, pla-
ced at a greater diftance, afftcts it in a diffe-
rent manner; thefe various affections of the
eye become iigns of the correiponding di-
stances. The means of perceiving diftance by
the eye, will therefore be explained, by fhew-
B b 2 ing

388 OF THE HUMAN MIND. [CHAP. 6,

ing in what various ways objects affect the
eye differently, according to their proximity
or diftance.

1. It is well known, that to fee objects di-
stinctly at various diftances, the form of the
eye muft undergo fome change. And nature
hath given us the power of adapting it to near
objects, by the contraction of certain mufcles,
and to diftant objects, by the contraction of
other mufcles. As to the manner in which
this is done, and the mufeular parts employ-
ed, anatomifts do not altogether agree. The
ingenious Dr Jurin, in his excellent effay on
diftinct and indiftinct vifion, feems to have gi-
ven the moil probable account of this matter ;
and to him I refer the reader.

But whatever be the manner in which this
change of the form of the eye is effected, it is
certain that young people have commonly the
power of adapting their eyes to all the di-
ftances of the objed, from fix to feven inches,
to fifteen or fixteen feet ; fo as to have per-
fect and diftinct vifion at any diftance within
thefe limits. From this it follows, that the
effea we confcioully employ to adapt the eye
to any particular diftance of objects within
thefe limits, will be connected and aifociated
with that diftance, and will become a fign of

it,

SECT. 22.J OF SEEING. 389

it. When the object is removed beyond the
fartheft limit of diftincl: vilion, it will be feen
indiftinctly ; but more or lefs fo, according as
its diilance is greater or lefs : fo that the de-
grees of indiftin&nefs of the object may be-
come the ligns of diftances confiderably be-
yond the fartheft limit of diftincl: vilion.

If we had no other mean but this, of per-
ceiving diftance of vifible objects, the moft di-
ilant would not appear to be above twenty or
thirty feet from the eye, and the tops of houfe&
and trees would feem to touch the clouds \
fpr in that cafe the ligns of all greater diftan-
ces being the fame, they have the fame figni-
fication, and give the fame perception of di-
ftance.

But it is of more importance to obferve,
that becaufe the neareft limit of diftincl: vifion
in the time of youth, when we learn to per-
ceive diftance by the eye, is about fix or fe-
ven inches, no object feen diftinctly, ever ap-
pears to be nearer than fix or feven inches
from the eye. We can, by art, make a fmall
object appear diftincl, when it is in reality
not above half an inch from the eye ; either
by uling a fingle microfcope, or by looking
through a fmall pin-hole in a card. When,
"by either of thefe means, an object is made ta
B b 5 appear

39° OF THE HUMAN MIND. [cHAP. 6.

appear diftind, however fmall its diftance is
in reality, it feems to be removed at lead to
the diftance of fix or feven inches, that is,
within the limits of diftinct vifion.

This obfervation is the more important, be-
caufe it affords the only reafon we can give
why an object is magnified either by a fingle
microfcope, or by being feen through a pin-
hole ; and the only mean by which we can
afcertain the degree in which the object will
be magnified by either. Thus, if the object
is really half an inch diftant from the eye,
and appears to be feven inches diftant, its dia-
meter will feem to be enlarged in the fame
proportion as its diftance, that is, fourteen
times.

2. In order to direct both eyes to an object,
the optic axes muft have a greater or lefs in-
clination, according as the object is nearer or
more diftant. And although we are not con*
fcious of this inclination, yet we are confcious
of the effort employed in it. By this mean
we perceive fmall diftances more accurately
than we could do by the conformation of the
eye only. And therefore we find, that thofe
who have loft the fight of one eye, are apt,
even within arm's-length, to make miftakes
in the diftance of objects, which are eafily a-

voided

SECT. 22.] OF SEEING. 39I

voided by thofe who fee with both eyes. Such
miftakes are often difcovered in fnuffing a
candle, in threading a needle, or in filling a
tea-cup.

When a picture is feen with both eyes, and
at no great diftance, the repreientation ap-
pears not fo natural as when it is {ctn only
with one. The intention of painting being
to deceive the eye, and to make things appear
at different diftances which in reality are up*
on the fame piece of canvas, this deception is
not fo eafily put upon both eyes as. upon one ;
becaufe we perceive the diftance of vilible ob-
jects more exactly and determinately with
two eyes than with one. If the fhading and
relief be executed in the belt manner, the pic*
ture may have almoft the fame appearance to
one eye as the objects themfelves would have,
but it cannot have the fame appearance to
both. This is not the fault of the artift, but
an unavoidable imperfection in the art. And
it is owing to what we juft now obferved, that
the perception we have of the diftance of ob-
jects by one eye is more uncertain, and more
liable to deception, than that which we have
by both.

The great impediment, and I think the

only invincible impediment, to that agreeable

JB b 4 deception

392 OF THE HUMAN MIND. fcHAP. 6.

deception of the eye which the painter aims
at, is the perception which we have of the di-
ftance of vifible obje&s from the eye, partly
by means of the conformation of the eye, but
chiefly by means of the inclination of the
optic axes. If this perception could be remo-
ved, I fee no reafon why a pi&ure might not,
be made fo perfect as to deceive the eye in"
reality, and to be miftaken for the original
objecl. Therefore, in order to judge of the
merit of a picture, we ought, as much as pof-
fible, to exclude thefe two means of percei-
ving the diftance of the feveral parts of it.

* In order to remove this perception of di-
ftance, the connohTeurs in painting ufe a me-
thod whieh is very proper. They look at the
picture with one eye, through a tube which
excludes the view of all other obje&s. JCy
this method, the principal mean whereby we
perceive the diftance of the obje&, to wit, the
inclination of the optic axes, is entirely ex-
cluded. I would humbly propofe, as an im-
provement of this method of viewing pic-
tures, that the aperture of the tube next to
the eye fhould be very fmall. If it is as fmall
as a pin-hole, fo much the better, providing
there be light enough to fee the pi&ure clear-
ly. The reafon of this propofal is, that when

we.

SECT. 22.J OF SEEING. MM*

J»

we look at an object through a fmall aper-
ture, it will be feen diftinctly, whether the
conformation of the eye be adapted to its di-
fiance or not, and we have no mean left to
judge of the diflance, but the light and co-
louring, which are in the painter's power.
If, therefore, the artift performs his part pro-
perly, the picture will by this method affect
the eye in the fame manner that the object
reprefented would do ; which is the perfec-
tion of this art.

Although this fecond mean of perceiving
the di fiance of vifible objects be more deter-
minate and exact than the firft, yet it hath its
limits, beyond which it can be of no ufe. For
when the optic axes directed to an object are
fo nearly parallel, that in directing them to
an object yet more diftant, we are not con-
fcious of any new effort, nor have any diffe-
rent fenfation \ there our perception of di-
flance flops ; and as all more diflant objects
affect the eye in the fame manner, we per-
ceive them to be at the fame diflance. This
is the reafon why the fun, moon, planets, and
fixed flars, when feen not near the horizon,
appear to be all at the fame diflance, as if
they touched the concave furface of a great
fphere. The furface of this celeflial fphere

is

^94 0F THE HUMAN MIND. [CHAt». 6.

is at that diftance beyond which all objects
affect the eye in the fame manner. Why this
celeftial vault appears moire diftant towards
the horizon, than towards the zenith, wili af-
terwards appear.

3. The colours of objects, according as
they are more diftant, become more faint and
languid, and are tinged more with the azure
of the intervening atmofphere : to this we
may add, that their minute parts become more
indiftinct, and their outline lefs accurately
defined. It is by thefe means chiefly, that
painters can reprefent objects at very diffe-
rent diftances, upon the fame canvas. And
the diminution of the magnitude of an ob-
ject, would not have the effed of making it
appear to be at a great diftance without this
degradation of colour, and indiftinctnefs of
the outline, and of the minute parts. If a
painter mould make a human figure ten times
lei's than other human figures that are in the
fame piece, having the colours as bright, and
the outline and minute parts as accurately de-
fined, it would not have the appearance of a
man at a great diftance, but of a pigmy or
Lilliputian.

When an object hath a known variety of
colours, its diftance is more clearly indicated

by

$ECT. 22.] OF SEEING. 395

by the gradual dilution of the colours into
one another, than when it is of one uniform
colour. In the fteeple which flands before
me at a fmall diftance, the joining of the
ftones are clearly perceptible \ the gray co-
lour of the ftone, and the white cement, are
diftinctly limited : when I fee it at a greater
diftance, the joinings of the ftones are lefs di*
ftincl, and the colours of the ftone and of the
cement begin to dilute into one another : at a
diftance ftill greater, the joinings difappear
altogether, and the variety of colour vanifhes.
In an apple-tree which ftands at the di-
ftance of about twelve feet, covered with
flowers, I can perceive the figure and the co-
lour of the leaves and petals ; pieces of branch-
es, fome larger, others fmaller, peeping through
the interval of the leaves, fome of them en-
lightened by the fun's rays, others fhaded ;
and fome openings of the fky are perceived
through the whole. When I gradually re-
move from this tree', the appearance, even as
to colour, changes every minute. Firft, the
fmaller parts, then the larger, are gradually
confounded and mixed. The colours of
leaves, petals, branches, and iky, are gradual-
ly diluted into each other, and the colour of
the whole becomes more and more uniform.

This

J5f6 OF THE HUMAN MIND. [CHAP. 6.

This change of appearance, correfponding to
the feveral diftances, marks the di (lance more
exactly than if the whole object had been of
one colour.

Dr Smith, in his Optics, gives us a very
curious obfervation made by Bifhop Berke-
ley, in his travels through Italy and Sicily.
He obferved, That in thofe countries, cities
and palaces feen at a great diftance, appeared
nearer to him by feveral miles than they real-
ly were : and he very judicioufly imputed it
to this caufe, That the purity of the Italian
and Sicilian air, gave to very diftant objects,
that degree of brightnefs and diftinctnefs,
which, in the groffer air of his own country,
was to be feen only in thofe that are near.
The purity of the Italian air has been affign-
ed as the reafon why the Italian painters
commonly give a more lively colour to the
iky, than the Flemilh. Ought they not, for
the fame reafon, to give lefs degradation of
the colours, and lefs indiftinctnefs of the mi-
nute parts, in the reprefentation of very di-
ftant objects ?

It is very certain, that as, in air uncom-
monly pure, we are apt to think vifible ob-
jects nearer, and lefs than they really are ; fo,
in air uncommonly foggy, we are apt to think

them

SECT. 22,] OF SEEING. 397

them more diftant, and larger than the truth.
Walking by the fea-fide, in a thick fog, I fee
an object which fecms to me to be a man on
horfeback, and at the diftance of about half a
mile. My companion, who has better eyes,
or is more accufiomed to fee fuch objects in
fuch circumflance9, affures me, that it is a
fea-gull, and not a man on horfeback. Upon
a fccond view, I immediately aftent to his
opinion ; and now it appears to me to be a
fea-gull, and at* the diftance only of feventy
or eighty yards. The miftake made on this
occaiion, and the correction of it, are both fo
iuddcn, that we are at a lofs whether to caR
them by the name pf judgment, or by that of
Jimple perception.

It is not worth while to difpute about
names ; but it is evident, that my belief, both
firft and laft, was produced rather by iigns
than by arguments ; and that the mind pro-
ceeded to the conclufion in both cafes by ha-
bit, and not by ratiocination. And the pro-
cefs of the mind feems to have been this.
Firft, not knowing, or not minding, the effect
of a foggy air on the vifible appearance of
objects, the object feems to me to have that
degradation of colour, and that indiftinctnefs
of the outline, which objects have at the di-
ftance

398 OF THE HUMAN MIND. [CHAP. 6,

ftance of half a mile ; therefore, from the vi-
sible appearance as arfign, I immediately pro-
ceed to the belief, that the object is half a
mile diftant. Then, this diftance, together
with the viiible magnitude, fignify to me the
real magnitude, which, fuppoling the diftance
to be half a mile, muft be equal to that of a
man on horfeback ; and the figure, confider-
ing the indiftindtnefs of the outline, agrees
with that of a man on horfeback. Thus the
deception is brought. about. But when I am
allured that it is a fea-gull, the real magni-
tude of a fea-gull, together with the vifible
magnitude prefented to the eye, immediately
fuggefl the diftance, which in this cafe can-
not be above feventy or eighty yards : the in-
diftjn&nefs of the figure likewife fuggefts the
fogginefs of the air as its caule : and now the
whole chain of figns, and things fignified,
feems ftronger and better connected than it
was before ; the half mile vanifhes to eighty
yards ; the man on horfeback dwindles to a
fea-gull ; I get a new perception, and won-
der how I got the former, or what is become
of it ; for it is now fo entirely gone, that I
cannot recover it.

It ought to be obferved, that in order to
produce fuch deceptions from the clearnefs or

fogginefs

$ECT. 22.] OF SEEING. 399

fogginefs of the air, it mull be uncommonly
clear, or uncommonly foggy : for we learn
from experience, to make allowance for that
variety of conftitutions of the air which we
have been accuftomed to obferve, and of
which we are aware. Biftiop Berkeley,
therefore, committed a miftake, when he at-
tributed the large appearance of the horizon-
tal moon to the faintnefs of her light, occa-
fioned bv its palling through a larger tract of
atmofphere : for we are fo much accuftomed
to fee the moon in all degrees of faintnefs and
brightnefs, from the greateft to the lead, that
we learn to make allowance for it ; and do
not imagine her magnitude increafed by the
faintnefs of her appearance. Befides, it is cer-
tain, that the horizontal moon, feen through
a tube which cuts off the view of the interja-
cent ground, and of all terreftrial objects,
lofes all that unufual appearance of magni*
tude.

4. We frequently perceive the diftance of
objects, by means of intervening or contigu-
ous objects, whofe diftance or magnitude is
otherwiie known. When 1 perceive certain
fields or tracts of ground to lie between me
and an object, it is evident, that thcfe may
become ligus of its diftance. And although

wc

400 OF THE HUMAN MIND. [CHAP. 6.

we have no particular information of the di-
menlions of fuch fields or tra&s, yet their fi-
militude to others which we know, fuggeftt
their dimeniions.

We are fo much accuftomed to mcafure
with our eye the ground which we travel, and
to compare the judgments of diflances form-
ed by fight, with our experience or informa-
tion, that we learn by degrees, in this way, to
form a more accurate judgment of the di-
ftance of terreftrial objects, than we could do
by any of the means before mentioned. An
object placed upon the top of a high build-
ing, appears much lefs than when placed up-
on the ground at the fame diftance. When
it Hands upon the ground, the intervening
trad of ground ferves as a fign of its diftance;
•and the diftance, together with the vifible
magnitude, ferves as a fign of its real magni-
tude. But when the object is placed on high,
this fign of its diftance is taken away : the
remaining figns lead us to place it at a lefs
diftance ; and this lefs diftance, together with
the vifible magnitude, becomes a fign of a
lefs real magnitude.

The two firft means we have mentioned,
would never of themfelves make a vifible ob-
ject appear above a hundred and fifty, or two

hundred

iECT. 2 2.] OF SEEING. 401

hundred feet, diftant ; becaufe, beyond that
there is no fenfible change, either of the con-
formation of the eyes, or of the inclination of
their axes. The third mean, is but a vague
and undeterminate iign, when applied to di-
itances above two or three hundred feet, un-
lefs we know the real colour and figure of
the object ; and the fifth mean, to be after-
wards mentioned, can only be applied to ob-
jects which are familiar, or whofe real mag-
nitude is known. Hence it follows, that
when unknown objects, upon, or near the fur-
face of the earth, are perceived to be at the
diftance of fome miles, it is always by this
fourth mean that we are led to that conclu-
fion.

Dr Smith hath obferved, very juftly, that
the known diftance of the terreftrial objects
which terminate our view, makes that part of
the iky which is towards the horizon, appear
more diftant than that which is towards the
zenith. Hence it comes to pals, that the ap-
parent figure of the iky is not that of a hemi-
fphere, but rather a lefs fegment of a fphere.
And hence likewife it comes to pafs, that the
diameter of the fun or moon, or the diftance
between two fixed ftars, ft en contiguous to a
hill, or to any diftant terreftrial object, ap-
C c pears

402 OF THE HUMAN MIND. fcHAP. 6.

pears much "greater than when no fuch object
ftrikes the eye at the fame time.

Thefe obfervations have been fuffictently
explained and confirmed by Dr Smith. I
beg leave to add, that when the vifible hori-
zon is terminated by very diftant objects, the
celeftial vault feems to be enlarged in all its
dimenfions. When I view it from a confined
ftreet or lane, it bears fome proportion to the
buildings that furround me : but when I view
it from a large plain, terminated on all hands
by hills which rife one above another, to the
diftance of twenty miles from the eye, me-
thinks I fee a new heaven, wtiofe magnifi-
cence declares the greatnefs of its Author, and
puts every human edifice out of countenance ;
for now the lofty fpires and the gorgeous pa-
laces fhrink into nothing before it, and bear
no more proportion to the celeftial dome, than
their makers bear to its Maker.

5. There remains another mean by which
we perceive the diftance of vifible objects,
and that is, the diminution of their vifible or
apparent magnitude. By experience, I know
what figure a man, or any other known ob-
ject, makes to my eye, at the diftance of ten
feet : I perceive the gradual and proportional
diminution of this vifible figure, at the di-
ftance-

SECT. 22.] 'OF SEEING, 403

fiance of twenty, forty, a hundred feet,, and
at greater ''di (lances, until it vanifh ahoge-
ther. Hence a certain vifible magnitude of
a known object, ; becomes the fign of a cer-
tain determinate diftance, and carries along
with it the conception and belief of that dif-
tance.

In this procefs of the mind, the fign is
not a fenfation ; it is an original perception.
We perceive the vifible figure and vifible
magnitude of the object, by the original powers
of vifion ; but the vifible figure is ufed only
as a fign1 of the real figure, and the vifible
magnitude is ufed only as a fign either of
the diftance, or of the real magnitude, of
the object ; and therefore thefe original per-
ceptions, like other mere figns, pafs through
the mind* without any attention or reflec-
tion.

This lafl mean of perceiving the diftance
of known objects, ferves to explain fome very
remarkable phenomena in optics, which would
otherwife appear very myfterious. When we
view objects of known dimeniions through
optical glaffes, there is no other mean left of
determining their diftance, but this fifth.
Hence it follows, that known objects, feenr
C c a through

404 OF THE HUMAN MIND. [cHAP. 6,

through glafies, muft feem to be brought near-
er, in proportion to the magnifying power of
the glafs, or to be removed to a greater dif-
tance, in proportion to the diminifhing power
of the glafs.

If a man who had never before feen ob-
jects through a telefcope, were told, that the
telefcope, which he is about to ufe, magnifies
the diameter of the object ten times ; when he
looks through this telefcope at a man fix feet
high, what would he expect to fee ? Surely
he would very naturally exped to fee a giant
fixty feet high. But he fees no fuch thing.
The man appears no more than fix feet high,
and consequently no bigger than he really is ;
but he appears ten times nearer than he is.
The telefcope indeed magnifies the image of
this man upon the retina ten times in diame-
ter, and mud therefore magnify his vifible fi-
gure in the fame proportion ; and as we have
been accuflomed to fee him of this vifible
magnitude, when he was ten times nearer than
he is prefently, and in no other cafe ; this vi-
fible magnitude, therefore, fuggefts the con-
ception and belief of that diftance of the ob-
ject with which it hath been always connect-
ed. We have been accuflomed to conceive

this

SECT. 22.] OF SEEING. 405

this amplification of the vifible figure of a
known object, only as the effect or iign of its
being brought nearer : and we have annexed
a certain determinate dillance to every degree
of vifible magnitude of the object ; and there-
fore, any particular degree of vifible magni-
tude, whether feen by the naked eye or by
glaffes, brings along with it the conception and
belief of the diftance which correfponds to it.
This is the reafon why a telefcope Teems not
to magnify known objects, but to bring them
nearer to the eye.

When we look through a pin-hole, or a fin-
gle microfcope, at an object: which is half an
inch from the eye, the picture of the object
upon the retina is not enlarged, but only ren-
dered diftinct ; neither is the vifible figure en-
larged '. yet the object appears to the eye twelve
or fourteen times more diflant, and as many
times larger in diameter, than it really is. Such
a telefcope as we have mentioned, amplifies
the image on the retina, and the vifible figure
of the object, ten times in diameter, and yet.
makes it feem no bigger, but only ten times
nearer. Thefe appearances had been longob-
ferved by the writers on optics ; they tortured
their invention to find the caufes of them
^ c 3 from

4C6* OF THE flPUMAN MIND. [>GHAP. 6.

from optical principles ; but in vain : they
mud be refolved into habits of perception,
which are acquired by cuftom, but are apt
to be miftaken for original perceptions. The
Bifhop of Cloyne firft furnifhed the world
with the proper key for opening up thefe myf-
terious appearances ; but he made confiderable
miftakes in the application of it. Dr Smith,
in his elaborate and judicious treatife of Op-
tics, hath applied it to the apparent diftance
of objects feen with glaffes, and to the appa-
rent figure of the heavens, with fuch happy
fuccefs, that there can be no more doubt about
the caufes of thefe phenomena.

SECT.

jSECT. 23.] OF SEEING. 4°7

SECT. XXIII.

Of the figns ufed in other acquired percep-
tions.

THE diftance of obje&s from the eye, is
the mod important leflbn in vifion. Ma-
ny others are eafily learned in confequence of
it. The diftance of the object, joined with
its vifible magnitude, is a fign of its real mag-
nitude : and the diftance of the feveral parts
of an object, joined with its vifible figure,
becomes a fign of its real figure. Thus, when
I look at a globe, which ftands before me, by
the original powers of fight I perceive only
fomething of a circular form, variously colour-
ed. The vifible figure hath no diftance from
the eye, no convexity, nor hath it three di-
menfions ; even its length and breadth are
incapable of being meafured by inches, feet,
or other linear meafures. But when I have
C c 4 learned

408 OF THE HUMAN MIND. [CHAP. 6.

learned to perceive the diftance of every part
of this objeft from the eye, this perception
gives it convexity, and a fpherical figure ; and
adds a third dimenfion to that which had but
two before. The diftance of the whole objcd
makes me likewife perceive the real magni-
tude ; for being accuftomed to obferve how an
inch or a foot of length affects the eye at that
diftance, I plainly perceive by my eye the li-
near dimenfions of the globe, and can affirm
with certainty that its diameter is about one
foot and three inches.

It was fhown in the feventh feclion of this
chapter, that the vii.ible figure of a body may,
by mathematical reafoning, be infei red from
it real figure, diftance, and pofition, with re-
gard to the eye : in like manner, we may, by
mathematical reafoning, from the viiible fi-
gure, together with the diftance of the feveral
parts of it from the eye, infer the real figure
and pofition. But this laft inference is not
commonly made by mathematical reafoning,
nor indeed by reafoning of any kind, but by
cuftom.

The original appearance which the colour
of an objedt makes to the eye, is a fenfation
for which we have -no name, becaufe it is ufed

merely

SECT. 23.] OF SEEING. 409

merely as a fign, and is never made an object
of attention in common life : but this appear-
ance, according to the different circumftances,
fignifies various things. If a piece of cloth,
of one uniform colour, is laid fo that part of
it is in the fun, and part in the (hade ; the ap-
pearance of colour, in thefe different parts, is
veiy different: yet we perceive the colour to
be the fame ; we interpret the variety of ap-
pearance as a fign of light and fhade, and not
as a lign of real difference in colour. But if
the eye could be fo far deceived, as not to
perceive the difference of light in the two
parts of the cloth, we fhould, in that cafe, in-
terpret the variety of appearance to figni-
fy a variety of colour in the parts of the
cloth.

Again, if we fuppofe a piece of cloth pla-
ced as before, but having the fhaded part fo
much brighter in the colour, that it gives the
fame appearance to the eye as the more en-
lightened part ; the famenefs of appearance
will here be interpreted to fignify a variety of
colour, becaufe we fhall make allowance for
the effect of light and fhade.

When the real colour of an object is known,
the appearance of it indicates, in fome cir-
cumftances, the degree of li^ht or fhade ; in

others,

41 .0 OF THE HUMAN MIND. [CHAP. 6\

others, the colour of the circumambient bo-
dies, whofe rays are reflected by it; and in
other circumftances, it indicates the diftance
or proximity of the object, as was obferved in
the laft ie&ion ; and by means of thefe, many
other things are fuggjefted to the mind. Thus,
an unufual appearance in the colour of fami-
liar objecls may be the diagnoflic of a dileafe
in. the fpedtator. The appearance of things
in my room, may indicate funfhine or cloudy
weather, the earth covered with ihow, or
blackened with rain. , It hath been obferved/
that the colour of thq iky, in a piece, of paint-
ing, may indicate the country of the painter,
becaufe the Italian Iky is really of a different
colour from the Flemifh.

It was already obferved, that the original
and acquired perceptions which we have by
our fenfes, are the language of nature to man,
which, in many refpecls, hath a great affinity
to human languages. The inflances which we
have given of acquired perceptions, fugged
this affinity, that as, in human languages, am-
biguities are often found, fo this language of
nature in cur acquired perceptions is not ex-
empted from them. We have feen, in virion
particularly, that the fame appearance to the
eye, may, in different circumftances, indicate

diiTerent

SECT. 23.] OF SEEING. 411

different things. Therefore, when the circum-
fiances are unknown upon which the interpre-
tation of the figns depends, their meaning
muft be ambiguous ; and when the circum-
ftances are miftaken, the meaning of the figns
mull alfo be miftaken.

This is the cafe in all the phenomena whichi
we call fallacies of the fenfes ; and particu-
larly, in thofe which are called fallacies in
vi/ion. The appearance of things to the eye,
always correfponds to the fixed laws of na-
ture ; therefore, if we fpeak properly, there
is no fallacy in the fenfes. Nature always
fpeaketh the fame language, and ufeth the
fame figns in the fame circumflances : but we
fometimes miftake the meaning of the figns,
either through ignorance of the laws of na-
ture, or through ignorance of the circumflan-
ces which attend the figns.

To a man, unacquainted with the princi-
ples of optics, almofl every experiment that
is made with the prifm, with the magic lan-
thorn, with the telefcope, with the micro-
fcope, feeois to produce fome fallacy in vifion.
Even the appearance of a common mirror, to
one altogether unacquainted with the effects
pf it, would feem moft remarkably fallacious.

For

+12 OF THE HUMAN MIND. [CHAP. 6.

For how can a man be more impofed upon,
than in feeing that before him which is real-
ly behind him ? How can he be more impo-
fed upon, than in being made to fee himfelf
feveral yards removed from himfelf ? Yet
children, even before they can fpeak their mo-
ther-tongue, learn not to be deceived by thefe
appearances. Thefe, as well as all the other
furprifing appearances produced by optical
glaffes, are a part of the vifual language ; and,
to thofe who underltand the laws of nature
concerning light and colours, are in no wife
fallacious, but have a diftinct and true mean^

SEC T.

SECT. 24.] OF SEEING. 4J3

SECT. XXIV.

Of the analogy hetvoeen perception, and the ere-
dit we give to human teftimony.

THE objects of human knowledge are in-
numerable, but the channels by which
it is conveyed to the mind are few. Among
thefe, the perception of external things by our
fenfes, and the informations which we receive
upon human teftimony, are not the lead con-
fiderable : and fo remarkable is the analogy
between thefe two, and, the analogy between
the principles of the mind, which are fubfer-
vient to the one, and thofe which are fubfer-
vient to the other, without further apology, we
fhall coniider them together.

In the teftimony of nature given by the fen-
fes, as well as in human teftimony given by
language, things are iignified to us by.figns :
and in one, as well as the other, the mind, ei-
ther

4*4 °F THE HUMAN MlND. [CHA*. &

ther by original principles, or by cuftom, paf-
fes from the fign to the conception and belief
of the things fignified.

We have diftinguiihed our perceptions in-
to original and acquired ; and language, into
natural and artificial. Between acquired per-
ception, and artificial language, there is a
great analogy ; but ftill a greater between
original perception and natural language.

The figns in original perception are fenfa-
tions, of which nature hath given us a great
variety, fuited to the variety of the things fig-
nified by them. Nature hath eftablifhed a real
connection between the figns and the things
fignified ; and nature hath alfo taught us the
interpretation of the figns ; fo that, previous
to experience, the fign fuggefts- the thing fig-
nified, and creates the belief of it.

The figns in natural language are features
of the face, geftures of the body, and modu-
lations of the voice ; the variety of which is
Fuited to the variety of the things fignified by
them. Nature hath eftablifhed a real con-
nection between thefe ligns, and the thoughts
and difpofitions of the mind which are figni-
•fied-by them ; and nature hath taught us the
interpretation of theie figns ; fo that, pre-
vious

S£CT. 24.] ' OF SEEINC. 4*5

vious to experience, the figns fuggeft the
thing fignifred, and creates the belief of it.

A man in company, without doing good or
evil; without uttering an articulate found, may
behave himfelf gracefully, civilly, politely;
or, on the contrary, meanly, rudely, and im-
pertinently. We fee the difoofrtions of his
mind, by their natural figns in his counte-
nance and behaviour, in the fame manner as
~we perceive the figure and other qualities of
bodies by the fenfations which nature hath
connected with them.

The figns in the natural language of the
human countenance and behaviour, as well as
the figns in our original perceptions, have the
fame fignification in all climates, and in all na-
tions v and the fkill of interpreting them is not
acquired, but innate.

In acquired perception, the figns are either
fenfations, or things which we perceive by
means of fenfations. The conneclion between
the fign, and the thing fignified, is eftablifh-
ed by°nature : and we difcover this connec-
tion by experience ; but not without the aid
of our original perceptions, or of thofe which
we have already acquired. After this con-
ne&ion is difcovered, the fign, in like manner
as in original perception, always fuggefts

the

4l6 ON THE HUMAN MIND. [CHAP. 6.

the things fignified, and creates the belief of
it.

In artificial language, the figns are articulate
founds, whofe conne&ion with the things
iignified by them is eftablifhed by the will of
men : and in learning our mother-tongue, we
difcover this connection by experience ; but
not without the aid of natural language, or
of what we had before attained of artificial
language. And after this connection is dif-
covered, the fign, as in natural language, al-
ways fuggefts the thing fignified, and creates
the belief of it.

Our original perceptions are, few, compared
with the acquired ; but without the former,
we could not poffibly attain the latter. In
like manner, natural language is fcanty, com-
pared with artificial ; but without the for-
mer, we could not poffibly attain the latter.

Our original perceptions, as well as the na-
tural language of human features and gc[-
tures, muit be refolved into particular prin-
ciples of the human conftitution. Thus, it
is by one particular principle of our conftitu-
tion, that certain features exprefs anger ; and
by another particular principle, that certain
features exprefs benevolence. It is in like
manner, by one particular principle of our

conftitution.

SECT. 24.] OF SEEING* 417

conftitution, that a certain fenfation fignifies
hardnefs in the body which I handle ; and it
is by another particular principle, that a cer-
tain fenfation fignifies motion in that body.

But our acquired perceptions, and the in-
formation - we receive by means of artificial
language, mufl be refolved into general prin-
ciples of the human conllitution. When a
painter perceives, that this picture is the work
of Raphael, that the work of Titian ; a jewell-
er, that this is a true diamond, that a counter-
feit ; a failor, that this is a fliip of five hun-
dred ton, that of four hundred : thefe diffe-
rent acquired perceptions are produced by
the fame general principles of the human
mind, which have a different operation in the
fame perfon, according as they are varioufly
applied, and in different perfons, according
to the diverfity of their education and manner
of life. In like manner, when certain arti-
culate founds convey to my mind the know-
ledge of the battle of Pharfalia ; and others,
the knowledge of the battle of Poltowa ;
when a Frenchman and an Englifhman re-
ceive the fame information by different arti-
culate founds ; the figns ufed in thefe diffe-
rent cafes, produce the knowledge and belief
of the things fignified, by means of the fame
P d general

4lS OF THE HUMAN MIND. [CHAP. 6,

general principles of the human conftitu-
tion.

Now, if we compare the general principles
of our conftitution, which fit us for receiving
information from our fellow -creatures by
language, with the general principles which
fit us for acquiring the perception of ^hings
by our fenfes, we fhall find them to be very fi-
milar in their nature and manner of operation.
When we begin to learn our mother-
tongue, we perceive by the help of natural
language, that they who fpeak to us, ufe cer-
tain founds to exprefs certain things : we imi-
tate the fame founds when we would exprefs
the fame things, and find that we are under-
ftood.

But here a difficulty occurs which merits
our attention, becaufe the folution of it leads-
to fome original principles of the human mind,
which are of great importance, and of very
extenfive influence. We know by expe-
rience, that men have ufed fuch words to ex-
prefs fuch things. But all experience is of
the/);///, and can, of it lei f, give no notion or
benef of what isfutztte. How come we then
to believe, and to rely upon it with aflurance,
that men who have it in their power to do
otherwiie, will continue to ufe the fame words

when,

SECT. 24.] OF SEEING. 419

when they think the fame things ? Whence
comes this knowledge and belief, this fore-
light we ought rather to call it, of the future
and voluntary a&ions of our fellow-creatures ?
Have they promifed that they will never im-
pofe upon us by equivocation or falfehood ?
No, they have not. And, if they had, this
would not folve the difficulty : for fuch pro-
mife mult be exprefTed by words, or by other
iigns ; and, before we can rely upon it, we
muft be allured, that they put the ufual
meaning upon the ligns which exprefs that
promife. No man of common fenfe ever
thought of taking a man's own word for his
honefty ; and it is evident that we take his
veracity for granted, when we lay any Itrefs
upon his word or promife. I might add,
that this reliance upon the declarations and
teftimony of men, is found in children long
before they know what a promife i9.

There is, therefore, in the humatt miiKi an
early anticipation, neither derived from ex-
perience, nor from reafon, nor from any corn-
pad: or promife, that our fellow-creatures will
ufe the fame iigns in language, when they have
the fame fentiments.

This is, in reality, a kind of prefcience of

$*uman a&ions ; and it feems to me to be an

•D d a original

420 OF THE HUMAN MIND. [cHAP.6.

original principle of the human conftitution,
without which we mould be incapable of lan-
guage, and confequently incapable of inftruc-
tion.

The wife and beneficent Author of nature,
whq intended that we mould be focial crea-
tures, and that we fhould receive the <;reateft
and moft important part of our knowledge by
the information of others, hath, for thefe pur-
pofes, implanted in our natures two principles
that tally with each other.

The firft of thefe principles is, a propenfity
to fpeak truth, and to ufe the figns of lan-
guage, fo as to convey our real fentiments.
This principle has a powerful operation, even
in the greateit liars \ for, where they lie once,
they fpeak truth a hundred times. Truth is
always uppermoft, and is the natural iffue of
the mind. It requires no art or training, no
inducement or temptation, but only that we
yield to a natural impulfe. Lying, on the
contrary, is doing violence to our nature ;
and is never pradifed, even by the worfl
men, without fome temptation. Speaking
truth is like uling our natural food, which we
would do from appetite, although it anfwer-
ed no end ; but iying is like taking phytic,
which is naufeous to the tafte, and which no

man

SECi\ 24.] OF SEEING. 421

man takes but for fome end which he cannot
otherwife attain.

If it mould be objected, That men may be
influenced by moral or political confidera-
tions to fpeak truth* and therefore, that their
doing fo, is no proof of fuch an original prin-
ciple as we have mentioned ; I anfwer, firlt,
That moral or political confiderations can
have no influence, until wTe arrive at year£ of
tinderftanding and reflection ; and it is cer-
tain from experience* that children keep to
truth invariably, before they are capable of
being influenced by fuch confiderations. be-
condly, When we are influenced by moral or
political confiderations, we muft be confcious
of that influence, and capable of perceiving
it upon refledion. Now, when I reflect up-
on my adions mod attentively, I am not con-
fcious, that, in fpeaking truth, I am influenced
on ordinary occafions by any motive moral or
political. I find, that truth is always at the
door of my lips, and goes forth fpontaneoufly,
if not held back. It requires neither good
nor bad intention to bring it forth, but only
that I be artlefs and undefigning. There
may, indeed, be temptations to falfehood,
which would be too ftrong for the natural
principle of veracity, unaided by principles of
D d 3 honour

4^2 OF THE HUMAN MIND. [CHAP. 6.

honour or virtue ; but where there is no fuch
temptation, we fpeak truth by inftind: ; and
this inftindt is the principle I have been ex-
plaining.

By this inftindt, a real connection is form-
ed between our words and our thoughts, and
thereby the former become fit to be figns of
the latter, which they could not otherwife be.
And although this connection is broken in
every intfance of lying and equivocation, yet
thefe inftances being comparatively few, the
authority of human teftimony is only weak-
ened by them, but not deftroyed.

Another original principle implanted in us
by the Supreme Being, is a difpofition to con-
fide in the veracity of others, and to believe
what they tell us. This is the counter-part
to the former ; and as that may be called the
principle of veracity , we (hall, for want of a
more proper name, call this the principle of cre-
dulity. It is unlimited in children, until they
meet with inftances of deceit and falfehood :
and it retains a very conliderable degree of
ilrength through life.

If nature had left the mind of the fpeaker
in cequitibrio, without any inclination to the
fide or' truth more than to that of falfehood ;
children would lie as often as they fpeak

truth,

SECT. 24.] . OF SEEING. 423

truth, until reafon was fo far ripened, as to
fugged the imprudence of lying, or confer-
ence, as to fuggeft its immorality. And, if
nature had left the mind of the hearer in aqui-
librio, without any inclination to the fide of
belief more than to that of difbelief^ we fhould
take no man's word until we had pofitive evi-
dence that he fpoke truth* His teftimony
would, in this cafe, have no more authority
than his dreams ; which may be true or falfe,
but no man is difpofed to believe them, on
this account, that they were dreamed. It is
evident, that, in the matter of teftimony, the
balance of human judgment is by nature in-
clined to the fide of belief; and turns to that
lide of itfelf, when there is nothing put into
the oppofite fcale. If it was not fo, no pro-
pofition that is uttered in difcourfe would be
believed, until it was examined and tried by
reafon ; and mod men would be unable to
find reafons for believing the thoufandth part
of what is told them. Such diftrufl and in-
credulity would deprive us of the greater! be-
nefits of fociety, and place us in a worfe con-
dition than that of favages.

Children, on this fuppofition, would be ab-
solutely incredulous ; and therefore absolute-
ly incapable of inftru&ion ; thofe who had
Dd4 "little

424 OF THE HUMAN MIND. [CHAP. 6„

little knowledge of human life, and of the
manners and characters of men, would be in
the next degree incredulous : and the mod
credulous men would be thofe of greater! ex-
perience, and of the deepeft penetration ; be-
caufe, in many cafes, they would be able to
find good reafons for believing teftimony,
which the weak and the ignorant could not
difcover.

In a word, if credulity were the effect of
reafoning and experience, it mud grow up
and gather ftrength, in the fame proportion
as reafon and experience do. But, if it is the
gift of nature, it will be ftrongeft in child-
hood, and limited and reftrained by experi-
ence ; and the mod fuperficial view of hu-
man life fhows, that the laft is really the cafe,
and not the firft.

It is the intention of nature, that we mould
be carried in arms before we are able to walk
upon our legs ; and it is likewiie the inten-
tion of nature, that our belief mould be guid-
ed by the authority and reafon of others, be-
fore it can be guided by our own reafon.
The weaknefs of the infant, and the natural
affection of the mother, plainly indicate the
former; and the natural credulity of youth,
and authority of age, as plainly indicate the

latter,

SECT. 24.] OF SEEING. 425

latter. The infant, by proper nurfing and
care, acquires ftrength to walk without fup-
port. Reafon hath likewife her infancy,
when fhe muft be carried in arms : then (lie
leans entirely upon authority, T)y natural in-
ftincl, as if fhe was confcious of her own
weaknefs ; and without this fupport, fhe be-
comes vertiginous. When brought to matu-
rity by proper culture, fhe begins to feel her
own ftrength, and leans lefs upon the reafon
of others ; fhe learns to fufped teftimony in
fome cafes, and to difbelieve it in others ,
and fets bounds to that authority to which
fhe was at firft entirely fubjed. But ftill, to
the end of life, fhe finds a neceffity of bor-
rowing light from teftimony, where fhe has.
none within herfelf, and of leaning in fome
degree upon the reafon of others, where fhe
is confcious of her own imbecillity.

And as in many inftances, Reafon, even
in her maturity, borrows aid from tefti-
mony ; fo in others fhe mutually gives aid
to it, and ftrengthens its authority. For
as we find good reafon to reject teftimony
in fome cafes, fo in others we find good
reafon to rely upon it with perfect fecu-
rity, in our moft important concerns. The
character, the number, and the difintereiied-

nefs

4^6 OF THE HUMAN MIND. [CHAP. 6*

nefs of witnefles, the impoffibility of collu-
fion, and the incredibility of their concurring
in their teftimony without collufion, may
give an irrefiftible ftrength to teftimony, com-
pared to which its native and intrinfic autho-
rity is very inconliderable.

Having now confidered the general prin-
ciples of the human mind which fit us for
receiving information from our fellow- crea-
tures, by the means of language ; let us
next confider the general principles which
fit us for receiving the information of nature
by our acquired perceptions.

It is undeniable, and indeed is acknow-
ledged by all, that when we have found two
things to have been conftantly conjoined in
the courfe of nature, the appearance of one
of them is immediately followed by the con-
ception and belief of the other. The for-
mer becomes a natural fign of the latter ;
and the knowledge of their conftant conjunc-
tion in time paft, whether got by experience
or otherwife, is fufficient to make us rely
with aflurance upon the continuance of that
conjunction.

This procefs of the human mind is fo fa-
miliar, that we never think of inquiring in-
to the principles upon which it is founded*

Wc

SECT. 24.] OT SEEING. 427

We are apt to conceive it as a felf-evident
truth, that what is to come mull be fimilar
to what is paft. Thus if a certain degree of
cold freezes water to-day, and has been
known to do fo in all time paft, we have no
doubt but the fame degree of cold will freeze
water to-morrow, or a year hence. That
this is a truth which all men believe as foon
as they underftand it, I readily admit ; but
the queftion is, Whence does its evidence
arife ? $ot from comparing the ideas, furely.
For when I compare the idea of cold with
that of water hardened into a tranfparent fo-
lid body, I can perceive no connection be-
tween them : no man can fhow the one to be
the neceflary effect of the other : no man can
give a fhadow of reafon why nature hath
conjoined them. But do we not learn their
conjunction from experience? True; ex-
perience informs us that they have been con-
joined in time paft : but no man ever had
any experience of what is future : and this is
the very queftion to be refolved, How we
come to believe that the future will be like
the paft ? Hath the Author of Nature pro-
mifed this? Or were we admitted to his
council, when he eftablifhed the prefent laws
of nature, and determined the time of their

continuance ?

4*8 OF THE HUMAN MIND. (cttAP. &

continuance? No, furely. Indeed, if we be*
lieve that there is a wife and good Author of
Nature, we may fee a good reafon, why he
fhould continue the fame laws of nature, and
the fame connections of things, for a long
time : becaufe, if he did otherwife, we could
learn nothing from what is pad, and all our
experience would be of no ufe to us. But
though this conlideration, when we come to
the ufe of reafon, may confirm our belief of
the continuance or the prefent courfe of na-
ture, it is certain that it did not give rife to
this belief; for children and idiots have this
belief as foon as they know that lire will burn
them. It muft therefore be the effed of in-
fhnct, not of reafon.

The wife Author of our nature intended,
that a great and neceffary part of our know-
ledge fhould be derived from experience, be-
fore we are capable of reafoning, and he hath
provided means perfectly adequate to this in-
tention. For, firft, He governs nature by
fixed laws, fo that we find innumerable con-
nections of things which continue from age
to age. Without this liability of the courfe
of nature, there could be no experience ; or,
it would be a falfe guide, and lead us into er-
ror and miichief. If there were not a prin-
ciple

SECT. 24.] OF SEEING. 429

ciple of veracity in the human mind, men's
words would not be ligns of their thoughts :
and if there were no regularity in the courfe
of nature, no one thing could be a natural
fign of another. Secondly, He hath implant-
ed in human minds an original principle by
which we believe and expect the continuance
of the courfe of nature, and the continuance
of thofe connections which we have obferved
in time pall. It is by this general principle
of our nature, that when two things have
been found connected in time paft, the ap-
pearance of the one produces the belief of
the other.

I think the ingenious author of the Treatife
of Human Nature firft obferved, That our be-
lief of the continuance of the laws of nature
cannot be founded either upon knowledge or
probability : but, far from conceiving it to be
an original principle of the mind, he endea-
vours to account for it from his favourite hy-
pothesis, That belief is nothing but a certain
degree of vivacity in the idea of the thing
believed. I made a remark upon this curious
hypothelis in the fecond chapter, and mail
now make another.

The belief which we have in perception,
is a belief of the prefcnt exiftence of the < b-

jecf;

43° OF THE HUMAN MIND. [CHAP. 6.

jed ; that which we have in memory, is a
belief of its pad exiftence ; the belief of
which we are now fpeaking, is a belief of its
future exiftence, and in imagination there is
no belief at all. Now, I would gladly know
of this author, how one degree of vivacity
fixes the exiftence of the object to the pre-
fent moment ; another carries it back to time
paft ; a third, taking a contrary direction,
carries it into futurity ; and a fourth carries,
it out of exiftence altogether. Suppofe, for
inftance, that I lee the fun riling out of the
fea ; I remember to have {ggii him rife yefter-
day ; I believe he will rife to-morrow near
the fame place; I can likewife imagine him
rifing in that place, without any belief at all.
Now, according to this fceptical hypothefis,
this perception, this memory, this foreknow-
ledge, and this imagination, are all the fame
idea, diverfified only by different degrees of
vivacity. The perception of the fun rifing,
is the moft lively idea ; the memory of his
rifing yefterday, is the fame idea a little more
faint ; the belief of his riling to-morrow, is
the fame idea yet fainter ; and the imagina-
tion of his rifing, is ftili the fame idea, but
iainteft of all. One is apt to think, that this
idea might gradually pais through all poflible

degrees

SECT. 24.] OF SEEING. 43I

degrees of vivacity, without ftirring out of its
place. But if we think fo, we deceive our-
felves ; for no fooner does it begin to grow
languid, than it moves backward into time
paft. Suppofing this to be granted, we ex-
peel: at lead that as it moves backward by the
decay of its vivacity, the more that vivacity
decays, it will go back the farther, until it re-
move quite out of light. But here we are de-
ceived again ; for there is a certain period
of this declining vivacity, when, as if it had
met an elaftic obftacle in its motion back-
ward, it fuddenly rebounds from the pall to
the future, without taking the prefent in its
way. And now having got into the regions
of futurity, we are apt to think, that it has
room enough to fpend all its remaining vi-
gour : but ft ill we are deceived ; for, by ano-
ther fprightly bound, it mounts up into the
airy region of imagination. So that ideas, in
the gradual declenhon of their vivacity, feem
to imitate the inflection of verbs in grammar.
They begin with the prefent, and proceed in
order to the preterite, the future, and the in-
definite. This article of the fceptical creed
is indeed fo full of myfterVj on whatever fide
we view it, that they who hold that creed,
pre very injurioufly charged with increduli-
ty:

43^ OF THE HUMAN MIND. [CHAP. 6,

ty : for to me it appears to require as much
faith as that of St Athanafius.

However, we agree with the author of the
Treatife of Human Nature in this, That our
belief of the continuance of nature's laws is
not derived from reafon. It is an inftin&ive
prefcience of the operations of nature, very
like to that prefcience of human acf ions which
makes us rely upon the teftimony of our fel-
low-creatures ; and as, without the latter, we
fhould be incapable of receiving information
from men by language ; fo, without the for-
mer, we mould be incapable of receiving the
information of nature by means of experi-
ence.

All our knowledge of nature beyond our
original perceptions, is got by experience, and
conliiis in the interpretation of natural iigns.
The conftancy of nature's laws connects the
fign with the thing iignified, and, by the na-
tural principle juft now explained, we rely
upon the continuance of the connedions
which experience hath discovered ; and thus
the appearance of the fign, is followed by the
beli.t of the thing fignified.

Upon this principle of our conftitution,
not only acquired perception, but all in-
dudive reaioning, and^all our reafoning from

analogy,

S.£CT.:24.] OF SEEING. 433

analogy^ is grounded: and, therefore, for
-want of another name, we ihall beg leave to
call it the inductive principle. It is from the
force of this principle, that we immediately
aifent to that axiom upon which all our
knowledge of nature is built, That effects of
the fame kind mull have the fame caufe.
For effecls and cai/fes, in the operations of na-
ture, mean nothing but figns, and the things
fignified by them. We perceive no proper
cafualty or efficiency in any natural caufe ;
but only a connection eftablifhed by the
courfe of nature between it and what. is call-
ed its effect* Antecedently to all reafon-
ing, we have, by our conftitution, an anti-
cipation, that there is a fixed and fteady
courfe of nature ; and we have an eager de-
iire to difcover this, courfe of nature. We at-
tend to every conjunction of things which pre-
fents itfelf, and expect the continuance of that
conjunction. And when fuch a conjunction
has been often obferved, we conceive the
things to be naturally connected,, and the ap-
pearance of one, without any reafoning or re-
flection, carries along with it the belief of the
other.

If any reader fhould imagine that the in-
ductive principle may be refolved into what
E e philofophers

434 0F THE human mind. [chap. 6.

philofophers ufually call the ajfociation of
ideas, let him obferve, that, by this principle,
natural figns are not aflbciated with the idea
only, but with the belief of the things figni-
fied. Now, this can with no propriety be
called an afibciation of ideas, unlefs ideas and
belief be one and the fame thing. A child
has found the prick of a pin conjoined with
pain ; hence he believes, and knows, that thefe
things are naturally connected ; he knows that
the one will always follow the other. If any
man will call this only an afTociation of ideas,
I difpute not about words, but I think he
fpeaks very improperly. For if we exprefs it
in plain Englifh, it is a prefcience, that things
which he hath found conjoined in time pall,
-will be conjoined in time to come. And
this prefcience is not the effect of reafon-
ing, but of an original principle of latflpan
nature, which I have called the induclive prin-
ciple.

This principle, like that of credulity, is un-
limited in infancy, and gradually reftrained
and regulated as we grow up. It leads us
often into miftakes, but is of infinite advantage
upon the whole. By it the child once burnt
fhuns the fire ; by it, he likewife runs away from
the furgeon, by whom he was inoculated. It

is

SECT. 24,] OF SEEING,

435

is better that he fhould do the laft, than that
he fhould not do the firft.

But the miftakes we are led into by thefe
two natural principles, are of a different kind.
Men fometimes lead us into miftakes, when
we perfectly underftand their language, by
fpeaking lies. But nature never mifleads us
in this way ; her language is always true ;
and it is only by milinterpreting it that we
fall into error. There muft be many acciden-
tal conjundions of things, as well as natural
connections ; and the former are apt to be
miftaken for the latter. Thus, in the inftance
above mentioned, the child connected the pain
of inoculation with the furgeon ; whereas it
was really connected with the incifion only*
Philofophers, and men of fcience, are not ex-
empted from fuch miftakes ; indeed all falfe
reafoning in philofophy is owing to them : it
is drawn from experience and analogy, as well
as juft reafoning, otherwife it could have no
verifimilitude : but the one is an unfkilful and
rafh, the other a juft and legitimate, interpre-
tation of natural figns. If a child, or a man
of common underftanding, were put to inter-
pret a book of fcience, wrote in his mother-
tongue, how many blunders and miftakes would
he be apt to fall into ? Yet he knows as much
E e 2 0|*

4^6 OF THE HUMAN MIND. [cHAP. 6.

of this language as is neceflary for his manner
of life.

The language of nature is the univerfal
ftudy ; and the ftudents are of different
claffes. Brutes, idiots, and children, em-
ploy themfelves in this ftudy, and owe to
it all their acquired perceptions. Men of
common underftanding make a greater pro-
grefs, and learn, by a fmall degree of re-
fleaion, many things of which children are
ignorant.

Philofophers fill up the highefl form in this
fchool, and are critics in the language of na-
ture. All thefe different claffes have one teach-
er, Experience, enlightened by the inductive
principle. Take away the light of this in-
dudive principle, and Experience is as blind
as a mole : fhe may indeed feel what is pre-
fect, and what immediately touches her; but
fhe fees nothing that is either before or be-
hind, upon the right -.hand or upon the left,
future or pa(t.:

The rules of inductive reafoning, or of a
juft interpretation of nature, as well as the fal-
lacies by which we are apt to mifinterpret her
language, have been, with wonderful fagacity,
delineated by the great genius of Lord Ba-
con : fo that his Novum orgcinum may ju Illy

be

SECT. 24.] OF SEEING. 437

be called a grammar of the language of na-
ture. It adds greatly to the merit of this
work, and atones for its defects, that at the
time it was written, the world had not fetn any
tolerable model of inductive reafoning, from
which the rules of it might be copied. The
arts of poetry and eloquence were grown up
to perfection when Aristotle defcribed
them ; but the art of interpreting nature was
yet in embryo when BacoiV delineated its man-
ly features and proportions. Aristotle drew
his rules from the befl models of thofe arts
that have yet appeared ; but the bed models
of inductive reafoning that have yet appeared,
which I take to be the third book of the Prin-
cipia and the Optics of Newton, were drawn
from Bacon's rules. The purpofe of all thofe
'rules, is to teach us to diftinguifti feeming or
apparent connections of things in the courfe
of nature, from fuch as are real.

They that are unfkilful in inducYive rea-1
foning, are more apt to fall into error in their
reafonings from the phenomena of nature,
than in their acquired perceptions ; becaufe
we often reafon from a few inftances, and
thereby are apt to miftake accidental con-
junctions of things for natural connections :
but that habit of palling, without reafoning,
E e 3 from

43&. OF THE HUMAN MIND. [CHAP. 6.

from1 the fign to the thing fignified, which
constitutes acquired perception, mull be learn-
ed by many inftances or experiments ; and
the number of experiments ferves to disjoin
thofe things which have been accidentally
conjoined, as well as to confirm our belief of
natural connections.

From the time that children begin to ufe
their hands, nature directs them to handle
every thing over and over, to look at it while
they handle it, and to put it in various por-
tions, and at various diftances from the eye.
We are apt to excufe this as a childiih diver-
lion, becaufe they muft be doing fomething,
and have not reafon to entertain themfelves
in a more manly way. But if we think more
juftly, we fhall find, that they are engaged in
the moil ferious and important ftudy ; and if
they had all the reafon of a philofopher, they
could not be more properly employed. For
it is this childiih employment that enables
them to make the proper ufe of their eyes.
They are thereby every day acquiring habits
of perception, which are of greater import-
ance than any thing we can teach them. The
original perceptions which nature gave them
are few, and infufficient for the purpofes of
life y and therefore fhe made them capable

of

SECT. 24.] OF SEEING. * 439

of acquiring many more perceptions by ha-
bit. And to complete her work, fhe hath given
them an unwearied affiduity in applying to
the exercifes by which thofe perceptions are
acquired.

This is the education which nature gives
to her children. And lince we have fallen up-
on this fubject, we may add, that another part
of nature's education is, That, by the courfe
of things, children mud often exert all their
mufcular force, and employ all their ingenui-
ty, in order to gratify their curiofity, and fa-
tisfy their little appetites. What they defire
is only to be obtained at the expence of la-
bour and patience, and many difapp ointments.
By the exercife of body and mind neceffary
for fatisfying their defires, they acquire agili-
ty, ftrength, and dexterity in their motions*
as well as health and vigour to their conftitu-
tions ; they learn patience and perfeverance ;
they learn to bear pain without dejection, and
difappointment without defpondence. , The
education of nature is mod' perfect in fava-
ges, who have no other tutor : and we fee,
that, in the quicknefs of all their fenfes, in the
agility of their motions, in the hardinefs of
their conftitutions, and in the ftrength of their
E e 4 mind£

440 OF THE HUMAN MIND. [cHA*, &

rnirids to bear hunger, thirit, pain, and difap-
pointment, they commonly far exceed the
civilized. A moft ingenious writer, on this
account, feems to prefer the favage life to
that of fociety. But the education of na-
ture could never of itfelf produce a Rous-
seau. It is the intention of nature, that hu-
man education mould be joined to her in-
ititution, in order to form the man. And
ihe hath fitted us for human education, by
the natural principles of imitation and cre-
dulity, which difcover themfelves almoft in
infancy, as well as by others which are of la-
ter growth.

When the education which we receive from
men, does not give fcope to the education of
nature, it is wrong directed ; it tends to hurt
our faculties of perception, and to enervate
both the body and mind. Nature hath her
way of rearing men, as me hath of curing
their difeafes. The art of medicine is to fol-
low nature, to imitate and to affift her in
the cure of difeafes ; and the art of educa-
tion is to follow Nature, to aflift and to imi-
tate her in her way of rearing men. The
ancient inhabitants of the Baleares followed
nature in the manner of teaching their child-
ren to be good archers, when they hung their

dinner

SECT. 24.] OF SEElNd* 44^

dinner aloft by a thread, and left the youn-
kers to bring it down by their (kill in ar-
chery.

The education of nature, without any
more human care than is neceffary to pre-
ferve life, makes a perfect favage. Human
education, joined to that of nature, may
make a good citizen, a fkilful artifan, or a
well-bred man. But Reafon and Reflection
muft fuperadd their tutory, in order to pro-
duce a Rousseau, a Bacon, or a New-
ton.

Notwithstanding the innumerable errors
committed in human education, there is hard-
ly any education fo bad, as to be worfe than
none. And I apprehend, that if even Rous-
seau were to choofe whether to educate a
fon ampng the French, the Italians, the Chi-
nefe, or among the Efkimaux, he would not
give the preference to the laft.

When Reafon is properly employed, fhe
Will confirm the documents of nature, which
are always true and wholefome ; fhe will
diftinguifh, in the documents of human edu:
cation, the good from the bad, rejecting the
laft with modefty, and adhering to the firft

with reverence.

Moft

44^ OF TH£ HUMAN MIND. [CHAP. 6.

Moil men continue all their days to be
juft what nature and human education made
them. Their manners, their opinions, their
virtues, and their vices, are all got by habit,
imitation, and inftrudtion ; and Reafon has
little or no fhare in forming them.

CHAP.

CHAP. 7-] CONCLUSION. 443

CHAP. VII.
CONCLUSION.

Containing Reflediions upon the opinions of
Philofophers on this fubjeft.

THERE are two ways in which men may
form their notions and opinions con-
cerning the mind, and concerning its powers
and operations. The firft is the only way
that leads to truth ; but it is narrow and rug-
ged, and few have entered upon it. The fe-
cond is broad and fmooth, and hath been
much beaten, not only by the vulgar, but
even by philofophers : it is fufficient for com-
mon life, and is well adapted to the purpofes
of the poet and orator : but, in philofophical
difquifitions concerning the mind, it leads to
error and delufion.

We

444 Of the human mind. £chap. 7,

We may call the firft of thefe ways, the
way of reflettion. When the operations of
the. mind are exerted, we are confcious of
them ; and it is in our power to attend to
them, and to reflect upon them, until they be-
come familiar objects of thought. This is
the only way in which we can form juft and
accurate notions of thofe operations. But this
attention and reflection is fo difficult to man,
furrounded on all hands by external objects,
which conftantly folicit his attention, that it
has been very little practifed, even by philo-
fophers. In the courfe of this Inquiry, we
have had many occafions to mow, how little
attention hath been given to the molt fami-
liar operations of the fenfes.

The fecond, and the moll common way,
in which men form their opinions concerning
the mind and its operations, we may call the
way of analogy. There is nothing in the
courfe of nature fo lingular, but we can find
fome refemblance, or at lead fome analogy,
between it and other things with which we
are acquainted. The mind naturally delights
in hunting after fuch analogies, and attends
to them with pleafure. From them, poetry
and wit derive a great part of their charms ;

and

/

£HAP. 7.] CONCLUSION. 445

and eloquence, not a little of its perfuafive
force.

Beiides the pleafure we receive from analo-
giesj they are of very confidcrable ufe, both
to facilitate the conception of things, when
they are not ealily apprehended without fuch
a handle, and to lead us to probable conjec-
tures about their nature and qualities, when
we want the means of more direct and imme-
diate knowledge. When I confider that the
planet Jupiter, in like manner as the earth,
rolls round his own axis, and revolves round
the fun, and that he is enlightened by feverai
fecondary planets, as the earth is enlightened
by the moon ; I am apt to conjecture from
analogy, that as the earth by thefe means is
fitted to be the habitation of various orders
of animals, fo the planet Jupiter is, by the
like nteans, fitted for the fame purpofe : and
having no argument more direct and conclu-
iive to determine me in this point, I yield, to
this analogical reafoning, a degree of aflent
proportioned to its ftrength. When 1 ob-
ferve, that the potato plant very much re-
fembles the folanum in its flower and fructifi-
cation, and am informed, that the laft is poi-
fonous, I am apt from analogy to have fome
fufpicion of the former : but in this cafe, I

have

446 OF THE HUMAN MIND. [CHAK 7-

have accefs to more dired and certain evi-
dence ; and therefore ought not to truft to
analogy, which would lead me into an error.
Arguments from analogy are always at
hand, and grow up fpontaneoufly in a fruit-
ful imagination, while arguments that are
more dired, and more conclufive, often re-
quire painful attention and application : and
therefore, mankind in general have been very
much difpofed to truft to the former. If one
attentively examines the fy Items of the an-
cient philofophers, either concerning the ma-
terial world, or concerning the mind, he will
find them to be built folely upon the founda-
tion of analogy. Lord Bacon firft delineated
the ftricl: and fevere method of induftion ;
fince his time it has been applied with very
happy fuccefs in fome parts of natural philo-
fophy ; and hardly in any thing elfe\ But
there is no fubjecl: in which mankind are fo
much difpofed to truft to the analogical way
of thinking and reafoning, as in what concerns
the mind and its operations ; becaufe, to form
clear and diftindt notions of thofe operation*
in the dired and proper way, and to reafon
about them, requires a habit of attentive re-
flection, of which few are capable, and which,

even,

CHAP. 7.] CONCLUSION. 447

even by thofe few, cannot be attained with-
out much pains and labour.

Every man is apt to form his notions of
things difficult to be apprehended, or lefs fa-
miliar, from their analogy to things which
are more familiar. Thus, if a man bred to
the feafaring life, and accu domed to think
and talk only of matters relating to naviga-
tion, enters into difcourfe upon any other fub-
ject ; it is well known, that the language and
the notions proper to his own profeffion are
infufed into every fubject, and all things are
meafured by the rules of navigation : and if
he fhould take it into his head to philofophize
concerning the faculties of the mind, it can-
not be doubted, but he would draw his no-
tions from the fabric of his fhip, and would
find in the mind, fails, mads, rudder, and
compafs.

Senlible obje&s of one kind or other, do no
lefs occupy and engrofs the reft of mankind,
than things relating to navigation, the fea-
faring man. For a confiderable part of life,
we can think of nothing but the objects of
fenfe; and to attend to objects of another
nature, fo as to form clear and diftinct no-
tions of them, is no eafy matter, even after
we come to years of reflection. The condi-
tion

44? OF THE HUMAN MIND. [CHAP. 7#

tion of mankind, therefore, affords good rea^
fon to apprehend, that their language, and
their common notions, concerning the mind
and its operations, will be analogical, and de-
rived from the objects of. ienfe ; and that
thefe analogies will .be" apt to impofe upon
philofophers, as well as upon the vulgar, an4
to lead them to materialize the mind audits
faculties ; and experience abundantly con-
firms the truth. of this.

How generally men of all nations, and in
all ages of the world, have conceived the foul,
or thinking principle in man, to be fome fub-
tile matter, like breath or wind, the names
given to it almoft in all languages fufficiently
teftify. We have words which are proper,
and not analogical, to exprefs the various
ways in which we perceive external objects
by the fenfes ; fuch as feeling, fght, tajle :
but we are often obliged to ufe thefe words
analogically, to exprefs other powers of the
mind which are of a very different nature.
And the powers- which imply fome degree
of reflection, have generally no names but
fuch as are analogical. The objects of thought
are faid to be in the mind, to be apprehended,
comprehended, conceived, imagined, retained,
weighed, ruminated.

It

CHAP. 7.] CONCLUSION.

449

It does not appear that the notions of the
ancient philofophers, with regard to the na-
ture of the foul, were much more refined than
thofe of the vulgar, or that they were formed
in any other way. We fhall diftinguifh the phi-
lofophy that regards our fubjedl into the old
and the new. The old reached down to Des
Cartes, who gave it a fatal blow, of which
it has been gradually expiring ever fince, and
is now almoft extinct. Des Cartes is the
father of the new philofophy that relates to
this fubjecl: ; but it hath been gradually im-
proving fince his time, upon the principles
laid down by him. The old philofophy feems
to have been purely analogical : the new is
more derived from reflection, but ftill with a
very confiderable mixture of the old analogi-
cal notions.

Becaule the objects of fenfe confift of mat-
ter and form, the ancient philofophers con-
ceived every thing to belong to one of thefe,
or to be made up of both. Some therefore
thought, that the foul is a particular kind of
fubtile matter, feparable from our grofs bo-
dies ; others thought that it is only a parti-
cular form of the body, and infeparable from
it. For there feem to have been fome among
the ancients, as well as among the moderns,
F f who

450 OF THE HUMAN MIND. [CHAP. 7.

who conceived that a certain ftrudure or or-
ganization of the body, is all that is neceffary
to render it fenfible and intelligent. The
different powers of the mind were, accord-
ingly, by the laft fed of philosophers, concei-
ved to belong to different parts of the body,
as the heart, the brain, the liver, the flomach,
the blood.

They who thought that the foul is a fub-
tile matter feparable from the body, difputed
to which of the four elements it belongs*
whether to earth, water, air, or fire. Of the
three laft, each had its particular advocates.
But fome were of opinion, that it partakes of
all the elements ; that it rauft have fomething
in its compofition fimilar to every thing we
perceive ; and that we perceive earth by the
earthly part \ water, by the watery part ; and
fire, by the fiery part of the foul. Some phi-
lofophers, not fatisfied with determining of
what kind of matter the foul is made, inqui-
red likewife into its figure, which they deter-
mined to be fpherical, that it might be the
more fit for motion. The moil fpiritual and
fublime notion concerning the nature of the
foul, to be met with among the ancient phi-
losophers, I conceive to be that of the Plato-
nifts, who held, that it is made of that cele,

ftial

CHAP. 7.] CONCLUSION. 45*

ftial and incorruptible matter of which the
fixed ftars were made, and therefore has a
natural tendency to rejoin its proper element.
I am at a lofs to fay, in which of thefe clafles
of philofophers Aristotle ought to be pla-
ced. He defines the foul to be, The firft »t(-
Ae^«« of a natural body which has potential
life. I beg to be excufed from tranflating
the Greek word, becaufe I know not the
meaning of it.

The notions of the ancient philofophers
with regard to the operations of the mind,
particularly with regard to perceptions and
ideas, feem like wife to have been formed by
the fame kind of analogy.

Plato, of the writers that are extant, firft
introduced the word idea into philofophy ;
but his doctrine upon this fubject. had fome-
what peculiar. He agreed with the reft of
the ancient philofophers in this, that all things
confift of matter and form ; and that the
matter of which all things were made, exift-
ed from eternity, without form : but he like-
wife believed, that there are eternal forms of
all poflible things which exift, without mat-
ter ; and to thefe eternal and immaterial
forms he gave the name of ideas ; maintain-
ing, that they are the only object of true
Ff2 knowledge.

452 OF THE HUMAN MIND. [CHAP.7.

knowledge. It is of no great moment to us,
whether he borrowed theie notions from Par-
menides, or whether they were the iffue of
his own creative imagination. The latter
Platonifts feem to have improved upon them,
in conceiving tKofe ideas, or eternal forms of
things, t;o exift, not of themfelves, but in the
Divine Mind, and to. be the models and
patterns according to which all things were
made :

Then liiid the Eternal One, then, deep retird
In his unfathomd eflence, view'd at large
The uncreated images of things.

To thefe Platonic notions, that of Male-
branche is very nearly allied. This author
feems, more than any other, to have been
aware of the difficulties attending the com-
mon hypothecs concerning ideas, to wit,
That ideas of all obje&s of thought are in the
human mind ; and therefore, in order to a-
void thofe difficulties, makes the ideas which
are the immediate objects of human thought,
to be the ideas of things in the Divine Mind ;
who being intimately prefent to every human
mind, may difcover his ideas to it, as far as

pleafeth him.

The

CHAP. 7.] CONCLUSION. 453

The Platonifts and Malebranche except-
ed, all other philofophers, as far as I know,
have conceived that there are ideas or images
of every object of thought in the human
mind, or at leaft in fome part of the brain,
where the mind is fuppofed to have its refi-
dence.

Aristotle had no good affection to the
word idea,, and feldom or never ufes it but
in refuting Plato's notions about ideas. He
thought that matter may exift without form ;
but that forms cannot exift without matter.
But at the fame time he taught, That there
can be no fenfation, no imagination, nor in-,
telle&ion, without forms, phantafms, or fpe-
cies in the mind ; and that things fenfible are
perceived by fenfible fpccies, and things in-
telligible by intelligible fpecies. His follow-
ers taught more explicitly, that thofe fenfible
and intelligible fpecies are fent forth by the
objects, and make their impreffions upon the
paffive intellect ; and that the active intellect,
perceives them in the paffive intellect. And
this feems to have been the common opinion
while the Peripatetic philofophy retained its
authority.

The Epicurean do&rine, as explained by

Lucretius, though widely different from the

F f 3 Peripatetic

454 0F T"* HUMAN MIND. [CHAP. J.

Peripatetic in many things, is almoft the fame
in this. He affirms, that flender films or ghofts
(tenuia rerum Jimulacra) are ft ill going off
from all things and flying about ; and that
thefe being extremely fubtile, eafily penetrate
our grofs bodies* and ftriking upon the mind,
caufe thought and imagination.

After the Peripatetic fyftem had reigned
above a thoufand years in the fchogls of Eu-
rope, almoft without a rival, it funk before
that of Des Carte9 ; the perfpicuity of whofe
writings and notions, contrafted with the ob-
fcurity of Aristotle and his commentators,
created a ftrong prejudice in favour of this
new philofophy. The characteriftic of Pla-
to's genius was fublimity, that of Aristo-
tle's, fubtilty ; but Des Cartes far excel-
led both in perfpicuity, and bequeathed this
fpirit to his fucceflbrs. The fyftem which is
now generally received, with regard tq the
mind and its operations, derives not only its
fpirit from Des Cartes, but its fundamental
principles ; and after all the improvements
made by Malebranche, Locke, Berkeley,
and Hume, may ftill be called the jCarteJian
fyjlem : we (hall therefore make fome remarks
upon its fpirit and tendency in general, and

upon

CHAP. 7.] CONCLUSION. 455

upon its doctrine concerning ideas in parti-
cular.

1. It may be obferved, That the method
which Des Cartes purfued, naturally led
him to attend more to the operations of the
mind by accurate reflection, and to truft lefs
to analogical reafoning upon this fubjecT:,
than any philofopher had done before him.
Intending to build a iyftem upon a new foun-
dation, he began with a refolution to admit
nothing but what was abfolutely certain and
evident. He fuppofed that his fenfes, his me-
mory, his reafon, and every other faculty to
which we truft in common life, might be fal-
lacious ; and refolved to dilbelieve every thing,
until he was compelled by irreiiftible evidence
to yield affent.

In this method of proceeding, what appear-
ed to him, firft of all, certain and evident,
was, That he thought, that he doubted, that
he deliberated. In a word, the operations of
his own mind, of which he was confcious,
mud be real, and no delufion ; and though
all his other faculties fhould deceive him, his
confcioufnefs could not. This therefore he
looked upon as the firft of all truths. This
was the firft firm ground upon which he fet
his foot, after being tofied in the ocean of
F f 4 fcepticifm j

456 OF THE HUMAN MJND. [CHAP. Jn

fcepticifm j and he refolved to build all know-
ledge upon it, without feeking after any more
firft principles.

As every other truth, therefore, and parti-
cularly the exiftence of the objeds of fenfe,
was to be deduced by a train of ftricl: argu-
mentation from what he knew by confciouf-
nefs, he was naturally led to give attention to
the operations of which he was confcious,
without borrowing his notions of them from
external things.

It was not in the way of analogy, but of
attentive reflection, that he was led to obferve,
That thought, volition, remembrance, and the
other attributes of the mind, are altogether
unlike to extenfion, to figure, and to all the
attributes of body ; that we have no reafon,
therefore, to conceive thinking fubftances to
have any refemblance to extended fubftances ;
and that, as the attributes of the thinking fub-
ftance are things of which we are confcious,
we may have a more certain and immediate
knowledge of them by refledion, than we can
have of external objedts by our fenfes.-

Thefe observations, as far as I know, were
firft made by Des Cartes ; .and they are of
more importance, and throw more light upon
the fubjecl, than all that had been faid upon

it

CHAP. 7. J CONCLUSION- 457

it before. They ought to make us diffident
and jealous of every notion concerning the
mind and its operations, which is drawn from
ienfible obje&s in the wray of analogy, and to
make us rely only upon accurate reflection,
as the fource of all real knowledge upon this
fubjecT:.

2. I obferve, that as the Peripatetic fyftem
has a tendency to materialize the mind, anc7.
its operations ; fo the Cartefian has a tenden-
cy to fpiritualize body, and its qualities. One,
error, common to both fyftems, leads to the
firft of thefe extremes in the way of analogy,
and to the laft, in the way of reflection. The
error I mean is, That we can know nothing
about body, or its qualities, but as far as we,
have fenfations, which refemble thofe quali-
ties. Both fyftems agreed in this : but ac-
cording to their different methods of reafon-
ing, they drew very different conclusions from
it ; the Peripatetic drawing his notions of fen-
fation from the qualities of body ; the Car-
tefian, on the contrary, drawing his notions of
the qualities of body from his fenfations.

The Peripatetic, taking it for granted that
bodies and their qualities do really exift, and
are fuch as we commonly take them to be,
inferred from them the nature of his fenfa-
tions,

458 OF THE HUMAN MIND. [CHAP. 7.

lions, and reafoned in this manner : Our
fenfations are the impreffions which fenfible
obje&s make upon the mind, and maybe com-
pared to the impreflion of a feal upon wax ;
the impreflion is the image or form of the
feal, without the matter of it : in like man-
ner, every fenfation is the image or form of
fome fenfible quality of the objecl. This is
.the reafoning of Aristotle, and it has an evi-
dent tendency to materialize the mind, and
its fenfations.

The Cartefian, on the contrary, thinks, that
the exiftence of body, or of any of its quali-
ties, is not to be taken as a firft principle;
and that we ought to admit nothing concern-
ing it, but what, by juft reafoning, can be de-
duced from our fenfations ; and he knows,
that by reflection we can form clear and di-
ftinct notions of our fenfations, without bor-
rowing our notions of them by analogy from
the objects of fenfe. The Cartefians, there-
fore, beginning to give attention to their fen-
fations, firft discovered that the fenfations
correfponding to fecondary qualities, cannot
refemble any quality of body. Hence, Des
Cartes and Locke inferred, that found, tafte,
fmell, colour, heat, and cold, which the vul-
gar took to be qualities of body, were not

qualities

CHAP. 7.] CONCLUSION. 459

qualities of body, but mere fenfations of the
mind. Afterwards the ingenious Berkeley,
confidering more attentively the nature of
fenfation in general, difcovered, and demon-
ftrated, that rto fenfation whatever could pof-
iibly refemble any quality of an infentient
being, fuch as body is fuppofed to be : and
hence he inferred, very juftly, that there is
the fame reafon to hold extenfion, figure, and
all the primary qualities, to be mere fenfa-
tions, as there is to hold the fecondary quali-
ties to be mere fenfations. Thus, by juft rea-
foning upon the Cartefian principles, matter
was ftript of all its qualities ; the new fyftem,
by a kind of metaphyfical fublimation, con-
verted all the qualities of matter into fenfa-
tions, and fpiritualized body, as the old had
materialized fpirit.

The way to avoid both thefe extremes, is,
to admit the exiftence of what we fee and feel
as a firft principle, as well as the exiftence of
things whereof we are confcious ; and to take
our notions of the qualities of body, from the
teftimony of our fenfes, with the Peripatetics ;
and our notions of our fenfations, from the
teftimony of confcioufnefs, with the, Carte-
fians.

3-*

460 OF THE HUMAN MIND. [CHAP. Ji

3. I obfervc, That the modern fcepticifm is
the natural iffue of the new fyftem ; and that,
although it did not bring forth this monfter
until the year 1739, n may be faid to have
carried it in its womb from the beginning.

The old fyftem admitted all the principles
of common fenfe as firft principles, without
requiring any proof of them ; and therefore,
though its reafoning was commonly vague,
analogical, and dark, yet it was built upon a
broad foundation, and had no tendency to
fcepticifm. We do not find that any Peripa-
tetic thought it incumbent upon him to prove
the exiftence of a material world ; but every
writer upon the Cartefian fyftem attempted
this, until Berkeley clearly demonftrated the
futility of their arguments ; and thence con-
cluded, that there was no fuch thing as a ma-
terial world ; and that the belief of it ought
to be rejected as a vulgar error.

The new fyftem admits only one of the
principles of common fenfe as a firft principle ;
and pretends, by ftricl: argumentation, to de-
duce all the reft from it. That our thoughts,
our fenfations, and every thing of which we
are confeious, hath a real exiftence, is admit-
ted in this fyftem as a firft principle ; but
^very thing elfe muft be made evident by the

light

chap. 7.] Conclusion. 4O1:

light of reafon. Reafon rauft rear the whole
fabric of knowledge upon this iingle prin-
ciple of confeioufnefs.

There is a difpoiition in human nature to
reduce things to as few principles as poflible ;
and this, without doubt, adds to the beauty
of a fyftem, if the principles are able to fup-
port what refts upon them. The mathema-
ticians glory, very juftly, in having raifed fo
noble and magnificent a fyilem of fcience, up-
on the foundation of a few axioms and defi-
nitions. This love of fimplicity, of reducing
things to few principles, hath produced ma-
ny a falfe fyftem ; but there never was any
fyftem in which it appears fo remarkably as
that- of Des Cartes. His whole fyftem con-
cerning matter and fpirit is built upon one
axiom, exprefled in one word, Cogito. Upon
the foundation of confeious thought, with
ideas for his materials, he builds his fyftem of
the human underftanding, and attempts to
account for all its phenomena : And having,
as he imagined, from his confeioufnefs, pro-
ved the exiftence of matter, and of a certain
quantity of motion originally imprefled upon
it, he builds his fyftem of the material world,
and attempts to account for all its pheno-
mena.

Thefe

46a Of THE HUMAN MIND. [CHAP. 7,

*

Thefe principles, with regard to the mate-
rial fyftem, have been found infufficient ; and
it has been made evident, that beiides matter
and motion, we mud admit gravitation, co-
hefion, corpufcular attraction, magnetifm, and
other centripetal and centrifugal forces, by
which the particles of matter attract and re-
pel each other. Newton, having difcovered
this, and demonftrated, that thefe principles
cannot be refolved into matter and motion,
was led by analogy, and the love of fimpli-
city, to conjecture, but with a modefly and
caution peculiar to him, that all the pheno-
mena of the material world depended upon
attracting and repelling forces in the particles
of matter. But we may now venture to fay,
that this conjecture fell fhort of the mark.
For, even in the unorganized kingdom, the
powers by which falts, cryftals, fpars, and
many other bodies, concrete into regular
forms, can never be accounted for by attract-
ing and repelling forces in the particles of
matter. And in the vegetable and animal
kingdoms, there are ftrong indications of
powers of a different nature from all the
powers of unorganized bodies. We fee then,
that although in the flructure of the material
world there is, without doubt, all the beauti-
ful

CHAP. 7.] CONCLUSION; 463

ful fimplicity confiftent with the purpofes for
which it was made, it is not fo fimple as the
great Des Cartes determined it to be : nay,
it is not fo fimple as the greater Newton
modeftly conjectured it to be. Both were
milled by analogy, and the love of fimplicity.
One had been much converfant about exten-
lion, figure, and motion ; the other had en-
larged his views to attracting and repelling
forces \ and both formed their notions of the
unknown parts of nature, from thofe with
which they were acquainted, as the fhepherd
Tityrus formed his notion of the city of
Rome from his country village :

Urbem quam dicunt Romam, Melibcee, putavi
Stultus ego, huic nqftra Jimilem, quo fope folemus
Pajiores ovium teneros depellere foetus.
Sic canibus catulos Jimiles,fic matribus hcedos
Nor am : Jlc parvis componere magna foleb am.

This is a juft picture of the analogical way
of thinking.

But to come to the fyftem of Des Cartes,
concerning the human underflanding ; it was
built, as we have obferved, upon confciouf-
nefs as its fole foundation, and with ideas as
its materials ; and all his followers have built

upon

4^4 OF THE HUMAN MIND. [CHAP. 7,

upon the fame foundation, and with the fame
materials.. They acknowledge that nature
hath given us various fimple ideas: Thefe
are analogous to the matter of Des Cartes's
phyfical fyftem. They acknowledge like-
wife a natural power by which ideas are
compounded, disjoined, afTociated, compared :
This is analogous to the original quantity of
motion in Des Cartes's phyfical fyftem.
From thefe principles they attempt to ex-
plain the phenomena of the human under-
ilanding, jufl: as in the phyfical fyftem the
phenomena of nature were to be explained
by matter and motion. It muft indeed be
acknowledged, that there is great fimplicity
in this fyftem as well as in the other. There
is fuch a fimilitude between the two, as may
be expected between children of the fame fa-
ther : but as the one has been found to be the
child of Des Cartes, and not of nature,
there is ground to think that the other is fo
like wife.

That the natural iflue of this fyftem is
fcepticifm with regard to every thing except
the exiftence of our ideas, and of their ne-
ceflary relations which appear upon com-
paring them, is evident : for ideas being the
only obje&s of thought, and having no exift-

ence

CHAP. 7.] CONCLUSION. 465

ence but when we are confeious . of them,
it necefiarily follows, that there is no object
of our thought which can have a continued
and permanent exigence. Body and fpirit,
caufe and effect, time and fpace, to which
we were wont to afcribe an exiftence inde-
pendent of our thought, are all turned out of
exiftence by this fhort dilemma : Either thefe
things are ideas of fenfation or refledion, or
they are not : if they are ideas of fenfation
or reflection, they can have no exiftence but
when we are confeious of them > if they are
not ideas of fenfation or reflection, they are
words without any meaning.

Neither Des Cartes nor Locke perceived
this confequence of their fyftem concerning
ideas. Bifhop Berkeley was the firft who
difcovered it. And what followed upon this
difcovery ? Why, with regard to the material
world, and with regard to fpace and time, he
admits the confequence, That thefe things
are mere ideas, and have no exiftence but in
our minds : but with regard to the exiftence
of fpirits or minds, he does not admit the
confequence ; and if he had admitted it, he
mud have been an abfolute fceptic. But how
does he evade this confequence with regard
to the exiftence of fpirits ? The expedient
G g which

466 OF THE HUMAN MIND. [CHAP. 7;

which the good Bifhop ufes on this occafion
is very remarkable, and fhows his great aver-
fion to fcepticifm. He maintains, that we
have no ideas of fpirits ; and that we can
think, and fpeak, and reafon about them, and
about their attributes, without having any
ideas of them. If this is fo, my Lord, what
ihould hinder us from thinking and reafon-
ing about bodies, and their qualities, with-
out having ideas of them ? The Bifhop ei-
ther did not think of this queftion, or did not
think fit to give any anfwer to it. However,
we may obferve, that in order to avoid fcep-
ticifm, he fairly ftarts out of the Cartefian fy-
ftem, without giving any reafon why he did
fo in this inftance, and in no other. This
indeed is the only inftance of a deviation
from Cartefian principles which I have met
with in the fucceffors of Des Cartes ; and
it feems to have been only a fudden (tart, ,
occafioned by the terror of fcepticifm ; for
in all other things Berkeley's fyftem is
founded upon Cartefian principles.

Thus we fee, that Des Cartes and Locke
take the road that leads to fcepticifm, with-
out knowing the end of it ; but they flop
ftiort for want of light to carry them farther.
Berkeley, frighted at the appearance of the

dreadful

CHAP. 7.] CONCLUSION. 467

dreadful abyfs, ftarts afide, and avoids it.
But the author of the Treatife of Human
Nature, more daring and intrepid, without
turning afide to the right hand or to the left,
like Virgil's Ale&o, (hoots directly into the
gulf:

Hie fpecus horrendum, et fa<oi fpir acuta Litis
Monjirantur : ruptoque ingens Acheronte vorago
Peftiferas aperit fauces.

4. We may obferve, That the account given
by the new fyftem, of that furniture of the
human underftanding which is the gift of na-
ture, and not the acquifition of our own rea-
foning faculty, is extremely lame and im-
perfect.

The natural furniture of the human un-
derftanding is of two kinds ; Firft, The no-
tions or fimple apprehenfions which we have
of things : and, Secondly, The judgments or
the belief which we have concerning them.
As to our notions, the new fyftem reduces
them to two clafles ; ideas of fenfation and
ideas of refledlion : the firft are conceived to
be copies of our fenfations, retained in the
memory or imagination ; the fecond, to be
copies of the operations of our minds where-
G g 2 of

468 OF THE HUMAN MIND. [CHAP. *]..

of we are confcious, in like manner retained
in the memory or imagination : and we are
taught, that thefe two comprehend all the ma-
terials about which the human understanding
is, or can be, employed.. As to our judgment
of things, or the belief which we have con-
cerning them, the new fyftem allows no part
of it to be the gift of nature, but holds it to
be the acquifition of reafon, and to be got by
comparing our ideas, and perceiving their
agreements or diiagreements. Now I take
this account, both of our notions, and of our
judgments or belief, to be extremely imper-
fect ; and 1 mall briefly point out fome of its
capital defects.

The divifion of our notions into ideas of
fenfation, and ideas of reflection, is contrary
to all rules of logic ; becaufe the fecond mem-
ber of the divifion includes the nrft. For,
can we form clear and juft notions of our fen-
fations any other way than by reflection ?
Surely we cannot. Senfation is an operation
of the mind of which we are confcious ; and
we get the notion of fenfation, by reflecting
upon that which wc are confcious of. In
like manner, doubting and believing arc ope-
rations of the mind whereof we are con-
fcious ; and we get the notion of them by

reflecting

CHAP. 7.] CONCLUSION.

reflecting upon what we are confcious of.
The ideas of fenfation, therefore, are ideas
of reflection, as much as the ideas of doubt-
ing or believing, or any other ideas whatfo-
ever.

But to pafs over the inaccuracy of this di-
vifion, it is extremely incomplete. For, fince
fenfation is an operation of the mind, as well
as all the other things of which we form our
notions by reflection; when it is averted,
that all our notions are either ideas of fenfa-
tion, or ideas of refledion, the plain Englifh
of this is, That mankind neither do, nor can
think of any thing but of the operations .of
their own minds. Nothing can be more
contrary to truth, or more contrary to the
experience of mankind. I know that Locke,
while he maintained this doctrine, believed
the notions which we have of body and of
its qualities, and the notions which we have of
motion and of fpace, to be ideas of fenfation.
But why did he believe this.? Becaufe he be-
lieved thofe notions to be nothing elfe but
images of our fenfations. If therefore the
notions of body and its qualities, of motion
and fpace, be not images of our fenfations,
will it not follow, that thofe notions are not
ideas of fenfation ? Moft certainly.

G g 3 There

470 OF THE HUMAN MIND. [CHAP. 7.

There is no doctrine in the new fyftem
which more directly leads to fcepticifm than
this. And the author of the Treatife of Human
Nature knew very well how to ufe it for that
purpofe : for, if you maintain that there is
any fuch exiftence as body or fpirit, time or
place, caufe or effect, he immediately catches
you between the horns of this dilemma ; your
notions of thefe exigences are either ideas of
fenfation, or ideas of reflection ; if of fenfa-
tion, from what fenfation are they copied ?
if of reflection, from what operations of the
mind are they copied ?

It is indeed to be wifhed, that thofe who
have written much about fenfation, and about
the other operations of the mind, had like-
wife thought and reflected much, and with
great care, upon thofe operations : but is it
not very flrange, that they will not allow it
to be poffible for mankind to think of any
thing elfe ?

The account which this fyftem gives of our
judgment and belief concerning things, is as
far from the truth as the account it gives of
our notions or fimple apprehenfions. It re-
prefents our fenfes as having no other office,
but that of furniihing the mind with notions
or fimple apprehenfions of things ; and makes

our

CHAP. 7-3 CONCLUSION. 471

our judgment and belief concerning thofe
things to be acquired by comparing our no-
tions together, and perceiving their agree-
ments or difagreements.

We have fhown, on the contrary, that every
operation of the fenfes, in its very nature, im-
plies judgment or belief, as well as fimple ap-
prehenfion. Thus, when I feel the pain of
the gout in my toe, I have not only a notion
of pain, but a belief of its exigence, and a
belief of fome diforder in my toe which oc-
cafions it ; and this belief is not produced
by comparing ideas, and perceiving their
agreements and difagreements ; it is included
in the very nature of the fenlation. When I
perceive a tree before me, my faculty of fee-
ing gives me not only a notion or iimple ap-
prehenfion of the tree, but a belief of its exift-
ence, and of its figure, diftance, and magni-
tude ; and this judgment or belief is not got
by comparing ideas, it is included in the very
nature of the perception. We have taken no-
tice of feveral original principles of belief in
the courfe of this inquiry ; and when other
faculties of the mind are examined, we fliall
find more, which have not occurred in the
examination of the five- fenfes.

Gg4 Such

472 OF THE HUMAN MIND. [CHA*. J.

Such original and natural judgments are
therefore a part of that furniture which na-
ture hath given to the human underftanding.
They are the infpiration of the Almighty, no
lefs than our notions or fimple apprehenfions.
They ferve to dired us in the common affairs
of life, where our reafoning faculty would
leave us in the dark. They are a part of our
conftitution, and all the difcoveries of our
reafon are grounded upon them. They make
up what is called the common fenfe of man-
kind; and what is manifeltly contrary to any
of thofe firft principles, i^ what we call abfurd.
The ftrength of them is *%od fenfe, which is
often found in thofe who are not acute in
reafoning. A remarkable deviation from
them, ariiing from a difordcr in the conftitu-
tion, is what we call lunacy ; as when a man
believes that he is made of glafs. When a
man fuffers himfelf to be reafoned out of the
principles of common fenfe, by metaphyseal
arguments, we may call this metaphyseal lu-
nacy ; which differs from the other fpecies
of the diftemper in this, that it is not conti-
nued, but intermittent : it is apt to feize the
patient i* folitary and fpeculative moments;
but when he enters into fociety, Common
Senfe recovers her authority. A clear expli-
cation

CHAP. 7.] CONCLUSION. 473

cation and enumeration of the principles of
common fenfe, is one of the chief dejiderata
in logic. We have only confidered fuch of
them as occurred in the examination of the
five fenfes.

5. The laft bbfervation that I fhall make
upon the new fyftem is, That, although it
profeffes to fet out in the way of reflection,
and not of analogy, it hath retained fome of
the old analogical notions concerning the ope-
rations of the mini ; particularly, That
things which do not now exift in the mind it-
felf, can only be perceived, remembered, or
imagined, by means of ideas or images of
them in the mind, which are the immediate
objects of perception, remembrance, and ima-
gination. This doctrine appears evidently to
be borrowed from the old fyftem ; which
taught, that external things make impreffions
upon the mind, like the impreffions of a feal
upon wax ; that it is by means of thofe im-
preffions that we perceive, remember, or ima-
gine them ; and that thofe impreffions muft
refemblc the things from which they are ta-
ken. When we form our notions of the ope-
rations of the mind by analogy, this way of
conceiving them feems to be very natural,
and offers itfelf to our thoughts : for as every

thing

474 0F THE HUMAN MIND. [CHAP, J.

thing which is felt muft make fome impref-
lion upon the body, we are apt to think, that
every thing which is underftood muft make,
fome impreflion upon the mind.

From fuch analogical reafoning, this opi-
nion of the exiftence of ideas or images of
things in the mind, feems to have taken its
rife, and to have been fo univerfally received
among philofophers. It was obferved alrea-
dy, that Berkeley, in one inftance, apoftatizes
from this principle of the new fyftem, by af-
firming, that we have no ideas of fpirits, and
that we can think of them immediately, with-
out ideas. But 1 know not whether in this
he has had any followers. There is fome dif-
ference likewife among modern philofophers,
with regard to the ideas or images by which
we perceive, remember, or imagine fenfibie,
things. For, though all agree in the exif-
tence of fuch images, they differ about their
place ; fome placing them in a particular part
of the brain, where the foul is thought to have
her refidence, and others placing them in the
mind itfelf. Des Caki es held the fir ft of thefe,
opinions; to which New ion feems likewife
to have inclined; for he propofes this query
in his Optics: " Annon fenfoiium animalium
" eft locus cui fubftantia fentiens adeft, et in

" quern,

CHAP. 7.} CONCLUSION. 475

" quern fenfibiles rerum fpecies per nervos et
" cerebrum deferuntur, ut ibi praefentes a
" praefente fentiri poffint ; " But Locke feems
to place the ideas of fenfible things in the
mind : and that Berkeley, and the author of
the Treatife of Human Nature ', were of the fame
opinion, is evident. The laft makes a very
curious application of this doctrine, by en-
deavouring to prove from it, That the mind
either is no fubftance, or that it is an extend-
ed and divilible fubftance ; becaufe the ideas
of extenlion cannot be in a fubjecl: which is
indivifible and unextended.

I confefs I think his reafoning in this, as in
moll cafes, is clear and ftrong. For whether
the idea of extenlion be only another name
for extenlion itfelf, as Berkeley and his au-
thor aflert ; or whether the idea of extenlion
be an image and refemblance of extenlion, as
Locke conceived ; I appeal to any man of
common fenfe, whether extenlion, or any
image of extenlion, can be in an unextended
and indivifible fubjecl:. But while I agree
with him in his reafoning, I would make a
different application of it. He takes it for
granted, that there are ideas of extenlion in
the mind ; and thence infers, that if it is at
all a fubftance, it muft be an extended and

divifible

476 OF THE HUMAN MIND. [CHAK 7.

divifible fubftance. On the contrary, I take
it for granted, upon the teftimony of common ,
fenfe, that my mind is a fubftance, that is, a
permanent fubject of thought ; and my rea-
fon convinces me, that it is an unextended
and indivifible fubftance ; and hence I infer,
that there cannot be in it any thing that re-
fembles exteniion. If this reafoning had oc-
curred to Berkeley, it would probably have
led him to acknowledge, that we may think
and reafon concerning bodies, without having
ideas of them in the mind, as well as concern-
ing fpirits.

I intended to have examined more particu-
larly and fully this doctrine of the exiftence
of ideas or images of things in the mind ; and
likewife another doctrine, which is founded
upon it, to wit, That judgment or belief is
nothing but a perception of the agreement or
difagreement of our ideas : but having alrea-
dy fhewn, through :the courfe of this inquiry,
that the operations of the mind which we
have examined, give no countenance to either
of thefe dodrines, and in many things con-
tradict them, I have thought it proper to
drop this part of my defign. It may be exe-
cuted with more advantage, if it is at all ne-
ceifary, after inquiring into fome other powers
of the hu man underftanding.

Although

chap. 7.3 CONCLUSION. 477

Although, we have examined only the five
fenfes, and the principles of the human mind
which are employed about them, or fuch as
have fallen in our way in the courfe of this
examination \ we fhali leave the further pro-
fecution of this inquiry to future deliberation.
The powers of memory, of imagination, of
talte, of reafoning, of moral perception, the
will, the paffions, the affections, and all the
acYive powers of the foul, prefent a vail and
boundlefs field of philofophical difquiiition,
which the author of this inquiry is far from
thinking himfelf able to furvey with accuracy.
Many authors of ingenuity, ancient and mo-
dern, have made excurfions into this vaft ter-
ritory, and have communicated ufeful obfer-
vations : but there is reafon to believe, that
thofe who have pretended to give us a map of
the whole, have fatisfied themfelves with a
very inaccurate and incomplete furvey. If
Galileo had attempted a complete fyftem of
natural philofophy, he had, probably, done
little fervice to mankind : but by confining
himfelf to what was within his comprehenfion,
he laid the foundation of a fyftem of know-
ledge, which rifes by degrees, and does honour
to the human underftanding. Newton, build-
ing upon this foundation, and in like manner

confining

47$ OF THE HUMAN MI^D. [CHAP. 7.

confining his inquiries to the law of gravita-
tion and the properties of light, performed
wonders. If he had attempted a great deal
more, he had done a great deal lefs, and per-
haps nothing at all. Ambitious of following
fuch great examples, with unequal Heps, alas !
and unequal force, we have attempted an in-
quiry only into one little corner of the hu-
man mind ; that corner which feems to be
mod expofed to vulgar obfervation, and to be
mod eafily comprehended ; and yet, if we
have delineated it juftly, it muft be acknow-
ledged, that the accounts heretofore given of
it, were very lame, and wide of the truth.

THE END.

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VICTORIA UMIVERSHT
LIBRARY

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