SCIENCE AND
THE HUMAN MIND

the Same Authors

x/

THE FAMILY AND THE NATION :
A Study in Natural Inheritance and
Social Responsibility. Svo. Long-
mans. 75. 6d. net.

HEREDITY AND SOCIETY.
Svo. Longmans. 6s. net.

A HISTORY OF THE LIFE OF
COLONEL NATHANIEL
WHETHAM, a forgotten Soldier
of the Civil Wars. With 6 Maps
and Plans and 10 other Illustrations.
Svo. Longmans. 8s. 6d. net.

BACK TO THE LAND: a Medley.
Crown Svo. Longmans. 45. 6d. net.

RECENT DEVELOPMENT OF
PHYSICAL SCIENCE: An
Account for the General Reader of
the Present Position of Physics.
Fourth Edition. Large Crown Svo.
Murray. 55. net.

STUDIES IN NATURE AND
COUNTRY LIFE. A Book for
Children and their Parents. Bowes
& Bowes. 2s. 6d. net. Paper covers,
is. net.

AN INTRODUCTION TO EUGEN-
ICS. Bowes & Bowes, is. net.

THE FOUNDATIONS OF SCIENCE.
Jack & Co. 6d. net.

SCIENCE AND
THE HUMAN MIND

A CRITICAL AND HISTORICAL ACCOUNT

OF THE DEVELOPMENT OF

NATURAL KNOWLEDGE

BY

WILLIAM CECIL DAMPIER WHETHAM

M.A., F.R.S.

FELLOW AND TUTOR OF TRINITY COLLEGE, CAMBRIDGE

AND

CATHERINE DURNING WHETHAM

HIS WIFE

LONGMANS, GREEN, AND CO.

39 PATERNOSTER ROW, LONDON

NEW YORK, BOMBAY, AND CALCUTTA

1912

All rights reserved

PREFACE

THOUGH there are many histories of the different
branches of science and of science itself, a general
survey of the progress of natural knowledge in its
relation to other fields of human thought seems not
previously to have been written. This attempt to
supply the need does not pretend to give a detailed
account of the growth of the various sciences. It is
evident that almost every section could be expanded
into a volume, and each chapter heading could
appropriately become the title for an exhaustive
treatise. We have deliberately constrained ourselves
to produce an outline, rather than the fuller study
towards which we were frequently tempted. We
have set out to tell in plain language the story of the
separation of science from the association with theology
and philosophy by which, of necessity, its origins were
beset. We have tried to recount the marvellous
extension of natural knowledge, following on the
liberation of science ; to trace and to justify the rise
of a mechanical theory of life, and to explain the
recent tendency once more to recognize its limitations.
Lastly, we have endeavoured to weigh the influence
which, in turn, science, now admittedly supreme within

256600

vi SCIENCE AND THE HUMAN MIND

its own kingdom, has had on sociology, on philosophy
and on religion.

Perhaps a word of personal explanation may be
forgiven. For the past ten years we have been
collecting material for the subjects of the present
volume. Science, like life, to be seen singly must be
seen whole. To estimate the value of any piece of
work, it must be fitted into the larger scheme of our
knowledge of nature, and that again must find its
proper place in the general record of human activity.
Therefore, merely as an apologia pro vita nostra, it
seemed inevitable, sooner or later, to write this book.

In the course of the work it has been necessary to
gain a knowledge of branches of science and depart-
ments of thought beyond the confines of the some-
what restricted region of physics in which our own
previous researches were carried on. At various
stages, problems appeared where personal experience
seemed essential. Hence, for instance, we have found
ourselves at one time carrying out unsuccessful
investigations on radio-activity, and, at another,
putting together pedigrees showing the descent of
mental or physical qualities, or breeding Mendelian
hens wherewith to supply the needs of our breakfast
table.

Among our former works, The Recent Development
of Physical Science (1904), The Family and the Nation
(1909), and Heredity and Society (1912) are milestones
along the road of preparation ; while the Life of

PREFACE vii

Colonel Nathaniel Whetham (1907) was a profitable
exercise in genealogical research as well as in historical
method and the use of records.

Thus, whatever be the fate of this work — the
result, in its present form, of the scanty leisure of ten
strenuous years — we take leave of the manuscript
with a sense that to us it sums up a period of widen-
ing mental outlook and of increasing interest in the
varied phenomena of society, of life, and of thought.

W. C. D. W.

CAMBRIDGE, C. D. W.

September 1912.

CONTENTS

FA9E

CHAPTER I
INTRODUCTION i

The Genesis of Natural Science— The Races of Europe-
Creation and Culture — Mysticism and Dogma.

-

CHAPTER II

SCIENCE IN THE ANCIENT WORLD . 21

Chaldea — Egypt — India — Greece — Religion and Philo-
sophy.—Early Greek Philosophy — The Problem of Matter —
The Atomists — Aristotle — Euclid and Geometry — Archi-
medes and the Origins of Mechanics — Medicine — The
Failure of Rome— The Influence of Alexandria.

CHAPTER III
THE MEDIAEVAL MIND 59

The Middle Ages— The Patristic Age— The Dark Ages—
The Reconstruction of Europe — The Coming of the North —
Arabian Science — The Revival of Learning — The School-
men— Thomas Aquinas— Dante— Roger Bacon — The Decay
of Scholasticism.

CHAPTER IV

THE RENAISSANCE AND ITS ACHIEVEMENT ... 99

The Origins— Leonardo da Vinci— Copernicus— Bruno-
Galileo — Gilbert of Colchester — Francis Bacon — The Re-
naissance in France — Descartes — Pascal — Tycho Brahe and
Kepler— Scientific Academies— Newton— Medical Science
during the Renaissance— William Harvey — The Rise of
Chemistry — Voyages of Discovery — Botany and Natural
History— Spontaneous Generation— Witchcraft — The Chris-
tian Platonists — Summary.

ix

'

x SCIENCE AND THE HUMAN MIND
CHAPTER V

PAGE

THE PHYSICS OF THE NINETEENTH CENTURY . . 153

The Mechanical View of Nature — The Popularization of
Science— Astronomy— The Nebular Hypothesis— " Phlo-
giston"— Lavoisier and the Conservation of Matter — Im-
ponderable Fluids — The Atomic Theory — The Wave
Theory of Light — Spectrum Analysis — Heat and the Theory
of Energy— The Rise of Electrical Science— Electric Waves
— The Theory of Ions — Summary.

CHAPTER VI
THE COMING OF EVOLUTION 188

The Significance of Biology — Embryology — Natural History
— Scientific Exploration — Organic Chemistry — The Physics
of Physiology — Microbes and Disease — Geology — Evolution
before Darwin — Darwin — The Fight for Evolution — The
Effects of Evolution — The Experiments of Nature — Anthro-
pology— History, Politics and Sociology — Religion.

CHAPTER VII
THE LATEST STAGE 233

The New Dispensation — The Expansion of Physical Science
— Corpuscles and Electrons — Radio-activity — The Indi-
vidual Atom — The Luminiferous ^Ether — The Principle of
Relativity — Mendel and the Laws of Inheritance— Neo-
vitalism— Modern Psychology— Comparative Religion — The
Theory of Scientific Knowledge — Science and Philosophy —
Science and the Human Mind.

BIBLIOGRAPHY . . 287

INDEX . 297

" Hark/' cried the priest of old,
" Within mine ear God breathed the hidden word."
Men came and listened, whispered, shook their heads —

" He hath not wholly heard/'

" Stay/' cried the gray-haired sage,
" Within my mind the plan, laid out, I see/'
His fellows drew around ; — " not so," they said ;

" He has not found the key.

" Here," cries the latest age,
" The atom breaks and life gives up her tale."
" Is the soul naught ? " the world-worn spirit sighs ;

" These men must also fail."

" Lo," wise men cry, " we stand,
Like children, picking pebbles on the shore ;
God of our fathers, give us still Thy light,

And when that fades, give more ! "

DUNSTANBURGH,

August 1912,

CHAPTER I

INTRODUCTION

The Genesis of Natural Science— The Races of Europe-
Creation and Culture — Mysticism and Dogma.

THE vast and imposing structure of modern science

is one of the greatest triumphs of the human mind.

The broad yet intimate knowledge of

The Genesis J -111

of Natural the phenomena of Nature now available

Science. gives not only a marvellous control over

natural resources, but permits an insight into the

workings of natural processes far beyond the dreams

of former ages.

Within the last century, physical science has
brought under its sway mechanical powers which make
the tools of the past five thousand years seem like
the playthings of children. Vistas have been opened
into the innermost recesses of the structure of matter
— vistas down which the eye of man is powerless to
follow the flight of his mind.

Biology has constructed consistent theories of the
mechanism of living organisms. It has revealed
hosts of microscopic beings, endless in number and
variety, beings pregnant with good or evil for the
human race ; while the study of heredity, expressed
in the new science of genetics, has arisen to light the

I

2 SCIENCE AND THE HUMAN MIND

stumbling footsteps of mankind along the dark paths
of social progress.

Psychology is extending every year the know-
ledge of mind and its processes, conscious and un-
conscious. Man, as a piece of work, noble in
reasbn, infinite in faculty, is finding himself to be
the foremost problem of the age. New light has
been thrown on the theory of knowledge and on
the difficult problem of how knowledge at all comes
to be possible to a being whose frame is but the
quintessence of dust. For the human mind is the
agent which has built up the goodly edifice of
applied thought to be examined in the succeeding
pages, and rightly claims a place in the record of the
construction.

Two courses are open to us. We may take know-
ledge as we find it at the present hour and draw a
picture of it, as it now stands ; or we may trace its
growth from first beginnings in the dawn of civil-
ization and watch the slow uprising of the various
parts of the structure.

To those whose interest lies in the workings of the
human mind, there is much to be learned from the
development of natural science. Its inner meaning,
its relations with other branches of learning, its
possibilities of future development, are best re-
vealed by some application of the historical method.
Moreover, it is through a critical examination of
its past history that we can obtain an insight into
the value of the present stage in the evolution of
any branch of the subject, and may be saved from
the danger of that error, lying in wait for each
generation in its turn— the error of believing that,

INTRODUCTION 3

in its own age, it has attained the final goal, at
a point which is, in reality, but a step in an endless
progress.

When we watch the fate of one scientific hypothesis
after another as they pass across the stage from a
life of active usefulness into the historical museum
of intellectual curiosities, we learn that not even
the youngest generation of the sons of men is to
be deemed infallible. The theory by which know-
ledge is best advanced at any given time is not
necessarily more permanent than its predecessors.
The best theory is only the one which suits best the
existing modes of thought, and suggests most clearly
the particular direction in which advance may be
made.

In natural science, as elsewhere, it is necessary to
distinguish between the passing and the permanent.
If the theories by which knowledge has been inter-
preted and extended are subject to flux and change,
knowledge of nature itself stands for no transitory
gain. The foundations are surely laid. Science has
continued to expand, and to show interconnections
and concordances between its parts which give con-
fidence in the stability of the whole.

This steady growth in effective knowledge, and the
maintenance by all competent observers of a common
belief in fundamentals, are the principal features
which distinguish science from philosophy and meta-
physics. The attainment of general agreement is
indeed the crucial point at which a subject passes
from the realm of philosophic conjecture into the
territory of scientific " fact."

All races at a certain stage of development treat

4 SCIENCE AND THE HUMAN MIND

both science and philosophy as a branch of that much
more fundamental and much more necessary mode
of thought — religion. Philosophy indeed is but the
attempt on one side to disentangle and analyse the
various elements which are involved in the concepts
of religion. It represents an endeavour to submit the
inherited traditions of a whole complex social group
concerning the " nature of things," the ultimate
verities, to the reasoning power of one individual
member of the society, who, viewing life from his own
personal standpoint, strives to find arguments in
support of the current conclusions. The work of
science in the field of human reason is to examine the
arguments, test the evidence adduced in their support,
pronounce on their validity, and to suggest new
methods of attack. Therefore it fell out in the logical
course of development that the earliest astronomers
were probably Chaldean priests ; while the ancient
Egyptians referred the origin of all knowledge to the
gods, who had revealed it to those in their service.
The Babylonian legend of the creation, attached by
the Hebrews to the Arabian Jehovah of Sinai, supplied
a cosmogony, not only to the Jews, but also to the
Christian races of Europe till quite recent years. To
the early Greeks, the sun was the flaming chariot of
Phoebus ; to the Indians, the clouds were kindly cows
from which milk descends as nourishing rain on the
fruitful earth.

It is possible that, at an earlier stage, religion itself
arose from the magic rites by which primitive men
try to control, by imitating, the processes of nature,
or to signalize the ceremonies of tribal initiation.
Magic would then be a lineal ancestor of modern

INTRODUCTION 5

science — a pleasing line of descent, since the man of
science, like the magician, seeks to control the forces of
nature and recognizes that knowledge is power. As
Mr Cornford says, in his book From Religion to Philo-
sophy, " Science, with its practical impulse, is like
magic in attempting direct control over the world,
whereas religion interposes between desire and its end
an uncontrollable and unknowable factor — the will of
a personal God. The perpetual, if unconscious, aim
of science is to avoid this circuit through the unknown,
and to substitute for religious representation, involving
this arbitrary factor, a closed system ruled throughout
by necessity." But whatever be the outcome of the
enquiries now being made by anthropologists and
archaeologists, it is yet too soon to attempt to trace
the origins of science in the dim regions of totemism.
We take up our tale when religion, still carrying, it is
true, signs of more archaic modes of thought, has
passed into the animistic or into the anthropomorphic
form.

At the stage when we begin to recognize the germs
of science, knowledge is not differentiated into definite
branches. The priest is also the philosopher and the
physician. The first requisite for growth is the
recognition of the need for separation, and the fearless
pursuit of one branch of knowledge, unhindered by
the trammels of methods of thought foreign to the
spirit of that particular enquiry. At a much later
stage, it is possible that some of the separate streams
may once more converge in a higher unity, and each
help the other in pushing forward a joint flood of
knowledge. But, in the beginning, clear separation
is necessary. Hence the first sign of advance, whether

6 SCIENCE AND THE HUMAN MIND

at the dawn of Greek history or at the Renaissance
of learning after the gloom of the Middle Ages, is the
liberation of philosophy from religion, and the next
stage is the separation of natural science from them
both.

The Greek philosophers effected completely the
first of these changes : they freed philosophy from
dependence on theology, but they never distinguished
science from philosophy.

Theories of the solar system, or of the continuous as
opposed to the atomic structure of matter, were to the
Greeks almost as much an affair of speculation as the
nature of reality or the conception of the absolute.
On a narrow basis of observation, the active mind of
each Greek philosopher built an imposing superstruc-
ture of conjecture, far in advance of any possibility of
demonstration. But he had not sought these prob-
lems in any spirit of arrogance. They were part of a
legacy from the earlier stages, an inheritance of out-
standing puzzles from religion and magic ; and, as
time has shown, true subject matter for scientific —
and therefore, at that early period, for philosophic —
enquiry. To the ancients, astronomy — except in
so far as the movements of the heavenly bodies
were noted and used to measure time — and physics —
outside the elements of geometry, land measurement
and engineering — were both in truth and fact branches
of philosophy, subjects as yet beyond the range of
experiment and inductive reasoning.

Yet science in its earliest days advanced far in direc-
tions where immediate practical application supplied
the necessary stimulus. Geometry, established on a
basis of experimental knowledge, won by the need of

INTRODUCTION 7

surveying and measuring land, developed on its true
method of logical deduction from a few self-evident
axioms. A beginning was also made in the co-ordina-
tion of information gleaned by experience of animals
and plants, and in the arts of agriculture and medicine.
But, in spite of these and other successful applications,
there was no conception of the power that lay in the
pursuit of learning for its own sake, in the possession
of organized knowledge ; and natural science re-
mained a strange mixture of the obvious and the im-
possible, in which the lore of the priest, the ingenuity
of the craftsman, and the fevered dreams of the
magician were inextricably blended with the self-
centred reason of the philosopher. Not until, follow-
ing the decay of the Roman Empire, the Dark Ages
had passed into the twilight of Medievalism, did the
attitude of mind begin to show signs of change ; and
the dawn of the modern world was breaking in the era
of the Renaissance before natural science took its stand
on the firm ground of slowly won observation. Then,
ceasing to be speculative philosophy, tossed about by
every wind of doctrine, it became an independent and
progressive branch of knowledge, developed by the
healthy interaction of inductive observation and
deductive reasoning.

This chronicle sums up the growth of science and
explains the slow retreat of philosophy, of which the
claims once filled the schools of Greece and Western
Europe. While a subject is not within reach of that
union of observation with logical or mathematical
deduction which constitutes science, as we know it
now, while it is only amenable to speculative treat-
ment and imaginative analysis, the philosophers

8 SCIENCE AND THE HUMAN MIND

retain their jurisdiction. When, based on fact and
supported by experiment, it passes over dry-shod to
science, the philosopher's work is done ; and, if he
be wise, he turns to other problems. The realm of
metaphysics is always contracting ; but each suc-
cessive concentration gives more power of intensive
attack on the deeper and better defined problems
which remain behind. The philosopher is continu-
ally losing to science ground which he has surveyed
for himself, and is always gaining by his loss.

The debt which science owes to philosophy is two-
fold. From philosophy it learns its limitations and
its interrelations ; from philosophy it takes over one
problem after another, often in an advanced state of
preparation for mathematical or experimental treat-
ment. Philosophy may recognize the existence of
the problem and formulate the possible solutions.
Science alone can decide between them. Greek
thinkers could point out that matter must be either
continuous or atomic, and follow some way along the
path of logical deduction from each hypothesis. But
each philosopher was at liberty to take either alterna-
tive, and was powerless to convince his neighbour of
the justness of his cause. It needed the slow accumula-
tion of the definite experimental knowledge of chemical
combination, available at the opening of the nineteenth
century, to enable Dalton and Avogadro to bring
forward overwhelming evidence in favour of the
atomic theory, and to establish it in the name
of science. It needed the marvellous advance of
another hundred years to demonstrate directly to
human eyes the existence and movement of the
individual atom.

INTRODUCTION 9

We must now endeavour to place on record some
aspects of the human mind, in its interrelation to
The Races of the growth of science. Let us admit, in
Europe. the first place, that it is possible for a
race to attain a high standard of civilization without
assigning any appreciable part in its development to
the effects of organized scientific discovery, which is
indeed mainly a creation of the last three or four
centuries. The knowledge of the workings of nature
and the interest in natural phenomena have fluctu-
ated from age to age, and from nation to nation.
Some races of high standing seem to be entirely
deficient in the necessary faculties either of observation
or experiment. From considerations such as these, we
must probably believe the growth of natural science to
be dependent ultimately on some peculiarity of brain
convolution and quality of mind inherent in certain
individuals or types of the human species, and capable
of stimulation by appropriate circumstances. The
properties of the human mind, in this as in everything
else, are but an indication of some biological factor.

When we pursue the problem a little further, it
seems possible fairly to treat European science as a
separate creation of persons or races dwelling in or
derived ancestrally from the one continent. Natural
science as we know it now is almost entirely the product
of the races of Western and North- Western Europe,
the part where the dominant elements of the nations
belong to a distinct, well-defined stock. The science
of ancient Greece was probably less isolated, and cer-
tainly received considerable accretions, for good or
evil, from the civilizations of Assyria and Egypt. But,
whether we are considering ancient or modern European

io SCIENCE AND THE HUMAN MIND

science, it is permissible to leave out of account the
achievements of the venerable Chinese empire as
having little influence, and to dwell but briefly on the
results in mathematics and philosophy due to the
dominant nations in India. We are then concerned
chiefly with the populations of Europe, and only to
a very small extent with those of the basin of the
Eastern Mediterranean, of Assyria and Egypt, and
with the Semitic races.

And here it might be worth while to recall to mind
the unique feature in continental topography pre-
sented by the great European inland sea. The lands
that approach these waters from the northern side are
remarkable for their detached and indented character.
Peninsula and island mark the coast-line, and we are
able to attach a definite history and record of separate
achievement to such small portions of the earth's
surface as Greece, Italy, and Spain ; while the islands
of the ^Egean Sea, Cyprus, Crete, Sardinia, Sicily, and
many others, have all been called upon to play a
distinct part in the pageant of civilization. Yet these
places are not so far from each other and from the sur-
rounding land but that, to a certain extent, communi-
cation must always have been open between them.
We have therefore a condition in which isolation after
invasion or conquest has produced the biological
potentialities and eventually the definite racial
qualities which become moulded into a clear-cut type,
either of the population as a whole or, as in ancient
Greece, of the conquering and governing class. But
at the same time the people have been subject to the
intellectual stimulus introduced by contact, not
necessarily biological in the sense of cross-breeding,

INTRODUCTION n

but contact of mind and civilization, which produces
the best effects in a race or section of a nation well
prepared by unity of blood and ideals to apprehend
and fertilize any new conceptions. As long as the
political and economic conditions did not permit of
the constant free mixing and consequent degradation
of races or types, as long as ideas or the great teachers
who inculcated them were the only things to circulate
freely, the countries of the Mediterranean each
possessed a certain intellectual distinction, developing
one after the other on lines best suited to the dominant
national type.

And so, at a later period, when the main stocks of
the Northern races had become civilized, the coasts
of northern France, of the Low Countries, Germany,
and the shores of the Baltic, with the peninsulas of
Denmark and Scandinavia, and the British Isles,
all abutting on the navigable waters of the North
Sea and English Channel, reproduced the condition
which had proved so fertile in earlier ages around the
Mediterranean.

In order to understand our subject, we must try
to glean some idea of the differences between the
inhabitants of different parts of these two areas ;
and though some countries will be considered briefly
in turn, as we have occasion to deal with them later on,
we will here consider the most general propositions.

In studying the ethnology of any continent, it is
important to distinguish clearly between race, language
and culture, which are not necessarily coterminous
in any direction. Culture may be indigenous or ac-
quired, the expression of an inborn need or the result
of an imitative and superficial disposition. Languages

12 SCIENCE AND THE HUMAN MIND

have been transferred from race to race, by con-
quest, or by proximity and slow absorption. Of the
three characteristics, race is the only one which is pro-
bably fundamental in determining the genius alike
of an individual and of a nation.

When first examined, the peoples of Europe seem
endless in the variety of their physical characters.
Yet, by studying the shape of the head, the texture
of the hair, the stature and the colouring, anthro-
pologists have found that, as we approach three
definite regions, three definite combinations of char-
acters are found in greater and greater purity. Hence
the broad outlines of European ethnology have been
explained by the hypothesis of three main races,
taking their respective origins in these three regions,
and giving rise to the complexity of existing conditions
by racial mixture and interpenetration across their
lines of contact. This view is in agreement with
what historical evidence is available ; indeed, the
history of Europe is in its essence the story of the
interaction of these races with each other, and with
those other peoples that touch them on the east and
south.

The earliest stratum of population still represented
largely in Europe were the comparatively short, dark-
haired and long-headed people, seen in their greatest
purity in present populations of southern and eastern
Spain, southern France, Italy as far north as Rome,
and to a less degree in Wales, Cornwall and West
Devon, the west of Ireland and parts of Scotland.

In the north-west of Europe and in lands, con-
tinental and insular, which are washed by the North
Sea, there has been, ever since historic and indeed

INTRODUCTION 13

prehistoric ages, a tall, fair-haired, long-skulled, blue-
or grey-eyed people, which may be known collectively
as the Germanic, Teutonic or Northern race.

It is immaterial to our present purpose to enquire
whether the first-named short dark race were indeed
offshoots of some original North African population,
which had found its way across the Mediterranean Sea,
and whether the Northern race is to be regarded
ultimately as a separate development or as an im-
memorial modification of the Mediterranean people,
created by isolation, environment, or natural or
artificial selection in the colder regions of Europe.

From the earliest dawn of civilization, these two
races have been coexistent, and intermingled at their
lines of contact. They differ alike in bodily and
mental qualities, and have made and are making
history by their actions and interactions.

Between the homes of these two races comes a
wedge-shaped area of upland central Europe, stretch-
ing from the Auvergne and the Cevennes in France
through Switzerland and Austria towards the Balkan
peninsula and the islands of the ^Egean Sea, and
beyond again into Asia Minor, Armenia and parts of
Palestine. This region is inhabited partially by the
so-called Alpine race, round-skulled and broad-headed,
and intermediate in stature and colouring of hair and
eyes between the other two. Men of this race, which
penetrated slowly down the Rhine valley into the Low
Countries, reached Great Britain, but are not found
in Ireland. The special characteristic of these people
is the decidedly Asiatic affinities which they display,
and probably we shall not be far wrong in regarding
them as the result of a slow infiltration from the East.

14 SCIENCE AND THE HUMAN MIND

Such then is the framework of the population of
Europe during the centuries in which we are to con-
sider one aspect of its intellectual achievements.

A race is essentially atomic in structure ; it is made
up of individual parts, which we call persons, and is
Creation and interpreted by these. But the individual
Culture. }ife is too short to give full expression
to racial possibilities. Hence each independent and
creative civilization depends for its existence and
progress on that continuity of tradition and definite
oneness of aim and character which are essential to
produce the environment suitable for the development
of the typical personalities ; a unity only to be at-
tained through a certain purity of breeding of the
effective and directing portion of the race.

Consequently, periods of chaos, of the biological
intermingling of races, are seldom periods of creative
power and high intellectual achievement. A super-
ficial culture may be attained thereby, a certain de-
nationalized temporary civilization may ensue, but
the great eras of this world's thought are records of
separate, distinct nationalities, expressing themselves
characteristically through great men, born and bred
in appropriate circumstances. Creation is usually the
outcome of one race working out its own salvation,
while culture appertains to a contact of ideals and
a mixture of peoples.

Our history of scientific thought will be largely the
history of individuals, and, through the individuals,
of the forces, biological and social, of which they were
the expression. Hence it will be pertinent, whenever
possible, to note the parentage and circumstances of

INTRODUCTION 15

birth of the men of genius whose life-work forms the
subject-matter of our pages. All nations contain
strains of blood, differentiated from each other either
in their origin, or through long periods of segregation
and inbreeding among the different sections of the
people, considered geographically, socially, or indus-
trially. But, conversely, identical racial offshoots
are found permeating and linking up nations widely
separated from each other ; and again, a similarity
of social standing added to a common ancestral origin
will produce a co-ordination of outlook in quarters
which are, geographically speaking, remote from each
other. Owing to the intermingling of peoples and
types throughout Western Europe, and especially to
the peculiar stratigraphical distribution of the Northern
race as administrators and directors, it is clear that
there is often greater community of intellectual
interest between the corresponding sections of various
similarly formed nations than between the different
strata of any one country. It is due to this pheno-
menon that science, the creation of the Northern
mind in varying environments, has always proved
more cosmopolitan within its limited range than,
for instance, such "popular" developments as the
technical or manual arts and crafts.

The essence of the mental state favourable to the
growth of science seems to be a recognition of the fact
that the careful and patient study of nature is the
true method to obtain a knowledge of this aspect of
the Universe. " Natura enim non nisi parendo
vincitur." From this attitude of mind, common to
all the heroes of the romance of science, it is but a
step to the religious position which regards inward

16 SCIENCE AND THE HUMAN MIND

spiritual experience and direct personal apprehension
of God as the fundamental religious verity.

This is the position of the moderate and sane mystic,
who, declaring that the Kingdom of God is within,

Mysticism studies the soul in its relations with the
and Dogma. rest of God's creation by an inward exten-
sion of the open-minded method of experience proper
to natural science. The passionate love of nature,
which is characteristic of such great mystics as St
Francis of Assisi, gives, when directed to its systematic
study, an intuitive insight concerning its workings
that bears other fruit in the life and work of Paracelsus,
of Kepler, of Newton, and countless pioneers, who
turned at times from the laborious methods of observa-
tion, experiment and mathematical calculation to fare
forth in travel, " voyaging over strange seas of thought
alone." " Truth and Freedom," as the birthright of
each individual, were alike the watchwords of mystic
and of man of science, although, setting out under
the same banner, they attained thereby very different
results.

If we contrast this attitude of mind with that pre-
valent among the peoples of the south of Europe, and
with that of the early inhabitants of Assyria and
Egypt, we are at once struck with a complete differ-
ence of outlook. St Francis, the Northerner, like
Pythagoras of Samos, man of learning and mystic,
some two thousand years before him, preached to
his brothers, the birds. The Southern Italian ill-treats
his mules, on the understanding that they, have
neither souls nor feelings ; while the modern Levantine
pursues the same course, dubbing the four-footed

INTRODUCTION 17

creation collectively " the unreasoning ones." The
Northern race, whether in its native plains or woods,
its less permanent resting-places in the hill cities of
the Apennines and the plain of Lombardy, on the
shores of Asia Minor and Magna Grsecia, or in the
Thracian wilds and amid the jealous rivalries of the
Hellenic states, preserves its racial characteristics.
The Northern mind is not a thing apart from nature,
but readily acknowledges his kinships, bestowing
spirits and souls of like kind to his own on the animate
and inanimate objects by which he is surrounded.

" Images and temples and altars," writes Herodotus
when describing the ancient Persian religion, the
creation of another branch of the Northern race, " it is
not in their law to set up — nay, they count them fools
who make such, because they do not hold the gods
to be man-shaped, as the Greeks do. Their habit is
to sacrifice to Zeus, going up to the tops of the highest
mountains, holding all the round of the sky to be Zeus.
They sacrifice to the sun, moon, earth, fire, water, and
the winds."

The Southerner in his pagan moods reverses the
process, and to express his religious convictions adds
bestial countenances to the human form in order to
obtain his inhuman gods. Such differences as these
represent unfathomable chasms of racial antipathy.

Throughout the ages, the Southern races appear
to have emphasized the necessity of form, of definite
and concrete statement such as finds its highest
expression in clear-cut dogma. There is a finite tree
of knowledge in their philosophy, attainable some-
where, yet impious for the ordinary mortal to aspire to.
Religion becomes an affair of the priesthood, of those

2

18 SCIENCE AND THE HUMAN MIND

set aside and devoted to the service, the propitiation,
or, it may well be, the outwitting of the gods. There
is a desire to get the conflict over, ascertain the limita-
tion of human will and power, produce a clear-cut
scheme of salvation, set the machinery in order under
suitable supervision, so that humanity may continue
with its worldly avocations and cease from troubling
about his internal relations with God and the Universe.

The Jewish Law, the Roman Empire, the Ultra-
montane Roman Catholic Church, represent the
culminating achievements of the advocates of uni-
versalist form and dogma. In none of these instances
can criticism be tolerated, nor is conscious expansion
of thought permissible. It is symbolic of the two
opposite attitudes of mind, that St Peter, the Jew
and upholder of the Law, with his very concrete
keys of the Babylonian heaven and hell, should
rule in Rome, the religious gathering-point of the
Southern race, while St Paul, with his Hellenic
affinities and mystical outlook, should hold sway in
the cathedral church of the Northern metropolis.

Now the thought, the essence of which is to create,
cannot long brook rigid forms or the constraint of
unchanging dogma, and the soul which acknowledges
a relationship with Nature demands the liberty to
consort freely with its kith and kin. Hence it has
been said that the " real high school of freedom from
hieratic and historical shackles is mysticism, the
philosophica teutonica, as it was called." And so,
indeed, at one critical point in the history of thought,
it will prove to have been, as we unfold our tale. The
light by which science ultimately advanced on its
way has always come from the North.

INTRODUCTION 19

But there is another mode of attack on outgrown
dogma and unyielding law. If, on the one hand,
authority in matters of reason has been undermined by
a natural mysticism, on the other it has been destroyed
by a rational scepticism, which was the weapon of the
Humanists of the Italian Renaissance, chiefly men of
Northern descent. The Northern mind, while quick
and sure in intuition, is slow and persistent in reason-
ing power, and pursues its age-long enemy, intellectual
authority, with the unerring instinct of a bloodhound ;
for the thought, the essence of which is to create and re-
interpret, can make no lasting truce with the prophets
and priests of the unchanging law. Erigena, Occam
and Martin Luther, the great apostles of mysticism,
are not more effective in the society of their day and
century than Petrarch with his daring criticism,
Erasmus with his Praise of Folly in bitter satire of the
whole external paraphernalia of the Roman Church, or
Voltaire and the rationalists of the eighteenth century.
Once the true conception of historical events had been
obtained, the free mind of the Northern race set to
work to find the correct interpretation of present
tendencies in the light of past history and thought.

If, therefore, in the light of recent research and of
age-long experience, we are compelled to attach so
much importance to the biological factors, it follows
that we are bound, in the course of our present enquiry,
to consider carefully the characters of the peoples
among whom science grew up. Their modes of
thought, their religion, their political condition, are all
pertinent to the subject we have in hand. And, as we
have said, since the history of science is best written in
the biography of its great men, any information that

20 SCIENCE AND THE HUMAN MIND

can be placed on record as to their nationality or the
ultimate origin of their family must not be regarded
as a ministration to idle curiosity, but as a piece of
our argument, playing an essential part in the struc-
ture of this book. It is not a fortuitous chance that
Origen, the earliest and most modern of the Fathers
of the Church, was born at Alexandria, of Greek
parents ; that Erigena was surnamed Scotus ; or that
Isaac Newton, who represents the supreme triumph
of mathematical and physical thought, should have
been tall, fair- or ruddy-haired and grey-eyed, and
should have first seen light on a Lincolnshire free-
hold, in the central home of that Anglo-Danish stock
which has proved the most fertile nursing mother of
pure science. Whoever is unable to appreciate the
inward meaning of these facts — often deemed irrelev-
ant by folk who are prepared to see miracles every-
where— will never comprehend the interrelations of
science and the human mind.

Some sciences grow from foundations set on the
firm ground of the practical arts. Others, however
they may arise, take over their problems ready framed
by philosophy and all possible answers formulated by
different and contending schools of thought. Some
races have made natural science and the scientific
frame of mind part of the birthright of their children ;
and some men of science have known and described
Nature with the unerring instinct of children dwelling
on the perfections of a beloved parent.

Guided by such clues as these, we shall follow in
detail the development of natural science in the
. human mind.

CHAPTER II

SCIENCE IN THE ANCIENT WORLD

Chaldea — Egypt — India — Greece — Religion and Philosophy — Early Greek
Philosophy — The Problem of Matter — The Atomists — Aristotle —
Euclid and Geometry — Archimedes and the Origins of Mechanics —
Medicine — The Failure of Rome— The Influence of Alexandria.

AT the dawn of history two civilizations stand up

out of the darkness — the civilizations of Egypt and

Chaldea — known to us chiefly by the

remains of buildings, sculpture, and

inscriptions preserved in their waste places, and by

the influence of their culture and religion on the

organization and beliefs of adjoining nations and

races.

As far back as 2500 years before Christ, standard
measures of length, weight and capacity were issued
under royal authority in Babylon, an indication that
the Chaldeans had already grasped the importance
of fixed units of physical measurement. Here we
have the first known signs of that co-ordination and
standardization of the knowledge of common sense
and of industry which gives the surest base for the
origin of science in its practical form.

The elements of arithmetic were also known to the
Babylonians. The multiplication table and tables of

21

22 SCIENCE AND THE HUMAN MIND

squares and cubes, have been found among their
tablets. A duodecimal system of units, making the
calculation of fractions easy, existed alongside a
decimal system. The circle with its subdivisions of
angular measurement, the fathom, the foot and its
square, the talent and the bushel — in fact, the com-
plete system of Chaldean weights and measures — were
based on the parallel use of this double system of
notation.

The beginnings of geometry, too, are found in rudi-
mentary formulae and figures for land-surveying, once
more illustrating the origin of an abstract science
from the needs of everyday life. Plans of fields
led to more complicated plans of towns, and even
to maps of the world as then known. But actual
knowledge was woven in an - inextricable manner
with magical conceptions. The ideas of the virtues
of special numbers, their connections with the gods,
and the application of geometrical diagrams to
the prediction of the future, passed from Chaldea
westward, and for centuries dominated European
thought.

As agriculture develops among a primitive people,
the importance of a knowledge of the seasons grows
also. It is a remarkable fact that the great majority
of cereals and cultivated food-plants originated either
in China and the Far East or at the eastern end of the
Mediterranean basin. As the chief part of these plants
are annuals, requiring seasonal treatment and ample
water-supplies, we have here probably one reason why
large centres of population early grew up in the basins
of the Euphrates and the Nile, in which great stress
was laid on astronomical observation. The cultiva-

SCIENCE IN THE ANCIENT WORLD 23

tion of cereals and other annual plants makes a
calendar almost a necessity, and Chaldean art shows
that the use of the plough was well understood.
It is to Babylon that we owe the division of the
year into months, days, hours, minutes and seconds,
and the invention of the sundial to mark the
passing hours. The Babylonian year was one of
360 days ; the necessary adjustments being made
from time to time by the interposition of extra
months.

The movement of the sun and planets among the
fixed stars was known, the journey of the sun across
the sky being mapped out into twelve divisions ac-
cording to the months. Each division was named
from some Babylonian god, and represented by the
symbol of that deity. Thus arose the association of
parts of the sky with the crab, the scorpion and other
beasts, which afterwards came to be connected with
the definite groups of stars which we still know by the
names of the signs of the zodiac.

Astronomical observation appears in the Babylonian
records more than twenty centuries before the Christian
era. From these early dates the Chaldean priests
had recorded on their clay tablets the aspect of the
heavens night after night, the brilliancy of the atmo-
sphere and the skill of long practice helping their
natural keenness of vision. Gradually the period-
icity of astronomical events was revealed to them,
till the prediction of eclipses of the moon became
possible.

On this basis of definite knowledge, a fantastic
scheme of astrology was built up, and, indeed, regarded
by the Chaldeans as the chief and most worthy object

24 SCIENCE AND THE HUMAN MIND

of the underlying science. Starting, doubtless, from
some observed coincidences, belief in the power of
predicting and even of influencing future events by ob-
serving the stars as interpreting the minds of the gods
became general, and gave the Babylonian priests a
power both over public and over private affairs. Each
temple put together a library of astrological literature
from which the methods of divination might be learnt.
One such library, consisting of some seventy clay
tablets, was of special repute in the seventh century
before Christ, and is considered to date originally
from some time about 3800 B.C. " Astronomy, as
thus understood, was not merely the queen of sciences,
it was the mistress of the world."

Astrology reached its zenith in Babylon about 540
B.C., and two centuries later it spread to Greece and
over the known world, although in its original home
it was showing signs of passing into a more rational
astronomy. But Chaldean astrologers continued to
be in request, while their ignorance of the elements
of medicine did not prevent an almost equal faith
in Chaldean sorcerers and exorcists.

These theories of magic naturally followed from the
conception of the powers of nature as animate. And
the special form the theories took in Chaldea arose
partly from the fact that on the whole the Babylonian
gods were inimical to man. Carved in the shapes of
monstrous beasts, their presentments terrified the eye,
while by magic alone could they be induced to delay
the decrees of destiny or modify the inexorable fate
which even they could not wholly avert. Dominated
by such a gloomy religion, no speculative science or
rational philosophy could arise.

SCIENCE IN THE ANCIENT WORLD 25

When we turn to consider the other great civilization

of early times — that of Egypt — a difference of religious

attitude is seen at once to produce a

different scientific spirit. While in Chaldea

and, more markedly, in Assyria the gods were usually

conceived as hostile to man, pursuing him in life and

death with an implacable hatred, in Egypt, as in Greece,

the divine powers were represented in mythology as

friendly, ready to watch over, to protect and to guide

mankind in life, in death and in the after-world.

It would be interesting to enquire what share the
external conditions of their lives have in shaping the
attitude of a people towards the forces of Nature and
the mythology by which they endeavour to interpret
the phenomena of the world and of consciousness.
In Egypt, the Nile, with its regular and unfailing rise
and fall, was the source of all fertility — steady,
trustworthy and friendly. In Chaldea, the tempestu-
ous and incalculable flooding of the Euphrates and
the Tigris made life near their banks dangerous and
uncertain. Nature was hostile, ready to sweep away
man and his puny works together in one unforeseen
ruin. The climate of Egypt is more equable, free
from the extreme variations and violent storms that
harry the highlands of Assyria and Armenia and the
shores of the Persian Gulf. It is possible, too, that
her isolated position both geographically and politi-
cally made Egypt less liable to the ravages of war, and
to the visitations of plague and other diseases which
would more easily reach Chaldea from the closely
populated East.

Even with an original or partial similarity of race,
these differences in natural conditions might modify

26 SCIENCE AND THE HUMAN MIND

profoundly the course of the development of the
human mind, and, in other cases, might accentuate
and intensify racial differences. In the one case, any
attempt to understand or to control the elemental
forces becomes an impious and useless action. Deceit
and trickery by magic and sorcery, or at the best
propitiation of the hostile powers by sacrificial bribes,
represent the logical outcome of this view of nature.
It is a good example of racial memory that compelled
the Greeks to leave Prometheus, outspread on the
Caucasus, punished for helping mankind with the gift
of fire, and decreed that the serpent which tempted
Eve should have been bred in the gardens of Asia
Minor. As we see in the story of Adam, the acquire-
ment of knowledge is a form of sacrilege ; it trenches
on the divine prerogative and must be expiated by
death, degradation or other punishment. But, in
the second case, when the deities are friendly, any
increase of man's mastery over his surroundings is
approved by the tutelary powers, and is probably
directed by them, since it is their good pleasure to
help him on his way.

One or other of these alternative attitudes of mind
predominates in every religious system, according to
the race and circumstances of those who hold to it,
according to the mode of its origin and the reaction
of philosophic thought on its history. And, in its
turn, the prevalent type of religious thought influences
philosophic tendencies and scientific progress.

In Egypt, as we have said, the gods on the whole
were friendly to mankind, and willing to help his
efforts in the acquirement of knowledge. From the
earliest times of which we have definite records,

SCIENCE IN THE ANCIENT WORLD 27

Egyptian civilization was at a comparatively advanced
stage of development. But the possibility of a long
and slow growth in art and science had not dawned on
the minds of men. It seemed clear that their ancestors,
left to their own human resources, could never have
made such discoveries as that of speech or of writing.
It was therefore natural to imagine a divine interven-
tion to account for the origin of every art, craft, or
science. All advance in knowledge was thus ascribed
to the revelation of the gods, and especially of Thot,
represented by the Ibis or Baboon, and of his ally
Mart, the goddess of truth. Thot, one of a legendary
race of divine sovereigns or legislators, was essentially
a moon-god, who measured time, counted days and
recorded the years. But he was also lord of the voice,
master of books and inventor of writing.

This theory of the method of progress continued to
be put forward officially even when it was scarcely
possible that the more intelligent of the people could
have been deceived by it, at all events as regards
recent changes. Thus, in a text-book on medicine,
a chapter on a special branch of disease, which was
known to be of a later date than the rest of the work,
was not referred to the learning of any physician, but
was stated to have been disclosed one night to a priest
who was watching by moonlight in the temple of Isis.

In arithmetic and geometry the knowledge of the
Egyptians was about on a level with that of the
Chaldeans. With the periodic submersion of the
land beneath the waters of the Nile and the obliteration
of boundaries, land measurement was of even more
importance, and doubtless accounts for the origin of a
science, once more referred to the benevolence of Thot.

28 SCIENCE AND THE HUMAN MIND

It was Thot, too, who had invented music and drawing,
and revealed their laws to mankind. It was Thot
who had established a service of observers, the
" watchers of the night " or the " great of sight,"
who followed and noted down from the temples the
principal astronomical changes and sequences. But,
while it may have rivalled the Chaldean astronomy
in age, the corresponding Egyptian science never
reached such an advanced stage of development.
Doubtless, the importance attached by the Chaldeans
to astrology gave a more powerful motive for astro-
nomical research, while the wealth and power at the
disposal of a successful astrologer gave to his pure
science the pecuniary resources and extended impulse
which in our own times have been found greatly to
aid those branches of knowledge capable of bearing
practical application to the arts of life.

If Egypt lagged behind Babylon in astronomy, and
possessed no astrologers with the reputation of those
from Chaldea, in medicine the relative positions were
reversed. Babylon possessed no school of rational
medicine, but relied on sorcery and exorcism for
the treatment of disease, which was referred ex-
clusively to the action of malignant powers. But
in Egypt medical knowledge was highly specialized
at an early date. There were physicians trained in
the priestly schools, bone-setters for the treatment of
fractures, while mental diseases alone seem systemati-
cally to have been left to exorcists, who, by means
of amulets and magic, drove out the evil spirits re-
sponsible for these infirmities. The art of dispensing
drugs and essences had been brought to a high state
of excellence, and many of the Egyptian remedies

SCIENCE IN THE ANCIENT WORLD 29

became of worldwide application. Indeed, Egyptian
medicine generally had an extended influence : the
Greeks acquired it, perhaps by way of Crete, and, in
after ages, from Greece it passed with the rest of their
learning into Western Europe.

The scientific development of the Indo-Teutonic
races in Northern India early reached a very high
point both in philosophy and mathe-
matics, in which subjects their influence
travelled to Greece by way of Persia and Assyria.
These people, in the first stages of their settlement,
possessed the open confidence in their own mission,
the friendly attitude towards their divine powers, the
broad sweep of thought, the restless energy, which are
characteristic of their stock, whether in Asia or Europe.
But, from various causes, of which, in spite of their caste
or colour restrictions, intermarriage with the native
races was probably the most effective, their scientific
development seems to have been checked, or, at least,
progressed only in certain restricted directions. The
advent of Buddhism arrested their normal expansion,
and turned the thoughts of their great men away from
the problems presented in the ordinary course of
existence. A religion took root and grew up among
them, which, emphasizing the transitoriness and vanity
of earthly existence, made self-annihilation and
loss of individuality a condition in the attainment
of spiritual completion. This attitude of mind,
apparently a concentrated and overbalanced form of
mysticism, by distracting the attention from all
immediate surroundings, must at once arrest that
desire for material improvement which is often the

30 SCIENCE AND THE HUMAN MIND

mainspring of an advance in scientific knowledge.
It is a mental state as extreme in the one direction
as the frankly materialistic view of life is in the opposite
way. Each fails ultimately in that it takes no account
of the dual nature of mankind, that it ignores the
interconnection of the mind and the body, of the
individual and the society.

But there is no doubt that at all times the philosophy
of India indirectly influenced the schools of thought of
Asia Minor ; and it is certain that, during the Arab
domination in the lands of the Eastern Mediterranean,
the mathematics and medicine of India mingled with
the stores saved from Greece and Rome, and re-
entered the schools of Western Europe by way of
Spain and Constantinople.

On Greece all the separate streams of knowledge

of the ancient world converged, there to be filtered

and purified, and turned into new and

more fruitful channels by the marvellous

genius of the first European race to emerge from

obscurity.

To understand the genesis of the natural philosophy
of the Greeks, a natural philosophy which formulated
so many of the problems afterwards attacked by
science, and suggested tentatively so many successful
solutions, we must consider briefly the Greek popula-
tions, their religion, and the physical and social
conditions of their existence.

It is probable that the effective part of the early
inhabitants of Greece were a tribe of conquerors
belonging to the great Northern race whose chief home
seems to have been on the shores of the Baltic. This

SCIENCE IN THE ANCIENT WORLD 31

dominant race, descending through Central Europe,
was superimposed in Greece on earlier inhabitants
among whom men of the Mediterranean stock pre-
dominated ; while in Asia Minor, and some of the
islands of the ^Egean Sea, it encountered chiefly Alpine
or Armenoid peoples, mingling with the darker folk
only on the coast-line. The so-called Minoan civiliza-
tion, of which the centre point seems to have been
discovered in the excavations of Cnossus in Crete,
may have represented the earliest achievements of
the Mediterranean peoples. It seems to have been
influenced considerably by Egyptian culture ; while
the contemporary and succeeding bronze age, with a
civilization which seems to start at an advanced stage
of development in some of the cities of the mainland
and the islands, has been associated with men of the
round-skulled type and may represent an early descent
of the Alpine stock, driven forward by the Northern
race, who were shortly to follow on their footsteps.

As we have said, the Mediterranean folk were and
are dark-haired and long-headed, while their Northern
conquerors were fair-haired and long-skulled. The
Mediterraneans buried their dead, while the heroes
of Homer, like the warriors of the North, passed to
the other world amid the flames of a funeral pyre. If
this hypothesis be correct, the peoples of ancient
Greece consisted of much the same elements, but in
different proportions, as those of England when the
earlier dark race had been overlaid by the influx of
Saxon and Dane and Northman ; and a natural
affinity of thought and outlook might be anticipated
therefrom. Moreover, the stimulus of an expanding
colonial dominion is common to both. The chiefs

32 SCIENCE AND THE HUMAN MIND

of the Homeric age had settlements on all the lands
which fringe the Mediterranean Sea, and Southern
Italy became known as Magna Grgecia. Intercourse
with these oversea outposts, and with the divergent
nations that surrounded them, doubtless played a
great part in developing the economic wealth of the
nation and the innate powers of the Greek mind.

While the citizens of the Greek states, the warriors
and the traders, were chiefly or exclusively of the
Northern stock, the Mediterranean people, retaining
their ancient culture and primitive conceptions, still
tilled the soil and appeared as the chief element of
that slave population on which Greek civilization was
built up.

In Greek religion we seem to catch traces of this
dual origin. There is an underworld of spirits of
doubtful or hostile intention towards men, and under-
lying this again are vestiges of totemistic beliefs, and
of that system of magic which springs naturally from
the confusion between the life of nature and the life
of the tribe, and seems prior to any idea of gods.
Here, probably, we have the influence of the religious
attitude which characterized the earlier dispossessed
population. But, in the Homeric poems, which sing
the heroes of the conquering Northern race, we find a
new joyousness of outlook, an attitude of friendly
relations with fully developed divine powers, who, as
the populations begin to mingle, are indeed figured
simply and naturally as supermen, and superwomen,
always interested in mankind, partisans and poli-
ticians of the most pronounced type, taking a share in
the life of the nation, its wars, its trials and its successes.
We find too the attribution of the invention of the arts

SCIENCE IN THE ANCIENT WORLD 33

and sciences to the gods and demi-gods, who are
always ready to appear among men, to build their
cities, and to beget heroes to be the fathers of the
nations, and to outwit the ancient shadowy powers,
looming distressfully in the background.

As far back as the year 546 before Christ, the philo-
sophical poet, Xenophanes of Colophon, recognized
that, whether or no it be true that God made man in
His own image, it is quite certain that man makes
gods in his. And from the gods of the old Greek
mythology we get an insight into the genius of the
Greek that nothing else can give. We see the picture
of a race, false, boastful and licentious perhaps, but
with a sense of beauty, a confident joy in life, a
warmth of affection that bespeak a gallant, vigorous,
open-hearted, conquering people, a people of extra-
ordinarily brilliant original intellectual endowment,
tempered and purified by the rigours of the North,
and then placed in a land of glorious beauty, where
the wine-dark sea brought the trade and knowledge
of the world to their doors, where the climate smiled
upon their fortified homesteads, where abundant
slaves made life easy, and gave leisure for the
growth of the highest forms of philosophy, literature
and art.

The main function of the Greek religion, as of

many others, was to interpret nature and its processes

Religion and m terms which could be understood—

Philosophy, to • make man feel at home in the

world. The animistic conceptions in which it was

expressed were of unusual beauty and insight. Each

fountain lived in its nymph, each wood in its dryad.

3

34 SCIENCE AND THE HUMAN MIND

The grain-bearing earth was personified as Demeter;
the unharvested sea came to life in Poseidon the earth-
shaker.

From generation to generation the divine figures
are multiplied and more clearly delineated, new
attributes are assigned to them, cycles of stories
cluster round each name. We watch a continual
process of evolution. Each poet is free to adapt the
myths to his own purpose ; to introduce a recovered
legend, to weave a new allegory ; to re-interpret at
his will. As the ages pass, and the intellect masters
the senses, a need for a higher creed is felt, until at
length ^Eschylus and Sophocles evolve out of the
older crude polytheism the idea of a single, supreme
and righteous Zeus. All this is wrought quite naturally,
with hardly an idea of innovation, by those whose
object is to preserve, purify and expound the old
faiths. The process culminates in the metaphysical
reconstruction of religion by the genius of Plato,
which, founded on the social and ethical needs of the
Hellenic people in the day of their greatest triumph,
rises to those highest flights of mysticism which
afterwards so profoundly influenced the theology of
Christianity.

But, alongside this process of conservative evolution,
a simultaneous sceptical criticism was going on. A
religion so frankly anthropomorphic appealed rather
to the imagination than to the intellect, and its weak-
ness on the philosophical side became apparent
when growing doubt ventured to express itself more
openly. This very weakness, coupled with the
essential freedom of intellectual outlook of the Greek
world, led to a natural and metaphysical philosophy,

SCIENCE IN THE ANCIENT WORLD 35

which, even from the earliest times, was untrammelled
by all theological preconceptions.

The beginnings of mediaeval philosophy and science
had to work under the hampering condition of a re-
ligious system of cast-iron dogma, which completely
dominated the thoughts of all men, even those working
at other problems, and supplied to all physical and
biological questions, as well as to those of metaphysics
and theology, an interpretation not to be gainsaid.
Hence, in the Middle Ages and at the Renaissance,
philosophy and science had to struggle for freedom
almost before they could begin their struggle for
existence.

In the growth of Greek natural philosophy the
circumstances were different. All things are com-
parative. Outward obstacles, of course, were not
wanting. Anaxagoras was driven from Athens as
an atheist, and the same charge was one of the counts
in the indictment of Socrates. Aristophanes could
not refrain his inimitable jesting at the expense of the
physical speculations current in his day. If as
nothing compared with the universal and vigilant
outward oppression and inward scrutiny of the Roman
Church, and later of its Inquisition, these obstacles
doubtless had a very real effect.

But, in the Middle Ages, a barrier to the birth and
development of rational ideas of nature greater than
the persuasions of the rack and the stake must be
recognized in the inevitable mental attitude even of
the physical enquirers themselves. The mediaeval
mind was completely dominated by the ideas of a
theology formulated in the last classical ages, and
crystallized into greater definiteness and rigidity by the

36 SCIENCE AND THE HUMAN MIND

acute dialectic of mediaeval scholasticism. Save in the
rarest cases, the mediaeval mind could not shake off the
trammels which compassed it about in every direction.
The tyranny of Rome and its dogmatic school pressed
more hardly inwardly over the workings of the mind
than outwardly over the expression of its opinions.

This inward intellectual constraint, this permanent
bent of the mind, in deference to traditional bonds
which could not be cast off and could scarcely be
loosened, seems to have been much less powerful
among the Greeks. The fluidity of their religion,
the variety of its ever-changing myths, its adaptability
to the needs of poetic and artistic beauty, its readiness
to incorporate and to adorn new ideas, led to a freedom
and openness of intellectual outlook quite foreign to
the Middle Ages.

The natural bias of the two religions — the Greek,
the expression of the genius of the Northern race set
free in a Southern atmosphere ; the Mediaeval, the
warping and distorting of the divine truths of Christi-
anity through the incorporation of late Jewish dogma
by the bewildered minds of the denizens of the early
centuries of chaos — this natural bias was exaggerated
by the difference in social conditions. The full and
fairly secure life of a Greek city contrasts with the
painful emergence of some sort of safety and ordered
though narrow existence under the protection of the
Church from the welter of economic ruin and social
confusion of the Dark Ages. It is no wonder that in
one case we get freedom and breadth of outlook, in the
other narrow preconceived ideas and rigid dogmatism
to which the mind clings for safety and dares not
contemplate an escape.

SCIENCE IN THE ANCIENT WORLD 37

But, if the fluidity of Greek religion gave one
advantage to philosophic thought, the very weakness
of that religion on the rational side gave another
even greater support. None but the most powerful
and acute of mediaeval minds could pierce the encircling
gloom of mediaeval Christianity, and detect the in-
tellectual failure of its philosophic and scientific
system. But any Greek philosopher at once could
see that the beautiful nature-myths of his national
faith were useless as a basis for physical speculation
on the origin and nature of the world. Hence, even
from the first, we find philosophers building on a
frankly rationalist theory. They differ in methods,
in results, but all alike gently lay aside the legendary
origins, reject the supernatural, and assume as an
axiom for the world of thought some physical
causation.

Now, whatever be the truth about metaphysical
reality, natural science can only advance by working
from hand to mouth on the assumption that each
step is to be explained by rational and natural causes.
Hence the success, such as it was, of the Greek
philosophers.

When the Greek states developed and outgrew
their earlier days, the geographical position of the
country, as well as its economic needs, brought them
into contact with the two older civilizations that we
have already briefly considered. Greece seems to
have drawn much of its philosophy, its mathematics
and its astronomy from Asiatic sources, while its
medicine and its geometry came from Egypt, possibly
by way of Crete. The area of Hellenic thought, the
product of this mingling of ideas, moved gradually

38 SCIENCE AND THE HUMAN MIND

westwards, beginning in the Ionian islands of the
jEgean Sea, where the Hellenes first met the men of
Asiatic descent. It then reached the zenith of its
philosophical and artistic development at Athens
and in the cities of the mainland, and spread gradually
to the colonies of greater Greece in Sicily and South
Italy, where the practical genius of Archimedes marks
its highest achievement in natural knowledge.

The first known European school of thought to
break away definitely from the mythological tradition

Early Greek was that of the Ionian philosophers.

Philosophy, jhe position of the cities of Ionia and
the adjacent isles as the starting-point of Hellenic
philosophy is of great interest. Either their situation
at an extremity of the region overrun by the northern
invaders enabled them at an early period to recover
the settled course of steady development, free for a
while from further intrusion, or else the character of
the existing population was already extraordinarily
favourable to the development of philosophic thought.
Possibly we may here encounter the effects of some
earlier unrecorded migration of a similar racial stock
which had already prepared the soil and leavened the
inhabitants. Thales of Miletus (580 B.C.) is the
earliest of the Ionian teachers whose fame has reached
us. He taught that water, or moisture, was the essence
of all things, that everything possesses a principle of
activity — has " soul in it "—and that this " soul " is
divine in origin, or, at any rate, is superhuman. The
importance of the Milesian school of philosophy lies
in the fact that it possessed a unity of purpose and
definite aim, setting out, by means of such research

SCIENCE IN THE ANCIENT WORLD 39

as was then possible, to answer the question, " Of what
and in what way is the world made ? "

Thales was followed by Anaximenes, who seems to
have been the first clearly to recognize that the heavens
revolved round the pole star, and to draw the con-
clusion that the visible dome of the sky was half of a
complete sphere at the centre of which was the earth.
Till Anaximenes gained this new outlook, the earth had
been imagined as a floor with a solid base of limitless
depth. It was now represented as a flattened cylinder,
floating within the celestial sphere, which, carrying
the stars with it as fixed luminous points, revolved
about the earth as the centre of all things. Thus, ifl^
its day, the now discredited geocentric theory was an
immense advance over the mythological ideas which
preceded it. A false hypothesis, if it serve as a
guide for further enquiry, may, at the right stage
of science, be as useful as, or more useful than, a
truer one for which acceptable evidence is not yet at
hand.

In this case, though a better theory was shortly
forthcoming, the time was not ripe, and, for many
centuries, mankind returned to the earlier view as
giving a more convincing picture. The school of
Pythagoras (c. 530) has been held to favour a mystical
attitude of mind, as opposed to the rationalistic
tendencies of the men of Miletus. A religious refor-
mation was probably involved in their teachings, and
in them we first meet with the conception of contrasting
principles, Good and Evil, Light and Darkness. The
Pythagoreans replaced Anaximenes' moving sky by a
moving earth, which was imagined to revolve round a
central point fixed in space like a stone at the end of a

40 SCIENCE AND THE HUMAN MIND

string, presenting its inhabited outer face successively
to each part of the surrounding sky.

In the fourth century before Christ, geographical
discovery was advanced greatly, especially by the
voyages of Pythias round Britain towards the north
polar seas. The knowledge thus gained of the varia-
tion with latitude of day and night, etc., led to the
simpler conception of the revolution of the earth on
its own axis, while Aristarchus of Samos (280-250 B.C.)
held that the sun was larger than the earth, formed
the true centre of our system, and was one among the
countless fixed stars of heaven. But this heliocentric
theory was too much in advance of the time to carry
general assent. The mass of mankind, even the
majority of philosophers, still considered the centre
of the Universe to be the earth, whether as a floating
ball round which the heavens revolved, or even as
the fixed, stable, bottomless solid it seemed to the
senses. The centuries from the days of Aristarchus
to those of Copernicus had to pass before enough
evidence accumulated to force men to revive the
speculative view of Aristarchus, and to establish it in
the light of all the new evidence as the universally
accepted theory of science.

The authority of Aristotle was too great for the new
theory of Aristarchus, and, about 130 B.C. Hipparchus,
the inventor of trigonometry, developed the geocentric
theory into a form which, expounded by Ptolemy of
Alexandria (fl. 127-151 A.D.), held the field till the
sixteenth century of our era.

The theory of Hipparchus, though erroneous in its
underlying assumption and in its results, was founded
on sound methods of induction. Accepting the earth

SCIENCE IN THE ANCIENT WORLD 41

as the centre, Hipparchus showed that the apparent
motion of the sun could be explained by supposing
that it was carried round a central point in an orbit or
epicycle, while this orbit, sun and all, was carried round
the earth in an immensely larger circular orbit or
cycle. From direct observation, solar tables could
then be calculated, from which the sun's position at
any future time could be predicted, and even solar
and lunar eclipses foretold with some accuracy. These
ideas were extended with success to the moon also,
Babylonian records being pressed into service for the
dates of past eclipses.

According to the accepted view, continued motion
needed a continued moving force, and thus it was
necessary to suppose the skies filled with crystal
circles, which, cycles and epicycles, carried round the
heavenly bodies as they revolved.

It is easy to ridicule this scheme of astronomy in
the light of modern times ; yet the fact remains
that, false as the theory was, it served successfully
to interpret knowledge for many centuries, and
guided the labours of such a competent astronomer as
Ptolemy. The theory most fruitful at a given time
is not always that which eventually survives, but
may be too much in advance of the age to be usefully
employed.

If astronomical phenomena are the more striking,

and therefore the first to arrest attention, the problem

The Problem °* tne nature of matter cries equally for

of Matter. an explanation to thoughtful minds,

And so we find the Ionian philosophers tracing the

changes of substance from earth and water to the

42 SCIENCE AND THE HUMAN MIND

bodies of plants and animals, and back again to earth
and water. They began to realize the conception
of the indestructibility of matter, and speculated on
the possibility of a single " element," a common
basis of all substances. But the rival hypothesis of
the Sicilian philosopher Empedocles (450 B.C.), the
wonder-worker, appealed more to contemporary
thought. Empedocles held that the primary
elements were earth, water, air and fire — a solid,
a liquid, a gas, and a type of matter still rarer
than the gaseous. These four elements were
combined throughout the Universe in different pro-
portions under the influence of two contrasted divine
powers, one attractive and one repulsive, which the
ordinary eye sees working among men as love and
hatred, a return to the conceptions of Pythagoras.
Empedocles illustrates in a most forcible manner the
essential unity of the mystic and the man of science,
on which we have already dwelt. He was able to
distinguish between the body substances of his four
corporeal " elements," and the soul substance of his
two divine forces. He separated energy from matter,
and, in so doing, took a real step in advance. This
doctrine of four elements held sway over the minds of
men till modern chemistry was brought up against the
eighty or more different types of irresolvable matter,
and it is still found in literature now that modern
physics is opening once more a glimpse into yet
more fundamental depths and discovering corpuscles,
common to all chemical elements — a return by the
path of modern experimental methods to the lucky
guess of the Ionian philosophers.

Empedocles' theory of a divine power or life passing

SCIENCE IN THE ANCIENT WORLD 43

from element to element seems to have been a way
of teaching the identity of the principles underlying
every phase of development from inorganic nature
to man. According to Empedocles, existence is
essentially one from end to end.

Empedocles saw that, by imagining his four elements
united in different proportions, he could explain all

the endless kinds of different substances

The Atomists. , , . , T ,

known to mankind. Leucippus and

Democritus developed this hypothesis into a theory of
atoms which we know best through the description
of it given at a later date by the Latin poet Lucretius.

The ground on which the atomic theory of the
Greeks was founded was very different from the
definite experimental facts known to Dalton and
Avogadro when they formulated the atomic and mole-
cular theories of to-day. The modern chemists had
before them exact quantitative measurements of the
proportions in which chemical elements combined by
weight and by volume. These limited and definite facts
led irresistibly to the idea of atoms and of molecules,
and gave to them at once relative atomic and mole-
cular weights. The theory thus formulated was then
found to conform with all the rest of the countless
facts and experiences which had become the common
possession of science, to be supported by other relations
as successively they were discovered, and to serve
as a useful guide in the study and even the prediction
of new phenomena.

But the Greeks had neither the definite experi-
mental facts to suggest the theory in the first place,
nor the power of testing by experiment the conse-

44 SCIENCE AND THE HUMAN MIND

quences of the theory when deduced. The theory
remained a doctrine, like the metaphysical systems
of our own day, dependent on the mental attitude
of its originator and his followers, and liable to be
upset and replaced from the foundations by the new
system of a rival philosopher. And this, indeed, is
what happened.

The Greek atomists reasoned from the general
knowledge of their day in the light of the prevalent
metaphysical ideas. When matter is divided and
subdivided, do its properties remain unchanged ?
Is earth always earth, and water water, however far
the process of division be carried ? In other words,
are the properties of bodies ultimate facts of which
no further explanation can be given ? Or can we
represent them in terms of simpler conceptions, and
thus push the limits of ignorance one step further
back ?

It is this attempt at a rational explanation which
gives to the atomic theory of the Greeks its importance
in the history of thought. According to the ideas
that preceded its birth, the qualities of substances
were thought to be of their essence ; the sweetness of
sugar, and the colour of leaves, were as much a reality,
not to be explained by reference to other facts, as the
sugar and leaves themselves.

In contra-distinction to this view, which made all
further enquiry useless, Democritus taught : " Accord-
ing to convention there is a sweet and a bitter, a hot
and a cold, and according to convention there is colour.
In truth there are atoms and a void."

The atoms of Democritus were uncaused and
existent from eternity. They were many in size and

SCIENCE IN THE ANCIENT WORLD 45

shape, but identical in substance. Empedocles ex-
plained differences in properties by different combina-
tions of his four elements. Democritus went further,
and referred differences in properties to differences
in size, shape, position and movement of particles
of the same ultimate nature. His theory, as trans-
mitted to us by Lucretius, effects a wonderful simpli-
fication in the mental picture of nature previously
held. In fact, the picture is too simple. The
atomists passed unconsciously over difficulties still
unsolved after the lapse of twenty-four centuries.
Fearlessly they applied their theory to problems of
life and consciousness which still defy explanation
in mechanical terms. Confidently they believed
they had left no mysteries, all blind to the great
question whether the conception of atoms they had
framed to describe phenomena corresponded with an
ultimate reality any more nearly than did the simple
sense-perceptions it was invoked to explain.

Nevertheless, the Democritan atomic theory is
nearer to the views now held by physicists than any of

the systems which preceded or replaced
Aristotle. ., \ ., . , , . , ,,

it, and its virtual suppression under the

destructive criticism of Aristotle (c. 384-322) must
be counted a loss to mankind.

The success of the Aristotelian philosophy shows
the danger to physical theories, even though sound
in themselves, when they are not founded on a broad
and detailed basis of experimental fact. Because
the consequences of the atomic theory did not agree
with Aristotle's preconceived ideas, he rejected it
altogether, and, in the absence of definite confirmatory

46 SCIENCE AND THE HUMAN MIND

evidence, he was able to obtain a general acceptance
of his views.

As an example of Aristotle's method, his treatment
of the problem of falling bodies is instructive. Demo-
critus had taught that in a vacuum all bodies would
fall at an equal rate, and that the observed differences
were due to the unequal resistance of the air. This
opinion is correct, though Democritus had no experi-
mental evidence to bring forward. Aristotle accepts
the statement that in a vacuum bodies would fall
equally fast, but argues that such a conclusion is
inconceivable, and that therefore there can never be
a vacuum. With the possibility of empty space he
rejects all the allied concepts of the atomic theory.
If all substances were composed of the same ultimate
material, Aristotle argued that they would all be
heavy by nature, and nothing would be light in itself
or tend to rise spontaneously. A large mass of air
or fire would then be heavier than a small mass of
earth or water, and the earth or water could not sink
through air or fire as it is known to do.

Aristotle's error arose from the fact that, in common
with other philosophers of his age, he had no notion
of the conceptions now known as density or specific
gravity ; he failed to see that it is the weight per unit
volume which is the determining factor in questions
of rise and fall, and attributed the motion to an innate
instinct leading everything to seek its natural resting-
place. This doctrine that bodies are essentially heavy
or light in themselves was accepted with the rest of
Aristotle's philosophy by the schoolmen and theo-
logians of the later Middle Ages, and his dead hand
held back the flowing tide of knowledge till Galileo,

SCIENCE IN THE ANCIENT WORLD 47

in the years 1589 to 1591, appealing to actual experi-
ments carried on from the top of the leaning tower of
Pisa, showed that heavy and light bodies do fall at the
same rate, and thus destroyed the Aristotelian con-
ception of heaviness and lightness as essential qualities
of bodies.

Aristotle, too, though he accepted the spherical
form of the earth, maintained the geocentric theory
of the Universe, and his authority did much to prevent
the heliocentric theory of Aristarchus from being
accepted in the next generation, and obstructed
its revival by Copernicus seventeen hundred years
later.

But nevertheless Aristotle was the greatest col-
lector and systematizer of knowledge produced by
the ancient world. His supreme importance in the
history of science consists in the fact that, till the
Renaissance of learning in modern Europe, no ap-
preciable advance in our knowledge of nature was
made in all the centuries that followed him. The
task of the Dark Ages was to preserve what it could
glean of his works from imperfect and incomplete
abstracts; and later mediaeval times spent their
strength in recovering his meaning when the full
text of his books reappeared in the West. Aristotle's
works are an encyclopaedia of the learning of his
generation, and, save in physics and astronomy, he
probably made real improvement in all the subjects
he touched. He gives careful descriptions of animals,
their life-histories and habits ; he laid good foundations
for the modern science of comparative anatomy,
and, the first embryologist, watched the heart beating
in the chick while yet in the egg. Even in physiology,

48 SCIENCE AND THE HUMAN MIND

though his conclusions and theories were often wrong,
his methods marked a great step in advance. For
instance, after giving an account of the views on
respiration held by earlier naturalists, he points out
that " the main reason why these writers have not
given a good account of these facts is that they have
no acquaintance with the internal organs, and that
they did not accept the doctrine that there is a final
cause for whatever Nature does. If they had asked
for what purpose respiration exists in animals, and
had considered this with reference to the organs, e.g.
the gills and the lungs, they would have discovered
the reason more speedily." Here the insistence on
the need of observation of anatomical structure
before the framing of views on the functions of organs
is the point, and, in the treatment which follows,
Aristotle passes in review the structure of a number
of animals, and describes the action of their lungs
or gills. In drawing conclusions, Aristotle had, of
course, no knowledge of chemistry to help him, the
idea of gases other than air was unknown, and the
only change in air which could be suggested was
its heating or cooling. Aristotle's theory that the
object of respiration is to cool the blood by contact
with air, though now seemingly absurd, was perhaps
the best of which his age was capable.

Aristotle took over from Plato, his master in philo-
sophy, many metaphysical ideas, some of which he
modified in accordance with his greater knowledge
of nature. Plato had no scientific insight ; his interests
were philosophical. Hence perhaps arises the fact
that Plato's theory of nature as a whole, and even
that of his pupil Aristotle, were less in accordance

SCIENCE IN THE ANCIENT WORLD 49

with what we now hold to be the truth than the
conclusions of the older nature-philosophers, though,
in points of detail, Aristotle far surpassed them in
knowledge.

With the more metaphysical aspects of Greek thought
we are not concerned. Yet, owing to its importance
in mediaeval controversy, it may be well to touch
lightly on Plato's doctrine of ideas, and Aristotle's
variation of it,

In nature we find numberless groups of objects
more or less similar ; animal and vegetable species
may stand as examples. To explain the similarity,
the mind conceives a primary type to which, in
some way, the individuals have to conform. Now,
when the mind begins consciously to frame definitions
and to reason about them in general terms applicable
to any particular case, Plato found that the defini-
tions and reasoning were concerned with these
hypothetical types. All natural objects are in a con-
stant state of change; alone the types imagined by
the mind remain constant and unchangeable. Hence
Plato was led to the theory that these ideas of
the mind are the only realities. For Plato, says
Aristotle, " the objects of sense were additions to the
ideas, and named after them, for it was by partici-
pation in the ideas that their material namesakes
existed."

To Aristotle, often immersed in the detailed study
of definite individual animals or other concrete objects,
this thorough-going idealism was not a convenient
attitude of mind. The influence of his master re-
mained, but he broke away from his extreme position.
While admitting the reality of the individuals, the

4

50 SCIENCE AND THE HUMAN MIND

concrete objects of sense, Aristotle recognized also a
secondary reality in the universals or ideas, which
he held to exist in and with the objects of sense as
their essence. In later times this view was developed
into pure nominalism, according to which the indivi-
duals are the only realities, the universals being taken
merely as names, or mental concepts. To this ques-
tion we shall be brought back in dealing with mediaeval
thought.

Now, whatever be the truth about Plato's doctrine
of ideas from a metaphysical or logical point of view —
and in a modern form it is still held by many philo-
sophers— the mental attitude which gave it birth is
not adapted to further the cause of experimental
science, before its exclusively logical or metaphysical
import is recognized. The school of Plato, including
even Aristotle, were far too prone to treat a scientific
problem under a preconception of the supreme import-
ance of words and their meanings, to consider that
hot is necessarily opposed to cold, heavy to light,
and to assume that bodies possessed essential qualities
corresponding to one or other of these contrasted
words.

The characteristic weakness of the inductive sciences
among the Greeks is explicable when we examine their
theories of knowledge. Aristotle, while dealing skil-
fully with the theory of the process of passing from
particular instances of judgments of sense to general
propositions, regarded this induction merely as a
necessary preliminary to true science of the deductive
type, which, by logical reasoning, deduces conse-
quences from the premises reached by the former
process.

SCIENCE IN THE ANCIENT WORLD 51

The best instance of a deductive science, in fact one
of the most striking results of Greek thought, is the
Euclid and Euclidean treatment of geometry. Euclid
Geometry. (c> ^oo B.C.) collected and systematized
and developed the work of preceding geometers.
From a few axioms which he regarded as properties
of space evident from our direct experience, he
deduced by logical self-evident principles a wonderful
series of propositions, in a manner which remained
till quite recent years the only accepted method.
As the science of the space known to our senses,
its results marked a permanent step in advance,
which, unlike some other products of Greek thought,
had never to be retraced.

The foundations of the sciences of mechanics and
hydrostatics are to be sought in the work of

Archimedes Archimedes of Syracuse (287-212 B.C.),
and the Origins whose work, more than that of any other

of Mechanics. Greek^ shows the tme modern spirit of

experimental enquiry in which hypotheses are set
forth only to be tested by experiment. The idea of
the relative density of bodies, which, as we have seen,
was unknown to Aristotle, was first formulated by
Archimedes, who, moreover, showed that, when a body
floats in a liquid, its weight is equal to the weight
of liquid displaced. Archimedes also considered the
theory of the lever, the use of which is illustrated in
the sculptures of Assyria and Egypt, two thousand
years earlier, for the purpose of moving colossal
figures and huge blocks of stone. Nowadays we treat
the law of the lever as a matter for experimental
verification, and deduce other, more complicated,

52 SCIENCE AND THE HUMAN MIND

results from it. But, with the Greek love of abstract
reasoning, Archimedes deduced that law from what
he regarded as self-evident propositions. Implicitly,
however, the principle of the centre of gravity, which
is equivalent to that of the lever, is contained in his
proof. Nevertheless, the co-ordination of the law
of the lever with ideas which seemed simpler to
Archimedes and his contemporaries, was a great step
in advance, and the type of all scientific explanation.

When we turn to biology, we find that there too
the Greek love of theorizing without facts sometimes
led them astray. Anatomy seems first
ne' to have attracted the attention of the
philosophers, but such knowledge as existed was
gained by the dissection of the lower animals only.
Considerable progress was made in purely descriptive
work. In natural history Aristotle, as we have seen,
put together an extensive collection of observations
on the animals then known, with some details of their
anatomy, probably gained personally by experimental
methods.

With regard to the earliest practice of medicine,
it is interesting to note that in Homer wounds are
treated in a simple, straightforward manner, showing
the wholesome tradition of a rational spirit in medicine
and surgery among the race of Homeric heroes. But
it appears that this view was confined to the one class.
Among the rest of the people, as in other southern
and eastern lands inhabited by Mediterranean stocks,
spells and incantations formed the prevalent mode of
treatment. Here again in early times the divergent
spirit of the two races makes itself manifest.

SCIENCE IN THE ANCIENT WORLD 53

As medicine developed, the deductive method so
dear to the Greeks took possession, and preconceived
views about the nature of man or the origin of life
were used as the basis of medical treatment, and
doubtless cost many patients their lives. When
theorizing was kept within bounds, the art of medicine
made rapid progress ; the status of the physician rose
with it, and an excellent code of professional life was
adopted.

Greek medicine culminated in the school of Hippo-
crates (450 B.C.), with a theory and practice of the art
resembling those which are current to-day, and far in
advance of the ideas of any intervening epoch till
modern times drew near. Disease was reckoned
as a process subject to natural laws. The insistence
on minute observation and careful interpretation of
symptoms led the way for the foundation of modern
clinical medicine, while many diseases were accurately
described and appropriate treatment indicated. But
it was not till later, probably at Alexandria, under
the sway of the Ptolemies, that human anatomy
and physiology received a proper basis of ascer-
tained fact by systematic human dissection, an
advance which may perhaps be attributed to the
opportunities afforded by the Egyptian custom of
preparing and embalming the bodies of the dead,
as well as to the influence of the old-established
medical science of the Nile valley.

The atomic theory, as we have said, was extended,
even more speculatively than in physics, to bio-
logical questions. Lucretius describes the formation
of worlds and all possible forms of life by the " for-
tuitous concourse of atoms " in the chances of infinite

54 SCIENCE AND THE HUMAN MIND

time, while only those systems persisted which were
fit for the environment. Here we see a faint fore-
cast of the nebular hypothesis and the Darwinian
theory of natural selection.

In classical times, original scientific thought seems

to have been confined to the Greeks. Although the

The Failure composition of the inhabitants in the

of Rome, adjoining peninsula, or at any rate in its
northern parts, and in the Roman State, was probably
of a similar character to that of Greece, i.e. an indi-
genous Mediterranean race, overlain and directed by
an incoming people from beyond the Alps, yet the
resultant population showed considerable differences
in development and achievement. The Romans, with
their incomparable instinct for the State, and their
transcendent power as administrators and framers
of law, had little academic intellectual force, although
the numerous compilations that came into being seem
to indicate a considerable curiosity about natural
objects. Their art, their science, even their medicine,
seem to have been borrowed from the Greeks ; and,
when Rome became mistress of the world, Greek
philosophers and Greek physicians resorted to the
banks of the Tiber, without establishing any native
schools, there or elsewhere, worthy to succeed those
of Athens.

One Roman citizen, born in North Italy, the elder
Pliny (23-79 A.D.), is to be remembered for having
produced in the thirty-seven books of his Natur-
alis Historia an encyclopaedia of the whole science
of the period. He placed on record the know-
ledge and beliefs of a series of forgotten writers and

SCIENCE IN THE ANCIENT WORLD 55

workers of Greece and Rome. Starting from the
world, the sky and the stars in space, which he regarded
as a kind of pantheistic deity, he passed in review the
earth, with terrestrial phenomena, such as earthquakes,
and dealt successively with geography, with man,
his mental and physical qualities, with animals, birds,
trees, agricultural operations, forestry, fruit-growing,
wine-making, the nature and use of metals, and the
origin and practice of the fine arts. Pliny discourses
with equal satisfaction on the natural history of the
lion, the unicorn and the phoenix, unable to distin-
guish between the real and the imaginary, the true,
the credible and the impossible. He preserves for us
the superstitions of the time, and recounts in all good
faith the practice and utility of various forms of
magic. But, to his credit, it must not be forgotten
that he died a victim to his curiosity in natural
knowledge. He was in command of the Roman fleet
at the time of the great eruption of Vesuvius which
destroyed Pompeii and Herculaneum. He landed in
order to watch the development of the upheaval,
advanced too far inland, and was overcome and borne
down by the storm of falling ashes.

The greatest physician of the Roman period was
Galen, born at Pergamos, in Asia Minor, about 130 A.D.
Galen reunited the divided schools of medicine,
and worked at the dissection of animals. His system
of medicine, in opposition to the materialistic views of
the atomists, was founded on the Hippocratic theory
of four elements, combined with the idea of a spirit
pervading all parts of the body. It was for dogmas
deduced with great dialectic subtlety from these views,
rather than for his experimental observations or prac-

56 SCIENCE AND THE HUMAN MIND

tical skill, that Galen became famous, and influenced
the practice of medicine for fifteen hundred years.

The chief name which distinguishes the later Graeco-
Roman Alexandrian school of science is that of
Ptolemy, who taught and made observations there
between the years 127 and 151 A.D. His great work
on astronomy, usually spoken of by its Arabian name
of Almagest, remained the standard treatise until the
days of Kepler and Copernicus ; but, in spite of
greater fullness of treatment, it does not alter the
theories of celestial phenomena already suggested by
Hipparchus. Ptolemy, like his master, improved and
developed the science of trigonometry, with the view
of basing his observations and their results on the
" incontrovertible ways of arithmetic and geometry,"
and laid down the general principle that, in attempting
to explain phenomena, it is necessary to adopt the
simplest hypothesis that will co-ordinate the facts.

Ptolemy is perhaps better known as a geographer
than as an astronomer, and he exercised an influence
in this department of knowledge which only gradu-
ally sank into the background under the stimulus of
the maritime discoveries of the fifteenth and sixteenth
centuries. But, here again, it is difficult to assign
the merit of much of the work to the respective
shares of Ptolemy himself and his immediate fore-
runner, Marinus of Tyre, whose writings have not
separately survived. Ptolemy undoubtedly placed
geography on a secure footing by insisting that correct
observations of latitude and longitude must precede
any satisfactory attempts at surveying and map-draw-
ing ; but his own materials for carrying out such a
design were very inadequate, since there was, indeed,

SCIENCE IN THE ANCIENT WORLD 57

practically no method then by which longitudes could
be determined with any accuracy. Nevertheless, put
together from information brought by traders and
explorers, Ptolemy's maps of the known world, ex-
tending from the shores of the Malay peninsula and
the coast-line of China to the Straits of Gibraltar and
the Fortunate Islands, from Great Britain, the Scandi-
navian lands, and the Russian steppes to a vague land
of lakes at the head-waters of the Nile, retain their
interest. His general treatment of the subject is that
of an astronomer rather than a geographer, for he
makes no attempt to describe climate, natural pro-
ductions or even the aspects which would now be
included under physical geography ; nor does he
avail himself, to any large extent, of the descriptions
and accounts of lands within the Roman Empire which
must have been accessible in the military "itineraries."
Whatever be the cause of the phenomenon, it is
clear that, even before the decay of Rome as a political
power, science, in common with other forms of thought,
had come almost to a standstill. No advance in
knowledge was being made, and all that was done was
in the direction of writing compendiums and com-
mentaries, chiefly on the Greek philosophers, and in
especial on Aristotle, who came to be regarded as
the great authority on all questions of scientific theory
and even of actual fact.

While Greek learning, receiving no reinforcements,

lost itself in the capital and the western territories

The Influence °f tne Roman Empire, it pursued a more

of Alexandria, fertile course in the lands and cities of

the Eastern Mediterranean, whence it had received its

58 SCIENCE AND THE HUMAN MIND

original stimulus. At Alexandria, a school of thought
arose, influenced alike by Hellenic culture and Jewish,
mingled with Babylonian, tradition. It must be re-
membered that but a small, and relatively unim-
portant, number of the Jews returned to Palestine
after the close of the Babylonian captivity, and that
many of the rest of the nation, establishing them-
selves as traders in the cities of Asia Minor and the
Levant, formed a network of communication, com-
mercial, political and intellectual, throughout the
East. Alexandria was the commercial, as Jerusalem
remained the religious, centre of this scattered but
most influential community. It was by their means
that much of the Greek influence retained its vitality,
and took part in the formation of thought in the
early Christian churches. The ideas of Plato thus
passed into the Christian philosophy, and became
current in mediaeval Europe long before their origin
was suspected by the schoolmen, who were afterwards
amazed to find the familiar doctrine imbedded in the
works of the heathen philosophers. Then, too, when
the natural line of descent failed in the fall of Rome,
the ancient learning found a way into the schools of
mediaeval Europe through the Moorish dominions
and the Arab conquerors of Spain, who themselves
obtained it from Alexandria.

CHAPTER III

THE MEDIAEVAL MIND

The Middle Ages— The Patristic Age— The Dark Ages— The Reconstruc-
tion of Europe — The Corning of the North — Arabian Science — The
Revival of Learning— The Schoolmen — Thomas Aquinas— Dante —
Roger Bacon — The Decay of Scholasticism.

UNTIL recent years, the term " Middle Ages " was
applied to the whole long interval of a thousand
The years between the fall of the ancient
Middle Ages, civilization and the rise of the Italian
Renaissance. But the revival of interest in the
history, art and religion of the thirteenth and
fourteenth centuries has led to a clear recognition
that by that time a new civilization had arisen,
and has produced a growing tendency to restrict
the name " Mediaeval " to the four hundred years
which preceded the Renaissance and followed what
soon came to be termed specifically the " Dark
Ages."

But, to the" historian of science, there are advantages
in the older classification. It is not till the period of
the Renaissance that modern science recovers the
knowledge of the ancients, learns to examine it
critically, and starts on a path of its own by the help
of the new experimental method. Hence the period

59

60 SCIENCE AND THE HUMAN MIND

from 1 100 onward, like the dark ages that preceded
it, is to the historian of science but a time of pre-
paration. The two divisions are part of the same
whole, and may well be treated together, though for
the historian of politics, literature or art they are
distinct and separable. To us, then, the Middle
Ages have their old significance — the ages that come
between the ancient learning and that of the Re-
naissance— the great dark valley across which mankind
had to struggle down the descent on one side from
the heights of the thought of Greece and the power
of Rome to the slow ascent on the other to the upward
slopes of modern science. We look across the cloud-
filled hollow and see the hills beyond more clearly
than the intervening ground, lit only by " the dim
light of scholasticism and theology."

In order to appreciate the causes which produced
the great failure of the Middle Ages to add to our
The stores of natural knowledge, it is necessary
Patristic Age. to understand the attitude which char-
acterized the mediaeval mind ; to realize that the one
and overwhelming fact is the universal dominance of
the religious motive of salvation. This conception
had been founded on the theology framed by the
early Fathers in terms of Hebrew dogma and Greek
philosophical concepts, and moulded by each succeed-
ing age chiefly as an instrument of controversy to
defend from the attacks of pagan or heretic the
scheme which each regarded as orthodox. Then, in
turn, it is necessary to understand why patristic and
mediaeval Christianity was inimical in spirit to secular
learning ; why under its influence philosophy became

THE MEDIEVAL MIND 61

the handmaid of theology, and natural science vanished
from the earth.

This result was not inherent in the nature of the
case ; in the earliest patristic age a different spirit was
abroad.

Of all the Fathers of the Church, Origen, one of
the earliest, is most nearly akin to the modern mind.
He was born at Alexandria, about 185, of parents
who were Greek by race and Christian in religion.
Origen laid the foundation of textual criticism of both
the New and the Old Testaments, applying critical
methods even in discussing the historical aspects of
Christ's life and person. He laboured to free Chris-
tianity from the tyranny of the Jewish-Babylonian
doctrines of damnation and hell ; and, by dwelling
on the harmony of the Christian faith, as it appeared
to him, with the scientific knowledge of the Alex-
andrian Greeks, in which he was proficient, he exercised
a great influence both in predisposing the more in-
tellectual classes of the community towards the new
religion and in directing the theological development
of the Church. But he did not escape persecution
and, probably, imprisonment during his lifetime ;
partly for political reasons and partly out of deference
to the prejudices of the more ignorant and ascetic
monastic communities of the age and district. His
teaching was finally anathematized at the Council of
Constantinople in 553, and his authority gave way
before the narrow and dogmatic bigotry of the later
Fathers. Had Origen's views prevailed, the Middle
Ages would have recovered far earlier and more com-
pletely the spirit of freedom and fearless enquiry in
which they were so lamentably wanting. But we

62 SCIENCE AND THE HUMAN MIND

must turn to the influence which displaced that of
Origen.

As we have seen, the older Greek philosophies were
founded frankly on observation of the visible world.
With Socrates and Plato the enquiry took a deeper
turn, and moved from questions of fact to those of
reality, from natural to metaphysical philosophy of
an idealistic and mystical tendency : " the Greek
mind became entranced with its own creations." To
Plato, external facts, whether of nature or of human
life and history, only become real when apprehended by
the mind. Their true meaning must lie in that aspect
of them that accords with the mind's consistent scheme
of concepts, for thus alone can the facts be thought
of, and therefore thus alone can they be. The
inconceivable is in truth the impossible.

Such a philosophy clearly could not foster accurate
and unprejudiced observation of nature or of history.
The structure of the Universe had to conform to
the ideas of Platonic philosophy ; history was in its
essence a means of vivifying argument or of pointing
illustration.

Aristotle was more interested in the observation
of nature than was Plato, though it was in metaphysic
and logic rather than in science that his greatest
strength lay. But Aristotle's influence, great though
it was, gradually ceased to be dominant, and by the
sixth century had passed out of fashion for seven
hundred years. We shall be brought back to Aristotle
at a later stage of our enquiry, but for the present we
may pass on.

The philosophy of the Stoics was especially suited
to the Roman mind, and must not be overlooked in

THE MEDLEVAL MIND 63

any estimate of the different streams of thought on
which the patristic theologians floated their Ark. For
the Stoic, the central reality was the human will.
Metaphysics and knowledge of the natural world were
only of import as they subserved the ends of his philo-
sophy to be a guide of life and conduct. Stoicism was
essentially a scheme of ethics, and physics this time
were turned from truthful observation by the pre-
conceptions of morals.

The modes of thought inaugurated by Plato were
developed into still more super-rational heights by
the Neo-Platonists, whose philosophy was the last
product of late paganism. From the Egyptian
Plotinus (d. 270 A.D.) to Porphyry (d. 300) and lam-
blicus, philosophy became less and less physical and
experimental, and more and more concerned with
super-rational ideas. In Plotinus, the highest good
was the super-rational contemplation of the Absolute.
Plotinus lived in a pure region of " metaphysics
warmed with occasional ecstasy." In Porphyry, who
had a rational side, and still more in lamblicus, these
views were brought down to practical life, and their
application led to growing credulity in magic and
sorcery. The soul needs the aid of god, angel,
daemon ; the divine is essentially miraculous, and magic
is the path to the divine. Thus Neo-Platonism
countenanced and absorbed every popular superstition,
every development of sorcery and astrology, and every
morbid craving for asceticism, of which a decadent
age was prodigal. The life of lamblicus, as told by
a Neo-Platonic biographer, is as full of miracle as
Athanasius' contemporary life of St Anthony.

This philosophic atmosphere was mixed with currents

64 SCIENCE AND THE HUMAN MIND

of such Eastern faiths as Mithraism and Manichaeism,
the latter of which enunciated a dualism of the powers
of good and evil, destined to appear again and again
in later times. The former, with its rites of initiation
and purification, disputed with Christianity the posses-
sion of the late Roman Empire. All were non-rational,
credulous and mystical.

In such an intellectual environment the light of
Christianity came to the Greek and Latin Fathers of
the Church. They were products of their age and
race, and, however superior in moral power to the
contemporary pagans, their intellectual standards were
the same, and their philosophy was the philosophy of
their time, merely changed in emphasis by the story
of the Gospel and the Hebrew dogmas with which the
Gospel had become entangled.

Christianity, like Neo-Platonism, was based on the
fundamental assumption that the ultimate reality of
the Universe was spirit, and it too accepted the super-
rational attitude. It has been well said that all men
except fools have their irrational sides. But, in the
early Fathers, the highest super-rationalism, the love
of God and the apprehension of the risen Christ,
passed down through every step to the lowest forms of
credulity held in common with the pagan populace
and the Neo-Platonic philosophers. While Plotinus
the pagan and Augustine the Christian lay little stress
on divination and magic, or on miracles of the saints,
Porphyry and lamblicus on the one side, and Jerome
and Gregory on the other, revel in the daemonic and
the miraculous.

Symbolism, which had shownitself in Neo-Platonism,
became extended and developed by the efforts of the

THE MEDLEVAL MIND 65

Fathers to co-ordinate the Old Testament with the
New, and both with the prevalent modes of thought.
What in the Scriptures or in the world of nature con-
forms to the Christian scheme as interpreted by each
Father may be received as fact ; what does not so
agree is to be understood in a symbolic sense. Here
we have the Christian equivalent to the idealism of
the Platonists.

Finally, to understand the patristic, and through
it the mediaeval, mind, it is necessary to appreciate
the overwhelming motive introduced by the Chris-
tian conception of sin, the need of redemption, and
the fears and hopes of the realistic Jewish-Christian
ideas of heaven and hell — the need of mediation to
obtain salvation to enter the one, and the fear of
damnation in the flames of the other. The pagan
world itself had become less self-confident. The
decadence of the race had carried mankind far from
the bright Greek spirit of life, and the stern Roman
joy in home and State. Men were coming to rely
more on authority in State and thought, were seized
with unrest and vague fears for their safety in this
world and the hereafter. The phase recurs at
various epochs of history. Even before the ministry
of Christ, in Palestine and wherever Jewish influence
was felt, eyes were looking for a catastrophic coming
of the Kingdom of God, a conception which made
the Christian faith of the Apostolic age largely a matter
of eschatology, and its rule of life but an interims
Ethik — a short preparation for the triumphant Second
Coming. Perhaps in the patristic age the end of the
world had receded a little into the future ; but the
day of judgment was still very near, and to each man

5

66 SCIENCE AND THE HUMAN MIND

death was an effective door into the mystery of the
next world and the horror of the Shade. Darkness
was covering the civilization of the ancient lands,
and thick darkness the spirit of mankind, almost
obscuring the one transcendent ray of Christ's
message of hope and reconciliation.

With such an outlook on life and such a prospect in
death, it is no wonder that the Fathers showed small
interest in secular knowledge for its own sake. " To
discuss the nature and position of the earth," says
St Ambrose, " does not help us in our hope of the life
to come." With Augustine, God's inscrutable will
is the direct and immediate source of all causation.
In this atmosphere, natural knowledge was valued
only as a means of edification, or as an illustration of
the doctrines of the Church or the passages of Scripture.
Critical power soon ceased to exist, and anything was
believed if it accorded with Scripture as understood
by the Fathers. The contemporary knowledge of
natural history in the Church, for instance, was soon
represented by a second-century compilation called
Physiologus, or the Bestiary, in which the subjects
and the accounts of them, originally Christian allegories
with imagery taken from the animal world, were
frankly ruled by doctrinal considerations. For ex-
ample, it is stated seriously that the cubs of the
lioness are born dead. On the third day the lion
roars, and they wake to life. This signifies our
Lord's resurrection.

And so with their views of history and biography.
The classical historians were always ready to modify
their accounts to. serve the rhetorical fitness of the
situation, and the Church historians carried this

THE MEDIEVAL MIND 67

tendency to much greater lengths. In their hands,
history became a branch of Christian apologetic, and
the lives of the saints, the characteristic form of
early mediaeval literature, became simply a means of
edification. Any legend which accorded with the
author's conception of the holiness of his subject was
received unhesitatingly.

The power of patristic theology was increased
indefinitely by the ecclesiastical organization which
grew up to enshrine it. And when, with the conversion
of the Empire, that organization had the decaying
but still overwhelming strength of Roman tradition
behind it, it became irresistible. The Roman Empire
died, but its soul lived on in the Catholic Church,
which took over its framework and its universalist
ideals. It was immeasurably easier for the Bishop
of Rome to acquire the primacy of the world, and
gradually to tighten the bands of uniformity, because
even barbarians had come to look on Rome as
their metropolis, their Holy City, and the Emperor
as their suzerain. Hence probably came the triumph
of the more legally minded and intolerant Latin
theologians over the less rigid and more philo-
sophical Fathers of the East. The great Council of
Nicaea met in 325, with characteristic modesty, to
" determine the true nature of God," and thereafter,
although St Gregory of Nazianus had declared that
he never knew a Council of the Church to end well, a
series of Councils defined doctrine more and more
accurately, and anathematized more and more forcibly
those who differed from their findings.

Thus, although some of the Northern nations were
converted to Christianity by Arian teachers, and

68 SCIENCE AND THE HUMAN MIND

maintained that form of the faith for many centuries,
a great central body of doctrine had been built up before
the Dark Ages began, and Rome had become the
recognized head of the Catholic Church, with all the
universalist tradition of the Empire behind it, and
the new power of a compelling religious faith to put
new life into its veins, and give it uncontrolled
dominion over the minds and consciences of mankind.

Such was the nature of the intellectual position

when the last gleams of sunset of the ancient civiliza-

Xhe ti°n were fading away into the dark night

Dark Ages. of the sixth and seventh centuries. And
such was the nature of the ideals to which the succeed-
ing ages looked back as they emerged into the feeble
light of the new morn, looked back as to a brighter
day whose glorious noon culminated in God's crowning
revelation by his Son, and whose resplendent eve was
illumined by the inspired writings of the Fathers of
the Church. It is small wonder that the men of the
new time took all that came to them from across the
darkness to be endowed with supernatural sanction,
and showed no power of critical insight, in which
the Fathers themselves had been equally deficient.
Almost the only traces of secular learning which
survived were the works of Boetius, a Roman of noble
birth, who was put to death in 525. Probably a
nominal Christian, Boetius was the last to show the
true spirit of ancient philosophy, and it is part of the
irony of history that he developed into a Christian
martyr after his death. He wrote compendiums and
commentaries on Aristotle and Plato, and treatises on
arithmetic, geometry, and music founded on those of

THE MEDIAEVAL MIND 69

the Greeks. After Boetius the classical spirit vanished

from the earth. The schools of philosophy at Athens

were closed in 529 by order of the Emperor Justinian.

The break with the past was much more complete

than the mere fall of Greece as a civilizing influence

and of Rome as a world-power necessarily involved.

Not only were Athens and Rome destroyed as political

states and social civilizations, but both the race of

the Greeks, the artists and philosophers, and the race

of the Romans, the lawyers and administrators, had

ceased to be. Malaria had made vast tracts of country

uninhabitable, swarms of alien immigrants had

corrupted the purity of the blood, while the fall in the

birth-rate among the nobler and abler stocks and the

constant drain of incessant wars and — among the

Romans — of foreign administration, had lowered the

average quality of the nations. The definite races

of Greece and Rome, which had effected such great

things in the history of the world, had given place

to mongrel, cross-bred populations, composed of

incompatible Northern, Mediterranean, African and

Semitic elements, fated, by their lack of cohesion,

want of common ideals and disregard of statecraft,

to inward decay and outward destruction at the

hand of the first strong, pure-bred people that

encountered them. Thus the overthrow of Rome by

Northern Teutons was not essentially a destruction

of civilization by barbarians. It was much more

the clearing away of a doomed and crumbling ruin,

in preparation for future rebuilding.

A new civilization had to be evolved from chaos ;
nations with definite ideals and well-marked character-
istics had to reform out of the medley of races comprised

70 SCIENCE AND THE HUMAN MIND

in the decadent universalist Imperialism ; and those
nations had to advance far in the reconstruction of
social order and the determination and specialization of
intellectual attributes before they could throw off
the spell of patristic and Semitic theology, and form
a suitable seed-bed for the germination and growth of
a new science and scientific philosophy.

Here and there, in the gloom of the Dark Ages, we
see tiny plants of knowledge struggling to the light. It
is probable that in Italy some of the secular schools
maintained their continuity in the large towns through-
out the times of turmoil and confusion. But the rise
of the monasteries gave the first chance of a secure
and leisured life, and, consequently, it is in the cloister
that the first signs of the new growth of learning
are seen.

In view of the character of the Gospel story, it was
impossible for the Fathers of the Church to despise the
art of healing as they despised or ignored more
speculative secular knowledge. Hence tending the
sick remained a Christian duty, and medicine was the
earliest science to revive. Monastic medicine was
at first a mixture of magic with a faint tincture of
ancient science. In the sixth century the Benedic-
tines began the study of compendiums on the works
of Hippocrates and Galen, and gradually spread a
knowledge of these writings throughout the West.

In the seventh century the first new secular home
for learning appears in the schools of Salerno, whence
proceeded many compilations founded on Hippo-
crates and Galen. In the ninth century Salernian
physicians were already famous, and the schools
flourished till overshadowed by the rise of Arab

THE MEDIEVAL MIND 71

medicine in the twelfth century. Since Salerno is
known to have been first a Greek and then a Roman
colony, it is likely that here there existed a direct
link between the learning of the ancient and the
modern worlds.

But it should be noted that countries at a distance
from Rome, the centre of the chaos, were among

f a new

Th R on

struction of distinctive creative spirit. The literary
Europe. an(j artistic development of Ireland, Scot-
land and the north of England, beginning with Irish
sagas full of poetic extravagances, was quickened by
the absorption of Christianity, and thereafter, in the
fervour of its missionary spirit, carried back some
culture into more southern lands. This northern
development culminated in the works of the Anglo-
Saxon monk, Bede of Jarrow (673-735), who incorpo-
rated into his writings all the knowledge then available
in Western Europe. He stands between the Latin
commentators Boetius, Cassiodorus, Gregory, and
Isidore of Seville, who caught the last direct echoes of
classical or patristic learning, and the scholars of the
schools of Charlemagne, chief among them Alcuin of
York, who carried the tradition into definitely
mediaeval times. Bede wrote in Latin chiefly for
monks ; but a hundred and fifty years later culture
had so broadened that Alfred the Great (849-901)
translated or caused to be translated into Anglo-
Saxon many Latin books. The influence of Latin
literature had begun to pass into the native languages.

And indeed by this time mediaeval Europe was
taking shape. Nations had crystallized out from the

72 SCIENCE AND THE HUMAN MIND

mixture of the Romanized Gauls with the vigorous
Teutonic tribes that overran the Roman provinces.
Northern lands that had never seen the Roman eagles,
or from which they had retreated, were developing a
culture and even a literature of their own, on which
Roman ideas and Roman civilization only acted as
external and foreign influences.

We have said that it is to the different branches
of the Northern race that modern science is mainly
The Coming due. Even in ItalY» when, first of nations,
of the North, the Renaissance touched her, experi-
mental science took its rise in the Northern regions
which had been permeated with streams of barbarian
blood by the influx of Goth and Lombard. Hence,
for our present purpose, it is well to learn what we can
of the religion and racial characters of those folk
with whose achievements we shall almost exclusively
be concerned in our later chapters.

Once more, as in the case of the Greeks, we may see
the genius of a people shadowed forth in their religion
and mythology. The heathen faith of Gaul and
Germany and Britain disappeared on contact with
Christianity, leaving well-nigh no trace. But Scandi-
navia kept its native gods far longer — long enough for
poetry, freed from religious prejudices, while deposing
the gods, to retain the myths, and to enshrine them
for ever in the deathless tales of the North. The
Icelandic edda of Snorri Sturlusen was written about
1222 in prose, but it contained quotations in verse from
heathen poems, some of which have survived in an
older edda. In these poems we catch glimpses of
generation behind generation, back into the dim

THE MEDIEVAL MIND 73

obscurity of the unfathomable past. It is then to
the literature of Norway and Iceland that we
must look for the purest example of Teutonic
mythology.

The most striking feature of the Norse legends is
their similarity to those of the Greeks. Odin is a
mixture of Zeus and Prometheus; Thor is Zeus in
another aspect, with attributes of the Roman Mars
superadded. Greeks and Teutons were branches of
the one great Northern race, and racial character is
reflected in beliefs drawn originally, perhaps, from
a common source. But the different environment
modified the different branches of the race by natural
selection, affected their outlook on life, and moulded the
mythology in which that outlook found its most charac-
teristic expression. With the same vigour and freedom
and joy in life and adventure as the Greeks, the Norse-
men had less sense of soft beauty and grace, and a
sterner, somewhat sadder outlook on the problems of
the world. The Greek gods had conquered the Titans
once for all. Thor and Odin wage perpetual war on
the giants of Jotunheim. The Greek gave little
thought to the edge of the world dropping down into
Tartarus, where sunless Cronos dwells. But the
Scandinavian is for ever preoccupied with the icy
barrier, closer to his threshold, beyond which lie the
gulfs of chaos.

In the early cosmogonies, the world is the body of
the giant Hymir, his skull is the heaven, his brains the
clouds, his blood the sea. The stars are sparks from
the great primordial fiery chaos. Then, as in Greece,
there are myths of nature. Thor, the thunder-god,
may be taken as the ideal of the Norse races — homely,

74 SCIENCE AND THE HUMAN MIND

fearless, steadfast ; with a slow brain perhaps, but
judgment sound at the last.

In a later age, when the advance of Christianity
threw the shadow of inevitable fate over the heathen
gods, the old nature myth of the death of Balder
became the symbolic tragedy of all death. Heaven
and earth and gods are to pass away, in one great
fight on the ramparts of Asgard, when the powers of
chaos overwhelm the world and the twilight of the gods
descends. The gods fight on the side of reason,
hopelessly, knowing that chaos wins, but fearlessly,
with steady courage — the glorification of Teutonic
self-will and inward freedom of the individual soul.
In the Viking age there rose a vision of Balder coming
again, and a new heaven and a new earth. But this
may be but a reflection of the Christian Apocalypse ;
the day of pagan myths was over.

But still the spirit of the North survives in the
Sagas, the epics of heroes and heroic kings. Olaf
Tryggvason is the ideal Norseman — tall, golden-haired,
excelling in sport and terrible in war, eager, glad and
kind. All Norway owns his sway, and, at his bidding,
turns to the White Christ. The Sagas are direct,
convincing ; free from unreality or absurdity ; thrill-
ing with the voice of the sea and the call of battle.
Their occasional supernaturalism conjures up visions
of trolls, portents and second sight; it is restrained,
almost modern in tone ; quite different in spirit from
the tissue of childish marvels and morbid asceticism
which characterize the contemporary lives of Southern
pseudo-Christian saints, heroes of the bewildered
cross-bred Mediterranean peoples.

The heathen faiths had vanished. But the genius

THE MEDIEVAL MIND 75

which gave them birth passed over into the new religion
of the Northern race. At first awed not only by the
light of the Gospel but also by the setting of patristic
theology and decadent Latin culture in which it had
become enshrined, they were long held in free sub-
mission to the form and constitution of the faith they
had accepted. " If I and my Franks had been there,
we would have avenged Him," said Clovis when
told the story of the Crucifixion ; and, to them, the
Gospel message which moved their hearts was in-
separable from the organization and prestige of the
Church, Arian or Roman, in which it reached them.

But, when the first bright charm wore off, famili-
arity with the tyranny of ecclesiastical power wrought
a change in their mental state. With alternate en-
thusiastic championship and rough chafing at the
slowly tightening chain of Roman Catholic theology,
their characteristic genius breaks out again and again
in history ; sometimes repressed with fire and sword,
with rack and stake, but triumphant at the last, till
the bonds are broken, till freedom of action and speech
and thought are established in all the lands where the
Teutons hold sway, established by the clash of the
warring parties and sects into which their independent
spirit for ever leads and sometimes betrays them.
Such is the race which laid the foundations and built
most of the superstructure of modern science.

Differences in genius among the various branches
of the race, ancient and modern, may be detected.
The Greek was too self-centred and consequently too
philosophical to grasp the essential spirit of experi-
mental science. The Roman had too little power of
abstract thought and too much fondness for legal

76 SCIENCE AND THE HUMAN MIND

forms. Thus it was the Teuton, observant, pains-
taking, sure, who created modern science, which still
remains chiefly a Teutonic achievement.

Even the Teutons, by the manifestation of their
typical genius, may be subdivided. For example, in
English history, the Saxons of the south and middle
west have most often excelled in administration and
imaginative literature, and it is to the Angles and
Danes of the east and north-east that we must turn
for the most frequent output of scientific ability. The
small, dark, indigenous race of the west have been
singularly barren of original scientific achievement.

But, in early mediaeval times, all this was still in
the womb of the future ; there was as yet little sign
of the birth of modern science. The great work of
that age was preparation, the consolidation of nations,
in which afterwards knowledge might develop in
accordance with the special genius of each people.
The traditional Latin culture survived in part in
countries where it had taken root, and permeated
slowly those which successively made their way into
the European comity. But, for some centuries, little
save this local tradition came over from the past.
For eight hundred years Greek was almost an un-
known language in the West, and Greek and Roman
learning but the faint trickle which found a tortuous
path through the late Latin writers of compendiums,
and the interpretations which mediaeval minds, satu-
rated with theological preconceptions, put in their
turn upon the views of those Latins.

In Italy, which might have given the best field for
direct contact of old and new, the population had
been corrupted too long and too completely by alien

THE MEDIEVAL MIND 77

Eastern and African blood to rally quickly from the
poison. The land had been laid waste again and again
by invasion, and almost all continuity of knowledge
was destroyed, not so much by the overthrow of social
conditions, as by the destruction of the minds capable
of transmitting it. Thus the natural course by which
culture and learning, following the old routes, could
reach the new Western nations had silted up, and the
stream, when it broke in at last, came by other channels.

It was by indirect paths that most of the re-
Arabian covered learning of the Greeks reached
Science, mediaeval Europe. Of these indirect
paths perhaps the earliest was the Arabian.

A certain amount of Graeco- Jewish culture sur-
vived for many centuries in Syria and in the neighbour-
hood of the Persian Gulf, with its chief centres at the
Eastern Imperial Court at Constantinople and at
Baghdad. It was probably along the Eastern trade
routes that the Indian numerals travelled to Europe,
where, under Arabian influence, they gradually dis-
placed the clumsy Roman figuring. In Damascus and
Baghdad, Greek medicine was still cultivated under
Jewish and Christian teachers, and received some ac-
cessions of knowledge, especially as regards drugs, from
Indian physicians, who began to travel westwards.

Progress was also made in astronomical calculations
by Mohamed El Batani (c. 850), who, from his observa-
tory at Antioch, recalculated the precession of the
equinoxes and drew up a new set of astronomical
tables ; while in the eleventh century various observa-
tions on solar and lunar eclipses were placed on record
by Ibn Junis, who worked near Cairo,

78 SCIENCE AND THE HUMAN MIND

The classical period of Arabian science may be
said to date from the tenth century, beginning with
the medical work of Rhazes, who practised in Baghdad
and compiled many encyclopaedic text-books. Fifty
years later, the great physician and philosopher
Avicenna, a native of Bokhara, wandered from court
to court among the rulers of Eastern Asia, vainly
seeking some place of settlement where he could find
an opening for his talents and carry on his literary
and scientific labours in peace and safety. His
" Canon," or compendium of medicine, afterwards
became the text-book of medical study in the European
universities, and up to the year 1650 it was still used
in the schools of Louvain and Montpellier.

But any prospect of the establishment of a stable
Arabian civilization was put an end to by the internal
quarrels of the Mahommedan princes and generals,
and by the gradual disintegration and destruction of
the gifted, noble and old-established families of Arabia
itself. These pure Arabs were the original conquerors,
and had provided the necessary governors, soldiers and
administrators for the vast empire which had been
put together so rapidly. With the accession of the
Abbaside Caliphs and the transference of the capital
to Baghdad, the real power passed into the hands of
a series of Persian, Tartar, and Turcoman ministers
and slaves. Gradually the distant provinces, one
after another, separated themselves from the weak,
overgrown and heterogeneous Empire, re-created
their native characters and reasserted their political
independence. The countries nearest the capital
have never recovered from the prolonged vicissitudes
of a line of impotent tyrants, with its fatal insecurity

THE MEDIAEVAL MIND 70

of universal lawlessness. The apparent quiet which
ultimately settled on them was not that of peace but
of exhaustion. Ease, wealth, trade, literature and
science, all eventually disappeared from the sphere
of influence of the Mahommedan domination.

It was in Spain, the farthest province of the Mahom-
medan conquest, that the first fruits of the inter-
course of Arabian, Jewish and Christian civilizations
became appreciable. For three centuries, from 418
to 711, the West Gothic kingdom had established and
maintained law and order from its capital at Toulouse.
The Sephardim Jews, originally deported from
Palestine to Spain under Titus, had preserved tradi-
tions of Alexandrian learning, amassed wealth, and
kept open communications with the East. But
the persecutions of the Jews, which set in after the
West Gothic kings exchanged the more tolerant
Arianism for the orthodox Roman Christianity, pre-
disposed the Jews for a change of governors, an
attitude which helped to turn what might have been
a mere Mahommedan plundering raid into a successful
conquest.

The tolerance of thought accorded by the Arabs,
as long as their supremacy remained unquestioned,
led the way for the establishment of schools and colleges,
which, however, owed their continued existence, not
to the general intelligence of the people as a whole,
but to the occasional and spasmodic patronage of a
liberal-minded or free-thinking ruler.

The course of Arabian philosophy developed on
much the same lines as that of the Christian schools,
which followed it a hundred years later. There was
the same attempt to harmonize the sacred literature

80 SCIENCE AND THE HUMAN MIND

of the nation with the teachings of Greek philosophy,
and an analogous contest between those who relied
on reason and rational authority and those who put
their faith in revelation, denying the validity of human
reason in matters of faith.

The chief fame of this Spanish-Arabian school of
thought is due to the work of Averrhoes, who was
born at Cordova in 1126. While showing a profound
reverence for the teachings of Aristotle, Averrhoes
nevertheless introduced a new conception into the
relations between religion and philosophy. According
to him, religion was not a branch of knowledge that
could be reduced to propositions and systems of dogma,
but a personal and inward power, distinct from the
generalities of " demonstrative " or experimental
science. Theology, the mixture of the two, he re-
garded as an unmixed source of evil to both, fostering,
on the one hand, a false impression of the hostility
between religion and philosophy, and, on the other,
corrupting religion by a pseudo-science.

It is not surprising that the teaching of Averrhoes
came into fierce conflict with that of the orthodox
theologians, but, in spite of unrelenting opposition,
especially from the great Dominican school of thought,
his words fell upon willing ears. By the thirteenth
century, Averrhoes had become a recognized authority
in the universities of North Italy, Paris and Oxford,
worthy to be placed, according to Roger Bacon and
Duns Scotus, by the side of Aristotle as a master of
the science of proof. That such a position should
have been accorded to a teacher who was not only
of non-European origin, but also of alien and anta-
gonistic religion, indicates the approach of a time

THE MEDIAEVAL MIND 81

when neither creed nor nationality should form an
insuperable barrier in the world of thought.

In the Europe which received and slowly absorbed
this Arabian stream of knowledge, the apparatus of
The Revival learning had made considerable pro-
of Learning, gress. As we have seen, a home of
secular studies, and especially of medicine, had existed
since the seventh century at Salerno, and, in Northern
Europe, the encouragement bestowed on scholars by
Charlemagne and Alfred had given an impetus to
teaching generally. The monastic and cathedral
schools, hitherto in most places the only educational
institutions, were soon found insufficient to meet the
growing needs, and new secular schools began to
assume their later form as definite universities.

A revival of legal studies took place in Bologna
about the year 1000, and, in the twelfth century,
schools of medicine and philosophy were added to
that of law. A students' guild, or Universitas, was
formed for the mutual protection, at first of the
foreign students, who were at the mercy of the in-
habitants, and later of all students, whether native
or foreign. These guilds hired their own teachers,
and thus the University of Bologna, even in its after
life, continued to be a students' university, in which
the governing power was in the hands of the learners.
On the other hand, a school existed at Paris in the
first decade of the twelfth century, conducted by
teachers of dialectic, and shortly afterwards a com-
munity or Universitas of teachers set the constitu-
tional model to all the subsequent universities of
northern continental Europe and England. Thus it

6

82 SCIENCE AND THE HUMAN MIND

is, that at Oxford and Cambridge the governing power
has always rested with the teachers and not with the
students, as at Bologna and to some extent in Scotland,
where the election of the Rector is one of the last
traces of undergraduate control.

As early as the Carolingian period, the academic
subjects of study had settled down into an elementary
trivium, comprising grammar, rhetoric and dialectic,
subjects which dealt with words, and a more advanced
quadrivium — music, arithmetic, geometry and astro-
nomy, which were supposed, at all events, to deal with
things. Music contained a half-mystical doctrine of
numbers, geometry merely a series of Euclid's pro-
positions without the proofs, while arithmetic and
astronomy were esteemed chiefly because they taught
the means of fixing the date of Easter. All were
studied as a preparation for the study of the sacred
science theology. All through the Middle Ages, this
division of the subjects of study held good for the
elements of academic learning, and, with the growing
interest in philosophy, that study was merely super-
added to the simpler logical dialectic.

The old controversy between Plato and Aristotle
on the nature of the idea of universals found its way
into the commentaries of Porphyry and Boetius, and
so reached the mediaeval mind. What is the meaning
of the power of classification ? Are the individuals
the only realities, the universals existing merely in
and with the objects of sense as their essence, as taught
by Aristotle, or even only as names or mental concepts
as the extreme Nominalists held ? Or had the ideas
or universals an existence apart from the phenomena
or the isolated beings, as in Plato's philosophy ?

THE MEDIEVAL MIND 83

In the ninth century the mystical theory of Erigena,
a native of the British Isles and disciple of Origen, a
theory based on the idea of the divine as the only
reality, contained a fusion of Platonic and Aristotelian
views, and the discussion only became acute later.
In the eleventh century pure nominalism appears
in Berengarius of Tours (999-1088), and later in
Roscellinus (d. c. 1125), who, holding the sole reality
of the individual, reached a tritheistic conception of
the Trinity, and at once crystallized, especially in
William of Champeaux and Anselm, the opposing
realism, and established it as the orthodox view for
several centuries. But its inherent difficulties led
to many varieties of the theory, and an interminable
discussion waged in the schools and employed all
the philosophic interests of the scholastic dialecticians
for two hundred years. Abelard, a Breton noble by
birth, attacked his master, William of Champeaux,
and himself taught a modified Aristotelian realism
verging on a nominalism not so consistent as that
of Roscellinus. In Abelard the doctrine of the Trinity
was reduced to the conception of three aspects of the
Divine Being. Abelard showed signs of rationalism,
such as the pregnant statements that " doubt is the road
to enquiry," that " by enquiry we perceive the truth,"
and that "it is necessary to understand in order to
believe," a saying that may well be compared with
the " Credo quia impossibile " of the patristic Tertul-
lian, and the " Credo ut intelligam " of Anselm. Abe-
lard was called to account by St Bernard, who held in
abhorrence the wisdom of this world, and did much
to fan the growing spirit of ecclesiastical suspicion
which saw heresy everywhere. In this controversy

84 SCIENCE AND THE HUMAN MIND

we find the first notable instance of that conflict of
ecclesiastical authority with the growing demands of
the human reason which became the dominant intel-
lectual feature of the coming centuries. But for a
time the speculative spirit was exhausted, and the
middle of the twelfth century marks the beginning of
a pause of fifty years in logical and philosophical
dialectic, and the return to a passing interest in
classical literature, an interest centred in John of
Salisbury and his school at Chartres.

If the intellectual task of the Dark Ages was to save

what it could out of the wreck of the ancient learning,

The that of the first succeeding centuries was

Schoolmen, to master and absorb what was recovered.
As we have seen, the intellectual achievement of
the mediaeval period was the welding together of
the remains of the ancient classical knowledge and
the Christian faith, as interpreted by the early
Fathers, in the minds of new races to whom both
were foreign. From the eighth century onward we
may watch this process at work, and there the
constructive period of the Middle Ages may be said
to begin.

By the middle of the twelfth century the dual
heritage from the past had been surveyed and mapped
out, absorbed and transformed by the Teutonic mind,
where it lay awhile, awaiting an opportunity to
germinate. Here we have the culmination of mediaeval
appreciation of classical literature. None of the more
advanced works of Aristotle were known in a complete
form ; thus no scientific and unliterary source had
come to hand to disturb the literary outlook of those

THE MEDIAEVAL MIND 85

scholars who cared for the classics as a bypath of
study, or as a means of understanding better the
language of Scripture and the writings of the Fathers.
The predominant theological attitude was still Platonic
and Augustinian, idealistic and mystical rather than
rationalistically philosophical.

But in the thirteenth century a great change of
outlook took place, coincident with and inseparable
from the humanizing movement, associated with the
coming and establishment of the Friars. Between
12 10 and 1225 the complete works of Aristotle were
recovered and rendered into Latin, first from im-
perfect Arab versions, and then by direct translations
from the Greek. In this latter work one of the fore-
most scholars was Robert Grosseteste, patron of
the new uncloistered mendicant orders, the great
Chancellor of Oxford, and Bishop of Lincoln, who
invited Greeks to England and imported Greek books,
while his pupil, Roger Bacon, a Franciscan friar,
wrote a grammar of the Greek language. Their
aim was not literary but philosophic — to unlock
the original tongue of Scripture and of Aristotle.
Their ultimate though distant achievement was to
set free the Western mind from the dialectic
subleties of the schoolmen and the Fathers of the
Church.

Aristotle opened a new world of thought to the
mediaeval mind. His attitude — at once more rational
and more scientific — was quite different from the
Neo-Platonism which hitherto had chiefly represented
ancient philosophy. His range of knowledge both
in philosophy and in the science of nature was far
greater than anything then available. It was a heavy

86 SCIENCE AND THE HUMAN MIND

task to absorb and adapt the new material to Middle-
Age Christian thought, and the work was not effected
without misgiving.

It is difficult now to understand the immense
influence that Aristotle came to possess over the
schoolmen of the thirteenth century. It is perhaps
easier to sympathize in the detestation with which
some of the harbingers of the Renaissance regarded
that philosopher and all his works, the loathing for
an authority that checked their eager minds at every
turn. But to the mediaeval churchman, convinced
of the intellectual supremacy of his Church as the
recipient of all revealed knowledge and the only
begetter of true thought, it was marvellous to find the
cherished doctrines enshrined in the work of men
who lived and died centuries before the revelation of
their Lord. It never entered their consciousness that
the recovered volumes were actually the source of
much of the inspiration of the holy Fathers. We may
realize some of their confusion in Dante's treatment of
his pagan master Virgil, who ranks highest amongst
mortal men, and is competent to guide the Christian
pilgrim far on his way and need only turn back at the
threshold of the supreme accomplishment.

At first the Arabian channels by which Aristotle
reached the West mixed his philosophy with some
Averrhoist leanings, and mystical heresies were the
result. Aristotle's works were condemned by the
provincial Council which met at Paris in 1209, and
this prohibition was renewed later. But the new
knowledge was irresistible, and in 1255 the University
of Paris formally placed Aristotle's works upon the
list of books to be studied.

THE MEDIEVAL MIND 87

The interpretation of Aristotelian thought in terms

of Christian dogma, and its incorporation into the

Thomas official philosophy of the Roman Church,

Aquinas. were chiefly the work of one man, Thomas
Aquinas, who systematized and reduced to order the
compendious writings of his master, Albertus Magnus.

The importance of Aquinas in the history of philo-
sophy and of the origins of science is great. He
delayed for many years the liberation of scientific
thought from the trammels of theology, and to
his indirect influence is chiefly due the obscurantist
attitude of Rome towards the initial development of
modern science at the Renaissance. Even as late
as 1879, Pope Leo XIII. directed Roman Catholic
teachers to found their philosophy on that of Aquinas.
Hence, for our purpose, it is necessary clearly to under-
stand the essence of the man and his work. His
task was to reconcile faith and reason — a task ad-
mirable in intention, boldly and skilfully executed,
yet disastrous for mankind in that it was at the least
premature, and therefore resulted in petrifying for a
time both theology and scientific philosophy into one
block of what soon became incompatible elements.

Thomas was born about 1225 in Southern Italy,
but his ancestry was of mingled Swabian and Norman
princely blood, and his father was Count of Aquinum.
At the age of eighteen he joined the Dominican order.
He studied at Cologne under Albertus Magnus, a native
of Swabia, taught at Paris and Rome, and, after a
life of incessant activity, died in 1274.

His greatest works, the Summa Theologize and the
Summa Philosophica contra Gentiles — the setting
forth of Christian knowledge for the ignorant — con-

88 SCIENCE AND THE HUMAN MIND

tain a complete and consistent body of doctrine, in
which the statements of Scripture and the physics
and metaphysics of Aristotle equally find a place.
There are two sources of knowledge, the mysteries
of the Christian faith as transmitted by the channels
of Scripture, of the Fathers and of Church tradition,
and the truths of human reason — not the fallible
individual reason, but the fount of natural truth of
which the chief channels were Plato and Aristotle.
The two sources cannot be contradictory, since they
flow from God as the one source. Hence philosophy
and theology must be compatible, and a Summa
Theologice should contain the whole of knowledge.
Even the highest mysteries of the Trinity and the
Incarnation, though they cannot be proved by reason,
can be examined and apprehended thereby. Hence
these mysteries also are welded into the Thomist
system. Throughout, Aquinas' interests are intel-
lectual. Perfect beatitude of any created intellectual
nature lies in the action of the intelligence directed
to the contemplation of God. Faith and revelation
are belief in a proposition and a presentment of truth.
With this outlook, Thomas proceeds to give an
account of the whole of knowledge in mingled terms
of Scripture, the Fathers and Aristotle. The existence
and attributes of God, of angels and of men are suc-
cessively passed in review. The whole of creation
is a processio, a going out of all creatures from God ;
ideas are prototypal forms existing in the divine mind,
and the meaning of individuation is to be sought in
the existence of determinate matter. This solution
of the old problem of universals involved the obvious
difficulty of explaining the individual existence of

THE MEDIEVAL MIND 89

angels and of the disembodied human soul. Averrhoes
had held that individuality was extinguished at death,
and to avoid this conclusion Aquinas assumed that
such spirits possessed a principle of individuation in
themselves. They are immaterial forms since they
can grasp the universal, and the soul unit is not
merely the rational spirit of Aristotle, but possesses
sensitive functions which depend on bodily perceptions
in life, but are in essence independent of them.

But, for us, more important is the fact that the
whole of the scheme of Aquinas was framed in accord-
ance with the Ptolemaic astronomy and saturated with
geocentric ideas, with the view that all motion implied
a continual exertion of force, and with the whole
spirit of Aristotelian science. From these premisses
Aquinas deduced results in accordance with the
theology of his age, such as : " Movetur igitur corpus
celeste a substantia intellectual*." The deductions
being thus regarded as verified, the premisses became
strengthened, and doubt thrown on them was soon
regarded as inconsistent with the Christian conclusions
with which in Thomas' scheme they were connected.
The whole of knowledge was welded with dogmatic
theology into one rigid structure, the parts of which
were believed to be interdependent, so that an attack
on Aristotelian science became an attack on the
Christian faith.

If Aquinas is the summit of the intellectual side

of mediae valism, Dante represents its highest poetic

achievement. In Dante the whole basis

is scholastic and especially Thomist, with

the characteristic mediaeval blending of classic and

go SCIENCE AND THE HUMAN MIND

patristic ideas, and symbolic interpretation of Scrip-
ture, history and nature. In the Paradiso especially
the structure of the physical and astronomical universe
and of animated creation is set forth in scholastic and
Aristotelian terms. Yet on this basis the genius of the
poet rises through intellectualist theology to the loftier
insight of direct contemplation, and reaches forward
to the more mystical ideas of the coming age.

The thirteenth century saw the triumphant and
applauded work of Thomas Aquinas, the greatest
Roger exponent of the scholastic philosophy, and
Bacon. ^ saw a}so the tragic life of Roger Bacon,
the only man throughout the Middle Ages, as far as
records have reached us, who approaches in spirit the
men of science of the Renaissance. The tragedy of
Bacon's life was as much internal as external, as much
due to the necessary limitations of his modes of
thought in the existing intellectual environment, as
to the persecutions of ecclesiastical authorities.

Roger Bacon was born about the year 1210, near
Ilchester, in the Somerset fens. His family seem to
have been people of position and considerable wealth.
Roger studied at Oxford, where he came under the
influence in especial of two men, both East Anglians,
Adam Marsh, the mathematician, and Robert Grosse-
teste, Chancellor of Oxford, and afterwards Bishop of
Lincoln. " But one alone knows the sciences, the
Bishop of Lincoln," said Bacon; and again, " In our
days Lord Robert, lately Bishop of Lincoln, and
brother Adam Marsh were perfect in all knowledge."

Grosseteste seems to have been the first in England,
perhaps in Western Europe, to invite Greeks to come

THE MEDIAEVAL MIND 91

from the East as instructors in the ancient form of their
language, which was still read at Constantinople.
Bacon himself was equally impressed with the import-
ance of the study of the original language of Aristotle
and the New Testament, and put together a book on
Greek grammar. He is never tired of insisting that
the prevailing ignorance of the original tongues was
the cause of that failure in theology and philosophy of
which he accused the doctors of the time. In anticipa-
tion of modern textual criticism, he points out how the
Fathers adapted their translations to the prejudices
of their age ; and how subsequent corruptions have
crept in through carelessness and ignorance, or by
that tampering with the text which had gone on,
especially among the Dominicans. Bacon himself
was a Franciscan, be it observed.

But that which marks Bacon out from among the
other philosophers of his time — indeed of the whole
period of the Middle Ages — is his clear understanding
that experimental methods alone give certainty in
science. This was a revolutionary change of mental
attitude, only to be appreciated after a course of study
of the other writings of his day. Instead of taking
the facts and inferences of natural knowledge from
Scripture, the Fathers or even Aristotle, Bacon told
the world that the only way to reach truth was to
observe and to experiment — again an anticipation,
this time of the famous doctrine of his more renowned
namesake, Lord Chancellor Francis Bacon, who lived
three hundred and fifty years later.

And the Franciscan friar, at all events, seems to have
practised his own theories, for he says he spent two
thousand pounds, an enormous sum for those days,

92 SCIENCE AND THE HUMAN MIND

on his researches. Naturally, he was accused of magic
— in which, indeed, he seems to have believed. After
spending some years in Paris, where he was made a
doctor, he returned to Oxford. But the growing
suspicions of his labours caused him to be sent back
to Paris for more strict supervision by his Order,
and he seems to have been forbidden to write or to
teach his doctrines. But now came the chance of
Bacon's life.

Guy de Foulques, an open-minded jurist, warrior
and statesman, who had become interested in Bacon's
work at Paris, was elected Pope, taking the name of
Clement IV. Bacon wrote to him, and in reply,
Clement sent a letter to " Dilecto filio, Fratri Rogerio
dicto Bacon, Ordinis Fratrum Minorum," commanding
him, notwithstanding the prohibition of any prelate
or the constitution of his Order, to write out the work
which he had been formerly asked for. For some
unknown reason, the Pope added an injunction of
secrecy, which added to Brother Roger's difficulties.
As a friar he was now pledged to poverty, but, by
borrowing from friends, he got together enough to
provide materials, and, in some fifteen or eighteen
months, despatched in 1267 three books to Clement :
an Opus May' us, containing his views at length, an
Opus Minus, or epitome, and an Opus Tertium, sent
after the others, for fear of miscarriage. It is from
these books that we chiefly know the work of Roger
Bacon.

Clement died soon after, and Bacon, deprived of his
protection, suffered without redress a sentence of
imprisonment passed in 1277 by Jerome of Ascoli,
General of the Franciscans, who became Pope

THE MEDIEVAL MIND 93

Nicholas IV. It is probable that Bacon was not
released till the death of Nicholas in 1292. In
that year he wrote a tract called Compendium
Theologicz, and we hear no more of the great Friar.

Bacon, for all his change of outlook, accepted
most of the mediaeval attitude of mind. No man
can do more than advance a little way in front of
the ranks of that contemporary army of thought to
which, whether he will or no, he belongs. Bacon
accepted the absolute authority of Scripture, could
the pure text be recovered, and the entire frame
of dogmatic theology in which Christianity was pre-
sented to that age. A more hampering preconcep-
tion was his agreement with the scholastic view,
which in other ways he assails so vehemently, that
the end of all science and philosophy was to elucidate
and adorn their queen theology. Hence came the
confusion and inconsistencies which at every turn
are seen in his writings, mixed with originality and
insight far beyond his time, or, indeed, of the next
three centuries. Struggle as he might, he never
cast off the shackles of the theological mind ; it mars
his work, as the persecution of his Order marred
his life.

It is one of the signs of Bacon's greatness that
he realized the importance of a study of mathematics
as a basis for other sciences. He tells us that mathe-
matics and optics, which he calls perspective, were
understood by Robert of Lincoln, and must underlie
other studies. Mathematical tables and instruments
are necessary, though costly and liable to destruction.
He points out the errors of the calendar, and calculates
that it had gained one day in excess for each 130 years.

94 SCIENCE AND THE HUMAN MIND

He anticipates some recent speculations in suggesting
that climate may influence the laws and social in-
stitutions of men. He gives a long description of the
countries of the known world.

He seems especially to have been interested in
optics, and describes the laws of reflection and the
general phenomena of refraction. He understands
mirrors and lenses, and describes a telescope, though
he does not appear to have made one. As an
example of the use of inductive reasoning he gives
a theory of the rainbow.

He describes many mechanical inventions, some
actually known to him and some as possibilities of the
future — among the latter, mechanically driven ships
and carriages, and flying machines. He considers
magic mirrors, burning-glasses, gunpowder, Greek
fire, the magnet, artificial gold, the philosopher's
stone, all in a confused mixture of fact, prediction
and credulity.

In trying to appraise the value of Bacon's work we
must not forget that his fame would have rested on
mere popular tradition of his magic had not Pope
Clement commanded him to write his books. Doubt-
less others besides Bacon were touched by the same
interests but have failed to leave direct traces. Indeed,
reflections of the work of such men are found in Bacon's
writings. ' There are only two perfect mathemati-
cians," he writes, " Master John of London, and Master
Peter de Maharn-Curia, a Picard." Master Peter
recurs when Bacon is dealing with experiment.

There is one science, Bacon says, more perfect than
others, which indeed is needed to verify the others,
the science of experiment, surpassing the sciences

THE MEDIEVAL MIND 95

dependent on argument, since they do not bring
certainty, however strong the reasoning, unless
experiment be added to test their conclusions. This
method of experiment no one understands save Master
Peter alone ; he, indeed, is dominus experimentorum,
but cares not to publish his work, nor for the honours
and riches it would bring — nor perhaps, one might
venture to surmise, for the risk of an ecclesiastical
prison it also might possibly entail.

But, whatever be the truth about these phantom
figures which flit across Bacon's pages, it is clear that
Friar Roger himself was in spirit a true man of science,
born out of due time and chafing unconsciously against
the limitations of his own restricted outlook, no less
than against the external obstacles at which he rails
so openly and so often ; a true harbinger of the ages
of experiment, of whom Somerset, Oxford and England
may well be proud.

Roger Bacon's criticism of the scholasticism of

Aquinas, though effective from the modern point of

The Decay of view, was out of harmony with the pre-

Scholasticism. vailing spirit of the time, and consequently

produced little effect.

Much more damaging were the philosophic attacks
which began towards the close of the thirteenth
century. Duns Scotus (c. 1265-1308), who taught
at Oxford and Paris, enlarged the theological ground
which even Aquinas had reserved as beyond the
demonstration of reason. He based the leading
Christian doctrines on the arbitrary Will of God, and
took free will as the primary attribute of man, placing
it high above reason. Here is the beginning of the

96 SCIENCE AND THE HUMAN MIND

revolt against the union of philosophy and religion
which the scholastics sought, and which his age
believed Thomas Aquinas to have finally and con-
clusively achieved. A revival of dualism appears,
essentially unsatisfying and incomplete, yet necessary
as a stage of progress in order that philosophy may
be set free from its bondage as the " handmaid of
theology," free in fertile union with experiment to give
birth to science.

The process went much further in William of
Occam, a native of Surrey (d. 1347), wno denied that
any theological doctrines were rationally demon-
strable, and showed the irrational nature of many of
the doctrines of the Church. He attacked the extreme
theory of papal supremacy, and headed a revolt of
Franciscans against the control of Pope John XXII.
His writings in defence of this action led to his trial
for heresy and imprisonment at Avignon. But he
escaped and sought protection of the Emperor Louis
of Bavaria, and aided him in his long controversy with
the Pope.

This principle of the twofold nature of truth, the
acceptance by faith of the doctrines of the Church,
and the examination by reason of the subjects of
philosophy, was bound up with the revival of nomi-
nalism, the belief in the sole reality of individual
things, and the reference of universal ideas to the rank
of mere names or mental concepts. Stress was laid on
the objects of immediate sense-perception, in a spirit
that distrusted abstractions, and made eventually
for direct observation and experiment, for inductive
research.

The new nominalism was opposed and banned by

THE MEDIEVAL MIND 97

the Church, and Occam's writings condemned by the
University of Paris, which tried to impose realism as
late as 1473. But irresistibly the doctrine spread, and
a few years later the show of resistance was abandoned.

Occam's final and most decisive triumph came fifty
years later, when Martin Luther (1483-1546) pored
over his works in the recently founded University of
Wittenberg, and based the new teaching on the nature
of the sacrament of the Eucharist on theories drawn
from the writings of his " lieber Meister." But, if
henceforward philosophy was more able to press home
its enquiries free from the need of reaching conclusions
foreordained by theology, on the other side religion was
for a time detached from rationalism, and given an
interval for the development of its no less important
emotional and mystical sides. Hence the fourteenth
and fifteenth centuries saw the growth of Northern
mysticism, especially in Germany, and the appearance
of many types of religious consciousness still existent
and of value.

The task of the Middle Ages was accomplished ;
the ground prepared for the Renaissance, with human-
ism, art, practical discovery and the beginnings of
natural science as its characteristic glories. With
the decay and death of scholasticism we turn a new
page in the history of the world.

For the historian of science mediaeval times are the
seed-bed of modern growth. They are a period of
surpassing interest, but they have no science of their
own till Roger Bacon stands roughly chafing at
his limitations external and internal, shaking the
door which shuts him from his natural home in later

7

98 SCIENCE AND THE HUMAN MIND

centuries. The interest for us of mediaeval thought
is the interest of tracing the changing attitude of the
human mind, as it passes through states where science
would have been impossible, to a condition in which
its rise follows naturally from the philosophic en-
vironment.

In a sense we have seen the worst aspect of the
Middle Ages. They are weakest on the intellectual
side, and on that side weakest of all in the special
department of thought necessary for scientific philo-
sophy. We have but glanced in passing at their work
of forming and consolidating the nations of Europe.
We have not touched on their wonderful achievements
in literature and art. The romances of chivalry are
outside our ken. Dante's Divine Comedy has for
us little significance, save as the enshrinement in
poetry of the scheme of Thomas Aquinas. The glories
of cathedral architecture are to us but illustrations
of the growth of the builder's art. Even mediaeval
religion, which on its unlucky philosophic side has
concerned us nearly, in its essence does not touch
our enquiry. Its saving faith in its divine Founder,
its spirit of humble reverence and love for all mankind
and all creation, its message of salvation to suffering
humanity, are hid from our eyes. We meet St Bernard
the suspicious Inquisitor, but St Francis of Assisi,
loving, joyous, simple-hearted, does not appear in our
pages.

CHAPTER IV

THE RENAISSANCE AND ITS ACHIEVEMENT

The Origins— Leonardo da Vinci— Copernicus — Bruno— Galileo — Gilbert
of Colchester — Francis Bacon — The Renaissance in France — Descartes
— Pascal — Tycho Brahe and Kepler — Scientific Academies — Newton
— Medical Science during the Renaissance — William Harvey — The
Rise of Chemistry — Voyages of Discovery — Botany and Natural
History — Spontaneous Generation — Witchcraft — The Christian
Platonists —Summary.

AFTER the thirteenth century there was a distinct
check in the intellectual development of Western
The Europe. The economic and social con-
Origins, fusion caused by the Black Death and
the ravages of the Hundred Years' War gave little
hope of settled life and quiet study, while in all
countries the vast influx of the best men and women
of the time into the celibate monastic orders must
have produced a disastrous effect on the stock of
hereditary ability in Christian lands.

Nevertheless, there was a continual process of
change in the mental outlook of mankind, and we may
trace, throughout this period of transition, the various
streams of thought which, when they met in full
vigour, formed the irresistible torrent of the Renais-
sance. The loosening of the universal grip of scholastic
ideas by the solvent influence of the philosophy of

99

ioo SCIENCE AND THE HUMAN MIND

Duns Scotus and William of Occam has already been
indicated, and the flight of Occam from a Papal
prison to the protection of Louis of Bavaria marks
a significant revolt against the power of the Church,
a setting up of the rights of nationalities against the
universalist tradition of ecclesiastical authority.

The spirit of the Renaissance made its first appear-
ance in Italy, then slowly recovering from the devasta-
tion of earlier times. Perhaps the remains of Roman
architecture made it easier for the love of the classics
to return. A vigorous Northern race had colonized
North Italy. They formed the upper class, and were
not yet exterminated by the local wars between
Italian states then and afterwards so fatal to the
nobility. But other lands had purer Northern blood,
and the chief Italian advantage in the growth of
learning must be sought elsewhere. The clue is given
by Salimbene of Parma, a thirteenth-century Francis-
can, who remarks on the difference between Italy
and other countries in one significant particular.
While north of the Alps only the townspeople dwelt
in the towns, and the " knights and noble ladies "
lived on their estates and superintended the manage-
ment of their lands in feudal isolation, in Italy the
upper class possessed houses in the cities and there
passed most of their time.

Now while the residence in the country of its natural
leaders makes for a healthy and stable political and
social life, in an age of slow communication it gives
little chance for that contact of mind with mind which
leads to creation and culture. The city life of the
leisured and intelligent class in Northern Italy gave
an ideal environment for the birth of the Renaissance.

THE RENAISSANCE lot

The Renaissance was very far from being an ex-
clusively literary movement. Many other influences
conspired to produce an unprecedented intellectual
ferment. But one of the most important elements
was literary, and with that we may begin our survey.

The harbinger of the literary Renaissance was
Petrarch (1304-1374), in whom we see a spirit quite
different from the scholastic medievalism which
underlay the poetry of Dante. Petrarch was the
first scholar who tried to restore a taste for good
classical Latin in place of the dog-Latin of the school-
men, and, an even more important fact, to recover the
true spirit of classical thought, with its claim of
absolute liberty for the reason.

Petrarch sang before his time, but, by the opening
years of the fifteenth century, a growing interest in
classical, and especially in Greek, literature attracted
many Greeks from the East, who, from their know-
ledge of the modern tongue, were able to teach its
ancient prototype. The capture of Constantinople
by the Turks in 1453 hastened this process, and led to
the arrival of many competent teachers, who brought
manuscripts with them to their new homes. The
search for manuscripts became a keen delight. The
monastic and cathedral libraries of Italy and then of
Northern Europe were ransacked, while merchant
princes with agencies in the Levant used all their
resources to procure the copies of Greek writers
which had remained for centuries hidden in the East
or had been scattered on the fall of Constantinople.
In this way, the language of ancient philosophy and
science became familiar to Western scholars after a
lapse of some eight or nine hundred years.

102 SCIENCE AND THE HUMAN MIND

But even of more value than the language was the
free spirit of enquiry it enshrined, and the impulse
toward study of all kinds that " humane letters "
gave once more to Europe after centuries of gloomy
medievalism. Though the stress laid on the teachings
of the Greek philosophers had dangers of its own, the
humanists prepared the way for the coming revival
of science, and to them is due the chief part in the
enlargement of the mental horizon which alone made
science possible. Without them, men with scientific
minds would never have thrown off their internal
fetters of theological preconception ; without them,
external obstacles might have proved insurmountable.
We seem to see the essential inward union of science,
waiting to be born, and religion, struggling to be free,
in such men as the Florentine patriot and martyr,
Girolamo Savonarola (1453-1498), who, grandson of
a skilful Paduan physician, was himself trained for
the medical profession, and the high-born Pico del
Mirandola (1463-1494), the disciple of Savonarola,
whose eager studies and learned wanderings resulted
in a great mystical exposition of the process of creation
and led him to pronounce the startling opinion that
Origen was more probably saved than damned by the
verdict of the Council of Constantinople.

For one bright interval, culminating with Pope
Leo X. (1513-1521), the Vatican itself was a vitalizing
centre of the ancient culture. But the capture of
Rome by the Imperial troops in 1527 broke up this
new Roman world of intellectual and artistic life, and
soon afterwards the Papacy, by reversing its previous
policy of liberal guidance, and opposing blindly when
it was no longer able to understand or to control,

THE RENAISSANCE 103

became the greatest obstacle in the way of modern
learning of all kinds. Hence the birth of modern
science took place amid the throes of persecution,
and won its greatest triumphs only in countries that
were able to free themselves both from the dead hand
of ecclesiastical authority and from the grievous
blight of religious warfare.

While the only method of reduplicating books con-
sisted in the laborious process of manual copying on
the somewhat costly and troublesome material parch-
ment, the possession of a library was within the reach
of but few individuals and not many institutions.
The introduction into Europe of the art of making
paper followed the later Crusades, and, about a
century afterwards, the invention of movable type
transformed the old attempts at printing with fixed
moulds into a practically useful art, and slowly put
books into the hands of all men.

Simultaneously, a renewed ardour of geographical
discovery was increasing the area of the earth known
to Europe. The Portuguese were the first in the field,
and, under the inspiration of Dom Henrique, Prince
Henry the Navigator, had pushed south along the
western shores of Africa, first on a mission to convert
the heathen, and then on the open search for slaves
and gold. Their success drove others to emulate
them. The Greek theory of the sphericity of the
earth was revived and became a general belief. It
led to the obvious idea, which indeed the Greeks them-
selves had propounded, that, by sailing westward
into the Atlantic Ocean, the eastern shores of Asia
might be reached, and the rich trade of Cathay brought
direct by sea to Europe. After many failures, there

104 SCIENCE AND THE HUMAN MIND

came the man and the hour. Columbus, born at
Cogoletto, on the Ligurian coast of North Italy, landed
on the Bahamas on October I2th, 1492, and claimed
the lands he had discovered for the crown of Spain.
Twenty-four years later Magalhags' vessel returned
after a three years' voyage, having demonstrated the
spherical nature of the earth by the convincing proof
of circumnavigation.

The wider mental outlook produced by these great
voyages of discovery, though the most direct, was not
their only effect on the human mind. As the trade
with the new lands expanded, the material resources of
Europe increased, and the stimulating stream of gold
produced an economic development unprecedented
in former ages. Wealth, and the leisure for intellectual
pursuits which wealth gives, thus spread into far wider
circles than were possible with the slender resources
of mediaeval times. It is worthy of note in the history
of mankind that the two periods in which the most
surprising intellectual developments are found — the
crowning age of Greece and the century of the Renais-
sance— are each times of expansion geographically and
of increased opportunities for a leisured life — in Greece
founded on a basis of slavery, and in Europe produced
by the wealth of the Indies. In Greece, the age of
intellectual triumph was followed all too soon by
political disintegration, while the numbers of the nation
were always comparatively small. In modern times
the Renaissance ushered in a period of four hundred
years during which the power of the nations of Europe
increased enormously on the whole, while the great
growth in population steadily put more and more able
men at the service of learning, till the enquirers

THE RENAISSANCE 105

surpassed in number almost immeasurably the philo-
sophers of Greece. It is perhaps well to bear in mind
this last fact when exalting modern achievements in
the realms of science.

But, when we have traced what we know of the
different tendencies which combined make up the Re-
Leonardo naissance, and given due weight to them
da Vinci, ai^ we cannot but feel that the attempt to
explain by obvious causes the amazing change of
mental attitude produced in so short a time is not
wholly successful. As Bishop Cr eight on said, " After
marshalling all the forces and ideas which were at work
to produce " this change, the observer " still feels that
there was behind all these an animating spirit which
he can but most imperfectly catch, whose power
blended all else together and gave a sudden cohesion
to the whole. This modern spirit formed itself with
surprising rapidity, and we cannot fully explain the
process."

We must, however, remember that we possess
records of but a tithe of the intellectual efforts of the
time. Few men then put their thoughts on paper,
and of the writings of those few not all have reached
us. In Italian city life, knowledge, and the change of
outlook which knowledge brings, must have passed
from man to man more by word of mouth than by
writings. Even in our days, the influence of a great
personality by direct action on others is not small,
and in the fourteenth and fifteenth centuries it must
have been greater in proportion.

The full greatness of one such personality is only
now coming to light as the inchoate manuscript note-

io6 SCIENCE AND THE HUMAN MIND

books of that tremendous universal genius Leonardo
da Vinci are transcribed and given to the world.
Leonardo may have meant to collect and systematize
his notes, and publish them as books. If so, he never
lived to carry out his intention. Hence his power
as a philosopher and a man of science has hitherto
been overshadowed by his fame as an artist.

Leonardo was the natural son of Ser Piero da Vinci,
a lawyer of great vigour and some eminence, and was
born at Vinci, between Florence and Pisa, in 1452.
His mother was a peasant girl named Catarina. He
was educated by his father, entered successively the
service of the courts of Florence, Milan and Rome,
and died in 1519 in France, the servant and friend
of Francis I. In early life he showed the remarkable
qualities which have impressed both contemporaries
and after ages as placing him in a class apart from
the rest of mankind. Beauty of person and charm
of manner did but adorn and increase the power of
mind and force of character which took all knowledge
for its study and all art for its expression. A painter,
sculptor, engineer, architect, physicist, biologist and
philosopher was Leonardo, and in each supreme.
Perhaps no man in the history of the world shows such
a record. His performance, extraordinary as it was,
must be reckoned as small compared with the ground
he opened up, the grasp of fundamental principles he
displayed, and the insight with which he seized the
true method of investigation in each branch of enquiry.
If Petrarch was the harbinger of the literary Renais-
sance, in spirit Leonardo was in advance of it in other
departments. He was not a scholastic, and neither
was he a blind follower of classical authority, as were

THE RENAISSANCE 107

many of the men of the Renaissance. To him,
observation of nature and experiment were the only
true methods of science. Knowledge of the ancient
writers, useful as a starting-point, could never be
conclusive.

Leonardo approached science from the practical
side, and it is owing to this lucky fact that much of
his modern spirit is due. To meet the practical
necessities of his crafts, he began experimenting,
though in his later years the thirst for knowledge
overcame the love of art. It was needful for an
artist to understand the laws of optics and the structure
of the eye, the details of human anatomy, and the
flight of birds. As an engineer, both civil and military,
Leonardo was faced by problems which could only
satisfactorily be solved by an insight into the prin-
ciples of mechanics, both static and dynamic. Now
Aristotle's opinion was of small help in correcting a
picture out of drawing, in managing water for irriga-
tion, or in taking a fortified city. For these problems,
the behaviour of things as they were was of more
importance than the opinion of the encyclopaedic
Greek as to what they ought to be.

But Leonardo was also a philosopher, and as a
philosopher he probably most affected the thought and
mental attitude of his contemporaries. The most
striking change we observe when comparing his mode
of thought with that of the preceding age, is his almost
complete emancipation from theological preconcep-
tions. Even Roger Bacon, with all his love of enquiry,
regarded theology as the true summit and end of all
knowledge, and doubted not that all learning would
prove consistent with the chief dogmas of his day.

io8 SCIENCE AND THE HUMAN MIND

But Leonardo reasons with a perfectly open mind.
When he turns to theology at all, he attacks openly
and lightly the ecclesiastical abuses and absurdities
which had become part of the system of the Church.
His own philosophical position seems to have been
an idealistic pantheism, in the light of which he saw
everywhere the living spirit of the Universe. Yet,
with the fine balance of a great mind, he saw the good
beneath the load of inconsequent evil, and accepted
the essential Christian doctrine as an outward and
visible form for his inward spiritual life. " I leave
on one side the sacred writings," he says, " because
they are the supreme truth." A great gentleman as
well as a great man, the fanaticism of the rude icono-
clast was far from Leonardo, and he lived in the
brief interval when the Papacy itself was liberal and
humanist, and all seemed pointing to a new and
comprehensive Catholicism, in which freedom of
thought could exist side by side with earnest mystical
faith. The dream passed, the Church of Rome
became reactionary, and freedom was won painfully
and slowly by the rough path opened by Luther.
Fifty years later, Leonardo's position would have been
impossible.

Leonardo's note-books have enabled us to trace the
origins of modern science in a way quite impossible
before. Da Vinci, great as he was, must not be
represented as the originator de novo of the scientific
spirit he displays. Before him Alberti (1404-1472)
had studied mathematics and made physical experi-
ments. At Florence Leonardo met Paolo Toscanelli
(d. 1482), an astronomer who had instigated the voyage
of Columbus ; Amerigo Vespucci gave him a book on

THE RENAISSANCE 109

geometry ; he knew Luca Pacioli the mathematician,
and was helped in his anatomical researches by Antonio
della Torre. It is clear that, a century before the days
of Galileo, a small circle of kindred spirits lived in
Italy who were more interested in things than in
books, in experimental enquiry than the opinions of
Aristotle.

But there is a link with Greek thought behind these
men too, a link with Archimedes. Archimedes' books
had not yet been printed, and good manuscripts were
rare. Leonardo notes the names of his friends and
patrons who could procure him copies, and expresses
admiration at the genius of the great Syracusan.
Interest in Archimedes grew rapidly ; in 1543 the
mathematician Tartaglia published a Latin translation
of some of his works, and other editions followed, so
that they were well known by the time of Galileo, who
studied them carefully. In Archimedes, the man
of science, and not in Aristotle, the encyclopaedic
philosopher, is to be sought the veritable Greek proto-
type of modern physical science, of which Archimedes
alone of the ancient writers who have survived
possessed the true spirit.

Leonardo da Vinci perceived intuitively and used
effectively the right experimental method a century
before Francis Bacon philosophized about it inade-
quately, and Galileo once more put it into practice.
Leonardo wrote no treatise on method, but incident-
ally his ideas about it clearly appear. He knew that
mathematics, arithmetic and geometry, gave absolute
certitude within their own realm ; they were concerned
with ideal mental concepts (e tutta mentale) of universal

no SCIENCE AND THE HUMAN MIND

validity. But true science, he held, began with
observation ; if mathematical reasoning could then
be applied, greater certitude might be reached, but
" those sciences are vain and full of errors which are
not born from experience, the mother of all certainty,
and which do not end with one clear experiment (che
non terminano in nota experientia)." Science gives
certainty, and science gives power. Those who rely
on practice without science are like sailors without
rudder or compass.

When we turn from Leonardo's method to his
actual results, we are astonished at his insight. In
face of all the prepossession of the centuries, of
the universal belief that all motion must be main-
tained by a cause continually acting, he enunciates
the principle of inertia, afterwards demonstrated by
Galileo. " Nothing perceptible by the senses," says
da Vinci, " is able to move itself ; . . . every body has
a weight in the direction of its movement. ' ' He knows
that the speed of a falling body increases with the time,
though he misses the right law for the space fallen
through.

He clearly understands the experimental impossi-
bility of " perpetual motion " as a source of useful
power, and inveighs against those who attempt it. He
uses this principle to demonstrate the law of the lever
by the method of virtual velocities, hitherto attributed
to Ubaldi and Galileo. The shorter arm raises the
greater weight slowly, while the longer arm is pushed
down by the smaller weight quickly ; these motions
must be in the proportion of the lengths of the arms,
so that the weights must be inversely as the lengths
of the arms. Leonardo regards the lever as the

THE RENAISSANCE in

elementary machine, and all other machines as modi-
fications and complications of it.

Leonardo recovered Archimedes' conception of the
pressure of fluids. He showed that liquids stand at
the same level in communicating vessels, while, if
different liquids fill the two arms, their heights will be
inversely as their densities. He deals also with
hydrodynamics — the efflux of water through orifices,
its flow in channels, the propagation of waves over its
surface. From waves on water he passes to waves in
air and the laws of sound, while he saw that light
showed many analogies which suggested that here too
a wave theory was applicable. The reflection of an
image is the echo of the source ; as with a ball thrown
against a wall, the angle of reflection is equal to the
angle of incidence.

In the realm of astronomy Leonardo conceived of
a celestial machine conforming to definite laws, in
itself a remarkable advance on the prevalent Aristo-
telian ideas that the heavenly bodies are divine, incor-
ruptible, essentially different from our world subject to
change and decay. He calls the earth a star, not differ-
ent from the others, and proposes in his projected book
to show that it would reflect light like the moon.
With errors in detail, Leonardo's astronomy is true in
spirit, and with him modern astronomy appears.

As things are older than writings, the earth bears
trace of its history before the records of books. Fossils
now on high inland mountains were produced in sea-
water, and could not have reached their present
position in the forty days of the Noachian deluge;
indeed the whole waters of the world, clouds, rivers
and ocean, could not cover the mountains of the earth.

H2 SCIENCE AND THE HUMAN MIND

There must have been changes in the crust of the
earth, and mountains have raised themselves in new
places. But no catastrophic action is needed ; " in
time the Po will lay dry land in the Adriatic in the
same way as it has already deposited a great part of
Lombardy " — Hutton's uniformitarian theory three
hundred years before its time !

As a painter and sculptor, da Vinci felt the need of
an accurate knowledge of anatomy. In the face of
ecclesiastical tradition, he procured many bodies and
dissected them, making anatomical drawings which
are works of art as well as most accurate in all detail.
Many of them still exist in his manuscripts preserved
at Windsor. " And you who say that it would
be better to look at an anatomical demonstration
than to see these drawings," he observes, " you would
be right, if it were possible to observe all the details
shown in these drawings in a single figure, in which,
with all your ability, you will not see nor acquire a
knowledge of more than some few veins, while, in
order to obtain an exact and complete knowledge of
these, I have dissected more than ten human bodies."

From anatomy the next step is physiology, and here
too Leonardo is found in possession of the field. He
describes how the blood makes and remakes con-
tinually the whole body of man, bringing material
to the parts and carrying off the waste products, as
a candle or furnace is fed. He studies the muscles
of the heart, and makes drawings of the valves which
in the opinion of Knox show a knowledge of their
functions. He compares the flow of blood with the
circulation of water from the hills to the rivers, from
the rivers to the sea, from the sea to the clouds and

THE RENAISSANCE 113

back to the hills as rain. It seems that Leonardo
understood the circulation of the blood a hundred
years or more before it was rediscovered and Harvey
gave the knowledge to the world. Once more his art
led him to a scientific problem, in the structure and
mode of action of the eye. He made a model of its
optical parts, and showed how an image was formed
on the retina. He ignores the view, still held by his
contemporaries, that the eye throws out rays which
touch the object it wishes to examine.

He dismisses scornfully the follies of alchemy,
astrology and necromancy ; for him nature is orderly,
non-magical, subject to immutable necessity.

But we have said enough to illustrate Leonardo
da Vinci's position in the history of scientific thought.
Had he published his work, science must have ad-
vanced by one step to the place it reached at least a
century later. It is idle to speculate on the influence
of such a change on the story of the human mind,
and the evolution of human society. It is safe to
say that both would have been modified profoundly.

But, though Leonardo never carried out his oft
referred to project of writing books on different
branches of his labours, his personal influence was
clearly immense. The friend of princes, he knew
also all the men of learning and affairs of his time.
His ideas were not all sterile, but some fell on the
good ground which, years later, gave birth to a new
growth of scientific achievement, springing from the
seed scattered by Leonardo and his disciples. If we
had to choose one figure to stand for all time as the
incarnation of the true spirit of the Renaissance, we
should point to the majestic form of Leonardo da Vinci.

8

H4 SCIENCE AND THE HUMAN MIND

In a society stirring with so many intellectual

interests we have a mental environment very different

from that of a hundred years earlier.

The theological atmosphere, which saw

everything in the light of the one overpowering

motive of salvation, had given place to a much

more independent outlook, in which many questions

were freely discussed from a rational point of view.

The world was still orthodox, but orthodoxy itself

had been aroused and for a time stretched its bounds.

Nicolaus Koppernigk (1473-1543), a Polish mathe-
matician and astronomer, had long been dissatisfied
with the prevalent Ptolemaic system, and he returned
from a long stay in Italy, where the Pythagorean
heliocentric theory was now well known as a Greek
speculation, determined to put it to the proof. With
scanty instrumental resources he made a series of
observations, and worked out his theory. He showed
how much simpler it was as an explanation of the
phenomena than the Ptolemaic system of cycles and
epicycles, in which the heavenly bodies moved round
the earth as centre. He finished a treatise setting
forth his scheme about 1530, and published a short
abstract in popular form in that year. Pope Clement
VII. approved, and sent the author a request for the
publication of the work in full. To this Copernicus
only consented in 1540, and the first printed copy
reached him on his deathbed in 1543.

But if in 1530 the Papacy showed a liberal interest
in the new system, by 1616 it had determined, by the
mouth of Cardinal Bellarmine, that it was " false and
altogether opposed to Holy Scripture," and Copernicus'
book was suspended till corrected. As no one cared

I

THE RENAISSANCE 115

to issue an edition with the authorized corrections,
it remained prohibited for over two hundred years,
for it was not till 1822 that the sun received the formal
sanction of the Papal authorities to become the centre
of the planetary system.

In the year 1822 the Roman Church at last removed
the works of Copernicus from the Index of prohibited
books and permitted instruction in the heliocentric
theory. Nevertheless, the Papal bulls by which it is
forbidden to believe in the motion of the earth still
remained in force, thus creating an extraordinary
predicament in the scientific beliefs of the devout
Roman Catholic.

It is very unfortunate for the historian of the pro-
gress of science and of the human mind, that the
Roman Index is far from containing a complete cata-
logue of works deemed at various periods to be in-
consistent with Catholic orthodoxy. It has thus lost
a great deal of the importance and interest that
otherwise it might have possessed, for the student
of the development of thought.

The system of Copernicus taught men to look on

the world in a new light. Instead of floating at the

centre of the Universe, the earth sank

to the lowlier place of one among the

planets. Such a change does not necessarily involve

the dethronement of man from his proud position

as the summit of creation, but it certainly suggests

doubts of that belief.

Thus, besides destroying that Ptolemaic system
which had been incorporated as a necessary part of
his scheme by Thomas Aquinas, Copernican astro-

n6 SCIENCE AND THE HUMAN MIND

nomy affected the human mind in other ways. Cer-
tainly it was one of the influences which led the fiery
Dominican Giordano Bruno (c. 1548-1600) to break
with the Roman Church, and to become an outcast
both from Catholic Rome and Calvinist Geneva.
Bruno used the work of Copernicus to discredit the
authority of Aristotle, for whom he had a perfect
hatred, contrasting him most unfavourably with the
older Greek philosophers. Passing from Paris to
England and England to Germany, Bruno every-
where attacked openly the Roman Church, its clergy,
and the doctrines they taught : the Jewish scriptures
he treated as myths, the miracles of the saints as
magical tricks.

Accepting a treacherous invitation to Venice in
1596, Bruno fell into the clutches of the Inquisition.
He was imprisoned, sent to Rome in 1593 and burnt
at the stake in 1600.

At last we see the ideas concealed in the manuscripts
of Leonardo da Vinci, then doubtless floating about in
the minds of his Italian successors, coming
to the light of day in the epoch-making
work of Galileo Galilei (1564-1642). In Leonardo, the
spirit of modern science is present everywhere, fram-
ing, moulding and developing his thoughts on all the
innumerable subjects on which he pondered. But in
Galileo it has gone further. With an equally sound
grasp of principle, he has learnt the modern need of
concentration, and works out his more limited problems
in a more complete and methodical way than the
wider sweep of Leonardo's soul could stop to accom-
plish. In reading Galileo we feel at once that modern

THE RENAISSANCE 117

science is not only born, but has come to an age of
steady work. Moreover, he collected and published
his researches, and thus gave them at once to the world.

As an astronomer, Galileo's fame rests on his applica-
tion of the telescope and the confirmatory evidence
he thus gave to the Copernican system. It was the
expression of his conclusions from these researches,
embodied in a volume of which the dedication was
originally accepted by the Pope, that brought Galileo,
when his book had been read and understood, within
reach of the Inquisition, and forced him to recant his
heresies.

But Galileo's chief and most permanent work was
the foundation of the modern experimental and mathe-
matical science of mechanics. In this he showed
himself a true master of method.

Before Galileo, in spite of Leonardo's superhuman
insight, most men's ideas of mechanics were a con-
fused medley of Aristotelian dogmas. Bodies were
thought to be intrinsically heavy or light and to fall
or rise with varying velocity because they " sought
their natural place " with varying power. Galileo set
himself to discover not why, but how, things fell. In
itself this attitude of mind marks a great achievement.

A body falling towards the ground moves with con-
stantly increasing speed. What is the law of the
increase ? Galileo's first hypothesis, quite reasonable
in itself, was that the speed was proportional to the
distance fallen through. But Galileo soon showed
that this supposition involved a contradiction, and
tried another, namely that the speed increased with
the time of fall. This hypothesis was found to involve
no obvious difficulty, and Galileo proceeded to deduce

n8 SCIENCE AND THE HUMAN MIND

its consequences, and to compare them with the
results of experiment.

A body falling freely moves too fast for easy and
accurate observation on its rate of fall, and, to bring
the speed within convenient limits, Galileo convinced
himself that a body falling down an inclined plane
acquired the same velocity as though it had fallen
freely through the same vertical height. He then
experimented with inclined planes, and found that the
results of his measurements agreed with those calcu-
lated from his hypothesis.

But another result, equally important, which had
already been grasped by Leonardo, followed from
Galileo's investigations with inclined planes. He
found that, after running down one plane, a ball will
run up another to a height equal to that of its starting-
point, whatever be the slope, provided that friction
be negligible. The second plane may be made as
long as we please, but still, if the final height be the
same as the initial height, the ball will reach its end.
It is the height that matters ; the speed of the ball
is acquired by virtue of its descent and is not destroyed
unless the ball rise. And, if the second plane be
horizontal, the ball will run along it for ever with
uniform velocity, until checked by friction or some
other force.

To appreciate the importance of this result, it is
necessary to realise that, before Galileo's day, except
by Leonardo and those he influenced, it was assumed
that every motion required the continual exertion of
some force to maintain it. The planets had to be
kept in motion by hypothetical vortices moving
through the heaven and carrying them round in their

THE RENAISSANCE 119

orbits, and similar complications appeared on every
side in mechanical problems. By Galileo's investiga-
tion, the whole position was reversed, and it was seen
that it was the destruction of motion or a change in
its direction which required the exertion of some
external applied force. Thus the planetary system
needed no vortices to keep it in motion, but some
cause was required to explain the continual deviation
of the planets from a straight course, as they swung
round the sun in their orbits. Never before had it
been possible even to formulate the problem correctly,
but now the way was open to a solution, and the man
was at hand. In 1642, the year of Galileo's death,
Isaac Newton was born.

But, before we follow the consequences of Galileo's

labours, and deal with Newton's supreme achievement,

Gilbert of we must pass in review other trains of

Colchester, thought which went to make that new
intellectual world in which Newton dwelt.

In the land of Newton the new method of experi-
ment, so well used by Galileo in Italy, was simultane-
ously and worthily put in action by William Gilbert
of Colchester (1540-1603), fellow of St John's College
in Cambridge, and sometime President of the College
of Physicians. In his book, De Magnete, Gilbert
collected all that was known about magnetism, and
added many new and valuable observations of his own.

The mariner's compass is said to have been known
to the Chinese from early times. Descriptions of it
seem first to have appeared in European literature
about the twelfth century, coming probably from
Saracenic sources, though the references indicate that

120 SCIENCE AND THE HUMAN MIND

it had been used for some time. Gilbert pointed out
that the set of the compass with reference to the earth
indicated that the earth itself possessed magnetic
properties, and could be represented as a huge magnet,
with magnetic poles nearly but not quite coincident
with the geographical poles.

To Gilbert also we owe the name electricity, derived
from the Greek word ?Xe/cr/ooi/, amber, a substance
which becomes electrified when rubbed. Gilbert
investigated the forces due to such electrification by
using a light metallic needle balanced on a point, and
extended the number of bodies which showed the
effect.

It is worthy of note, as an indication of the apprecia-
tion of such researches by the Government of England,
that Gilbert, who was Court physician to Elizabeth
and James I., was given a pension to set him free to
continue his experiments in physics and chemistry.

Meanwhile the philosophy of the new experimental
method was considered by Francis Bacon (1561-1626),

Lord Chancellor of England. Bacon was
Francis Bacon. , . . ., - , . , .. . J -

deeply impressed by the failure of the

scholastic philosophy to advance man's knowledge of
and power over nature. He felt that mankind was
still but the plaything of untamed forces, and had not
yet grasped that imperium hominis which should be
his birthright. ' To extend more widely the limits
of the power and greatness of man," he laid down rules
by which advance towards mastery might be made
more sure.

Bacon taught that by recording all available facts,
making all possible observations, performing all

THE RENAISSANCE 121

feasible experiments, and then by collecting and
tabulating the results, it would be possible to determine
what phenomena varied together, and thus to discover
the true and inevitable relations between them.

The obvious criticism of Bacon's method is that,
while partially applicable to purely descriptive sciences
like natural history, it is never applicable elsewhere.
The numbers of phenomena and possible experiments
are too numerous to be treated thus. At an early
stage of the enquiry, scientific insight and imagination
must come into play to exercise a selective action ;
a tentative hypothesis must be framed, and the
multitude of possible experiments reduced to the
manageable number needed to confirm or refute the
hypothesis. Hypothesis plays an essential part in
science, and research seldom or never proceeds on
pure Baconian lines.

Many years later, the method of Bacon was criti-
cized by T. H. Huxley in the following words : —
" Those who refuse to go beyond fact," he wrote,
" rarely get as far as fact ; and any one who has
studied the history of science knows that almost every
great step therein has been made by the ' anticipation
of nature/ that is, by the invention of hypotheses,
which, though verifiable, often had very little founda-
tion to start with ; and, not unfrequently, in spite
of a long career of usefulness, turned out to be wholly
erroneous in the long run."

There is much that compels our assent in this
nineteenth-century criticism of the Baconian method ;
but we must remember that up to the time in which
Bacon wrote, the world had listened to many theories
and hypotheses, and had seen no corresponding

122 SCIENCE AND THE HUMAN MIND

accumulation of facts whereby to test them. Rightly
therefore, in Bacon's eyes, facts — observed, authenti-
cated facts — were the crying need of his age.

Although Francis Bacon himself made no contribu-
tions to natural knowledge, and although his treatment
of method was over-ambitious in range and incapable
of general application in practice, he was nevertheless
a foremost figure in the early advance of modern
science. In terms of conscious power and states-
manlike eloquence, he expressed ideas that were
floating inarticulately in the society around him.
The authority of theology in the realm of natural
philosophy had been set on one side, at any rate in
England. The doctrines of the schoolmen had been
both outgrown and worn out. The world of thought
was astir, and time was ripe for a change. Bacon
gathered up the scattered threads, set the ship of
progress firmly on what was roughly the right track,
sped it on its way and gave to it its sailing directions
in the Novum Organum.

Some of the work that was accomplished by Francis

Bacon in England, was carried out somewhat earlier in

Th France, but in a very different way, by

Renaissance Michel de Montaigne. Montaigne (1533-

in France. ^92) was bom m the family chateau, not

far from Bordeaux, in a district where much Northern
blood had been left behind after the English occupa-
tion ; and, like his father, served in the army and in
the local parliament. Living at a time when the French
Renaissance was at its height, when, indeed, the tide
was beginning to turn, Montaigne's essays fore-
shadow the coming period of disenchantment and give

THE RENAISSANCE 123

voice to the change of attitude which was then mani-
festing itself throughout the country. All aspects
of human life and activity, all varieties of belief
interested him profoundly, and are set down in his
famous volumes with an impartiality of outlook
which gives a strong impression of scepticism and
independence. The Essays were widely read and
translated, and exercised an enormous influence,
more than their contents would seem to justify,
showing that they were felt to be in harmony with a
frame of mind that must have been widely prevalent.

A generation later than Montaigne and Francis

Bacon, a man of French birth and ancestry laid the

foundations of modern critical philosophy.

Descartes. _. , _ ., - . ,

Rene Descartes (1596-1650) was born in
Touraine, of a family of the demi-noblesse, and died at
Stockholm in the service of Queen Christina of Sweden.
His chief work was accomplished during a twenty
years' sojourn in Holland, to which country he origin-
ally went to serve under Prince Maurice of Orange
in the wars of independence against Spain.

The distinguishing feature of Descartes' work was
its combination of far-reaching and sound mathematical
advance, somewhat speculative physical theory and
a critical philosophy which took nothing for granted.
Descartes showed how much unverified assumption
underlay even generally received philosophic ideas,
and from him modern " philosophic doubt " took its
origin : de omnibus dubitandum est.

Descartes turned from the old accumulations
of interwoven thought, and tried to build up a new
philosophy, based only on human experience and

124 SCIENCE AND THE HUMAN MIND

consciousness. As he found in human consciousness
an apprehension of God, he passed neither to material-
ism nor to that complete divorce between faith and
reason which, necessary for the well-being of both
at a certain stage of development, leads eventually to
the decay of faith. Descartes indeed remained a good
Catholic. But his belief in the possibility of proving
the existence of God by philosophic evidence savoured
of heresy to the theologians both of Utrecht and of
Leyden, and, more than once, Descartes had to appeal
to the protection of the Prince of Orange.

In mathematics, Descartes' greatest achievement was
the application of algebra to the problems of geometry,
in which hitherto each problem had to be solved by
special treatment and by a fresh display of ingenuity.
For the first time, Descartes introduced a general
method by which this isolation was broken down.
The primary idea of co-ordinate geometry is easily
stated. If two straight lines or axes start from a
point or origin and set out at right angles to each
other, it is possible to specify the position of any point
in their plane by stating its distance x from one axis
and its distance y from the other ; x and y are called
the co-ordinates of the point, and different relations
between x and y correspond to different lines or curves
in the plane of the diagram. Thus if y be proportional
to x, or y = x x const ant, we get a straight line; if
y= x2 x constant, a parabola; and so on. The pro-
blems of geometry are reduced to the operations of
algebra.

Descartes' physical speculations were less successful
than his mathematical discoveries. We hear an echo
of the old ideas of contrasted words which deceived

THE RENAISSANCE 125

many a Greek philosopher. Descartes contrasts
matter anc spirit, and, since spirit is individual and
exists in personal units, matter must be continuous.
In a continuous, closely packed universe, movement
is only possible if it occur in closed circuits, every part
of which must move together. Hence Descartes
arrived at his famous theory of vortices, which for
twenty years reigned supreme, and contested for a
time even the Newtonian system, which the Cartesians
argued gave no explanation, since it depended on the
hypothesis of unknown and mysterious forces.

Yet Descartes' physical ideas did good service to
science. Though barred by Protestant orthodoxy,
and put on the Catholic Index at the instigation of the
Jesuits, his works became the fashion. They offered
an explanation of the phenomena of the astronomical
universe by mechanical processes ; they banished
for ever Aristotle's distinction between the essential
nature of the sublunary sphere, which included the
earth, and the starry sphere beyond of incorruptible
and perfect heavenly bodies ; they made unnecessary
the animate being of Aquinas or the genii believed in
by Kepler as the cause of planetary motion. Whether
or no the Cartesian explanation stood, the solar
system was susceptible of physical treatment ; in
common words, the thing could be understood.

Descartes spent most of his working lifetime outside
France, and seems to have been to a great extent

independent of contemporary French
Pascal. . n . , ,

influences, such as that exercised by

Montaigne — or, at any rate, unconscious of them ; but
in another direction the sceptical attitude of current

126 SCIENCE AND THE HUMAN MIND

thought came directly within the ken of natural science.
Blaise Pascal (1623-1662) always acknowledged his
indebtedness to the writer of the famous Essays;
and the whole of the Jansenist colony of Port- Royal,
with their rationalist and mystical outlook, in which the
Pascal family were deeply involved, displayed much of
Montaigne's attitude of mind in their dealings with
the orthodox Roman Catholic Church. Pascal was
born at Clermont-Ferrand, in the Auvergne, the family
having been ennobled during the fifteenth century.
As a philosopher, he is best known by his Lettres
a un Provincial, attacking the teaching and methods
of the Jesuits ; as a mathematician he worked, like
Descartes, to generalize the theory of endless particular
propositions, and he was the founder of the mathe-
matical theory of probability, a study which originated
in a discussion concerning the division of stakes in
games of chance. His experiments and subsequent
treatise on the equilibrium of fluids place him with
Stevin and Galileo in developing the science of hydro-
dynamics ; while his direction of the famous experi-
ment with the barometer on the Puy de Dome, which
showed that the height of the mercury column did
indeed diminish as the instrument was carried upward,
brought home to men's minds the meaning of the
discoveries of Galileo and Torricelli.

But if Galileo and Descartes cleared and prepared

the ground for Newton, the subject-matter which

Tycho Brahe his genius moulded into shape had been

and Kepler. put forth ready to his hand, chiefly

by Tycho Brahe and John Kepler (1571-1630).

The planetary motions had been measured of old

THE RENAISSANCE 127

and described in terms of Ptolemaic cycles and epi-
cycles. But, inspired by the Copernican ideas,
Brahe, working on his island home off Copenhagen,
carried such observations to a higher degree of accuracy
than had ever before been known, and the accumula-
tions of his chequered lifetime fell into the hands
of an apt and eager follower.

Working with Brahe's results, Kepler, whose
official occupation consisted chiefly in calculating
the astrological almanacks which, at that period,
were in favour at the petty courts of Germany and
Austria, after most laborious investigations, found a
series of laws which described the motion of the
planets. He showed, for instance, that they travelled
in paths which were ellipses, and that the sun was
at one of the two foci of the orbits, and this result,
with his other laws, led Newton to apply his unrivalled
mathematical powers to the planetary problem.

But we must pause yet once more to trace another
influence in Newton's intellectual environment. The
Scientific number of those interested in natural
Academies, philosophy was now increasing rapidly,
and one sign of this increase was the establishment
of societies or academies consisting of men who met
together to discuss the new subjects and to further
their interests. The earliest of such societies appeared
at Naples in 1560 under the name of Academia Secret-
orum Naturae. In 1651 Florence followed by founding
the Accademia del Cimento. In England a society
began in 1645 to meet at Gresham College or elsewhere
in London. In 1648 most of its members moved to
Oxford owing to the Civil War, but in 1660 the meetings

128 SCIENCE AND THE HUMAN MIND

in London were revived, and in 1662 the society was
formally incorporated by charter of Charles II. as the
Royal Society of London for Promoting Natural
Knowledge. In France the corresponding Academic
des Sciences was founded by Louis XIV. in 1666, and
similar institutions soon appeared in other countries.
Their influence in focussing scientific opinion, and
making known the researches of their members, has
had much to do with the more rapid growth of science
since their foundation.

Isaac Newton (1642-1727), by universal consent
the greatest man of science of all time, the delicate,

posthumous and only child of a yeoman,
Newton. J . . J

was born at Woolsthorpe in Lincolnshire,

and educated at Grantham Grammar School and at
Trinity College, Cambridge, where he was greatly influ-
enced by the work of Descartes. About 1666, driven
to Woolsthorpe by an outbreak of plague at Cam-
bridge, he turned his attention to planetary problems.
Galileo's researches had shown the need of a force to
keep the planets in their orbits and prevent them
moving off in a straight line. The Dutch physicist
Huygens had calculated the intensity of the force
needed to keep a body whirling in a circular orbit with
a known velocity. It remained to show that such a
force existed in the case of the moon and the planets.

Newton is said to have grasped the clue while idly
watching the fall of an apple in the orchard at Wools-
thorpe. If the earth pulled the apple, would it not
also pull the moon ; and would not the sun by a
similar force pull the planets round in their orbits ?
The distance of the moon is 60 radii of the earth, so

THE RENAISSANCE 129

that the force would be less at the distance of the
moon than at the surface of the earth in the ratio of
(60) 2 or 3600 to i. With the only estimate of the
earth's radius available in 1666, this calculation gives
a force too great to explain the moon's motion round
the earth, and Newton, always dissatisfied with the
slightest inaccuracy, put aside the enquiry. But in
1679 a redetermination of the size of the earth, giving
a markedly different value, led Newton once more to
take up the problem, and, in a state of excitement
which is said to have been so great that he could
hardly see his figures, he proved that the fall of
a stone to the earth and the majestic sweep of the
moon in her orbit may be ascribed to one and same
cause.

Newton then proceeded to attack the general
problem of the motion of a body under a force directed
towards a fixed point, and showed that the sup-
position that every particle of matter attracts every
other particle in accordance with the law of inverse
squares was necessary and sufficient to explain Kepler's
planetary observations. The simple law of the heavens,
the universal rule of gravity, was thus revealed — the
greatest achievement in the history of science.

The mechanism by which the force is exerted re-
mained unexplained by Newton, and has hitherto
baffled all subsequent enquiry. As always, one of
the chief results of new scientific knowledge was to
define more accurately the limits of our ignorance.
Newton indeed described himself as a child gathering
pebbles of knowledge by the shore of the boundless
ocean of the unknown. The larger grows the sphere
of knowledge, the greater is its surface of contact

130 SCIENCE AND THE HUMAN MIND

with what lies beyond, and the clearer are the gaps
within it.

One of the immediate results of the application of
mathematical mechanics to the problems of astro-
nomy was the need of improvement in the mathe-
matical tools used in the researches. Hence the same
period which saw the labours of Kepler, Galileo,
Huygens and Newton was marked also by a great
increase in mathematical knowledge and skill.

Perhaps the most noteworthy of these achievements
was the invention of the infinitesimal calculus,
developed by Newton and Leibniz. Algebra and
geometry had begun to assume their modern shapes,
trigonometry had been extended to imaginary quan-
tities, but the introduction of the idea of varying
velocity demanded a method of dealing with the
rates of variation of changing quantities. A con-
stant velocity is measured by the space s described
in a time t, and the quantity s/t will be the same
however great or small s and t may be. But, if the
velocity vary, its value at any instant can only be
found by taking a time so short that the velocity does
not change appreciably, and measuring the space
described in that short time. When s and t are re-
duced without limit and become infinitesimal, their
quotient gives the velocity at the instant, and was
written by Leibniz as ds/dt, which is called the differ-
ential coefficient of s with regard to t. Newton, in
his method of fluxions, wrote the same quantity as
S, a notation which is less convenient and is now
superseded by that of Leibniz. We have taken space
and time as an example, but any two quantities which
depend on each other may be treated in the same

THE RENAISSANCE 131

way, and the rate of variation of x with y written as
dx/dy or x. These conceptions may be said to be
the starting-point of the whole vast structure of
modern pure and applied mathematics.

Newton also took the lead in the development of
physical optics. In 1669, when he was appointed
to a professorship at Cambridge, he chose optics as
the first subject of his lectures and researches. The
discovery of the decomposition of white light by the
prism, and the explanation of the rainbow, soon
followed, as did the invention of a new form of re-
flecting telescope. Two theories of light were known.
On the corpuscular or emission theory, luminous
bodies emit a stream of minute particles or " cor-
puscles " which by impact affect the eye. On the
other theory, light consists of waves or undulations,
and on this view it appeared necessary to revive a
conception which we owe originally to the Greek philo-
sophers ; and thus it has been usual, till lately, to
invent a subtle medium or aether, which is imagined to
possess certain material properties and to fill all space.
Owing to the difficulty of explaining the straight path
of light, Newton inclined to the corpuscular theory,
while Huygens did much to develop the theory of
waves. It is certain that the great weight of Newton's
name helped to prevent the earlier acceptance of
Huygens' views — another instance of the danger of too
much reliance on authority. But the recent undoubted
discovery of the existence of moving particles, closely
resembling Newtonian corpuscles, and shot off from
radio-active bodies with velocities approaching that
of light, has once more made clear the almost super-
human insight into nature possessed by Newton's mind.

132 SCIENCE AND THE HUMAN MIND

We must now return to the influence of the Renais-
sance on other branches of science, and, in chief, on
Medical medicine, from which most of the others

during the took their rise. It was at first supposed

Renaissance, that the revival of Greek learning
would produce the same brilliant results in medicine
as in literature and philosophy ; and a school of
medical humanists arose who from 1450 to 1550
turned men's minds from mediaeval medicine, developed
through Arabian channels from commentaries on
Greek writers, to what were regarded as the fountain-
heads of the science — the writings of Hippocrates and
Galen themselves.

But even from the first there were revolts against
the domination of the newly translated authorities,
and, once again, an actual observation of nature formed
the starting-point. Paracelsus (c. 1490-1541), a man
of Swiss birth, broke away from the schools and the
chemistry of his period, and in the mines of the Tyrol
studied indifferently rocks, minerals, mechanical
contrivances and the conditions, accidents and dis-
eases consequent on the miner's life and occupation.
He then wandered over a great part of Europe studying
the diseases and remedies of different nations, before
settling down for a while as " town physician " at
Basle, where he roused the opposition of the vested
interests by the efficacy of his treatment and the
guaranteed purity of his drugs. With independent
arrogance, Paracelsus taught in the German language
contempt for Galen and Avicenna, whose works he
burnt publicly in the lecture-room, and relied on his
own experience, interpreted in the light of a personal
reading of neo-Platonic philosophy. But perhaps

THE RENAISSANCE 133

his most lasting innovation was the application of
the chemical knowledge, gained by alchemists in their
search for gold, to medical problems. " Chemical
medicine " marked the follower of Paracelsus, and
for long distinguished him from an orthodox Galenic
school. Chemistry began to develop in new directions
when it was studied for the sake of discovering
substances to cure disease, as well as for the illusive
vision of metallic transmutation.

In 1543, Andreas Vesalius, a Fleming by birth,
trained in the French school and afterwards professor
simultaneously at Padua, Bologna and Pisa, published
a book on human anatomy, founded, not on what
Galen taught, but on what he himself had seen in
dissection and was prepared to demonstrate in the
lecture-room. But he was denounced to the Inquisi-
tion, forced as a penance to undertake a pilgrimage
to the Holy Land, was wrecked and probably devoured
by wild beasts on the coast of Zante.

Nevertheless, before the end of the sixteenth century,

anatomy, first of all the sciences, was freed from the

William trammels of ancient authority. Physiology

Harvey. iay longer in bondage, till William Harvey,

who had studied in Italy, was led " to give his mind

to vivisections," and thereby made clear the true

mechanism of the circulation of the blood — " of

motion as it were in a circle."

William Harvey's life and work deserve more than
a passing reference. He was born in 1578, the son of
a prosperous Kentish yeoman or small squire, and
died in 1657. After studying in Cambridge, he spent
five years abroad, chiefly in Padua. Returning to

134 SCIENCE AND THE HUMAN MIND

England when he was about twenty-four years of age,
he began to practise as a physician, numbering Francis
Bacon himself among his patients. He was in
attendance on James I., and it fell to the lot of the
most modern physiologist of the time to superintend
the medical examination of women accused of witch-
craft. With Charles I. Harvey was on terms of
intimacy. The King had placed the resources of the
deer parks at Windsor and Hampton Court at the
disposal of his Court physician for experimental
purposes, and, with him, watched the development of
the chick in the egg and the pulsations of the living
heart. Harvey followed the King and was in charge
of the royal princes at the battle of Edgehill, viewing
the fight from the rear. He retired to Oxford with his
master, where for some time he was Warden of
Merton College. Having no children, he bequeathed
his paternal estate to the Royal College of Physicians,
directing them to use the proceeds " to search out and
study the secrets of nature."

The essence of Harvey's great discovery lay not so
much in demonstrating the circulation of the blood
in the veins, which indeed had already been made clear
by the anatomists of the sixteenth century, as in
revealing the mechanism by which the circulation
was maintained. The existence and use of the valves
in the veins was also known, and Michael Servetus
(1511-1553), the Aragonese physician and theologian
who was burnt at Geneva by Calvin's orders, had
possessed himself of many of the actual facts of circula-
tion. Harvey's claim to fame lies in his correct
setting forth of the true meaning of the action of the
heart, as the organ responsible for maintaining the

THE RENAISSANCE 135

whole circulation, and in his convincing correlation
of all parts of the circulatory system. He described
accurately everything that was visible to the naked
eye, so that it remained only for Malpighi, a few years
later, to point out, in work communicated to the
Royal Society of London in 1672, the capillary tubes
by which the blood passes from the arteries to the
veins, at that time first made visible by means of the
newly invented microscope.

Harvey's first treatise, a small volume entitled,
Exercitatio Anatomica de Motu Cordis et Sanguinis,
was printed at Frankfort in 1628 and dedicated to
Charles I. His second and larger work, De Generatione
Animalium, was published in 1651, and contains
almost the first advance in embryology recorded since
the time of Aristotle.

Throughout the sixteenth and seventeenth centuries,
new chemical substances were quickly coming to
The Rise of light, discovered in the search for fresh
Chemistry, remedies and industrial materials. But,
for some time, there was no corresponding advance in
chemical theory. Chemists continued to accept the
ancient view of three " elements " or " principles " in
the form of sulphur, mercury and salt. At last, in 1661,
Robert Boyle, a younger son of the great Earl of Cork,
in his Skeptical Chemist attacked the prevailing views
and revived the atomic theory, incidentally indicating
the true nature of heat. But for this step in advance
the time was not yet ripe, and the conceptions which
proved best suited to the needs of the age, and by which
the immediate advance in knowledge was won, were
much less in accordance with quite modern views.

136 SCIENCE AND THE HUMAN MIND

George Ernest Stahl (1660-1734), physician to the
King of Prussia, developed the idea of a volatile
" principle " to explain the phenomena of combus-
tion. When bodies were burnt something apparently
escaped, and this something Stahl named phlogiston,
the " principle of fire." Although this view regarded
burning as a loss of substance, and was thus in con-
tradiction to facts known to Boyle, who had shown
that metals increased in weight on burning, it was so
powerfully advocated, and expressed so well the ideas
of the age, that it gained general acceptance, and
dominated the chemical ideas of the whole eighteenth
century. Stahl also opposed the somewhat crude,
and at all events premature, materialistic views which
were beginning once more to appear in physiology.
He held that the chemical changes in living bodies,
though carried on in accordance with those produced
in the laboratory, were directed and governed by
the " sensitive soul " described by Aristotle — a view
which lived long under the name of vital force, and
in another form is perhaps once more coming to be
thought necessary to explain the phenomena of the
living organism as a complex adaptive synthesis of
matter and energy.

During the seventeenth and eighteenth centuries
the systematic exploration of the world began to take
Voyages of its place m the organised pursuit of know-
Discovery, ledge. If the explorers of this period
cannot claim for their voyages the romance associated
with the pioneers of discovery in the fifteenth and
sixteenth centuries, pioneers who first revealed the
existence of the earth as we now know it and mapped

THE RENAISSANCE 137

the main configuration of continents and oceans, the
work of the later navigators is remarkable for the
growth of the scientific spirit of observation.

William Dampier (1653-1715) in particular showed
the new attitude of mind. His keen eye noted every
strange bird and beast, every new tree and plant, and
his facile pen described their forms and hue with
marvellous accuracy and recorded them in his volumes
of Voyages. His Discourse on Winds became a classic
of meteorology, and Humboldt, long afterwards,
praised him as the best hydrographer of his age.

The development of medicine in the treatment of dis-
ease by drugs soon reacted on the knowledge of plants,
B , originally a province of the traditional

Natural lore of monastery and convent garden.

History. Mediaeval symbolism was slow to loose its
grip of the plant world, where it took the form of the
doctrine of " signatures," and regarded the shape of
the leaf or the colour of a flower as an index or sign of
the use for which the plant had been intended by its
Creator. However, the increased security of life led
to the laying out of private gardens and parks, and to
the more general cultivation of trees, vegetables and
flowers. Thus, partly owing to the use of herbs as
remedies, partly to natural curiosity and to a growing
love of beauty and colour, made possible by the
advances in ordered existence, the sixteenth century
saw a great development in botanical knowledge.
Medicine, virtually freed from the control of the
Church, soon acquired its own gathering grounds and
distilleries. Botanic gardens were established at
Padua in 1545, and afterwards at Pisa, Ley den and

138 SCIENCE AND THE HUMAN MIND

elsewhere, and there the rare plants brought home by
the explorers and adventurers were deposited and
cared for. Each society of apothecaries had its
physic garden, one of which yet survives amid the
crowded thoroughfares of London. A number of
" herbals " containing descriptions of plants and their
properties — medicinal and culinary — began to appear
and to find their place in the libraries of the country
gentlemen. Such an one, illustrated by woodcuts, was
published in England by John Gerard in 1597, Gerard
himself being a member of the court of Barber-
Surgeons and superintendent of Lord Burghley's new
gardens at his house near Stamford.

The anatomy of ^plants was studied as soon as the
microscope made the subject possible for investigation,
and, led by Malpighi and Nehemiah Grew, men began
to form correct ideas about the functions of the different
plant organs. Although from early times the fruit
of plants had been recognized to be connected with
a female element, it was not till the end of the seven-
teenth century that definite experimental proof was
given by Camerarius (1665-1721), to show that the
anthers were the necessary male organs, that in their
absence no fertilization of the female element was
possible, and that without fertilization seed could not
be formed.

The earlier classifications of both animals and plants
were chiefly based on utilitarian ideas — or on such
obvious external signs as led to the division of plants
into herbs, trees and shrubs. Ray, by giving definite-
ness to the idea of species, pointed the road to a
more natural scheme.

It was on the sex-organs of plants that Linnaeus

THE RENAISSANCE 139

(1707-1778), the botanist, son of a Swedish clergyman,
founded his famous system of classification. Linnaeus'
classification held its own till replaced by the modern
system, which, by considering all the characters of
the organism, tries to place plants in groups which
express their natural relationships.

Linnaeus also turned his attention to the varieties
of the human species, having been struck by the
obvious differences of race brought to his notice
during his wanderings among the Laplanders in search
of arctic plants. In his System of Nature he
placed man with apes, lemurs and bats in the order
of " Primates," and subdivided man into four groups
according to skin colour and other characteristics.

Development in the knowledge of animals was
stimulated by the arrival in Europe of rare and strange
beasts to grace the various royal menageries. The
comparison of different organs, and the study of the
functions of different parts of the bodies of man and
of other animals, led to a growth of comprehensiveness
of outlook, while improvements in the microscope
allowed a far closer insight into the problems of the
structure and function of the different organs of the
body, and soon disclosed the existence of vast classes
of minute organisms unsuspected before.

Buff on (1707-1788), the first of the great French
naturalists, was born in Burgundy of a good family.
After travelling on the Continent, he settled in Paris,
where he was appointed keeper of the Royal Gardens
and Museum. Buffon's genius, as well as his oppor-
tunity, lay in descriptive work, and his Natural
History of Animals has all the merits of an encyclo-
paedia. While not consenting with Linnaeus to classify

140 SCIENCE AND THE HUMAN MIND

man among the animals — " une v6rit6 humiliante
pour 1'homme " — Buff on could not close his eyes to
the evidence pointing towards such relationships, and
ventured the remark, which he was afterwards obliged
to withdraw, that had it not been for the express
statements of the Bible, one might be tempted to
seek a common origin for the horse and the ass, the
man and the monkey.

Both in ancient times and in the Middle Ages,

men firmly believed that living things might arise

Spontaneous &e novo from dead matter. "FromAris-

Generation. totle to Augustine, from Lucretius to
Luther, the belief in spontaneous generation remained
unshaken." Frogs might be generated from mud by
sunshine, and perhaps the aboriginal Americans, whose
descent from Adam was difficult to trace, might have
the same origin. But Francesco Redi (1626-1697)
showed that, if the flesh of a dead animal be protected
from insects, no grubs or maggots appeared in it.

Redi's experiments were considered to controvert
the Scriptures, and were attacked on that ground ; an
interesting fact in the light of its reversal in recent years,
when an unsuccessful attempt to prove spontaneous
generation was prematurely reprobated as going to show
that life might arise without direct creation. It seems
as though the theological mind when ill-regulated hates
a novelty for its own sake. But it is refreshing to
find that Redi's work was upheld and extended by
the Abbe" Spallanzani (1729-1799), who showed that
even minute forms of life did not develop in decoctions
which had been boiled vigorously and then protected
from the air.

THE RENAISSANCE 141

We cannot close an account of the progress of
scientific thought during the Renaissance and the

succeeding years without some reference
Witchcraft. ^10 -, ,, , ,. £ - .,_

to witchcraft and to the belief in the

active interference of unseen and generally speaking
evil forces in the affairs of mankind. At the time
when Bacon was directing the advance of know-
ledge in England, when Luther, Calvin and Knox
were reforming the churches of Germany, France
and Scotland, a belief in witchcraft dominated practi-
cally the whole civilised world. It is easy now to
laugh at such fears, to ridicule the stories which
were then implicitly believed, and to explain away
the long series of occurrences on which the epidemic
of prosecutions throughout Western Europe was
based. But we must face the fact that the move-
ment went on side by side with the Renaissance, and
to some extent seems to have been the popular
representation of a belief in that possibility of man's
control over the unknown forces of nature which,
on the scientific side, Bacon foresaw and desired.
The particular form which the accusation usually
took, that of commerce with the powers of darkness
for evil purposes, was probably due to the prominence
given to the personality of the Devil in the Protestant
theology of the day. Many of the great men of science
of this period were either accused of heresy or involved
in dealings of some sort with witchcraft. The one
charge predominated in the south, the other in the
north of Europe, as we should have anticipated.
John Kepler, himself suspected of heresy, spent five
years of his life, from 1615 to 1621, defending his
mother from a capital charge of witchcraft. William

142 SCIENCE AND THE HUMAN MIND

Harvey assisted at the examination of reputed witches.
Giordano Bruno and Michael Servetus were burnt
respectively by Catholic Rome and Calvinist Geneva
for their religious opinions and their intellectual pre-
eminence. The same penalty of death in the flames
was reserved for both sets of victims. In each case,
the civil authorities were only executing the decrees
of the representative citizens of the day. The voice
of the people was on the side of the powers whose
actions condoned the popular alarms ; and Kepler's
mother, after her acquittal, was preserved with
difficulty from an indignant crowd.

It may be thought fanciful to connect witchcraft and
witch-hunting with the advance of natural science or
to associate them in any way with the prevalence
of a mystical attitude of mind. Yet the evidence of
racial susceptibility would accord with such a connec-
tion. Broadly speaking, the Northern races supplied
the men of science, the witches and the mystics ; the
East Anglian area, for instance, is remarkable for its
contributions to all three categories.

The belief in witchcraft decayed with as little ap-
parent reason as it rose. The civilized world, class
by class, nation by nation, gradually discovered that
it had ceased to believe in the existence of witches
even before it had given up the practice of burning
them. It was not that the world grew more tolerant
or more humane, but that it had become more sceptical,
and was preparing itself for the rationalistic philo-
sophy and the intellectual tyranny of the eighteenth
century.

To what was this change of attitude due ? Probably,
to some extent, to the advance of science, which slowly

THE RENAISSANCE 143

defined the limits of man's mastery over nature and
disclosed the methods by which this mastery is attained.
Then, too, the extreme prepossession with theological
matters, the natural result of the first popular contact
with the material for the construction of religious belief,
subsided as the years went on, and after a while the
Devil and all his works ceased to perplex the mind
of men. We now know more about these strange
waves of unreasoning belief and religious exaltation
which pass over nations, attracting especially within
their sphere of influence the more ignorant, more
neurotic, more highly strung of the population, and we
may believe that the prevalence of a belief in witch-
craft was, in certain aspects, an example, in an
extended form, of such an epidemic.

But it is perhaps hardly wise to waive on one side,
as the fancies of excited and ill-regulated brains,
the whole of the phenomena which were classified
under the general term of witchcraft during the hey-
day of the intellectual life of the Renaissance. Joseph
Glanvill, a Restoration rector of Bath Abbey, who
preserved for us the tale of the Scholar Gipsy made
famous in Matthew Arnold's poem, found the evidence
for some sorts of unexplained manifestations suffi-
ciently strong to justify enquiry and examination.
With Henry More, one of the band of Christian
Platonist scholars at Cambridge who at that time
exercised considerable influence in stemming the tide
of naturalistic philosophy expounded by Hobbes and
his school, Glanvill established what was virtually
a small society for psychical research. He endeavoured
in a manner worthy of the recently founded Royal
Society, to which he belonged, either to confirm or

144 SCIENCE AND THE HUMAN MIND

disprove the phenomena under dispute. He investi-
gated with some care a case of rappings at a Wiltshire
house, in circumstances which recall the similar dis-
turbances connected with the Wesley family. Again,
associated in friendship with More, we find the
" stroker," Valentine Greatrakes or Greater ex, who
served in the Parliamentary forces under Roger Boyle,
afterwards Lord Broghill and Earl of Orrery, and in
later life found himself possessed of the power of curing
many diseases, especially scrofula, by the touch of
his fingers, accompanied with prayer. The efficacy of
Greatrakes' ministry of healing, to which he devoted the
latter part of his life, is testified to by Robert Boyle,
the chemist, by Andrew Maxwell, by Benjamin
Whichcote, and by many of the best-reputed men of
the day. Two hundred years later, when another
school of materialistic philosophy was in the ascendant
in England, a second Society for Psychical Research
was again founded by Cambridge men to investigate
kindred phenomena, and a fresh outburst of healing
by prayer and contact spread through certain sections
of the community.

At the close of the seventeenth century Cambridge

was the home of a group of idealist scholars and

The Christian divines of mystical tendencies, who were

Platonists. endeavouring to combine the new know-
ledge with the mysteries of the Christian faith.
They felt that any merely mechanical explanation
of the Universe, such as that attempted by Descartes,
was unconvincing and inadequate in its essence, and
expressed their conviction that the primordials of the
world are not mechanical but vital. They developed

THE RENAISSANCE 145

elaborate theories of the immortality of the soul,
accepted some form of reincarnation, and believed
in the possibility of communication between spirits
existing in the aethereal, aerial and terrestrial states.

Human progress does not hold on its way in a steady
line. The general trend of the curve may be upwards,
as it certainly has been, in the matter of
scientific thought, for the past four cen-
turies. But superposed on the general curve are
oscillations, often violent, which disturb its course.

At the Renaissance, the movement towards ration-
alism in science became appreciable ; the triumphs of
that spirit mark the years we have surveyed. The
ideas of the French Encyclopaedists, and the other
tendencies of thought for the half-century preceding
the Revolution, show the swing of the pendulum,
which, as always, overshot its point of equilibrium,
and, a century later, reached an extreme from which
retreat was necessary by another path.

At the close of the Middle Ages, Thomas Aquinas
gives the great example of a complete scheme of uni-
versal knowledge, including science, framed in accord-
ance with orthodox Roman theology. From his day
onwards we see a change. Duns Scotus and Occam
at once began the separation between faith and reason
necessary for the development of natural knowledge
at that time. Yet the liberation of science from theo-
logical preconceptions was long delayed. The works
of Descartes and Leibniz contain theological reasoning
inextricably interwoven with physical facts. Even
Euler (1744) based the principle of least action on
the ground that the construction of the Universe is

10

146 SCIENCE AND THE HUMAN MIND

the most perfect creation possible, being the handiwork
of an all-wise Maker, so that nothing can be found
in the world in which some maximal or minimal
property is not displayed.

It is true that in some of the greatest minds this
confused thought is not found. Newton had a deep
religious sense, and, indeed, wrote on theology. But his
scientific work is quite free from theological arguments.
Nevertheless, with less clear-sighted intellects, the
theological prepossession gave an inward obstacle
to scientific progress long after the danger of external
persecution had passed away.

But a new tendency is seen in Locke and his followers.
Aquinas built up a joint structure of knowledge,
starting from the side of patristic theology. Locke,
with characteristic British practical sense, and a wide
experience of life and thought acquired at a critical
period of history, essayed to found a rational Christi-
anity on the sure ground of experience. Both at-
tempted a synthesis. But while Aquinas' scheme
had the rigidity and absoluteness of its chief con-
stituent, Locke's contained the possibility of continual
adaptation to the varying needs of intellectual
development.

In the second half of the eighteenth century, the
change of outlook became much more general. The
ablest men in all branches of life became for the most
part sceptical in matters of religion. Voltaire's
attacks on the clergy and their teaching were but the
most witty example of a wide-spread tendency of
thought. Locke and the English Deists had their
Continental counterparts, who undermined orthodoxy,
just as the success of the Whig Monarchy in England

THE RENAISSANCE 147

tended to loosen the authority of legitimism in other
countries.

Towards this general wave of sceptical thought
the mechanical philosophy brought an important
contribution. The astonishing success of the New-
tonian theory in explaining the mechanism of the
heavens led to an overestimate of the power of
mechanical conceptions to give an ultimate account
of the whole universe. As Mach says : " The French
Encyclopaedists of the eighteenth century imagined
they were not far from a final explanation of the
world by physical and mechanical principles ; Laplace
even conceived a mind competent to foretell the pro-
gress of nature for all eternity, if but the masses, their
positions, and initial velocities were given." Few
would venture to hold such a sweeping conclusion
nowadays, but, when first formulated, it was a natural
exaggeration of the power of new knowledge which
had impressed the minds of men with its range and
scope, before they had realized its necessary limits.
In fact, we have a repetition in changed circumstances
of the story of the Greek atomists, who extended their
successful speculative views of physics to the world
of life and thought, all unconscious of the logical
chasms which lay between — chasms only to be revealed
and partially explored, but not bridged, by the tre-
mendous accumulations of knowledge of two thousand
years.

Another line of thought which reacted against the
belief in the value of steady, unchanging dogma and
authority, in religion and philosophy no less than in
politics, was the growing idea of the progress of man-
kind in moral worth and intellectual power, and the

148 SCIENCE AND THE HUMAN MIND

not unnatural association of this progress with the
achievements of the past few hundred years. Looking
back to the mediaeval times, it was impossible not
to realize the immense step forward taken by the
visible world of societies and nations in a compara-
tively short space of time. What was more natural
to eager minds and generous impulses than first to
imagine and then to believe that the process of develop-
ment might be extended throughout the whole social
body, that it needed but opportunity to enable all
men to enter upon, share in and profit by the new
inheritance ?

Nowadays we know more about the limitations of the
human mind, and we are perhaps more apt to dwell
on them and on its imperfections than to dream of
any yet unrevealed possibilities. To us, the marvellous
epoch of the Renaissance is best interpreted as the
first coming into free action of the intellectual forces
of the Northern race ; we share in the early triumphant
breaking forth of the vanguard ; we stand astonished
at the extent of the conquest ; we examine critically
the details of the sober settlement. But as we read
history, as we study more closely the great men of this
great period, we realize that in truth but certain
small sections of the social structure were affected,
that only a very small and carefully prepared pro-
portion of the whole population took active part in
providing the festival. Of all the countries of Europe,
five or six alone — Italy, France, Germany, England,
the Low Countries and for a short time Spain — con-
tributed appreciably to the intellectual sum total of
the Renaissance. Again, in each country, the chief
centres of activity are often obvious to us ; and in

THE RENAISSANCE 149

England, at any rate, we can almost circumscribe the
portions of the nation, geographical and social, that
ministered chiefly to the success of the whole move-
ment. Thus we lose confidence^ in the idea of any
general regeneration of the race by artificial means
working from the outside, and recognize that there is
some more fundamental, more elusive principle at
the bottom of success or failure in scientific discovery
as in all the other various walks of life.

It is difficult to realize that in the eighteenth century
the idea of progress, still unproven perhaps, but
familiar to ourselves, was strange and new. Scattered
traces of the doctrine of the sustained and progressive
advance of mankind are found in history " from
Lucretius and Seneca to Pascal and Leibniz," but its
first clear exponent seems to have been Turgot. When
combined with the ideas of Rousseau about the
natural equality of men, it did much to prepare the
atmosphere of the French Revolution. It led to the
conclusion, equally far from truth, that given favourable
circumstances the people in the mass would prove
necessarily as sincere, incorrupt, true and infallible
as their greatest men — a conclusion indeed as old as
Alcuin, though now first provided with a basis, demon-
strably false to us, but convincing to certain minds
in that age.

" The reign of reason," and the pathetic follies to
which it led, are the real and tragic end of the period
which began with the bright hopes of the Renaissance.
After the French Revolution, we enter a new
scientific age, which starts with the advantage of one
more great disillusion, and a fresh determination on
the part of the leaders of thought, as far as may be,

150 SCIENCE AND THE HUMAN MIND

to see things as they are. The a priori methods of
the French Revolution were gradually left behind, to
consort with the yet older relics of mediaeval scholas-
ticism in the chilly confines of outworn, buried age.

In the period under review, not only did science
emancipate itself from theological prepossessions,
but it gained freedom from metaphysical trammels
also. This was a step in advance which the Greeks
failed to make, and it marked a change of outlook
necessary for success at that time in scientific thought.
Nothing is more striking than the difference between
the confusion of metaphysics and science which the
Aristotelian tradition imposed on the opening years of
the Renaissance, and the entire freedom from such
mixture with which the eighteenth century drew
towards its close. A general consensus of opinion in
fundamental scientific conceptions had removed their
subject-matter from the airy realm of philosophy to
the clearly defined territory of science.

At the beginning of the period, science had to con-
form to theology and to philosophy, in both of which
it was believed that something like finality had been
reached, in the first by the Roman Church, in the latter
by Aristotle. At the close of the epoch, science had
come into sure possession of its own new heritage,
and both theology and philosophy had realized that,
while still and for ever supreme each in its own em-
pyrean space, they must defer to the superior authority
of experience when they touched the firm ground of
natural science.

Pari passu with this separation of subjects, we get
a parallel separation of men of science on the one
hand from theologians and philosophers on the other.

THE RENAISSANCE 151

The first requisite of the modern world as it emerged
from chaos was authority, and it proved to a great
extent that those who have the power of marshalling
men have also the power of marshalling thoughts.
The feudal system grouped men on an administrative
basis, depositing authority with those strains of
blood which had shown themselves competent to
exercise it. The ecclesiastical organization was but
one aspect of the art of government, but one method
of organizing and directing the activities of the whole
community. If the more ambitious and active mem-
bers of the administrative classes usually found their
scope in military and civil occupations, and established
great families to perpetuate their hereditary talents,
the more thoughtful, more acute, or more contempla-
tive frequently entered the service of the Church,
where at first learning of whatever kind, legal, medical
and scientific, was concentrated, living in conditions
of celibacy that probably circumscribed its develop-
ment. Broadly speaking, the higher territorial families
of England have supplied her with administrators,
and the more numerous lesser gentry and yeomen
furnished the doctors, lawyers and the men of science.
Geographically speaking, the West and South of
England sent the critics, the philosophers and the
future administrators of England to Oxford, while
the East Anglian area supplied to Cambridge the
imaginative qualities, shown alike by scientific insight
and poetical genius, in a long line of men of science and
poets.

By the end of the eighteenth century, the social
area from which most frequently the workers in
science were drawn had begun to increase. It is an

152 SCIENCE AND THE HUMAN MIND

open question how far this change is due to the numeri-
cal expansion of the nation and its reorganization on
lines of industrial efficiency, which would provide
greater opportunities for intermarriage between the
different sections of the community, and thus tend
to enlarge, though possibly to dilute the quality of,
production. Or it may be that science itself has
changed, at least in one direction, and that the marvel-
lous and successful application of its principles to in-
dustrial operations has required the co-operation of a
new type of man, with a mind and body having an
instinctive grasp of mechanical processes and technical
skill wherewithal to apply the theoretical discoveries
of the workers in pure science.

In the succeeding age, to which we must now turn,
this process proceeds apace ; and science, hitherto with
little message for the practical arts, unless therein we
include medicine, opened wide the doors of technical
application, and revolutionized the external circum-
stances of the life of mankind, just as, in the period
we have just brought to a close, it had transformed
the mental outlook.

CHAPTER V

THE PHYSICS OF THE NINETEENTH CENTURY

The Mechanical View of Nature — The Popularization of Science —
Astronomy— The Nebular Hypothesis— " Phlogiston"— Lavoisier and
the Conservation of Matter — Imponderable Fluids — The Atomic
Theory— The Wave Theory of Light— Spectrum Analysis— Heat and
the Theory of Energy— The Rise of Electrical Science — Electric
Waves— The Theory of Ions— Summary.

IF, in the story of knowledge, the French Revolution

marked the end of the period which began with the

The Renaissance, yet many of the ideas which

MVkwnofal influenced the thought of the succeeding
Nature. years were moving within its turmoil.
Indeed the lines of advance which were to be charac-
teristic of the new age had begun to appear here and
there before that political cataclysm closed the
eighteenth century. Thus, in the various branches
of knowledge whose fortunes we pursue, our division
cannot be made at a definite point of time. In
every case we must turn back a few years to trace
the origins of the threads we shall follow.

The broad tendency of the period now under review
is to be sought in the gradual extension of the mechani-
cal view of nature, which took its rise in the triumphs
of the Newtonian astronomy as interpreted chiefly
by French mathematicians, to other branches of know-

'53

154 SCIENCE AND THE HUMAN MIND

ledge, till, in the Darwinian theory of natural selec-
tion, its less clear-sighted advocates saw a complete
account of life and its phenomena. In a future
chapter we shall trace the widening of this sharply-
cut but somewhat dry and meagre philosophy into a
broader and fuller idea of the complexity and wonder
of the Universe. But, throughout the greater part of
the nineteenth century, the true method of advance
lay in building up this naturalistic edifice in new and
extending directions, and in proving its capacity to
interpret phenomena, of which some were thought
inexplicable and others were then unknown.

For the work of the Renaissance and the succeeding
ages had been to bring within the circle of the com-
prehension of man phenomena with which he had
long been acquainted, and most of which were easily
apparent to his unaided senses. But now we pass
to a time when scientific work consisted largely
in revealing the hitherto unknown and hitherto
unknowable as well as in explaining them when re-
vealed. An extension of the senses had been produced
by the perfectioning of such instruments as micro-
scopes and telescopes, and their adaptation to photo-
graphy. Hence followed the discovery of living cells
as the units of the organism, and of the structure of
far-distant stars and suns. Then the disclosure of
all the vast and complex phenomena of electricity,
to name but the most striking instance out of many,
opened up fresh worlds for science to conquer, worlds
which proved amenable to the same logical methods
of investigation that were first tested in dynamics
and astronomy.

When the nineteenth century opened, the great

PHYSICS OF NINETEENTH CENTURY 155

industrial development which is still in progress had
already begun. One of its chief instruments, the
steam engine, reached a serviceable form when, in 1769,
James Watt patented the principle of the condenser.
The steam engine was a practical invention, to which
scientific principles were applied at a later stage to
carry out developments and improvements. But the
electric telegraph, the other great agent in revolu-
tionizing the social conditions of the world, was a
direct consequence of research in pure science.

To some people, the practical applications of science
stand for its main achievement. But their effect on
the human mind and its thought, though great, is
indirect. That effect is slow and cumulative. The
gradual and apparently inevitable extension of man's
power over the material resources of nature gives
applied science, by which the advance is chiefly
secured, an importance in the eyes of the outside world
with which no amount of abstract thought endows
pure knowledge. Indeed, in the eyes of the world,
applied science attains the position which Francis
Bacon foresaw and desired. As one triumph after
another is won, the effect to all appearance is that
of an invincible if slow advance. It seems that no
limits can safely be assigned to the extension of man's
mastery over nature ; it comes to be assumed that
the mechanical principles by the application of which
that extension is made are competent to account for
and explain the whole of the Universe.

Save in this indirect way, with the technical applica-
tions of science we shall have little to do. It is indeed
a very grave question whether the consequent advance
in material wealth and resources has produced any

156 SCIENCE AND THE HUMAN MIND

corresponding elevation of tone or deepening of in-
sight in the human mind. Sometimes it looks as
though one effect had been an actual lowering of ideal,
an increase in bodily servitude and spiritual despair.
We have come to regard physical comfort and personal
security as the main object of human endeavour, and
have forgotten the old truth that he who would save
his life must be ready to lose it.

Even on the material side, a rapid advance in the
means of exploiting the resources of Nature has brought
many perils. In the early years of the nineteenth
century, an enormous increase of available energy,
produced by the new means of drawing on the limited
and stored supplies in the coalfields, was brought
within reach by the mechanical inventions of a small
number of able men. This energy gave the means
of supporting a larger population, and at once the
population rose in response. But organization, social,
civil and religious, failed to keep pace with the in-
dustrial changes, and to adjust itself to the new pro-
portions in which the grades of this rapidly growing
population became divided. The tremendous increase
of wealth fell largely into irresponsible hands, and the
directing and controlling power of the State, at any
rate for a time, became almost indistinguishable in the
medley of conflicting interests. Thus it is that, as the
period we are now studying draws on, as a result of
the industrial development and the unstable social
conditions it created, we shall find men driven to
study their corporate history and their social maladies
by methods learned in biological and statistical
science, and discovering facts and formulating pro-
blems undreamed of by their predecessors. In this

PHYSICS OF NINETEENTH CENTURY 157

latest field added to its estate, science has set itself
to examine experimentally the properties and needs
of the social organism, and to deal with the needs
of the human mind as well in its collective as in its
individual aspect.

But, during the greater part of the period under
review, the complication of the social problem was not
understood, and social questions were answered in
the same confident spirit which was manifested in
other branches of science. Thus the cumulative
effect of the general tendency, in pure science, in its
technical applications, and in social philosophy,
became very great. It seemed that the human mind
was fast coming to a complete explanation of all
things on a mechanical and materialistic basis.

The diffusion of this limited and one-sided aspect
of Nature, unaccompanied by historical or critical
insight, among minds unsuited by character and educa-
tion to apprehend the underlying deeper problems,
produced the narrow and dogmatic type of scientific
thought prevalent during a great part of the nineteenth
century and generally associated with a materialistic
outlook on life. A knowledge of the history of science,
an appreciation of the inadequacy and temporary
nature of many of its hypotheses which have done
good work in their time, together with the realization
of the deeper metaphysical questions which lie all un-
answered beneath science at every point, are tending
to release the human mind from the iron domination
of nineteenth-century scientific scholasticism, which
was threatening to outlive its period of usefulness as
a corrective to the older dogmatism of the modes of
thought it superseded.

158 SCIENCE AND THE HUMAN MIND

Throughout the century, it is true, we find that most
of the great leaders in science, both in their own per-
sonalities and in the general trend of their teaching,
keep their touch with the deeper realities of the un-
sounded depths of the human soul. They, at all
events, still grasp, unconsciously it may be, the con-
nection between the experimental method in natural
science and an attitude of open-minded reception of
spiritual experience ; between the intuitive religious
instinct of the great mystics and the scientific insight
of a Leonardo or a Faraday, who apprehend intui-
tively the essence of a problem and frame conceptions
fit to guide not only their own experiments and those
of the lesser men who follow, but also to throw light
on the meaning of life itself. Such men as Faraday,
Pasteur, Stokes, Kelvin (who is said to have begun
his lectures on physics with the Collect for the
day) were very far from the materialistic dogmatism
of some of their followers. This humility, this sane
and calm balance of mind, is oftener found in great
physicists who deal with subjects of the more funda-
mental kind, subjects in which such conceptions as
matter and force, in which other sciences are apt to see
complete and conclusive explanations of natural pheno-
mena, are themselves analysed and, as ultimate verities,
found wanting. It is less common among those who
have to apply the more fundamental concepts to the
secondary sciences, nor is it often developed among
those whose business it is to apply the results of science
to the arts of practical life. An overestimate of the
function and power of science becomes as common in
one direction as an ignorance of the breadth and scope
of the ground it may rightly claim is in another.

PHYSICS OF NINETEENTH CENTURY 159

The social philosophy of the nineteenth century
bore marks of the hopes of the Encyclopaedists for
the explanation of the Universe, and of the French
Revolution for the regeneration of mankind. Once
again immense strides were taken ; once again the
forward movement gradually became overshadowed
with the certainty of another great disillusionment for
those who had mistaken the means for the end.

Like the Israelites in the wilderness, the modern
world cried out to science to make it a golden calf.
The golden calf was duly made and greatly admired, for
it had its uses ; but it has been found wanting as an
object of worship. Meanwhile, new tables of the law
are being delivered to the prophets of pure knowledge,
and a fresh revelation is forthcoming of the terms of
the covenant by which alone it is possible for human
nature to fulfil the immediate purpose of its existence
in the age now beginning.

Newton and his contemporaries wrote in Latin.
Their works were thus the common property of that

small section of each nation that under-
The

Popularization stood the ancient tongue — sections that
of Science. were robabl akjn to each other in race

as well as in modes of thought. The very limitation
and detachment inseparable from publication in a
classical language produced advantages to set against
its drawbacks. Science was cosmopolitan ; it was
apart from the national life ; but was thereby saved
from the dangers of popular interference, and the
degradation of popular approval of the material
benefits it may confer.

When we take up the tale once more, in the latter

160 SCIENCE AND THE HUMAN MIND

half of the eighteenth century, there has been a
general change to the vernacular in scientific literature.
Science thus became part of the general intellectual
development of each people. The change did much
to make possible the technical application of scientific
results and the industrial upheaval of the nineteenth
century. But it came at a period when a materialistic
view of science was in the ascendant, and the nations
of Christian Europe, as a whole, received as their first
impression of the new knowledge the idea that the
object of scientific enquiry is the creation of wealth
and the provision of practical benefits — an attitude of
mind that is still widely prevalent in om\ midst — and
that a mechanical explanation of existence is possible
or even has been accomplished.

The popularization of science was a slow process.
At first, in the seventeenth century, the foundation
of the Royal Society of London and of similar societies
in other capitals gave a focus and meeting-place for the
men of science within reach. During the succeeding
century the great extension of interest in scientific
matters led to the foundation of various provincial
societies which had considerable influence in the spread
of the new knowledge. The Royal Society of Edin-
burgh, which still survives, was founded in 1783 on
the framework of an older Philosophical Society. The
Lunar Society flourished in the Midlands of England
at the close of the eighteenth century, and brought
together such men as Erasmus Darwin, S. J. Gait on,
and Priestley, who rode across country at each full
moon to the appointed rendezvous, to discuss the
scientific problems of the hour. These local societies
for the most part decayed when the facilities of railway

PHYSICS OF NINETEENTH CENTURY 161

locomotion drew all such interests to London or the
two Universities, where, for fifty years, learning in
England became chiefly concentrated. It is only of
recent years that the foundation of provincial Uni-
versities has re-established local centres of interest
and intercommunication.

The first line of scientific achievement we have to

follow into the new era is an extension of old methods

rather than an invention of new ones.

Astronomy. T »**•••• • j ,,

Newton s Pr^nc^p^a carried the gravita-
tional theory as far as the existing mathematical tools
allowed ; but during the years 1773 to 1787 that
theory was developed much further by the use of
modern mathematics by J. L. Lagrange and Pierre
Simon, afterwards created Marquis de Laplace. In
Laplace's second great period of activity, 1799-1825,
he systematized all such knowledge in his monu-
mental treatise, Mecanique Ctteste, and popularized
the Newtonian philosophy in a smaller book, Systtme
du Monde.

Almost all the complicated planetary motions
were explained broadly by this school of mathematical
astronomers, though some details of lunar and planet-
ary theory were left to be worked out in future years.
It may be said at once that the final test was given
to Newton's theory by its use to predict the existence
of an unknown planet, thus reversing the methods
of Newton, Lagrange and Laplace. The perturbations
from its orbit of the planet Uranus were not to be
accounted for fully from the action of the other known
bodies, and, to explain these irregularities, the influence
of a new planet was assumed, and its necessary position

ii

162 SCIENCE AND THE HUMAN MIND

calculated independently by John Couch Adams of
Cambridge and the French mathematician Leverrier.
Turning his telescope to the position indicated by
Leverrier, the astronomer Galle of Berlin detected
a planet to which the name of Neptune was given
(1846). These researches give the final verification
of Newton's fundamental hypothesis that each particle
of matter in the solar system may be supposed to
attract every other particle with a force proportional
to the product of the masses, and inversely pro-
portional to the square of the distance between
them. The probability in favour of the hypothesis
as the embodiment of a correct relation is possibly
as great as that in the case of any other physical
theory hitherto propounded.

Newton's theory, as developed by himself, Lagrange
and Laplace, proved sufficient to co-ordinate all the
The Nebular observations made concerning the solar
Hypothesis, system as now in existence ; it was
therefore natural to try to extend its sway over the
past, and to adapt it to an attempt to explain the
origin of that system. Hence Laplace framed a
" nebular hypothesis," which pictured the primordial
chaos as filled with scattered matter like a diffused
cloud, spread throughout the space now occupied
by the solar system. Laplace showed that known
dynamical principles were consistent with the drawing
together and gradual solidification into distinct
fiery masses of such space-scattered particles. He
thus made conceivable to the human imagination the
formation of the sun and planets from a formless
chaos. The existence of luminous nebulae in the

PHYSICS OF NINETEENTH CENTURY 163

heavens, fulfilling the required condition of vapour-
like diffusion, is a well-ascertained fact, and the nebular
hypothesis gains rather than loses support from recent
astronomical research. The French Encyclopaedists,
earlier in the eighteenth century, had begun to think
that they could see their way to explain all nature on
mechanical principles, and, as we have said, Laplace
imagined " a mind competent to foretell the progress
of nature to all eternity, if but the masses, their posi-
tions and initial velocities were given." This may
be regarded as the complete view of thorough-going
mechanical philosophy, which gained increasing hold
over the scientific world in the period now under con-
sideration. Its confident completeness is well illus-
trated by Laplace's reply to Napoleon's query about
the place of God in the scheme of nature, " that he
had no need of that hypothesis."

But while mechanical science developed in paths

already mapped out, chemistry underwent an entire

fl transformation. Thus, at the beginning

"Phlogiston." , A, . , A1_ ,.,,,.

of the period, the Aristotelian conception
of a body essentially light kept its hold in Stahl's
hypothetical substance " phlogiston." Misled by the
phenomena of flame, which naturally suggest an
escape of something from the burning body, Stahl
framed a theory in which that something was accepted
and named " phlogiston." Since, when all the
products are collected, the balance shows a gain,
phlogiston must possess a negative weight. In terms
of this hypothesis chemical science had learnt to
express its facts, and, owing to its influence, isolated
investigations, which pointed to more modern views,

164 SCIENCE AND THE HUMAN MIND

had failed to impress the minds of chemists, and had
to be rediscovered when time had gradually under-
mined the theory and prepared the way for the natural
reinterpretation of the phenomena. In 1669, a century
before Priestley's final discovery of oxygen, its exist-
ence in air and its significance in the phenomena of
respiration and combustion had been demonstrated
by John Mayow (1640-1679), a physician who practised
in Bath and London. Again oxygen was prepared
from heated saltpetre by Borch in 1678, and once more
in 1729 by Hales, who actually collected it over water.
The isolation of hydrogen may even be traced back to
Paracelsus, who described the action of iron filings
on vinegar. Yet all these observations were forgotten
and their meaning lost ; air was still believed to be
the only ponderable gaseous element.

Thus once more we are impressed by the rarity of
finding that the accepted discoverer of a scientific
phenomenon, or the received originator of a scientific
theory, stands alone or even at the beginning of the
episode. A study of previous records nearly always
discloses others who trembled on the verge of the
discovery, or beheld premonitory visions of the
coming revelation. Leonardo da Vinci buried in his
note-books many of the ideas which created the
science of the succeeding centuries — ideas which only
attained an accepted position in the structure of
knowledge when Galileo or Huygens had fitted them
into place. Behind Leonardo, again, stand other
shadowy figures of whom we catch here and there a
faint glimpse. It is only when the frame is ready,
when a place is waiting for the new conception, that
it can be certain of an immediate and enduring re-

PHYSICS OF NINETEENTH CENTURY 165

cognition. A discovery or a theory that is too much
before its age stands but a poor chance in the ordeal
of selection. Of many men's work it may be said,
as Kant said of his own writings, that they had come
a century too soon.

The beginning of the change appears in the work
of Dr Joseph Black of Edinburgh, who about 1755
discovered that a new ponderable gas, distinct from
atmospheric air, was combined in the alkalies. This
gas he named " fixed air " ; it is what we now call
carbon dioxide or carbonic acid. Nevertheless, for
yet a time phlogiston lived.

In Joseph Priestley (1733-1804), theologian and
experimenter, we find the man who stood at the
threshold of the new era. He prepared oxygen by
heating mercuric oxide, and discovered its marked
power of supporting combustion. But he described
it as dephlogisticated air, and failed to perceive that
his discovery turned a new page. As Cuvier said,
he was the father of modern chemistry, but never
acknowledged his daughter. Priestley had the distinc-
tion of having his critical history of the corruptions
of Christianity burned by the common hangman at
Dort, and his papers and experimental laboratory
destroyed by a Birmingham mob.

The theory of phlogiston maintained its hold also
on Henry Cavendish (1731-1810), a grandson of the
second Duke of Devonshire, who inherited alike his
scientific ability and the means wherewith to develop
it from a family where both attributes are not uncom-
mon. Cavendish made many discoveries, especially
in electricity, which have been credited to other men.
His retiring and secretive disposition led him often to

166 SCIENCE AND THE HUMAN MIND

neglect the duty of publishing to the world the results
of experiments made solely to satisfy his own curiosity.
This was not the case with his chief chemical discovery,
the compound nature of water. But when, in 1781,
Cavendish thus dethroned water from its old and
proud position as one of the elements, he still described
its constituents as phlogiston and dephlogisticated air.

But, with this gradual accumulation of knowledge,
the accepted theory was becoming more and more in-

T , adequate. New ideas were better able

Lavoisier and

the Conserva- to describe the phenomena, and, in due
tion of Matter. tim6j the new ideag appeare<l. In 1783,

Lavoisier repeated Cavendish's experiment, and
grasped the fact that there was no need to invent
a body with properties fundamentally unlike those of
other material substances. Lavoisier regarded the
constituents of water as ordinary gases possessing
mass and weight, and named them hydrogen (the
water-forming element) and oxygen (the acid-forming
element). The conception of phlogiston became
unnecessary, and with it vanished the last of the
essentially light bodies with negative weights. Thus
the principles which, for a century and a half, had
revivified the science of mechanics were carried over
into chemistry.

In Lavoisier's hands, too, another principle which
had slowly been emerging from obscurity became
clear : the principle of the persistence of matter, or
conservation of mass. Throughout any series of
chemical changes, the matter involved may alter its
state of chemical combination, and change its form
from solid to liquid or seemingly disappear as a gas.

PHYSICS OF NINETEENTH CENTURY 167

Yet, when collected and tested by the balance, the
products of the reaction weigh the same as the reagents.
This principle is accepted by Lavoisier in all his
investigations ; he states it in definite form : " The
quantity of matter is the same at the end as at the
beginning of every operation. "

Nevertheless, in spite of the disappearance of
phlogiston, and the establishment of the principle of
Imponderable the conservation of mass, the conception
Fluids. Of a weightless fluid had still many
years of useful life before it. Although the most
acute of the natural philosophers, such men as
Newton, Boyle and Cavendish, inclined to the
opinion that heat was due to a vibratory agitation
of the particles of bodies, in the absence of definite
conceptions corresponding to our modern notions
of energy, that opinion could not be developed
into a useful working hypothesis. The advance
which was waiting to be made was the idea of heat
as a measurable quantity, unchanged in amount
as it passed by contact from one body to another.
To experiment with this conception as a guide, men
needed a definite and suitable representation of the
nature of heat. This conception was at hand in
the theory that heat might be a subtle, invisible,
weightless fluid, passing between the particles of bodies
with perfect freedom. It was in the light of this
theory that Black discovered and investigated the
phenomena of the latent heat required to produce a
change of state from solid to liquid, or liquid to gas,
and the specific heat needed to raise the temperature
of a substance. He thus established the science of

168 SCIENCE AND THE HUMAN MIND

calorimetry, or the measurement of a quantity of
heat.

A similar theory, or rather two similar rival theories,
enabled Franklin, and his fellow- workers, to throw
light on the phenomena of electricity, which were
now drawing men's attention. The attractions and
repulsions between electrified bodies may be expressed
on the supposition that there is a substance, electricity,
which, like heat, may be treated as a quantity sub-
ject to the laws of addition and subtraction. With
electricity, however, the existence of two distinct and
opposite varieties was revealed in an early stage
of the history of its discovery. An electric charge
developed by friction on glass will neutralize a charge
produced in the same way on ebonite. These results
were explained by the supposition either of two fluids
with opposite properties, or of one fluid, of which the
excess or defect from the normal quantity gave rise
to the electrified state. The terms of speech appro-
priate to the one-fluid theory, with its positive and
negative electricities, are still with us, though, as we
shall see later, the fluid has given place to the newer
conception of electric particles or corpuscles, or to
the vaguer one of disembodied charges or electrons,
the excess of which constitutes the conventionally
negative, and the defect the conventionally positive,
electrification.

The overthrow of the theory of phlogiston had the

effect of bringing clearly to light the three states of

The Atomic matter, solid, liquid and gaseous, as

Theory. we know them now — different physical

phases of the same substance, which primarily may be

PHYSICS OF NINETEENTH CENTURY 169

best known in any case in one of the phases, but in
suitable conditions can exist in either of the three.
This advance in knowledge was followed by the study
of the laws of chemical combination, since gases, in
which the laws can be traced most simply, had been
now brought into a correct relation with other bodies.

As the result of careful analysis, it was found that a
chemical compound was always made up of precisely
the same amount of the constituent parts, and this
fact of the fixity of composition played an essential
part in the scheme of the new chemistry. Water,
however obtained, always consists of hydrogen and
oxygen combined in the ratio of one to eight. Thus
the conception of combining weight was reached, the
combining weight of oxygen being eight, if that of
hydrogen be taken as unity. Once again, if two
elements combine in more than one way, to form more
than one compound, the proportion of the constituents
in one compound is simply related to the proportion
in the other : fourteen parts of nitrogen combine
with eight of oxygen in one compound, and with
sixteen parts in another, exactly double the first
proportion.

John Dalton (1766-1844), a colour-blind Quaker
chemist, who was born in Westmoreland and worked
and died at Manchester, saw that these phenomena
pointed to the conclusion that matter was not in-
finitely divisible, and that combination took place
between discrete particles with definite weights char-
acteristic of each substance. Led by these con-
siderations, he revived the old atomic theory in modern
guise, the essence of the new form of it being that it
was possible to arrive at a knowledge of the relative

170 SCIENCE AND THE HUMAN MIND

weights of the atoms of two elements from a deter-
mination of the proportions in which those elements
combine in their simplest compound. Thus the com-
position of water indicates that the atom of oxygen is
eight times as heavy as the atom of hydrogen, and
that the constitution of water should be represented
as HO, where H stands for one atom of hydrogen
and O for one of oxygen. By such methods Dalton
assigned atomic weights to some twenty elements
(1804).

The insufficiency of Dalton's conceptions as they
stood became apparent when the phenomena of
gaseous combination were studied more extensively.
Gay-Lussac (1778-1850) showed that gases always
combine in volumes that bear simple ratios to each
other, and Americo Avogadro, Conte di Quaregna
(1776-1856), pointed out that on Dalton's theory it
followed that equal volumes of all gases must contain
numbers of atoms that bear simple ratios to each
other. But it was soon found, both from further
study of gaseous combination and from physical con-
siderations, that a distinction was necessary between
the chemical atom, the smallest part of matter which
can enter into combination, and the physical molecule,
the smallest particle which can exist in the free state.
The simplest method of expression of Avogadro's
hypothesis is to suppose that equal volumes of gases
contain the same number of molecules. The physical
theory developed in mathematical form by Waterston
and Joule, that the pressure exerted by a gas is due
to the impacts of the molecules, which are in a state
of perpetual movement and collision, also leads to
this result.

PHYSICS OF NINETEENTH CENTURY 171

But, to return to the case of water, two volumes
(and therefore molecules) of hydrogen combine with
one of oxygen to form two volumes (or molecules) of
steam. It will be seen that the simplest theory which
will explain these relations is one which supposes that
the physical molecules of hydrogen and oxygen
each contain two chemical atoms, and that the
molecule of water vapour has the chemical composi-
tion represented by H2O. Thus Dalton's combining
weights need to be brought into line with the facts
revealed by the later experiments before we are in
a position to assign to the elements their true atomic
weights.

Dalton's theory, when developed by the addition
of Avogadro's hypothesis, arose naturally out of de-
finite experimental knowledge. Other phenomena
were waiting to be interpreted by its light, and still
more were discovered and co-ordinated as time went
on. Except for a temporary tendency in the last
few years of the nineteenth century to replace the
theory of chemical atoms by relations based on the
theory of energy, it may be said that atomic and
molecular conceptions have inspired most of the
chemical and physical research which has distinguished
the past century.

One result of Dalton's work was to give a working
definition of an element, as a substance possessing
a distinct and unchanging atomic weight from
whatever source it was obtained. Hence, since it
was now possible, it became of high importance
to extend the knowledge of the substances which
were in truth elements, incapable of further analysis
or subdivision.

172 SCIENCE AND THE HUMAN MIND

The number of known elements has grown from the
twenty recognized by Dalton till now some eighty
different kinds of matter have been recorded. The
work of discovery has proceeded fitfully. When any
new method of research has been applied to chemical
problems, a new group of elements has frequently
come to light. The separating power of the galvanic
current enabled Sir Humphry Davy to isolate the
alkaline metals potassium and sodium in 1807. At a
later date, spectrum analysis showed the existence of
such substances as rubidium, caesium, thallium and
gallium ; while, in recent years, the still more delicate
methods of radio-activity have disclosed bodies like
radium and its allied family of elements.

The atomic weights of the elements, first calculated
by Dalton, are constants of fundamental importance
in natural science. Relations between the values for
different elements which possessed somewhat similar
properties were pointed out by Prout and Newlands,
and in 1869 the Russian chemist Mendele*eff showed
that, if the elements be arranged in a table in order
of ascending atomic weight, there is a remarkable
likeness in the physical and chemical properties of
various groups of elements as they fall at certain
regular intervals in the table. An evident gap in
the series, which could not be filled without introduc-
ing confusion into the scheme, even led Mendeleeff
to prophesy the existence and to predict the pro-
perties of an element which was not discovered till
some time afterwards.

This " periodic law " shows that the physical and
chemical properties of the elements depend on the
mass of their atoms. And, since it also thus makes

PHYSICS OF NINETEENTH CENTURY 173

clear the existence of some relation between the atoms
themselves, it leads us back once more to the old idea
that different substances are made up of the same
fundamental stuff, with its ultimate particles differ-
ing in arrangement or in number in the different
atoms. Here the required penetration into natural
phenomena grows too intense for the methods proper
to chemical research, and the actual discovery of an
ultimate particle, common to all kinds of matter, is
one of the latest triumphs of physics to be described
below.

Meanwhile a vast extension of chemical knowledge
was made by optical methods. As we have already
The seen, Newton preferred the emission to the
Wave Theory undulatory theory of light because of the
of Light, difficulty of explaining the phenomena of
straight rays and shadows on any hypothesis of wave
motion. But in 1801-3 Thomas Young revived the
wave theory to account for his newly discovered
phenomena of the interference of two rays of light to
form coloured fringes, as well as the colour of thin
plates studied by Newton. Young's ideas were de-
veloped in mathematical form by Fresnel, who also
showed that rectilinear propagation would be a pro-
perty of waves which were very small compared with
the dimensions of the obstacles or the distances con-
cerned, and thus met Newton's objection to the theory.
Moreover, the phenomena of polarization, which indi-
cate that a ray of light possesses different properties
on different sides of the ray, were shown by Young to
prove that the direction of the vibrations which con-
stitute the wave is at right angles to the direction

174 SCIENCE AND THE HUMAN MIND

of propagation. Finally, since the hypothesis of
waves certainly connotes the idea of something to
vibrate, it was thought necessary to revive the old
conception of an all-pervading universal aether to
supply what the late Lord Salisbury once called " a
nominative case to the verb ' to undulate/ '

The wave theory gave an explanation of the
phenomena which led to the triumphs of spectrum
Spectrum analysis. Joseph Fraunhofer (1787-1826)
Analysis, had mapped the black lines which cross
the coloured band of light, or spectrum, which is
obtained by passing a beam of parallel rays of sunlight
through a glass prism. The nature of these lines seems
first to have been made plain by Sir George Gabriel
Stokes (1819-1903) in his lectures at Cambridge, though
with characteristic modesty he gave his ideas no wider
publicity. A child's swing is set in motion by giving
it a series of small impulses which coincide with
its natural period of oscillation, and, in similar manner,
any mechanical system will absorb energy which falls
on it in rhythmic unison with its own natural vibra-
tions. Hence the molecules of the vapours in the outer
envelope of the sun will absorb the energy of those
particular rays coming from the hotter interior, of
which the oscillatory period coincides with their own.
The light which passes on, then, will be deprived
of light of that particular colour (i.e. frequency of
vibration), and a black line in the solar spectrum is
the result. Bunsen and Kirchhoff saw that, if this
explanation be the true one, the black lines due to
absorption should correspond in position with the
bright lines the molecules of the same element them-

PHYSICS OF NINETEENTH CENTURY 175

selves give out when heated. Thus, when one of
Fraunhofer's lines coincides with the bright line in the
laboratory spectrum of a terrestrial substance, the
presence of that element in the envelope of the sun is
to be inferred. Moreover, by passing the intensely
white light of the electric arc through sodium vapour,
volatilized in the cooler flame of a spirit-lamp, it
should be possible to reproduce artificially the dark
absorption line of sodium. Such an experiment indeed
had been carried out by L£on Foucault in 1849, but
had passed unnoticed and been forgotten. It was
performed once more by Bunsen and Kirchhoff in
1860, in the light of the theory given above, and its
success at once opened up the new science of the
chemistry of the sun and stars. By analysis of their
light, it became possible to detect the existence in
the depths of space of elements known on our globe.
Moreover, since the colour of light and the relative
position of spectral lines depends on the frequency
of the vibrations which reach the eye, a luminous
source approaching an observer will crowd more
waves into his eye per second than if the source were
at rest. Thus a slight shift, in one direction or the
other, in the position of spectral lines which can be
measured microscopically indicates relative approach
or retreat between the source of the light and the earth.
In this way the velocities and movements of stars
can be investigated by a study of the light which they
emit. Although many stellar spectra are too faint
to affect the eye, in photography small effects can
be made cumulative, so that, by long exposure, lines
invisible to the unaided eye can be detected on a
photographic plate.

176 SCIENCE AND THE HUMAN MIND

As we have seen, the caloric theory, by which heat
was pictured as an imponderable fluid, played a

Heat and the use^ Part m suggesting and making in-
Theory of telligible experiments on the measurement
Energy. Qf quantities of heat. But, as a physical
explanation, it had always seemed insufficient to the
more acute natural philosophers. Investigations by
Count Rumford on the boring of cannon, and by
Sir Humphry Davy on the rubbing together of two
lumps of ice, had shown that heat was developed
by friction to an unlimited extent in a way
inexplicable on the caloric theory. But more direct
experimental proof was needed. James Prescott
Joule, during the years between 1840 and 1850,
measured accurately the amount of heat produced
by the expenditure of a known quantity of work, and
proved that, however the work was expended, the
same amount of heat was produced. When these
experiments became known, an exact equivalence
between heat and work was generally recognized, and
heat accepted as a form of motion. It was now
regarded as the average energy of motion of the
molecules of a body, and when, as in a gas, the
molecules are supposed to be free from each other's
influence, it is easy to obtain a vivid physical con-
ception of the state of affairs. Owing to moment-
ary collisions, at any instant there will be molecules
moving with any number of different velocities in
all sorts of directions. The impact of the molecules
on the walls of the vessel constitutes the pressure
of the gas, while the average energy of the molecules
measures its temperature. On these lines Joule
gave an elementary mathematical kinetic theory

PHYSICS OF NINETEENTH CENTURY 177

of a gas, which was extended and made more
rigorous by James Clerk Maxwell. On this theory,
most of the physical relations of a gas can be explained
directly in terms of simple movements of the hypo-
thetical molecules of which it is imagined to be
composed.

Joule's definite experimental result that work and
heat were equivalent gave point and power to a more
general conception which was then arising, known as
the " correlation of forces," and developed it into the
important physical principle of the conservation of
energy. Energy, as a definite physical conception,
was new to science. The idea which underlay it had
previously been expressed by an inaccurate and
confusing extension of the meaning of the word force.
Energy may be defined as the power of doing work,
and, if the conversion be complete, may be measured
by the work done.

Joule's experiments showed that, in one definite
case, the total amount of energy in a system is constant,
the quantity lost as work reappearing as heat. General
evidence led to the extension of this result to other
changes, where, for instance, mechanical energy is
converted into electrical energy, and then perhaps into
chemical energy. All known facts are consistent
with the statement that, in all cases in present con-
ditions, the total energy of an isolated system is
constant in amount.

The principle of the conservation of energy, thus
established, is comparable with the long -known
principle of the conservation of mass. Newtonian
dynamics are founded on the recognition that there is
a quantity, for convenience called the mass of a body,

12

178 SCIENCE AND THE HUMAN MIND

which remains constant throughout all motion. In
the hands of the chemists, the balance showed that
this principle held good also when chemical changes
occurred. A body burning in air was not annihilated.
When the resultant gases were collected, the total
weight of body and air remained unaffected.

And so it is in the case of energy. We find another
quantity besides mass which remains unchanged
throughout a series of transformations. Hence it is
convenient to recognize the existence of that quantity
and to give it a name. We call it energy, and measure
its changes by the amount of work done or by the
amount of heat developed.

As we can neither create nor destroy matter, so we
can neither create nor destroy energy. We can but
convert matter or energy from one form into another.

The importance of this result in the history of
physical science was immense. It gave a new method
of investigation, a new point of view from which
physical problems could be regarded. Since the final
energy of a closed system must be the same as that at
the beginning, it became possible in some cases to
predict the final state of the system without reference
to intermediate steps, to pass at once to the solution
of a problem without tracing the process by which the
goal was attained. As a practical guide in scientific in-
vestigation, the principle of the conservation of energy
is one of the great achievements of the human mind.

But, if the principles of the conservation of matter
and energy hold good in all the circumstances we can
investigate, and to all the accuracy we can attain by
experiment, it was natural to stretch the principles
into the form of general laws. Matter became

PHYSICS OF NINETEENTH CENTURY 179

eternal and indestructible ; the amount of energy in
the Universe became constant and immutable, in all
conditions and for all ages. The principles passed
from safe guides for empirical advance in knowledge,
into philosophic dogmas of doubtful validity.

When heat is transformed into work, or work into
heat, the equivalence between them is completely
expressed by Joule's results. But, although it is
always possible to transform the whole of a given
quantity of work into heat, it is not generally possible
to perform completely the reverse change. In steam
engines, and other heat engines, it is always found
that only a fraction of the heat supplied is transformed
into mechanical energy ; the remainder, which passes
from hotter to colder parts of the system, does not
become available for the performance of useful work.
Every heat engine needs a difference of temperature,
a hot body or source of heat and a cold body or con-
denser. The possible efficiency of the engine increases
as this difference of temperature increases, and, in a
theoretically perfect frictionless engine, the efficiency
is independent of the form of the engine or the nature
of the working substance, and gives a clue to an
absolute scale of temperature which also is independent
of the properties of any one substance.

On these lines the principle of the relations between
heat and work, the science of thermodynamics, was
established, chiefly by the labours of Sadi Carnot
(1796-1832), William Thomson, afterwards Lord
Kelvin (1824-1907), and R. J. E. Clausius (1822-1888).

The consequences of thermodynamic reasoning
have not only enabled the engineer to place on a firm
footing the theory of the heat engine, but have aided

i8o SCIENCE AND THE HUMAN MIND

materially the progress of modern physics and chemistry
in many other directions. They led to the theory of an
absolute scale of temperature, and pointed the way
to that series of researches at low temperatures which
eventually liquefied all known gases and completed
the proof of the continuity of all types of matter in its
three states.

For the gain of useful work from a supply
of heat, a temperature inequality is necessary.
But, in nature, temperature inequalities are con-
tinually being diminished by conduction of heat and
in other ways. Hence, in a closed system, the heat
energy tends steadily to become less and less available
for the performance of useful work. When the avail-
able energy becomes a minimum, no further work
can be done, and thus we determine the necessary
conditions of equilibrium of the system. In this way
the mathematical theory of chemical and physical
equilibrium has been built up by Kelvin, Helmholtz
and Willard Gibbs.

Similar ideas, extended to the whole solar system,
indicate that mechanical energy is continually wasting
into heat by friction, and heat energy continually
becoming less available by the reduction of inequalities
of temperature. Hence we are led to contemplate a
distant future in which all our stores of energy shall have
been converted into heat uniformly distributed through
matter in mechanical equilibrium, and all further
change becomes for ever impossible. But it should
be noted that this conclusion rests on several unproved
assumptions. It supposes that the solar system, or
the Universe if it be extended thereto, may be treated
as an isolated system into which no energy is entering ;

PHYSICS OF NINETEENTH CENTURY 181

it supposes that individual molecules, the velocity
of which is subject to continual alteration owing to
collisions, cannot be followed and separated into fast-
moving and slow-moving groups, for, as Maxwell
pointed out, such a power would enable diffused
energy to be reconcentrated. Nevertheless, in the
conditions of Nature as then known, the conclusion
stood; the energy by which we live and move was
seen to be becoming continually less available, the
iron hand of mechanical necessity stretched out to
grasp and crush the life of the Universe.

The steam engine was developed by practical men
to meet industrial needs, and owed little, except

The Rise of m ^S ^ater sta£es> *o tne ne^P °f Pure
Electrical science. But, as regards the other
Science. great physical agency of modern civilisa-
tion— electricity — the case was very different. Here
the practical applications followed, and were a direct
consequence of, the researches of men who sought for
knowledge alone. Modern electrical science began with
the discovery of the phenomena of " galvanism " or
current electricity by Galvani in 1786, and Volta of
Pavia in 1800. Volta's cell, from which he produced
the first electric current, consisted essentially of two
plates of unlike metal, placed in the solution of an acid
or a salt. This apparatus was found to show effects
which were soon correlated with those of the older
frictional electric machines. While the frictional
machine supplied isolated charges of small quantities
of electricity at a very high tension, showing their
existence on discharge by visible sparks, the new voltaic
battery gave a steady large current at a much lower

i82 SCIENCE AND THE HUMAN MIND

electromotive force. The chemical decompositions
produced by these currents were the first of their pro-
perties to be investigated, and led to the industry
of electro-plating, while, more recently, they have
been used extensively in many processes of chemical
manufacture and in metallurgical operations.

In theoretical science, one of the earliest and most
striking of the results of the use of the voltaic cell
was the separation in 1807 of the alkali metals potas-
sium and sodium from their oxides in the researches
of Sir Humphry Davy (1778-1829). Davy, a native
of Penzance, was the first Professor of Chemistry at
the newly founded Royal Institution. It is a sign of
the growing general interest in science that an institu-
tion for diffusing scientific knowledge should have
come into existence, and that Davy's lectures should
have attracted a large audience composed both of
" men of science and numbers of people of rank and
fashion." Davy's attractive personality had much
to do with this success, while his imaginative and
poetic nature was an essential part of his power as a
framer of scientific hypotheses fit to be tested by
experiment.

Electrically, Davy's work marks an important step.
The use of electrical forces to separate chemical com-
pounds into simpler constituent parts indicates a
connection between electrical and chemical phenomena
which is of fundamental importance in the theory
of both subjects. Davy's work was taken up again
and carried further by his pupil and successor, Michael
Faraday (1791-1867), whose instinctive genius we shall
meet again in future pages. Faraday showed that
the amount of chemical action was strictly proportional

PHYSICS OF NINETEENTH CENTURY 183

to the quantity of electricity which passed, and that
the mass of substance separated was proportional
to its chemically equivalent weight.

The great industrial applications of electricity, made
possible by the invention of the telegraph on one hand
and the dynamo on the other, are founded on the
scientific discoveries of two physicists. In 1820 Hans
Christian Oersted of Copenhagen discovered that, if
a wire be placed above or below a magnetic compass
needle and parallel with it, the needle is deflected from
its north-and-south position when an electric current
is passed along the wire. By the construction of
galvanometers, this magnetic force was at once
applied to the measurement of currents, and underlies
all our modern quantitative science of electro-mag-
netism. In 1831 Michael Faraday demonstrated at
the Royal Institution that, when the current in one
circuit of wire is started or stopped, a momentary
secondary current is induced in another coil of wire
placed near the first one. A similar current is pro-
duced by the motion of magnets, or by any other
change in the magnetic force in the coil. These
currents, barely perceptible to Faraday's primitive
instruments, were set up by means the same in prin-
ciple as those which now drive our electric trains and
supply thousands of horse-power to many industrial
manufactures.

Faraday's experimental researches were guided by

his instinctive grasp of the importance of the dielectric

Electric or insulating medium in electric pheno-

Waves. mena. When a current deflects a magnetic

needle across space, or induces another current in an

184 SCIENCE AND THE HUMAN MIND

entirely unconnected circuit, we have either to
suppose an unexplained " action at a distance," or
to conceive the intervening space bridged with some-
thing through which the effect is transmitted. When
Clerk Maxwell in 1865 developed mathematically
Faraday's ideas, it became clear that the propaga-
tion of electric forces was similar to the propagation
of light ; whatever be the means by which one is
transferred must also be the means of conveyance of
the other.

Hence the idea of a universal all-pervading aether,
which had been accepted owing to the success of the
wave theory of light, received a great access of credit,
and science entered on what might be described as an
aethereal stage. Experiments were made to measure
the velocity of the earth " relatively to the aether,"
and, when it appeared that they were relatively at
rest, it was assumed that the earth carried the aether
with it in its path, and attempts were made to demon-
strate that whirling steel discs dragged the aether with
them — once more with a negative result. However,
a slight change in the dimensions of bodies with
change in direction of motion — a change too small to
be otherwise detected — was shown to be enough to
explain the discrepancy, and it was universally
assumed that time would bring a complete scheme
of physics, in which the aether, interpreted in
mechanical terms, would form a means of unifying
the whole range of phenomena — an expectation
which, indeed, has since seemed almost on the point
of realization.

Maxwell's theoretical results were verified and
interpreted to wider circles by the experiments of

PHYSICS OF NINETEENTH CENTURY 185

Heinrich Hertz, who in 1888 demonstrated directly
the passage through space of electro-magnetic waves,
and showed that their properties were identical with
those of waves of light of very great wave-length.
By the invention of improved methods of producing
and detecting these waves by Lodge, Marconi and
others, they have become available for practical use
in wireless telegraphy.

The work of Maxwell and Hertz for a time shifted
the point of interest in electrical science from the

The Theory electric charges and currents to the
of Ions. dielectric medium. But, in more recent
years, another line of investigation, simultaneously
pursued, has concentrated the thoughts of men of
science once more on the electric charge as a funda-
mental physical entity.

As we have already seen, the passage of electric
currents through solutions of salts and acids produces
chemical changes at the points where the current
enters and leaves the liquid, the salts being there
decomposed chemically into their constituent parts.
To explain these phenomena, and to co-ordinate them
with the other electrical properties of solutions, it is
necessary to suppose that the opposite parts of the
salt move in opposite directions under the action of
the electric forces. Hence Faraday called these
moving particles the " ions " — the travellers — and
his conceptions have been successfully developed to
explain the passage of the electric current as effected
by the conveyance of discrete charges of electricity
by moving atoms or groups of atoms of the dissolved
salt. The motion of the ions may even be made

186 SCIENCE AND THE HUMAN MIND

visible to the eye by watching coloured ions move
through an otherwise colourless liquid, and the
velocities calculated by theory have been thus
verified by experiment.

The ionic theory, framed to explain the conduction
of electricity through liquids, has been adapted also
to the case of gases. But the development of this
subject belongs to a later period, and its consideration
must, for the present, be postponed.

We have now reached what may be taken as the end

of the period in physical science most characteristic

of the nineteenth century. With the

Summary.

unchanging, apparently eternal chemical
atoms, which " bore all the stamp of manufactured
articles," as basis, science had built up a scheme
which pictured a Universe of mechanism all but
understood, and actuated by a limited amount
of energy which could neither be increased nor
diminished. Even the atoms were waiting expect-
antly for someone to find a successful hypothesis
which would explain them away and turn them
into contortions of the all-embracing aether. It
seemed as though the main outlines of physical
knowledge had been laid down once for all, and
that the task of succeeding generations would
be but to fill in those outlines, and carry to yet
greater accuracy the measurements of known physical
constants.

At a later stage of our enquiry we must trace the
revolution in outlook which soon disturbed this
prematurely completed scheme, and the immense
broadening and deepening of the range of known

PHYSICS OF NINETEENTH CENTURY 187

physical phenomena. For the present we must return
and describe how a system of thought, the complement
of that which had come to dominate physics, spread
to the domain of biology, and was accepted as an
adequate explanation of some of the deepest problems
of life.

CHAPTER VI

THE COMING OF EVOLUTION

The Significance of Biology — Embryology — Natural History — Scientific
Exploration — Organic Chemistry — The Physics of Physiology —
Microbes and Disease— Geology — Evolution before Darwin— Darwin
—The Fight for Evolution— The Effects of Evolution.

IN the epoch of science which began with the Re-
naissance, it was astronomy that produced the greatest
The revolution in the thoughts of mankind.
Significance It so happened that when Copernicus de-
of Biology. throned the earth from its proud position

as the centre of the Universe, and Newton brought
the phenomena of the heavens under the sway of the
mechanical laws familiar in everyday life, they also
undermined the evidence on which a whole theory of
Divine revelation had been built up. A complete
change of outlook was thus brought about, although
many years passed by before the full effects were
realized, and, as we must now show, the current con-
ceptions were attacked in a fresh direction before it
was possible to begin the work of reconstruction.

In the great advance which marked the nineteenth
century, it was not the vast development of physical
knowledge, and still less the enormous superstructure

188

THE COMING OF EVOLUTION 189

of industry raised on that knowledge as a basis, which
most effectually widened man's mental horizon and
led to yet one more revolution in his ways of thought.
The point of real interest shifted from astronomy
to geology, and from physics to biology and the pheno-
mena of life. " Life," wrote Robert Hunter, the
great surgeon of the eighteenth century, " is a property
we do not understand. We can only see the necessary
steps leading to it." It was this property that men
now set themselves to examine critically. The neces-
sary steps began gradually to show signs of falling
into order in a scheme of natural knowledge, and
the theory of natural selection, which gave an accept-
able basis for the old and somewhat discredited
idea of evolution, carried the human mind over the
next long stage of its endless journey. Darwin was the
Newton of biology — the central figure of nineteenth-
century thought.

To trace the history and appreciate the significance
of evolutionary philosophy, we must follow the out-
lines of the growth in biological knowledge from the
point where we dropped the threads of its story in a
previous chapter.

One of the principal lines of evidence in favour of
the theory of evolution has come from a comparison
of animals, a branch of enquiry which in
the eighteenth century was in the hands
of travellers and explorers ; but there is another
source of information which has proved no less con-
vincing to the trained scientific mind. The forma-
tive process through which every living thing, animal
or vegetable, passes before it takes up its final and

SCIENCE AND THE HUMAN MIND

specific character has been shown to contain some
record of the much more general and infinitely more
prolonged development of the whole species.

Harvey had put the science of observational em-
bryology on a correct basis in his De Generatione
Animalium in 1651, but the true founder of the
modern development was Caspar Frederick Wolff (1733-
1794), who was born in Berlin, and died at St Peters-
burg, whither he had been summoned by the Empress
Catherine and where he had long occupied a professor-
ship. Wolff's work was neglected and discredited
during his lifetime, but in truth he foreshadowed all
the modern theories of structure. He made a study
of cells, by means of the microscope, and showed the
progressive formation and differentiation of the various
organs in a germ originally homogeneous in character,
thus destroying the previous belief that every organ
made a separate and distinct start.

It is now known that the multiplication and differen-
tiation of cells is a process common to all embryonic
development, and that organic growth proceeds on
identical lines throughout the whole animal creation.
It becomes probable that the development of the higher
animals repeats, within certain limits, the different
stages of the process gone through by creatures who
are lower in the scale of existence. It remained only
for Von Baer, about 1820, to show that the pre-natal
growth of man took place on lines identical with those of
all other animals, and thus to forge one link in the chain
of evidence which binds man to the rest of creation.
It is perhaps difficult for the untrained mind to
appreciate fully the value we must attach to such
discoveries, which provide the most convincing and

THE COMING OF EVOLUTION 191

suggestive evidence to those who are accustomed to
labour in these directions. Yet embryology disclosed,
in the history of each indivdual, facts which were only
to be synthesized with infinite difficulty and after much
opposition, from the whole survey of animals, existing
and extinct, as mapped out by the students of natural
history.

After Buffon had accomplished his great work of
description of the animal world, another Frenchman
Natural took up the subject of classification,
History, which always appeals to the Gallic mind,
and placed it on a clear and definite basis. Georges
Cuvier (1769-1832) was the son of a Protestant officer,
who had migrated from the Jura district into the
region of the Wurtemberg protectorate in consequence
of religious persecutions. He spent the period of
the Revolution and the Reign of Terror studying
peacefully in Normandy, and, at their close, returned
to Paris, where he soon occupied a foremost position
in the College de France. His great claim to distinc-
tion is due to the fact that, first among naturalists,
he compared systematically the structure of existing
mammals, fishes, and molluscs with that shown by the
remains of extinct fossil vertebrates and shells, so
that the past was taken into account, no less than the
present. Cuvier stands on the threshold of the new
age of scientific discovery, and his great book, Regne
animal distribue d'apr&s son organisation, forms a con-
necting link between the work of men who studied
the world and its phenomena as a stationary problem
and those who were impelled to see in it a transitory
stage of the great drama of evolution.

192 SCIENCE AND THE HUMAN MIND

During the second half of the eighteenth century,
the systematic exploration of the world proceeded
Scientific apace, and much of it was undertaken
Exploration. jn a true scientific spirit. Captain James
Cook (1728-1779), born at Marton in Yorkshire, and
present at the capture of Quebec in 1759, had
published work on a solar eclipse in the Philo-
sophical Transactions of the Royal Society, before
he sailed in the Endeavour to observe the transit
of Venus from the South Pacific Ocean. His later
voyages of discovery were conducted with keen
appreciation of their opportunities for the advance-
ment of knowledge, and he was one of the earliest
recipients of the Copley gold medal of the Royal
Society.

In any account of the progress of knowledge during
the period under review, it is not easy to classify the
work of Baron von Humboldt (1769-1859), the dis-
tinguished Prussian naturalist and traveller, who for
a great period of his life found his most congenial
home in Paris. He spent five years in exploring the
continent of South America and the seas and islands
of the Mexican Gulf. It was on observations collected
during this expedition that he laid the foundations
of the claims of physical geography and meteorology
to be considered as accurate sciences. Von Humboldt
was the first to map the earth's surface in lines of
average equal temperature — isothermal lines — by which
he obtained a method of comparing the climates of
different countries. He studied the rate of decrease
of temperature with increase of height above the sea-
level, during his ascents of Chimborazo and other
peaks of the Andes. He considered the origin of

THE COMING OF EVOLUTION 193

tropical storms and atmospheric disturbances ; he
noticed the position of zones of volcanic activity, and
suggested that they corresponded to subterranean
cracks in the earth's surface ; he investigated the
distribution of plants and animals as affected by
physical conditions ; he studied the variations of
intensity of the earth's magnetic force from the poles
to the equator, and invented the term " magnetic
storm " to describe a phenomenon first placed on
record through his labours.

When he settled in Paris in 1808, to put into form
and to publish the results of his explorations, he prob-
ably shared with Napoleon Bonaparte the distinction
of being thought the foremost man in Europe. His
Kosmos, containing the entire fruits of his life's
work, was not produced till the end of his career,
between the years 1850 and 1859. ^n these volumes
von Humboldt endeavoured to give at once an accurate
description and an imaginative conception of the
world as known to our senses. It is impossible to
attain complete success in an undertaking of such
infinite magnitude and daring inception, and doubtless
its abiding value will consist in the fact that it places
on record the aspirations and comprehensive intelli-
gence of a great man.

The interest excited by von Humboldt's labours and
personality gave an impetus to scientific exploration
among the nations of Europe. In 1831 the Beagle
was despatched by Great Britain on her memorable
expedition " to complete the survey of Patagonia and
Tierra del Fuego ; to survey the shores of Chili, Peru,
and some islands in the Pacific ; and to carry a chain
of chronological measurements round the world."

13

194 SCIENCE AND THE HUMAN MIND

The expedition was declared to be " entirely for
scientific purposes," and Charles Darwin sailed on
board as official " Naturalist."

A few years later (1839), Joseph Hooker (1817-1911),
son of the well-known botanist Sir W. J. Hooker,
joined Sir James Ross's Antarctic expedition and spent
three years studying plant life amid the frozen seas ;
proceeding later on to the northern frontiers of
India, on an expedition of which the cost was also
partly defrayed by the Government.

In 1846, T. H. Huxley left England as surgeon in
the Rattlesnake, and spent several years surveying
and charting in Australian waters ; his eager mind
and keen powers of observation chafing at the lack
of opportunity given for accurate scientific observa-
tions of general interest.

Thus three of the men who played a chief part in
revolutionizing the thought of the nineteenth century,
each served an apprenticeship on one of the scientific-
ally planned voyages of exploration.

The culminating point of organized discovery and
research on the grand scale was reached in the despatch
of the Challenger in 1872, to cruise for several
years in the waters of the Atlantic and Pacific, and
to take a long series of records dealing with every
branch of oceanography, meteorology, and natural
history that came under the notice of the explorers.

The chemistry of the complicated substances which

are found in the bodies of plants and animals is chiefly

Organic tne chemistry of the remarkable element

Chemistry, carbon. The atoms of carbon possess
the unique property of combining with each other,

THE COMING OF EVOLUTION 195

as well as with atoms of other elements, to form
very complex molecules. We have seen how Para-
celsus and Stahl carried on the old theory of a distinct
vital principle in opposition to the equally old idea
that in living bodies, as in the outside material world,
mechanism would ultimately explain all happenings.
It was long thought that the specially complicated
substances which are characteristic of animal and
vegetable tissue could be prepared only under the
influence of vital processes, and the belief in a spiritual
interpretation of the phenomenon of life was thought
to stand or fall with the truth of this view. But the
artificial preparation of urea by Friedrich Wohler in
1828 showed that the methods of the laboratory
were capable of creating substances hitherto reserved
for living processes. Other preparations followed,
till in 1887 Fischer and Tafel succeeded in mak-
ing sugar from its elements. The secrets of the
chemistry of the body seemed in a fair way to become
known.

Simultaneously with the extension of chemistry to
cover many vital changes, much advance was made
The Physics m applying physical principles to the
of Physiology, problems of physiology. Harvey ex-
plained the motion of the blood as that of a moving
fluid pumped through the tubes of arteries and veins
by the mechanical action of the heart, and thus
gave a naturalistic turn to physiological enquiry.
But, in the second half of the eighteenth century,
the difficulty of the problem led to the almost
universal adoption of the hypothesis of vitalism, the
force hyperm&canique of the French school, which

196 SCIENCE AND THE HUMAN MIND

held sway till the middle of the nineteenth century.
Then the change of view begun by the synthesis of
urea was reinforced on the physical side by the applica-
tion by Mayer and Helmholtz to the living organism
of the principle of the conservation of energy. All
the manifold activities of the body were thus traced
ultimately to the chemical and thermal energy of the
food taken in, and it was natural, if not strictly logical,
to conclude that, if the total output of energy was
governed by physical laws, the intermediate pro-
cesses could be described completely by those
laws also.

The naturalistic standpoint was further strengthened
by the work of Schleiden and of Schwann, who showed
that all organisms were built up of living cells as
biological units, and by other investigations on similar
lines into cell-structure and cell-function. The know-
ledge of physical phenomena associated with solution,
and especially with the solution of jelly-like sub-
stances or colloids, was rapidly applied to physio-
logical problems, while the phenomena of nerve were
found to have electrical concomitants. It came to be
believed that physiology was but a special case of
" the physics of colloids and the chemistry of the
proteids." And, whatever be the truth about the
whole physiological problem, and the psychological
and metaphysical questions that underlie it, it is
necessary for the increase of knowledge to assume
that, at each step, the process is understandable
by those natural principles which have already
been elucidated, and find their best ultimate state-
ment in the fundamental concepts of physics and
chemistry.

THE COMING OF EVOLUTION 197

One of the most striking developments of nineteenth-
century science, and one which, by increasing our
Microbes and direct control of the environment, has
Disease. na(j a marked influence on our ideas of
the relative positions of man and of " nature," was
the growth in knowledge of the origin and causes of
microbic disease in plants, in animals and in mankind.
About 1838 Schwann discovered that the yeast
present in fermentation consists of minute living
vegetable cells, and that the chemical changes which
go on in the fermenting liquor are due in some way
to the action of the life of these cells. Schwann also
perceived that putrefaction was a similar process, and
showed that it too did not occur if precautions were
taken to destroy by heat all existing living cells in
contact with the substance examined, and to preserve
it thereafter from contact with all air save what had
passed through red-hot tubes. Thus both fermenta-
tion and putrefaction were proved to be due to the
action of living micro-organisms.

These results were extended about 1855 by Louis
Pasteur (1822-1895), who disproved the old idea of
spontaneous generation in any known case, and showed
that the presence of bacteria could always be traced
to the entrance of germs from outside, or the growth
of those already present. Pasteur thus showed that
certain diseases, such as chicken-cholera and the
silk- worm disease, were caused by specific microbes;
and gradually the germs characteristic of other
diseases, many of them prevalent among mankind,
have been discovered and their life-history traced.
Though chronologically much of the results of
Pasteur's discoveries have only been reached in

198 SCIENCE AND THE HUMAN MIND

recent years, it is well to trace the whole story at
this point.

It has been found that, in some cases at all events,
it is the presence of a definite substance in the microbic
cells, or its production by their activity, that causes
the changes associated with their life. Thus in 1897
Biichner discovered the first-known of these active
substances or enzymes in yeast cells, and showed that,
when extracted from them, it could cause the same
fermentation that living yeast cells produce. Ap-
parently the enzyme itself remains unchanged at the
end of the operation ; its mere presence is sufficient
to start and maintain the chemical action.

At the end of the eighteenth century, Jenner had
introduced the process of vaccination, by which in-
oculation with the virus of small-pox, after its atten-
uation into cow-pox by transmission through a calf,
causes partial or complete immunity to the severer
form of the disease. This principle of attenuation
was extended to other diseases by Pasteur, and, in
the case of rabies or hydrophobia, it was shown that
inoculation was generally effectual even after infection.
The mortality from this horrible and previously in-
curable disease was thus reduced to about one per cent,
of the cases treated ; while in England the rigid en-
forcement of a muzzling order for dogs for a short
period, and subsequent quarantine precautions against
the reintroduction of the specific poison from the
Continent, has freed the country from the shadow of
this dread scourge.

The life-history of these pathogenic organisms is
often very complicated, and some of them pass certain
stages of their career in different hosts. Only by

THE COMING OF EVOLUTION 199

most careful experiments, carried out by the inocula-
tion of living animals, can their properties be investi-
gated. The hosts themselves sometimes remain un-
affected by the invading microbe, and this immunity
makes it exceedingly difficult to forecast the direction
in which the source of infection must be sought. The
final conquest of malaria or ague is an excellent ex-
ample of the difficulties and dangers which surround
research in microbic disease. Malaria, as the name
shows, had always been associated with the bad air
of swampy districts and undrained tracts of country.
Many ingenious theories had been constructed and
experiments undertaken, in order to show the connec-
tion between the poisonous gaseous exhalations of
the marshes and the fever that they were assumed to
produce. The most convincing proof of the connection
lay in the fact that those men who undertook to study
the disease in its favourite localities invariably fell
victims to the infection. At last, the possibility of
a secondary dependence only on the swampy nature
of the district occurred to some of the investigators,
and volunteers were found ready to spend the most un-
healthy season of the year among the Italian marshes,
having first provided themselves with wire and gauze
protections against the insect life of the district.
The experiment was successful : it was clear that the
marsh alone was not the primary cause of the disease.
The germ of malaria was discovered by Laveran,
a French army surgeon, about 1880. Five years
later, Italian observers had shown that infection
reached man from the bites of mosquitoes, and in
the years 1894-7 Manson and Ross proved that one
special kind of mosquito (Anopheles] was infested

200 SCIENCE AND THE HUMAN MIND

by parasites that turned out to be malaria germs
in an early stage of development. Thus the correct
method of attacking the ravages of malarial fever
is neither to search for new drugs nor to hunt down
existing mosquitoes, but to drain the marshes and to
take note of all pools of standing water which provide
suitable breeding-places, in order to destroy the larva
by a thin coating of oil or other deterrent.

Similarly Maltese or Mediterranean fever has been
traced to the action of a microbe which passes part of
its life in goats, and is communicated to man by means
of the goats' milk, the goats themselves remaining
meanwhile apparently perfectly healthy. The con-
nection between bubonic plague, rats, and the fleas
or other parasites which help to bring the infection
from the rats to human beings gives another instance
of the indirect methods by which disease can now be
fought with greatest success. By taking precautions
founded on such new investigations, vast tracts of
the earth's surface formerly uninhabitable, or only
habitable at great cost of life and health, have been
made fit for occupation. Of late years our general
knowledge of microbic diseases, knowledge won by
laborious and in some cases dangerous experiments,
has led to ceaseless improvements in sanitation and
preventive medicine on the one hand, and on the
other, by the application of Pasteur's results by Lord
Lister to surgery, has, in conjunction with the dis-
covery of anaesthetics, made possible the wonderful
operations now carried out to relieve human suffering.
The practical results of these discoveries in hygiene,
medicine and surgery are perhaps most clearly shown
in the reduction of the annual death-rate of cities

THE COMING OF EVOLUTION 201

like London from about 80 per thousand two centuries
ago to the present figure of some 15 per thousand.
From the scientific aspect, the great alteration
has been the opening up of a whole new world of
organic life, previously undreamed of, existing in close
contact with, and indeed thriving upon, the animal
world previously believed to represent the sum total
of life on this globe. The principal features of this
discovery were the minute size of the organisms, by
which they have hitherto escaped notice, their in-
calculable numbers, and the rapidity and simplicity
of their reproductive methods, which enable them,
despite their invisibility, to become, when they are
of harmful nature, the most formidable enemies of the
human race.

By his attempt to give a rational theory of the
origin of the solar system, Laplace directed men's
attention to the existence of the problem,
and thus led to a quickened interest in
the study of the earth itself — a study which had
already begun to make some headway. Unfortunately,
the countries in which freedom of thought had most
prevailed against the claims of papal authority were
also those in which the tyranny of the theory of the
verbal inspiration of the Bible had been most firmly
established, and a new contest, in which, however,
the final issue was never doubtful, had therefore
to be waged before any view of the earth's origin,
other than that to be found in the book of Genesis,
could win a general approval. Even in the early
years of the nineteenth century, it was seriously
contended that the fossils had been hidden in the

202 SCIENCE AND THE HUMAN MIND

ground by the Devil, the better to test the faith of
mankind.

Some knowledge of rocks, metals and minerals
had been acquired in the processes of mining at very
early dates ; but, although Leonardo da Vinci and
Bernard Palissy in the fifteenth and sixteenth centuries
had recognized in fossils the remains of animals and
plants, they were generally regarded as lusus naturce,
and the products of a mysterious vis plastica, or a
tendency in nature to produce certain favourite
forms in various ways. The large collections of
James Woodward (1665-1772), which form the basis
of the geological collections of the University of
Cambridge, did much to establish the view that
fossils were really of animal and vegetable origin,
but their use in telling the tale of the earth was
not understood, save by scattered observers like
Nicolaus Stensen (1669), whose ideas gained no general
acceptance. Attempts made to explain how the
earth reached its present state were still forced into
accordance with the Biblical accounts of Creation and
the Deluge, or were based on purely speculative cosmo-
gonies involving cataclysmic origins by water or fire.

The first systematically to contend against these
views was James Hutton (1726-1797), who published
his Theory of the Earth in 1785. Once more a direct
observation of nature and natural processes paved the
way for scientific advance. Hutton, in order to im-
prove the husbandry on his small paternal estate in
Berwickshire, studied farming in Norfolk, and methods
of agriculture in Holland, Belgium and Northern
France. During fourteen years he pondered over the
familiar ditches, pits and river beds, and then, returning

THE COMING OF EVOLUTION 203

to Edinburgh, laid the foundations of the modern
science of geology. Hutton saw that processes able
to produce stratified rocks and to embed fossils there-
in were still going on in sea, river and lake. " No
powers," said Hutton, " are to be employed that
are not natural to the globe, no action to be admitted
of except those of which we know the principle " — a
true precept of science, to avoid the framing of all
unnecessary hypotheses.

Nevertheless, Hutton's " uniformitarian theory "
was not generally accepted till William Smith had
assigned relative ages to rocks by noting their
fossilized contents ; till Georges Cuvier had recon-
structed the extinct mammalia of the district from
fossils and bones found in the Paris area ; till Jean
Baptiste de Lamarck had made a classification and
comparison of recent and fossil shells ; and finally
till Sir Charles Lyell had collected all available evidence
bearing on the manner and extent to which the earth is
still being moulded into new forms by water, volcanoes
and earthquakes, as well as all known facts about
fossils, into his Principles of Geology, first published in
1830-3. The cumulative effect of long-continued pro-
cesses was then fully grasped for the first time ; and the
possibility was realized of tracing the history of the
earth, at any rate throughout its habitable ages, from
the record of the rocks, by inferences based on obser-
vation of operations that were still taking place.

The problem of the age of man is one of special
interest to the human race. The discovery of flint
implements, such as are still in use among primitive
peoples, and of carved pieces of bone and ivory, in
conjunction with the remains of animals that are

204 SCIENCE AND THE HUMAN MIND

now unknown or have long been extinct in Europe,
enabled Lyell in 1863 to place man in a position in
the long series of organic types, and to show that his
existence on the earth must have extended over
periods vastly greater than any contemplated by the
accepted Biblical chronology. The subject is not yet
closed. More recently, remains have come to light
showing that man, as we know him now, was also pre-
ceded by types to which it is hard to give a name or
to classify definitely either among the lower races of
mankind or among the species of the higher anthropoid
apes. The human form apparently has varied and
developed, and is probably still subject to the possi-
bility of change.

The idea of an evolutionary process in nature is
at least as old as the days of the Greek philosophers.

Evolution Heracleitus believed that all things were
before Darwin. m a state of flux — travra pel. Em-
pedocles taught that the development of life was
a gradual process, and that imperfect forms were
slowly replaced by forms more perfect. By the time
of Aristotle, speculation seems to have gone farther,
and to have conceived the idea that the more perfect
type might have developed out of, as well as pre-
ceded, the less perfect. But the atomists, who are
often claimed as evolutionists, seem again to have
contemplated the arising of each species de novo.
Nevertheless, in their belief that only those types
survived which were fitted for the environment, they
touched in spirit the essence of the theory of natural
selection, though their basis of fact was insufficient.
But, in science, it has been truly observed that

THE COMING OF EVOLUTION 205

" being right is no excuse whatever for holding an
opinion which has not been based on any adequate
consideration of the facts involved in it." As in so
many branches of knowledge, the time was not ripe
for the Greeks to do more than formulate the problem,
and make avowedly philosophic guesses at its solution.
Indeed, it needed two thousand years of time, and
the labours of many quiet and unphilosophic physio-
logists and naturalists, before sufficient experimental
and observational evidence could be collected to make
the idea of evolution worth examining by science.
It is a good illustration of the true scientific attitude
of suspension of judgment in face of inconclusive
evidence, that for the most part naturalists left the
idea of evolution to the philosophers, and that, till
Darwin and Wallace published their simultaneous
work, the balance of scientific opinion was clearly
against the theory. On the other hand, the philo-
sophers also played their true part in maintaining
speculation about a theory not ripe for scientific
treatment, in keeping open a question of paramount
importance, and in formulating solutions which, in due
time, might serve as working hypotheses for the men
of science with whom lay the ultimate decision.
Hence it is in the nature of the case that, when, in
the revival of learning, the idea of evolution once
more appears, it is to be found chiefly in the writings
of Bacon, Descartes, Leibniz and Kant, while the men
of science were only slowly working far behind at
facts which eventually would point in the same direc-
tion, through the embryology of Harvey and the
system of classification of Ray. Moreover, some of
these philosophers speculated on the possibility of

206 SCIENCE AND THE HUMAN MIND

quite modern methods in their conceptions of the
present mutability of species and its experimental
examination. On the other hand, it must not be
overlooked that some philosophers who are claimed
as evolutionists — forerunners of Darwin — took evolu-
tion in an ideal, not in a real, sense. Some of Goethe's
views of evolution seem to have been of this nature,
as were those of Schelling and Hegel. To them, the
connection between species lay in the inner ideas which
represented species in the conceptual sphere. " The
metamorphosis/' says Hegel, " can be ascribed only to
the notion as such, because it alone is evolution . . .
it is a clumsy idea ... to regard the transformation
from one natural form and sphere to a higher as an
outward and actual production."

But this ideal outlook of some philosophers does
not destroy the usefulness of the philosophic contribu-
tion to evolutionary theory. It is most interesting
and remarkable that the division of labour and the
difference of outlook between philosophers and natural-
ists was continued up to the very last moment. The
philosopher Herbert Spencer was preaching a full-
grown concrete evolutionist doctrine in the years that
immediately preceded the publication of Darwin's
Origin of Species, while as yet, from the want of
definite evidence, the naturalists would have none of
it. Philosophers were right, and naturalists were
right ; they were each following the law of their
being. The philosophers were dealing with a philo-
sophic problem, one not ripe for scientific examina-
tion. The naturalists were exercising true scientific
restraint in not taking, even as a working hypothesis,
a speculation for which there was little observational

THE COMING OF EVOLUTION 207

or experimental evidence, and no satisfying suggestion
of a mode of operation.

Nevertheless, through the eighteenth century and
increasingly in the first half of the nineteenth, one
naturalist after another ran counter to the prevailing
consensus of scientific opinion, and upheld some form
of evolutionary theory. First Buffon, who oscillated
between the orthodoxy of the Sorbonne and a belief
in " Tenchainement des toes," put forward a theory
of the direct modification of animals by external con-
ditions ; next Erasmus Darwin, poet, naturalist and
philosopher, caught a glimpse of the revelation which
was to be given in its fullness to his grandson, and
taught that, from " the metamorphoses of animals, as
from the tadpole to the frog, . . . the changes produced
by artificial cultivation, as in the breeds of horses, dogs,
and sheep, . . . the changes produced by conditions
of climate and season, . . . the essential unity of
plan in all warm-blooded animals, — we are led to con-
clude that they have been alike produced from a
similar living filament."

But the first connected and logical theory is that
of Lamarck, who sought the cause of evolution in
the cumulative inheritance of modification induced
by the action of the environment. While, pace
Buffon, the effect of change in environment is small
on the structure of the individual, Lamarck held that,
if the necessary changes in habits became constant
and lasting, they would modify old organs, or, by the
need for new organs, call them into being. Thus the
ancestors of the giraffe acquired longer and longer
necks by continually stretching for leaves on trees
just beyond their reach, and the change of structure

208 SCIENCE AND THE HUMAN MIND

thus acquired became developed and intensified by
inheritance. Though no direct evidence of such in-
heritance could be adduced, it gave a reasonable and
consistent working hypothesis for future examination.

The attention drawn to the effect of environment
on the individual, and the extent of the changes which
may rightly be attributed to external circumstances,
has probably had an enormous influence alike on
thought and action. It is difficult to believe that,
where the individual can sometimes be modified
so profoundly, the species will remain unchanged.
Hence, much of the social and philanthropic efforts
of the nineteenth century were built up on the theory
of modification through environment.

Two more evolutionists who maintained the direct
action of the environment on the individual were
litienne Geoffrey Saint-Hilaire and Robert Chambers,
whose anonymous book, Vestiges of Creation, had a
great vogue, and helped to prepare men's minds
for Darwin.

But the man to whom Darwin was solely indebted
for the central idea of his work, the man who, strange
to say, gave the same clue to Wallace also, was the
Rev. Thomas Robert Malthus (1766-1834), at one
time curate of Albury in Surrey. Malthus, an able
economist, lived at the time when the expanding
resources of the country, and its need for men to wage
a war of existence, made possible and required a great
growth of population. In 1798 Malthus published
the first edition of the Essay on Population. In it
he proclaimed that human population always tends
to outrun its means of subsistence, and can only be
kept within bounds by famine, pestilence or war,

THE COMING OF EVOLUTION 209

whereby the redundant individuals are eliminated.
In later editions of the book, he admitted the import-
ance of the prudential check, which then acted chiefly
in the postponement of marriage, and thus, as far as
man is concerned, destroyed his main contention in
its striking simplicity.

Darwin has himself recorded the effect of this work
on his mind. " In October 1838," he says, " I hap-
pened to read for amusement Malthus on Population,
and being well prepared to appreciate the struggle
for existence which everywhere goes on from long-
continued observation of the habits of animals and
plants, it at once struck me that under these circum-
stances favourable variations would tend to be pre-
served, and unfavourable ones to be destroyed. The
result of this would be the formation of new species.
Here then I had a theory by which to work."

The man to whom came this flash of insight was
well fitted both by heredity and environment to make
. full use of it. Charles Robert Darwin
(1809-1882) was the son of a remarkably
able country doctor of ample means, Robert Waring
Darwin of Shrewsbury. His grandfathers were Eras-
mus Darwin, of whom we have already written, and
Josiah Wedgwood, the potter of Etruria, who also was
a man of scientific power and ingenuity. The Wedg-
woods were Staffordshire people, an old family of small
landowners ; but the Darwins, of the same landed class,
came from the Anglo-Danish country of Lincolnshire,
and Charles Darwin's outward share of inheritance
from the Northern race was made manifest by his
tall stature and blue-grey eyes. Educated at Edin-

210 SCIENCE AND THE HUMAN MIND

burgh with the idea of medicine, and at Christ's
College, Cambridge, when he intended to take Holy
Orders, Darwin got his best training as a naturalist
on the five years' voyage of the Beagle in South
American waters. In tropical and subtropical lands,
teeming with life, Darwin received the impression of
the interdependence of all living things, and within
a year of his return he began to compile the first of
his note-books on the facts bearing on the transmuta-
tion of species, led thereto by his study of South Ameri-
can fossils. Fifteen months later he read Malthus'
book, and found the clue which enabled him to frame
a theory of the means whereby new species might
develop.

The individuals of a race differ from each other in
innate qualities. If the pressure of existence or the
competition for mates be great, any quality which
is of use in the struggle for life or mate has " survival
value," and gives its possessor an advantage which
carries with it an improved chance of prolonging life,
or of securing a mate and of rearing successfully a pre-
ponderating number of offspring to inherit the favour-
able variation. That particular quality therefore tends
to spread throughout the race by the progressive
elimination of those individuals who do not possess it.
The race is modified, and a different and permanent
variety may slowly be established. This was the
new conception ; and it was well put by Thomas Henry
Huxley, who by his power of exposition, skill in
dialectic and courage in controversy did more than
any other man to compel general acceptance for the
views of Darwin and Wallace : — " The suggestion that
new species may result from the selective action of

THE COMING OF EVOLUTION 211

external conditions upon the variations from the
specific type which individuals present — and which
we call * spontaneous ' because we are ignorant of
their causation — -is as wholly unknown to the historian
of scientific ideas as it was to biological specialists
before 1858. But that suggestion is the central idea
of the Origin of Species and contains the quint-
essence of Darwinism."

With this idea as a working hypothesis, Darwin
spent twenty years collecting facts and making ex-
periments. He read books of travel and treatises on
sport, natural history, horticulture, and the breeding
of domesticated animals. He carried out experiments
on the crossing of tame pigeons ; he studied the trans-
port of seeds, and the geological and geographical
distribution of plants and animals. In the assimila-
tion of facts, in appreciating their bearing on all the
complicated questions which arose, and in marshalling
them at the last, Darwin showed himself supreme.
His transparent honesty, burning love of truth, and
calm and even balance of mind, form a model of the
ideal naturalist. Fertile in hypotheses as a guide to
work, he never let a preconceived view blind him to
facts. " I have steadily endeavoured," he writes, " to
keep my mind free so as to give up any hypothesis,
however much beloved (and T cannot resist forming
one on every subject), as soon as facts are shown to be
opposed to it."

By 1844 Darwin had convinced himself that species
were not immutable, but still he worked on year after
year to gain yet surer evidence. In 1856 Lyell urged
him to publish the results of his researches ; Darwin,
not satisfied with their completeness, delayed. On June

212 SCIENCE AND THE HUMAN MIND

i8th, 1858, he received from Alfred Russel Wallace a
paper, written in Ternate in the space of three days
after reading Malthus' book. In this paper Darwin at
once recognized his own theory set forth in its essence.
Unwilling to seize the priority of twenty years, which
was rightly his but might destroy the interest of
Wallace's contribution, Darwin placed himself in the
hands of Lyell and Hooker, who arranged with the
Linnaean Society to communicate on July ist, 1858,
Wallace's paper together with a letter from Darwin
to Asa Gray dated 1857, and an abstract of his
theory written in 1844.

Darwin then set to work and wrote out in condensed
form the results of his labours of twenty years, and on
November 24th, 1859, this book was published under
the name of The Origin of Species.

We have already traced the various converging
streams of thought — cosmological, anatomical, geo-

The Fight logical and philosophic, which, blocked by
for Evolution, the evidence in favour of the fixity of
species, were yet collecting deeper and ever deeper
behind it. Darwin's great contribution to know-
ledge, driven forward by the quickening force of the
conception of natural selection, broke the barrier
with irresistible power, and set loose the fertilizing
torrent over all the realms of science and of human
thought.

At first the stream seemed to many people a devas-
tating flood, obscuring without reason the whole out-
look of the human race ; but we should not condemn
without consideration the attitude of those to whom
the new knowledge appeared impious and distasteful.

THE COMING OF EVOLUTION . 213

Now that the conception of evolution has become
general property, it is difficult to realize how very
limited were the numbers of men who were in a position
really to judge of the value of the evidence laid before
them, evidence that depended on the detailed examina-
tion of living creatures and fossil remains, forms un-
familiar and for the greater part unknown to those who
felt compelled either to deny the validity of the conclu-
sion or to give up beliefs which had sustained long
generations of their forefathers. Before we condemn
them, let us ask ourselves honestly whether, in ignorance
of the intermediate stages, it is more obvious to postu-
late a common ancestor or a separate creation for the
frog and the peacock, the salmon and the humming-
bird, the elephant and the mouse ; or, to go back to
an earlier stage in the evolution of knowledge, let us
make a list of the number of persons in the circle of
our acquaintance who could immediately offer con-
vincing evidence of the three-century-old heliocentric
theory of the Universe.

And even to some naturalists the new ideas were re-
pugnant. Owen, the great anatomist, wrote a strongly
adverse criticism in the Edinburgh Review, and most
systematists agreed with his opinion. But Hooker
gave in his adhesion at once, and was immediately
followed by Huxley, Asa Gray, Lubbock and W. B.
Carpenter, while Lyell announced his conversion at
the Royal Society Dinner in the autumn of 1864.

From the first, Huxley was the protagonist of this
band of evolutionists — " Darwin's bulldog," as he
called himself. With magnificent courage, ability,
and clearness of exposition, he bore the chief brunt
of the attack made from all sides on Darwin's book,

214 SCIENCE AND THE HUMAN MIND

and again and again led successful counter-attacks
on his discomfited foes.

Thomas Henry Huxley was born at Ealing in 1825,
the seventh son of an assistant schoolmaster ; but
his parents came from families located at Coventry
and on the Welsh Marches, and Huxley himself had
the true fighting temperament of a border race.
Huxley tells us that, to the men of science of that
generation, the publication of the Origin of Species had
the effect upon them of a flash of light in the darkness.
" We wanted," he writes, " not to pin our faith to
that or any other speculation, but to get hold of clear
and definite conceptions which could be brought face
to face with facts and have their validity tested. The
Origin provided us with the working hypothesis
we sought. Moreover, it did the immense service
of freeing us for ever from the dilemma — Refuse to
accept the creation hypothesis, and what have you
to propose that can be accepted by any cautious
reasoner ? In 1857 I had no answer ready, and I
do not think that anyone else had. A year later we
reproached ourselves with dulness for being perplexed
with such an enquiry. My reflection, when I first made
myself master of the central idea of the Origin, was,
* How extremely stupid not to have thought of that ! '

The famous scene between Bishop Wilberforce and
Huxley at the Oxford meeting of the British Associa-
tion in 1860 has often been described. Wilberforce
had obtained a first-class in the Oxford Mathematical
Schools in his youth, and therefore, being regarded by
his University as a master of all branches of natural
knowledge, had been selected to uphold the cause
of orthodoxy. The Bishop endeavoured to kill the

THE COMING OF EVOLUTION 215

notion of evolution with ridicule and sarcasm —
ridicule for Darwin and his labours, sarcasm for Huxley
and his courage. It seems strange now to think that
a majority of the hearers were probably on the side of
the Bishop, and were totally unable, from preconceived
ideas, to weigh the value of the facts laid before them
on behalf of Darwin's theory, or to appreciate the
embryological evidence for evolution on which Sir
John Lubbock, now Lord Avebury, insisted.

It would be a mistake to think that the evidence
offered in favour of some form of evolution through
natural selection was considered conclusive, even by
Huxley himself. Two years after the Oxford meeting,
Huxley wrote to Sir Charles Lyell : —

" If Darwin is right about natural selection — the
discovery of this vera causa sets him to my mind in a
different region altogether from all his predecessors —
I should no more call his doctrine a modification of
Lamarck's than I should call the Newtonian theory
of the celestial motions a modification of the Ptolemaic
system. Ptolemy imagined a mode of explaining those
motions. Newton proved their necessity from the
laws and a force demonstrably in operation. If he
is only right Darwin will, I think, take his place with
such men as Harvey, and even if he is wrong his
sobriety and accuracy of thought will put him on a
far different level from Lamarck."

At one point in the controversy, much had been
held to depend on certain supposed differences of
structure in the human brain as compared with that
of the anthropoid apes. Huxley set to work to throw
light on the matter, " skull-measuring all day at the
College of Surgeons." As the result of this study he

216 SCIENCE AND THE HUMAN MIND

extended his field of observation, and helped to create
the modern science of ethnology, of which we shall
have occasion to speak on a later page. Of Huxley's
work in this direction, Professor Virchow, who led
the Continental ethnologists, said in 1898 that it was
sufficient to secure immortal reverence for his name.

In attempting to estimate the influence of the
establishment of the theory of evolution on philo-

The Effects sophic thought and on the general opinions
of Evolution. of mankind, we are faced by the diffi-
culty that we are still in the period which is under
the domination of evolutionary ideas as a new force
in the realm of knowledge. We are still testing evolu-
tion, natural selection and all the kindred conceptions
they have called into being as guides for our footsteps
in science, philosophy, sociology and religion. Hither-
to, the main concepts have stood the ordeal well,
and the modifications which experience has sug-
gested have been in matters of detail. But we are
still too near the date of the publication of the Origin
of Species to see the whole of its consequences in true
and just proportion. Nevertheless, certain conclu-
sions stand out clearly, and may be stated with some
approach to confidence.

As the history of thought moves on, the mechanical
and spiritual theories of the Universe alternate with
each other in recurring pulsations which are as neces-
sary to a healthy growth of knowledge as the alternate
diastole and systole of the heart are to the well-being
of the body. With each great advance in scientific
knowledge, with each subjection of a new kingdom
to the rule of natural law (as the process comes to be

THE COMING OF EVOLUTION 217

regarded) , the human mind, by an inevitable exaggera-
tion of the power of the new method, tends to think
that it is on the point of reaching a complete mechanical
explanation of the Universe. The Greek atomists
made a guess at the structure of matter which chances
to concord with modern views, though their evidence
for it from the scientific point of view was most
exiguous. Not content with applying their theory
to the inorganic world, they framed accounts and
explanations of life and its phenomena on the idea
of a " fortuitous concourse of atoms," all unconscious
of the vast complexity of inorganic nature, and the
still vaster world of new phenomena which had to be
explored before the problem of life, for which they
gave a confident solution, could even be approached.
Yet the atomists did good work, and did it under
the inspiration of a wave of materialistic philosophy.
But the insufficiency of their conceptions was recog-
nized by Plato and Aristotle, and, for equally transient
reasons, an idealistic spiritualism returned.

The faith of the Middle Ages, where it depended
on the exercise of the human reason, was constructed
from argument based on doubtful premisses, and
fortified by a theory of divine providence adapted
to an undeveloped science. Hence, when the growth
of knowledge began afresh with the Renaissance, the
natural oscillations of opinion were increased. Each
step in advance was feared as an offence against
orthodoxy, and its leader was denounced as an
impious heretic.

But here again we must not condemn the conserva-
tors of ancient creeds without some thought. They
had inherited a scheme of religion and philosophy,

2i8 SCIENCE AND THE HUMAN MIND

complete in itself, which satisfied the majority of their
followers, and was in accord with nature, as appearing
in their daily life. The new facts brought to light
in the upheaval of the Renaissance, although they put
out of gear several minor parts of the great mediaeval
scheme of salvation, were not sufficient of themselves
to justify or to permit the reconstruction of a whole
new consistent model of theological opinion and re-
ligious practice. The mass of mankind require
emphatic warrant for their beliefs, and cannot be
reconciled to the twilight of faith in which greater
minds can soberly acquiesce. It may be perfectly true
that there is sometimes more faith in honest doubt than
in the majority of oft-repeated creeds ; but this is not a
proposition of general application, as the great Lincoln-
shire poet and mystic — another typical Anglo-Dane —
well knew. Therefore those people may have been
well advised who tried blindly to maintain the ancient
beliefs until a time came when it should be possible
to put something more satisfying than mere negation
in their place.

The triumph of Copernicus, the success of Newton
in interpreting the phenomena of the heavens, led up
to the overestimate of the power of their methods
by the French Encyclopaedists, who at once conceived
a mind competent to calculate the whole of the future
history of the world from a knowledge of the initial
configuration and velocities of the masses. At each
step made, this joyful overestimate of the possi-
bilities of mechanism becomes a marked feature of
contemporary thought. As each piece of knowledge
becomes assimilated, it is seen that old problems are
in their essence unaltered ; the poet, the seer and the

THE COMING OF EVOLUTION 219

mystic again come to their own, and, in new language,
and from a higher ground of vantage, proclaim their
message to mankind.

Now, speaking broadly, this recurrent phenomenon
of a wave of mechanical philosophy was the first main
result of Darwin's success. Quite legitimately and
without exaggeration, the establishment of the prin-
ciple of evolution strengthened greatly the feeling of
continuity in nature, and gave new confidence to those
who based their view of life on scientific ground. It
was the complement on the biological side of the
contemporary tendencies in physics we have traced
in the last chapter — tendencies which pointed to a
complete account of the inorganic world in terms of
eternal, unchanging matter, and a limited and strictly
constant amount of energy. These conceptions seemed
to destroy the need for an overseeing Providence
or for any act of creation, or at the least implied
that the Author might well be supposed to have
turned away, and left the great machine to spin on
unheeded, unwatched, down the ringing grooves of
change. The application to living beings of the
principle of the conservation of energy, led to the
exaggerated belief that all the various activities,
physical, biological and psychological, of the existing
organism would soon be explained as mere modes of
motion of molecules, and manifestations of mechani-
cal or chemical energy. The acceptance of the theory
of evolution produced the illusion that an insight into
the method by which the result had been obtained
had given a complete solution of the problem, and
that a knowledge of his origin and history had laid
bare the construction of the inward spirit of man as

220 SCIENCE AND THE HUMAN MIND

well as of the human organism regarded from without.
Now whether a complete knowledge even of the out-
ward problem, based on mechanical principles, will
ever be reached it is impossible to say. But it is
quite certain that as yet it has not been attained, and
will not be attained till many more alternations
towards and away from mechanical philosophy have
passed like waves over the human mind. Indeed, we
are already moving out of the particular wave induced
by the coalescence of nineteenth-century physics and
the coming of evolution. The present tendency is on
the whole away from thorough-going materialistic or
even mechanical views. Our opinions as to whether
this tendency is in the direction of final truth, or
whether it is but a passing eddy on the broad current
of thought which, with temporary set-backs, moves
for ever onwards, will depend on the inborn qualities
and predispositions of our minds, as modified by
education and environment. Moreover, it must be
remembered that the type of mind to be satisfied
may alter. The mystic of the Northern race will
never rest content with a mechanical universe if it
be held to regulate inward consciousness as well as
outward phenomena. Minds which rely on law and
form will require some ordered and comprehensive
scheme to satisfy their mental outlook. But whatever
be the outcome, it must be admitted that the pro-
blem is too vast to be solved in any finite time. The
very principle of evolution itself requires us to look
forward to an ever-changing stream of thought, which
will develop from age to age, while past experience
goes to show that the development will be not steady
and secure, but intermittent and oscillatory.

THE COMING OF EVOLUTION 221

In one sense, the acceptance of the theory of natural
selection is the completion of the philosophic work
The Experi- begun and mapped out by Francis Bacon,
mentsof Nature.Bacon taught that the method of empirical
experiment was the sole road to natural knowledge
for mankind. Darwin showed that Nature herself
uses the method of empirical experiment, both in the
animal and vegetable worlds. She tries all possible
variations, and, out of countless trials, a few succeed
in establishing that new and greater harmony between
the being and its environment from which evolution
proceeds.

If accepted in its fullest sense, natural selection is
the negation of all teleology. There is no end in view :
merely a constant haphazard change both of indivi-
duals and of environment, and sometimes a chance
agreement between them, which, for a brief moment,
may give some appearance of finality.

Herbert Spencer's phrase for natural selection,
" the survival of the fittest/' standing alone, begs the
question. What is the fittest ? The answer is : "The
fittest is that which best fits the existing environ-
ment." It may be a higher type than that which
preceded it, but it may be a lower. Evolution by
natural selection may lead to advancement, but it may
lead to degeneration. As Mr Balfour has pointed out,
on the full selectivist philosophy the only proof of
fitness is survival : — that which is fit survives, and that
which survives is fit. We may seek to break away
from the circle by declaring that, on the whole,
evolution has produced a rise in type, that man is
higher than his simian ancestors. But then we take
on us to pronounce on what is higher and what is

222 SCIENCE AND THE HUMAN MIND

lower, and the thoroughgoing selectionist may reply
that our judgment is itself formed by natural selection,
and thereby is framed to appreciate and rate as higher
that which, in reality, merely has survival value —
that which, in fact, has permitted us to exist. From
the purely naturalistic standpoint, there seems no
escape. We have to accept an absolute judgment
by some other standard of what is high and low,
good and evil, if we seek another outlook.

Indeed, it may be pointed out that the order in
which we place creation is largely a matter of race
and racial religion. To the oriental Buddhist, exist-
ence is an evil, consciousness a greater evil. To him,
then, logically, the highest form of life is a simple cell
of protoplasm in the tranquil depths of the ocean's
bed, and all the evolution of the ages is in truth
downward from that calm ideal, which is itself a fall
from the inorganic matter that probably preceded it.

Of all the sciences regenerated by Darwin, none
gained more benefit than anthropology, the com-
parative study of mankind. Indeed, it
Y' is hardly too much to say that modern
anthropology took its rise from the Origin of Species.
Huxley's study of human skulls was the beginning
of that exact measurement of physical characters on
which so much of the science now depends, and the
ideas of natural selection and evolution underlie all
succeeding work.

Yet the ground had been prepared for anthropology
also. The same love of novelty, the same eager
curiosity, the same acquisitive collector's instinct,
which introduced the plants and animals of other

THE COMING OF EVOLUTION 223

climes into the European gardens and museums,
brought back the artistic and industrial products of
other people and the ceremonial objects of other
religions, in all stages of development. First as a
source of wonder and interest, then as a matter for
commiseration and missionary enterprise, and finally
as objects of admiration, study, and investigation, we
of the West have come into contact with older civiliza-
tions than our own — older in origins, older and far
anterior to our own in the sequence of the ages.

The ingenious diplomatist who enriched our British
Museum with the sculptures of the Parthenon, the
men who first brought back from Asia Minor and
Babylonia the spoils of earlier ancient empires, were
not anthropologists in our present sense of the word.
They were true treasure-seekers — pirates and buc-
caneers of the Northern art world — at best, bent on
confirming, for their own satisfaction, the most striking
passages of the classical historians who ruled in the
schools of the period. The plunder of their Eastern
voyages was deposited in the capitals of Western
Europe ; trophies of the chase, which have taught
us that art is but one aspect of the development of the
human mind — as a record, incomplete in itself — and
that history is but the detailed account of human
evolution, as its progress appears to the subjects of
the experiment. Thus, when the anthropologists
were ready to take the field, much of the necessary
material was at hand, already familiar, or partially
classified, awaiting only the new gift of reinterpreta-
tion to give up another aspect of its inward meaning.

As an example of modern methods and results we
may take the analysis of the population of Europe,

224 SCIENCE AND THE HUMAN MIND

to which reference has already been made. Con-
sidered physically, European people differ chiefly in
three characters : — stature, coloration, and skull-
shape. On the average of large numbers, moving
northward, until we approach the arctic region, the
stature becomes greater and the colouring fairer,
while, the farther to the south we go, the shorter and
darker becomes the population. In the intermediate
Alpine region, stature and colouring are intermediate
also. But the head shape tells a different tale.
While both north and south folk are long-skulled,
the people of the hills are broader skulled than
either of the others.

To explain these facts we have to suppose three
primary races — a tall fair race, found in its greatest
purity round the shores of the Baltic, a short dark
race stationed about the Mediterranean coasts and up
the Atlantic seaboard, both with long skulls, and a
broad-headed race, intermediate in colour and stature,
inhabiting the mountainous regions of Central Europe.
We have already pointed out that the history of Europe
is the story of the interaction of these three races.

Similar methods of investigation, using often other
characters such as the texture of the hair, have been
applied to the physical anthropology of other con-
tinents, where more primitive folk are to be found.

The Origin of Species raised anew the great question
of the origin of the human race. It was treated in
detail in 1863 by Huxley in his book, Man's Place in
Nature, and by Darwin himself in 1871 in a work
named The Descent of Man.

It is a curious psychological fact that, whether in
studying family history or in speculating about the

THE COMING OF EVOLUTION 225

origin of the human race, man prefers to believe that
he has fallen from the state of ancestors better than
himself rather than that he has risen in the social or
racial scale. This touching faith in the efficacy of
heredity as opposed to the merits of education,
environment, and personal endeavour appears to be
ingrained in our constitutions. Like other such
prepossessions, it has probably some survival value,
and should be treated with more respect than it often
encounters. Hence new men may be forgiven when
they provide themselves, if Nature and the College of
Arms have omitted to do so, with noble forebears,
and primitive races when they postulate a direct
descent from the gods, or, if somewhat more modest,
ask only a specific divine act of creation to have been
exercised in their favour. And civilised man, con-
fronted with the choice between the Book of Genesis
and the Origin of Species, at first naturally proclaimed
with Disraeli that he was " on the side of the angels."
Yet the evidence of man's affinity with animals
was overwhelming, and soon prevailed within the
limited circle where rational discussion was possible.
His body contains the same tissues built into the same
organs. He bears numerous vestiges of structures
useless to him, but advantageous to his lowly ancestors.
Many of his emotions and mental processes are evident
in less developed states in the minds of animals. His
origin is explicable by natural and sexual selection
from hypothetical forms more ape-like than himself.
His very weakness and defencelessness against the
wild beasts, his earliest foes, may be held to explain
his social instincts, the origin of moral qualities, for
by them alone could he learn to combine for defence,

15

226 SCIENCE AND THE HUMAN MIND

and to develop speech and those mechanical arts
whereby he obtained homes and tools and weapons.

Since the days of Darwin, discoveries have been
made whereby the existence of modern races has been
pushed back into more remote times than were
formerly thought conceivable. We know that twenty-
five thousand years ago the cave-men artists were
decorating their walls with spirited likenesses of the
bison and wild boar. At Neanderthal in 1856, and
at Spy in 1886, still older remains have come to light,
showing the existence of more primitive forms of man ;
and in 1893 bones were discovered in Java which
most authorities hold to be those of a being inter-
mediate in structure between the anthropoid apes and
the earliest known forms of men.

Whether man descends from any existing form of
ape is uncertain. But if not a lineal descendant, he
is at least a distant cousin. More variable forms may
have preceded all those now extant, and have been
their common ancestors. The separate shoots that
rise above the visible plain of history may spring
from a common root-system, buried in the dark ground
of the irrecoverable past.

As Copernicus removed the earth from its position
at the centre of the Universe, so Darwin took man from
his cold pedestal of isolation as a fallen angel, and
forced him to recognize his kith and kin in St Francis's
little brothers, the birds. As Newton proved that
terrestrial forces hold sway in the heights of heaven
and the depths of space, so Darwin showed that the
familiar variation and selection by which man moulds
his flocks and herds may explain the development
of species and the origin of man himself. Organic

THE COMING OF EVOLUTION 227

nature, like physical nature, became one problem.
Creation, if never to be understood, at least is
something to be investigated by methods we can
understand — a new and mighty revelation to the
human mind.

Evolutionary philosophy has modified profoundly
our conceptions of human society. In a word, it has \*
History destroyed for ever the idea of finality.

Politics, and Never again shall we set forth to build
'cio ogy. doud-cuckoo-boroughs between heaven
and earth, nor sail across the seas to found a new
Utopia with More, or a Pittsburg, Pa., with the
Pilgrim Fathers. The legitimist Tory, with his un-
changing, divinely ordered State, and the philosophic
Radical with his ideal Republic only delayed by Tory
stupidity and cupidity, become equally obsolete.
They go, with the hansom cab in which they drove,
to South Kensington Museum. Political institutions,
no less than living beings, must fit their environment.
Both are subject to variation, and, for social health,
must develop pari passu. Institutions successful in
one racial environment may fail lamentably in another.
Even Liberals are coming to learn that represen-
tative government on the British model may not be
applicable to every nation. The Hottentot may be
right in preferring the clear evening fire that awaits
him in his primeval kraal to tea on the terrace of
the House of Commons at Westminster.

A similar change is passing over economics. The
formal political economy of the earlier days of the
science sought for a state of society, eternal, universal,
valid for all times, in all places, for all peoples. The

228 SCIENCE AND THE HUMAN MIND

economist desired to emulate, without understanding,
the discoveries of Newton. His view, analogous to
the immutability of species of the older zoology, was
undermined by the historical school, which, in many
directions, has shown that economic laws are only
valid in suitable circumstances, and that their appli-
cation changes with the ever- varying environment.

But, as in biology, the changes in political institu-
tions and in economic conditions are alike slow. We
cannot take short cuts to the next stage by means of
a surgical operation ; nor indeed do we know where
the next stage will lead us. Survivals of past times
are found side by side with rudimentary forms ready
for new growth. As morphology discloses in the
animal body vestiges of organs useful in past phases
of organic evolution, so the study of social institutions
shows traces of the older stages through which they
have passed. From these traces, rightly interpreted,
their history and origin may ofttimes be inferred. And
from a knowledge of history and origin light is cast
on present meaning and true significance. Such books
as Tylor's Primitive Culture and Frazer's Golden Bough
show how the concepts of evolution illumine the study
of sociology.

If man has been brought into being by the same pro-
cesses of evolution as the animal races, he must be sub-
ject still to the same variation and selection. Darwin's
cousin, Francis Galton, working on this idea, traced the
inheritance of physical and mental qualities in mankind,
and showed that, to secure the continued progress of
the race in the direction that civilized men have agreed
to consider upward, even to prevent its deterioration,
it was necessary that selection should continue.

THE COMING OF EVOLUTION 229

In civilized states, it is probable that the most
effective selective agent is disease. Those specially
liable to any particular weakness tend to die early
and leave no offspring. Thus, the hereditary predis-
position to the complaint is bred out of the race.

But, in order that natural selection should be
effective, it is necessary that successful survival
should be accompanied by preponderating repro-
duction. From the point of view of the race, it is
of no use for the higher types of men to survive if
they do not leave children to inherit their qualities.
Hence the power of voluntarily restricting the birth-
rate, which has become a marked feature of European
civilization since 1876, has modified fundamentally
the biological problems of sociology. The thrifty and
far-seeing in all ranks of life now tend to restrict closely
the number of their children. Their average family
has sunk from over six to about three, and shows
signs of further diminution. On the other hand, the
careless and improvident, and, still more ominous,
the mentally weak, still breed at nearly their old
natural rate ; while, owing to the advance of modern
scientific hygiene, they have a greatly diminished
death-rate, and rear a high proportion of decadent
citizens. The good hereditary qualities of the race are
threatened with decay. It is probable that nothing
short of the religious motive, which is certainly
effective among many Jews and Roman Catholics,
will suffice to reverse these tendencies of the better
stocks. In this way, religion would acquire once more
an effective survival value.

When we pass to the bearing of Darwin's work on
theories of politics, no consensus of opinion has been

230 SCIENCE AND THE HUMAN MIND

reached. The principle of the survival of the fittest
has been used to revivify aristocratic ideas by Vacher
de Lapouge, Bourget, Ammon, and Nietzsche. But,
on the other hand, it has been urged that evil qualities
may have an advantage in present conditions ; that
a secure aristocratic position removes competition and
therefore selection ; that " equality of opportunity "
is of the essence of Darwinian progress. Moreover,
socialists point to the societies formed by animals
for mutual aid and their great " survival value,"
finding in the lives of the bee and the ant arguments
for a communistic order of society, and possibly, also,
for a finality of development, which might end by
becoming stationary, could such a system of control
become universal. The bee world has shown no sign
of progress during the two thousand years that it has
been under observation. It is rigid, utilitarian, self-
sufficing — a model for communal life, when human
desire and individual initiative have been bred out of
the race. In truth, the application of the principle of
natural selection to sociology is so complex a problem
that almost any school of thought can draw illustra-
tions from an endless series of examples, choosing
them at will, and may thus obtain valid arguments
for their special tenets from the Origin of Species.

If the influence of the work of Darwin and his
successors on sociology has been great, no less pro-
found has been its effect on religious
Religion. thought The destruction of the crude

dogma of separate specific acts of creation, though
the most immediately obvious, was but the most
superficial of its results.

THE COMING OF EVOLUTION 231

The principle of natural selection weakened im-
measurably the old " argument from design " of the
Christian apologists. Adaptation of means to ends in
plants and animals received a naturalistic interpreta-
tion, which, if not complete in the deepest recesses of the
problem, went far towards solving it. It was thought
to be no longer necessary to invoke an intelligent and
beneficent Artificer to explain the details of bodily
structure or the protective markings on a butterfly's
wing. The need for a Supreme Being, Jehovah, Jove,
or Lord, was driven further back, inward, into the heart
of man.

But the destruction of untenable positions was not
the only service rendered to an unwilling theology by
the revelation of evolution. Forced to reconsider its
premisses, it created the new spirit of reverent enquiry,
of co-operative thought, of receptive attention. The
Metaphysical Society was founded in 1869 by James
Knowles, afterwards editor of the Nineteenth Century,
with the encouragement of Alfred Tennyson. The
meetings brought together such men as Archbishop
Thompson, Bishop Ellicott and Dean Stanley, Car-
dinal Manning and W. S. Ward, W. E. Gladstone,
Lord Selborne, Henry Sidgwick, James Martineau,
Frederic Harrison, Lubbock, Huxley, Tyndall, Andrew
Clark, John Morley and Leslie Stephen ; while Tenny-
son, Ruskin and many other distinguished men were
present at the discussions. The personal relations
between members of the society made wilful mis-
understanding and ill-feeling impossible, and thus
created an opportunity for distinguishing between the
essential and unessential differences in the issues at
stake, and for initiating a change of attitude in the

232 SCIENCE AND THE HUMAN MIND

leaders of religious thought in accordance with the
sudden expansion in the domain of natural know-
ledge. In place of the theory of a rigid and
complete body of doctrine, delivered once for all
to the Saints — a theory constantly liable to dis-
location from the shocks of historical discovery —
we gain the conception of an evolution of religious
ideas, of revelation if we will, marked by supreme
outpourings at certain times, but never ceasing to
interpret the Will of God to mankind. The gift
of prophecy is restored to us. We are driven back
to that observational method in religion which has
proved so necessary in science, to the study and
recognition of the validity of individual religious
experience, to the mystical standpoint, which once
again proves a sure rock of defence.

Finally, we are led to the careful consideration of
religious origins, to the reverent examination of those
primitive religions through which the " heathen in
his blindness " teaches civilized man the psychological
meaning of his own ritual and his own creeds, and to
the exploration of the unknown, transcendental and
subliminal manifestation of the human mind — of
which traces are to be found in nearly all societies,
religions and races. But the outcome of these re-
searches belongs to a later phase of human thought,
and will be dealt with in the next chapter.

CHAPTER VII

THE LATEST STAGE

The New Dispensation — The Expansion of Physical Science— Corpuscles
and Electrons — Radio-activity — The Individual Atom— The Lumini-
ferous ^Ether— The Principle of Relativity — Mendel and the Laws
of Inheritance — Neo-vitalism — Modern Psychology — Comparative
Religion — The Theory of Scientific Knowledge — Science and Philo-
sophy— Science and the Human Mind.

THE last two chapters have described the character-
istics of the science of the nineteenth century, and their

The New bearing on the eternal problems that face
Dispensation, the human mind. We have seen how
the physical concept of everlasting unchanging atoms,
placed in a Universe containing a definite and limited
amount of energy, was pointing anew to the old
theory of a rigid determinism, described by mechanical
laws and leading to a hard, materialistic philosophy.
This tendency was increased and completed by the
application of the principle of the conservation of
energy to the functions of living beings, and by the
theory of natural selection, which undermined theo-
logical ideas then current and gave to evolution a
method of action independent of teleological influence.

We have now to trace the modification of the
attitude of mind induced by nineteenth-century
science. We must describe the widening of mental

233

234 SCIENCE AND THE HUMAN MIND

horizon caused by recent physical discoveries, and
note the gradual recognition that, however successfully
the mechanism of physiological processes may be
described in physical or chemical terms, and however
clearly the story of organic evolution may be pictured
by natural selection, the fundamental problems
which underlie the mysteries of consciousness and
of the existence of the Universe remain unsolved if
not unaffected.

Matter is more complex than was thought. The
atom has been resolved into units of electricity, and
shattered into a thousand fragments. Energy,
though constant in amount, continually becomes less
available in all physical conditions known to us ; but
those conditions may be far from exhausting the
possibilities of creation. Darwin and Mendel have
thrown light on the methods of evolution and the laws
of inheritance, but the confident anticipations of some
of Darwin's early followers that the wonders of creation
were in a fair way to cease to be wonderful, have
passed away. A naturalistic explanation of external
Nature may be a little less remote, but the secret of
the inner consciousness of man remains untouched.

Till the year 1895, it seemed that the main lines of
physics, laid down during the middle of the nine-
The Expansion teentn century, had settled the limits, as

of Physical well as the foundations, of the sciences of
ce' matter and energy. There seemed little
left to do but to fill in the details of the scheme.
But at that date a new series of phenomena began
to come to light and soon revolutionized the whole
outlook.

THE LATEST STAGE 235

The passage of an electric discharge through rare-
fied gases had been studied by Crookes, J. J. Thomson
and others for many years, and the theory of electric
ions, framed, as we have seen, to explain the conduc-
tion of electricity through liquids, had been adapted
to this case also. But in 1895 W. Rontgen of Munich
discovered accidentally that photographic plates stand-
ing in the neighbourhood of an electric discharge tube
were affected though covered with an opaque screen,
and thus revealed the rays associated with his name.

When an electric discharge is passed between two
wires in a gas which has been very highly rarefied,
Corpuscles straight rays are found to proceed from
and Electrons. j-ne negatively electrified wire or cathode,
and to produce Rontgen rays when they strike solid
objects. These straight cathode rays have been
studied closely, especially by Sir Joseph John Thom-
son and his pupils. Thomson has also more recently
examined the positive rays which, also in straight
paths, proceed from the positive wire or anode. By
making these rays pass through intense fields of
magnetic and electric force, they may be deflected
from their straight course, and, from the deflection
caused by known forces, their velocity and their mass
can be calculated. They are found to consist of flights
of isolated atoms, and the experiments give an accurate
means of measuring the atomic weight.

By similar methods, the negative or cathode rays
had already been examined. They were shown to
consist of flights of more minute particles negatively
electrified, and, again by measuring the electric and
magnetic forces required to deflect the particles from

236 SCIENCE AND THE HUMAN MIND

their straight path, Thomson was able to calculate
their velocity and their mass. The velocity proves
to range round a value of about 18,000 miles a second,
or one-tenth that of light, while the mass of each of
them is about the eight-hundredth part of the mass
of the lightest chemical atom known — the atom of
hydrogen. These " corpuscles " seem to be identical
from whatever source they come, and whatever be
the conditions of the experiment. They form a
constituent part of all chemical elements, while the
charge of electricity they carry seems to be the true
natural unit of negative charge. They approach,
at all events, the old conception of a common basis
for matter formulated by Greek thinkers two thousand
five hundred years ago.

But, at this point, the ideas we have been following
come in contact with those suggested by another
and independent enquiry, set on foot by the mathe-
maticians Lorentz and Larmor. Maxwell's work had
shown long ago that light was to be regarded as a
series of electromagnetic waves. It followed that the
waves must be started by the oscillations of minute
electric charges, and that every substance capable
of emitting light when raised to incandescence must
contain electric charges ready to be set in oscillation.
But moving electric charges carry electromagnetic
energy and momentum with them in the surrounding
space, and thus themselves possess inertia or mass.
Now these two properties are sufficient to endow
matter with its known characteristics, and thus
matter itself may be explained as an electrical pheno-
menon, while the ultimate electric charges or " elec-
trons " may be identified with the corpuscles of the

THE LATEST STAGE 237

cathode rays. We may, in fact, resolve the concep-
tion of electricity into that of matter, or the conception
of matter into that of electricity. It is impossible to
say that one of these conceptions is more fundamental
than the other. Owing to our muscular sense, the
forces required to set matter in motion are direct
sense-perceptions, and thus to our minds matter
seems more familiar than electricity ; but, had we
an electrical sense, as the fish torpedo may possibly
possess, we might find the positions reversed, and
think it simpler to paint our picture of nature in
electrical colours. Thus clearly we see how the
structure of our minds, nay of our bodies too, affects
our scheme of science.

Another consequence of the theories we are con-
sidering is of philosophic interest. A corpuscle or
electron, as we have seen, owes its apparent mass to
the field of electromagnetic momentum it carries with
it. Now, while this momentum remains constant at
all ordinary speeds, the mathematical equations show
that it should increase very rapidly as the velocity
of light is approached. If that velocity could be
reached, the apparent mass would be infinite, for no
exertion of force could cause any further increase in
velocity.

Now, in the next section, we shall describe the
phenomena of radio-activity in which corpuscles
are found moving with speeds which in some cases
approach to within some five per cent, of the velocity
of light. By measuring their deflection by electric
and magnetic forces, the mass of these particles can
be measured, and it is of great interest to find that
once more our scheme of science corresponds with

238 SCIENCE AND THE HUMAN MIND

observed phenomena ; the measured mass of the
corpuscle shows the calculated increase.

Thus, at speeds such as these, the constancy of mass,
one of the fundamental axioms of the Newtonian
dynamics, fails us. A new dynamic must then come
into action. We shall be brought back to this re-
markable conclusion later by another road.

Both cathode rays and Rontgen rays produce
luminosity when they strike phosphorescent screens.

This phenomenon suggested the idea that
Radio-activity. , , • i_. At.

phosphorescent substances might them-
selves emit similar rays, and in 1896 led to the dis-
covery by Henri Becquerel that compounds of the
metal uranium, whether phosphorescent or not,
constantly emitted rays which affected a photographic
plate through opaque screens, and rendered gases
through which they passed conductors of electricity.
In 1898 M. and Mme. Curie, finding that the mineral
pitchblende was more radio-active than its contents
of uranium suggested, succeeded in isolating from it
compounds of an intensely active new element, to
which they gave the name of radium.

Radio-active substances emit several types of radia-
tion. Two of these certainly consist of projected
electrified particles, which are deflected from their
straight paths by the action of electric and magnetic
forces, to an extent which shows that, while one type
is identical with the sub-atomic corpuscles of cathode
rays, the other consists of a stream of particles of
atomic dimensions, now known to be atoms of the
gas helium.

The emission of rays is always accompanied by

1

THE LATEST STAGE 239

chemical change, new substances appearing. Thus
radium evolves continuously a radio-active gas or
emanation, which itself deposits radio-active matter
on solid surfaces. Moreover, these changes are
associated with the emission of large amounts of energy,
which may be measured as heat, and are shown to
transcend by far the energy liberated by any ordinary
chemical action.

These striking phenomena are explained and co-
ordinated by a theory propounded by Rutherford and
Soddy in 1903. Radio-activity is due to the explosive
disintegration of individual atoms, one in many millions
breaking up each hour. In this way it is calculated
that half of a given quantity of radium would disappear
in some two thousand years, passing successively into
the emanation and various kinds of solid matter,
while each act of disintegration involves the explosive
emission of one atom of helium. Radium itself is
probably formed by a similar even slower change from
a substance now called ionium, which itself is derived
directly or indirectly from uranium. Uranium thus
becomes the first known ancestor of the family of
radio-active elements of which radium is the most
distinguished representative.

In this way the dream of the mediaeval alchemist
at length has ^ome true. Chemical elements are not
all indestructible and eternal, though their changes
seem to be beyond our control. We can but watch
one type of matter arising from another ; no philo-
sophers' stone will produce the change ; even the
resources of a modern laboratory seem powerless to
hasten or delay the disintegration of a single
atom.

240 SCIENCE AND THE HUMAN MIND

While all this new knowledge has expanded amaz-
ingly the bounds of science as conceived thirty years
The Individual ag°> in many ways it has but served to
Atom. confirm and give confidence in some of
the fundamental concepts in which that science was
expressed. In especial, the atomic theory has come
triumphantly out of the ordeal, and has proved its
continued value as an interpreter of nature at the
present stage of the advancement of learning.

Till recent years, the theory that matter consists
of an enormous number of discrete molecules and
atoms rested on physical and chemical evidence of an
indirect character. The effects of the individual
molecule or atom seemed for ever beyond the power
of direct perception. We could but infer them from
the effects of many millions acting together, as the
scout in an airship at a high altitude might infer the
presence of individual soldiers from the movement
of the columns of an army on the march. Even
after the striking success which attended the applica-
tion of the atomic theory to the co-ordination of the
phenomena of electric conduction in liquids and gases
and of radio-activity, there were not wanting sceptics
who held that individual atoms must remain purely
conceptual entities, removed from the possibility of
direct sense-perception.

But single atoms of helium, shot off by radium as
a rays, have been revealed in two ways. Each
atomic projectile produces a long train of electric ions
as it passes through a gas before its energy is exhausted,
perhaps by knocking loose corpuscles out of the mole-
cules it encounters in its path. These ions have two
effects. They make the gas a conductor of electricity,

THE LATEST STAGE 241

while they exist, so that, by placing the gas in circuit
with a battery and an electrometer, Rutherford has
shown the effect of each a particle by the sudden throw
of the needle of the instrument. Secondly, the ions
act as nuclei for the condensation of mist, and, in this
way, C. T. R. Wilson has made visible as a line of
cloud the track of each particle.

As we have seen, the revival of the old theory of an
all-pervading aether was due to the researches of
The Lumini- Young and Fresnel, who re-established
ferous .Ether, the wave theory of light. If light be
waves, something to undulate must exist through
space. Maxwell's electrical theory demanded a simi-
lar something to carry electromagnetic waves, and
strengthened greatly the tendency to assume that
this something was a subtle, material or quasi-
material substance, extended permanently throughout
all space, linking together the most distant stars, and
capable of being described in mechanical terms.

It was, however, clear at once that aether must
have properties unlike those of any other type of
matter known to us. Light-waves oscillate in direc-
tions at right angles to the line of sight. Hence the
medium which carries them must possess elasticity
of shape. In this it must be analogous to a solid.
Yet, since it offers no appreciable resistance to the
motion of planets, it must be not only fluid but ex-
cessively attenuated. Reconciliation between these
results was sought in different ways. For instance,
a medium was invented rigid to very rapid movements,
but offering no resistance to movements compara-
tively slow. Others followed one another fast — our

16

242 SCIENCE AND THE HUMAN MIND

conceptual space became filled with turbulent motion,
with interlinked vortex filaments, even with solid,
densely packed spheres.

But worse difficulties remained. If space be filled
with a stagnant aether, it must either be unaffected
by the movement through it of ordinary matter, or
the moving matter must disturb it, and carry some of
it along in the path of motion. For instance : was the
aether near the surface of the earth moving with it,
or was it at absolute rest in space ? A test was
possible on the velocity of light. Was that velocity
the same in the direction of the earth's motion as
across it ? In a famous series of experiments, Michel-
son and Morley found no relative movement between
the earth and the aether, and concluded that the
earth swept an atmosphere of aether along with it.

On the other hand, Lodge, who sought to detect
the drag of the aether by whirling masses of steel,
found no effect. However fast the steel moved, it
left the aether just outside it at rest. Similar dis-
crepancies came to light in other optical problems.

An explanation of the result of the Michelson-
Morley experiment was offered simultaneously by
Fitzgerald and by Lorentz. If matter be an electrical
manifestation, the forces between its particles, and
therefore its dimensions, might change as it moved
through the aether, and this change of size in Michelson
and Morley's apparatus might just compensate for
the effect they sought.

But whether this explanation were right or no, the
authority of the aether remained supreme. No one
doubted the fundamental validity of the conception.
Indeed, attempts were constantly made to express

THE LATEST STAGE 243

matter in aethereal terms. Lord Kelvin's idea of
vortex rings in a perfect fluid, Karl Pearson's view
that matter might be aether coming into and going
out of three dimensions from and to an unknown space
of four dimensions, Osborne Reynolds' mechanism of
chasms in a medium made of hard spheres packed
closely together, Larmor's picture of an electron as a
strain knot in the aether — all are attempts to explain
matter in terms of aether, and thus to bring unity into
physical science.

In spite of the incompleteness of these attempts,
few doubted that success was but a question of time.
The splendid vision of a conceptual Universe, framed
in its physical aspect out of the known properties of
one all-pervading medium, led men on. It seemed
that the vision might be realized any day, and all
science become but the physics of the aether. Materi-
alists who wished to be specially forward in the
stream of progress began to call themselves aethereal-
ists. Whether they were wise time alone can show.

The difficulties which surround the theory of a stag-
nant aether at absolute rest in space have been evaded
The Principle by a new principle evolved in different
of Relativity. ways by Einstein and by Minkowski. By
reason of the failure of all attempts to measure
absolute translatory motion through space by means
of reference to the aether, Einstein concludes that
it is a principle of nature that such absolute motion
can never be detected. The only translatory motion
that has meaning for us is the relative motion of
one body and another. To use this principle as a
basis of deduction, Einstein also assumes that the

244 SCIENCE AND THE HUMAN MIND

velocity of light in free space appears the same to all
observers, regardless of the motion of the observer
or of the source of light.

These two statements taken together form what
is called the Principle of Relativity. They are in
accordance with all facts known at present, and,
although they lead to unexpected and startling results,
none of those results have been yet shown to be
inconsistent with each other or with the results of
observation and experiment.

If we imagine two bodies to be moving past each
other in free space on parallel paths, as two railway
trains may pass each other on opposite lines, a simple
geometrical construction will convince us that, which-
ever body we assume to be at rest and whichever in
motion, on the principle of relativity, the unit of time
on the moving body is to the unit on the stationary
body as unity is to Ji — v2/c2, where v is the velocity
of the body, and c the constant velocity of light.
Thus, to an observer on either body, the time scale of
the other body seems different from his own. Similarly,
there is a corresponding change in the unit of length,
a change equal to that suggested by Lorentz and
Fitzgerald.

When we pass to dynamics, we find once more that
the principle of relativity requires that the mass of a
moving body should vary, and, in terms of the mass of
a stationary body, should be i/ Ji--v2/c2. If the body
moved with the velocity of light, v would be equal
to c, and the mass would become infinite. Here
again, the principle leads to the same result as the
ordinary electromagnetic theory, and is in equal
accord with the results of experiment.

THE LATEST STAGE 245

It will be seen that, on the principle of relativity, all
attempts to measure the velocity of anything rela-
tively to a stagnant aether are foredoomed to failure.
Compensating adjustments in the standards of time,
length and mass conspire together to defeat us.

In fact, the attempt to investigate the aether itself
may have to be abandoned. It may be that in
inventing " a nominative case to the verb to undulate "
we have gone too far in imagining an all-pervading
stagnant medium with the mechanical or quasi-
mechanical properties suggested to our minds by the
too vivid words " universal aether."

We can but feel that once more the self-sufficient
structure of nineteenth-century science has sustained
a rude shock. It may recover therefrom, and the
universal stagnant aether once more surround us.
Or that section may fall and have to be rebuilt on
newer lines, and the universal stagnant aether pass
into the great historical museum of intellectual
curiosities. It will be in good company, and may
wait in patience, with the firm hope of welcoming in
due course the conceptions which now may supplant
it, and may even cherish the possibility of a tri-
umphant reappearance on the acting stage of science.

Simultaneously with the later work of Darwin

(1865), a series of researches was being carried on in the

Mendel and cl°^s^er °f Briinn which, had they come

the Laws of to his notice, might have modified the

Inheritance. history of Darwin's hypothesis. Gregor

Johann Mendel, a native of Austrian Silesia, an Augus-

tinian monk, and eventually Abbot or Pralat of the

Konigskloster, not satisfied that Darwin's view of

246 SCIENCE AND THE HUMAN MIND

natural selection was sufficient alone to explain the
formation of new species, undertook a series of experi-
ments on the hybridization or cross-breeding of peas.
He published his results in the volumes of the local
scientific society, where they lay buried for forty years.
Their rediscovery, confirmation and extension by
William Bateson and other workers marks the first
step in the recent development of heredity as an
exact experimental and industrial science.

The essence of Mendel's discovery consists in the
disclosure that in heredity certain characters may be
treated as indivisible and apparently unalterable
units, thus introducing what may perhaps be termed
an atomic conception into the field of biology. An
organism either has or has not one of these units ;
its presence or absence are a sharply contrasted pair
of qualities. Thus the tall and dwarf varieties of the
common eating pea, when self-fertilized, each breed true
to type. When crossed with each other, all the hybrids
are tall and outwardly resemble the tall parent.
Tallness is therefore said to be " dominant " over
dwarf ness, which is called " recessive." But when
these tall hybrids are allowed to fertilize themselves
in the usual way, they are found to be different in
genetic properties from the parents whom they re-
semble outwardly. Instead of breeding " true," their
offspring differ among themselves ; three-quarters are
tall and one-quarter are dwarf. The dwarfs in turn
all breed " true," but of the tails only one-third breed
true, giving rise solely to tall plants, while in the
next generation the remaining two-thirds repeat the
phenomena of the first hybrid generations, again
giving birth to pure dwarfs and mixed " tails."

THE LATEST STAGE 247

These relations are explained simply if we suppose
that the germ cells of the original plants bear " tall-
ness " or " dwarf ness " as one pair of contrasted
characters. When a tall plant is crossed with a dwarf
one, all the hybrids, though externally similar to the
dominant parent, have germ cells half of which bear
" tallness " and the other half " dwarf ness " in their
potential characters. Each germ cell bears one or
other quality, but not both. Thus when, by the chance
conjunction of a male with a female cell from these
hybrids, a new individual is formed, it is an even chance
whether, as regards the qualities of tallness and dwarf-
ness, we get two like or two unlike cells to meet ;
and, if the cells be like, it is again an even chance
whether they prove both " tall " or both " dwarf."
Hence, in the next generation, we get one quarter
pure " tails," one quarter pure " dwarfs," while the
remaining half are hybrids, which, since tallness is
dominant, resemble the pure " tails," and in appear-
ance give three-quarters of the seedlings that character,
It will be seen that the methods of inheritance are
different in the cases of dominant and recessive
characters. While an individual can only transmit
a dominant character to his descendants if he himself
shows it, a recessive character may appear at any time
in a pedigree if two individuals mate who carry the
recessive character concealed in their germ cells,
though not outwardly visible in themselves. But in
the majority of cases the conditions of inheritance are
far more complicated than would appear from the
study of two simply contrasted qualities in the green
eating pea. For instance, qualities may act as
dominants or recessives according to sex or other con-

248 SCIENCE AND THE HUMAN MIND

ditions. Characters may be linked in pairs so that
one cannot appear without the other, or again they
may be incompatible and never be present together.

Many Mendelian characters have now been traced
in plants and animals ; while, as a practical guide
in breeding, the method has been successfully applied
to unite certain desirable qualities and to exclude
others of harmful tendency. By this means, Biffen
has established new and valuable species of wheat,
in which immunity to rust, high cropping power and
certain baking qualities have been brought together
in one and the same species owing to a long series
of experiments based on the Mendelian laws of
inheritance.

The extension of this new method of research to
mankind at once cleared away many old puzzles and
opened up fresh fields of study. Many diseases and
malformations have been proved to be dominant
Mendelian characters ; while deaf-mutism, and other
defects, appear to be recessive, and therefore especially
liable to appear in cousin marriages between sound
individuals who come from families liable to the
affliction.

Of normal healthy characters, eye colour alone has
yet definite!}/ been proved to show Mendelian pheno-
mena in its line of descent, brown colour being domin-
ant to gray, though indications are not wanting
that further analysis will disclose similar relations in
many other directions.

The application of such results is obvious. We can
already predict accurately the probable results of
human matings when the potential parents possess
a character which has proved to be Mendelian in

THE LATEST STAGE 249

its line of descent. Increase of this knowledge is
coming fast, and should soon form a valuable guide
to the physician, to the sociologist, perhaps to the
statesman.

From the more philosophic aspect, the results of
Mendel and his rediscoverers complete on one side the
Darwinian period, and on another show its insufficiency,
and open a new chapter. In the original theory of
the origin of species by natural selection, still held as
against the Mendelians by many biologists, it is the
small variations of organisms round the mean form
that supply the material for selection to work upon.
It is not easy to see how enough isolation of more
successful beings can occur to establish inbreeding,
and so build up a new species. But the large differ-
ences found by Mendelians, and the complete separa-
tion of unit characters, do much to diminish this
difficulty. In their view, new varieties may arise
almost per saltum, and establish themselves at once.

On the other hand, these new and unexpected
phenomena showed that Darwin, as he himself well
knew, had not said the last word on evolution, and
gave a welcome check to some of the more confident
speculations of the newer prophets of Darwinism.

Another aspect of evolutionary philosophy also has
been affected by recent research. Though Lamarck's
theory gave up its pride of chief place to that of
Darwin, many accredited evolutionists continued to
preach and act as though characters in man acquired
by the reaction of the environment — as by exercise,
training, or education — were handed down in their
developed form to his offspring. Thus a comforting
doctrine arose that we need but improve the acquire-

250 SCIENCE AND THE HUMAN MIND

ments of one transient generation for the next to be
better innately — that the race by mere well-directed
philanthropic enterprise would continue to improve
indefinitely in mental and moral worth. Then came
Weismann, who, led by the evidence that the germ cells
of one individual are derived by direct descent from
those of his parents, asked how characters acquired dur-
ing life could affect the germ cells present almost before
life began? He examined critically every suggested
case of the inheritance of such a superimposed char-
acter, and found each case to crumble away under his
analysis. We have not reached certainty. Some
indications are believed to point to possible though
rare occurrence of partial inheritance in a few insects
and plants when modified by the environment. But,
as a chief actor in the hereditary drama, the acquired
character is discredited.

Here again we touch the problems of sociology.
Though political and social institutions acquired by
one generation are certainly inherited by the next,
and if well suited to the natural development of the
people may help them progressively to advance in
social organization by a process of cumulation, this
inheritance of social organization is not evolution in
the Darwinian sense. And, in the far more important
and fundamental inborn qualities of the race, no rise
of one generation by improved hygiene, exercise or
education can affect, save indirectly, the qualities of
the next. Selective parenthood, natural or conscious,
is alone capable of raising our race or preventing its
degeneration. In the light of the indications of danger
referred to on p. 229, these considerations are of
momentous import.

THE LATEST STAGE 251

But it is time to turn to other biological tendencies,
in which, perhaps, even greater philosophic interest
lies. Here too we have to trace an old
story in a new form. As the premature
determinist mechanical theory of life of the Greek
atomists gave way before the equally premature
vitalistic dogmas of Aristotle, so the still premature
mechanicism of the too ardent physiologists and
Darwinians of the nineteenth century shows signs of
yielding for the time before the continued analysis of
the problem of life. Charles Darwin himself, be it
noted, kept an open mind on questions authoritatively
answered by ultra-Darwinians, especially in Germany.

The success of physiologists in co-ordinating many
functions of living organs with physical and chemical
changes led to a belief that life itself could be stated
completely in physical and chemical terms, and that
organic beings were but more complicated inorganic
machines. The fact that all living changes cannot
yet be explained by known physical principles is a
poor argument against a mechanical philosophy, for it
is supremely foolish to found our faith, in any depart-
ment of human thought, on mere gaps in knowledge,
some of which, at all events, can only be temporary.

Each year sees an increase in the number of bodily
functions which can be described in physical and
chemical terms. In particular, the chemical action
of certain internal secretions poured into the blood is
being found to influence the functions of distant cells,
and thus to control such characters as stature, the
movement of the heart, even the development of the
brain.

But, nevertheless, some biologists have held that

252 SCIENCE AND THE HUMAN MIND

recent work leads away from and not towards a
complete and satisfying explanation of many vital
processes by physical principles. The organism, it is
argued, uses physical processes, as indeed is obvious,
but it does not necessarily, or even probably, follow
that the controlling agent itself is purely physical.
Moreover, in comparing a living being with a mechani-
cal machine, it must be remembered that the machine
" is no ordinary sample of the inorganic world. It is
an elaborated tool, an extended hand, and has inside
of it a human thought. It is because of these qualities
that highly complex machines come to be so like
organisms. But no machine profits by experience,
nor trades with time as organisms do."

Indeed, many biologists, such as Driesch, Wolff,
Bunge, and J. A. Thomson, hold that the essence of
the problem is overlooked when attention is focussed
solely on the details of organic life, and the mechanical,
physical and chemical processes used therein. From
a more complete survey, they see reason to believe
that there are facts concerning organisms considered
as wholes which are not covered by any possible
extension of the domain of mechanics, physics and
chemistry. A living being, they believe, is autono-
mous ; it is in a sense an ultimate unit in nature, and
cannot be explained by a study solely of the detailed
phenomena of its parts and organs. Besides the
obvious purposefulness of the higher animals and
plants, a similar intention appears throughout all
living beings even from the first.

As an instance of the phenomena on which they rely,
we may describe one of the many results of recent
work on the process of egg-development — " Entwicke-

THE LATEST STAGE 253

lungsmechanik," as it is not very happily called.
Driesch found that if the essential part of the egg
of the sea-urchin (Echinus m^crot^tberculatus) were
separated into two cells, each cell divided and
developed in the normal way. For some stages, the
product of development resembled what would have
been obtained by cutting in half the product of a
complete egg, but soon the hemisphere became rounded
into a sphere, and a whole larva, smaller than usual,
but complete in all its parts, ultimately developed.

Such phenomena as these, the facts of adaptation
to changes of environment, the restitution of injured
parts in adult organisms, acquired immunity, the
reproduction of complex beings by the hereditary
process, above all the marvellous properties of mind
and consciousness studied by psychology, cannot be
put on one side. They make it impossible for a grow-
ing number of biologists to regard life as a cumula-
tion of chemical and physical changes, and have gone
far to re-establish biology as an independent science.
They have led to the revival of the old hypothesis of
vitalism, or, as some now prefer to call it, of the
autonomy of life — an old theory with a new name,
arising refreshed from its years of retirement with
stronger claims to notice.

Still, the majority of biologists remain convinced
that physiology in its essence is but applied physics
and chemistry, and that, although we are yet far
from a complete account of the organism, it is ulti-
mately explicable with no reference to unknown prin-
ciples, such as vitalism, old or new. Whatever be the
truth, it is probable that this attitude will inspire
much of the work of the coming years. It must not

254 SCIENCE AND THE HUMAN MIND

be forgotten that, even if the whole of life regarded
externally as a subject of scientific study be reduced
to physical or mechanical terms, the internal pheno-
mena of consciousness, when the mind looks inward
on itself, remain a world apart.

The extreme Darwinian position — a position
Darwin himself never claimed — has been criticised
by Wigand, Nageli, Wolff and others. Natural
selection is allowed by all to be a vera causa in deter-
mining the limits of species. But it is now pointed
out that it can only eliminate what cannot survive,
never create diversities. To explain by natural
selection the existence of some organic character is,
says Nageli, as though one explained the presence of
certain leaves on a tree by saying that the gardener
had not cut them away. That statement may explain
why other possible leaves are not there, and why only
the actual leaves to be seen have survived, but behind
it is the marvel of why — gardener or no gardener —
there are leaves at all.

Natural selection, it is said, fails to account for
mutual adaptations, such as those existing between
plants and insects. It fails too to explain organs
which are composed of many parts, such as the eye,
and still act as functional units. It fails once more to
account for the first origin of organs, which only
become of survival value at a later stage of develop-
ment. Through all life appears an inherent purpose-
fulness, as an essential and fundamental property of
the organism. This evidence of purpose, of direction,
of intention, underlies the whole of biological develop-
ment, and may give the clue to a revaluation and
extension of the facts now available for discussion.

THE LATEST STAGE 255

While the relationships and similarities between
different species point to a common origin, and enable
us to assert a near connection between certain types,
such as man and ape, the facts seem to warrant little
else. We cannot tell what really happened in former
ages, when, perhaps, the stream of protoplasm was
more plastic and more variable than it is to-day.
The elaborate theories of descent which have succes-
sively traced the origin of the vertebrates to amphioxus,
worms, spiders and crayfishes, have been compared
in scientific value by Emil du Bois-Reymond with
the pedigrees of the heroes of Homer.

If we accept the conception of descent, the theory
of evolution — and no one proposes to jettison it — the
evidence of purposefulness in living beings suggests
that some unknown principle of organization must
have been at work from the very beginning. Here
again we are brought back to neo- vitalism.

Whether these vitalistic tendencies will persist,
and crystallize into a consensus of opinion, it is im-
possible to say. The analogy of the past points to
the probability that here too we are but watching a
passing phase in the rhythmic wave of human thought.
Perhaps some new " explanation " of vital phenomena
may be offered in the years to come, and once more
give rise to a complete mechanical conception of life.
Once more mechanism may fail when subjected to a
closer scrutiny, and a still newer vitalism come to its
own. Let us at least hope that each alternation may
mark a step in knowledge, and lead to the more
exact formulation of fundamental problems which
as yet we can but dimly discern. The historian
of thought tends to be sceptical about ultimate

256 SCIENCE AND THE HUMAN MIND

solutions. Yet to the scientific protagonist at each
stage, an animating faith in the eternal verity of his
own creed, whether of vitalism or mechanicism, is a
priceless possession. A man without convictions
cannot be convinced. Let him therefore face his
facts fairly and choose his line. As long as he does
not try to fit his conclusions to any preconceived ideas
of what may be good for man to believe, he will play
a useful part ; but, " die Philosophic muss sich hiiten
erbaulich sein zu wollen."

Introspective psychology is at least as old as the

Greeks. Experimental psychology, and comparative

Modern Psycnol°gy> the study of the minds of

Psychology, different races of men and animals, are

among the newest born of the sciences.

Experimental determinations can now be made of
the sharpness of the senses, and the action on them of
injury, fatigue and other changes ; of the power of
memory and the effect of association of ideas on
memory and on action.

The human mind possesses the special faculty of
constructing complex ideas and following trains of
thought. Here too association comes into play ;
association not only of sense impressions which have
followed each other in the past, but also of things
similar in various ways but perhaps never before
associated. In this formative process of comparison
the importance of language becomes manifest. The
possibility of giving all similar things a class-name
helps the mind to frame a universal or general con-
cept of that class. To call all dogs dogs, and not
merely Joe, Nelson, Caesar and Smut, is a very real

THE LATEST STAGE 257

mental achievement. To the savage, indeed, this
power of classification is so mysterious that from the
spoken word, to us indicating a class association,
springs the idea of a mystic or divine unity, binding
together in blood-relationship all the members of that
class. Hence comes tabu, and perhaps a tutelary
deity. The continued fascination of the concept of
class is seen passing from Plato and Aristotle to the
Scholastics of the Middle Ages.

Besides our conscious mental processes, a subliminal
mind may be traced, working " sub limine " — beneath
the threshold. At length the phenomena of trance,
of hypnotism, of suggestion, of multiple personality,
are being submitted to scientific examination. The
results of these researches are not confined to the
special states inquired into ; they throw light also
on our normal psychological processes and are in-
timately connected with the phenomena now being
investigated in " psychical research." To some ob-
servers recent experiments appear to reveal direct
thought-transference from mind to mind, and even
to suggest the continued existence of the spirits of
the dead, and the possibility of difficult, but still in-
telligible, intercourse between them and the living.
We seem to return to the " aerial " and " terrestrial"
states of the soul, outlined by the Cambridge Christian
Platonists of the late seventeenth century, and to be
testing some of their theories of possible intercom-
munication between the two conditions.

The realization of the importance of conscious and
subconscious association of ideas is helping us to
understand in a new way many dark phases of human
life and society. We find that our social, political and

17

258 SCIENCE AND THE HUMAN MIND

religious actions are profoundly affected by association.
In the eighteenth century a general intellectualistic
theory of politics and religion was developed by social
philosophers, and in the nineteenth it was applied
freely in practice. Man was (so they assured us) or
should be — save as to human imperfection — governed
exclusively by the cool light of reason. Passion and
prejudice were transient storms that merely ruffled
the surface of the normally unclouded mind. A crowd
was but a number of individuals, each a potential
philosopher with the torch of Reason in his hand.
The " People," could their real will be ascertained,
would govern not only themselves but each other
with the calm wisdom of the sage, the intellectual
acumen of the statesman, and the irresistible claims
to righteousness of a numerical majority.

Now this a priori intellectualism has been shattered
by the patient study of facts. Men are not and never
have been governed by reason. The number of things
about which we, even the best of us, consciously
reason is very small. Economy of thought is as
important to success as economy of wealth. For the
most part, education and training are but practice
in association, either of ideas with ideas or of ideas
with action. Indeed, as Dr Whitehead tells us,
" civilization advances by extending the number of
important operations which we can perform without
thinking about them. Operations of thought are
like cavalry charges in a battle — they are strictly
limited in number, they require fresh horses, and
must only be made at decisive moments." The
simple association of twice two with four, the complex
series of associations which enables a mathematician

THE LATEST STAGE 259

to solve a differential equation, are the same in kind
as — though founded on a more general consensus of
competent opinion, and therefore on a more legitimate
basis than — the impressed associations of our youth,
which taught us to identify Lord Beaconsfield and
Peace with Honour, or Mr Gladstone's special variety
of Peace with Retrenchment and Reform. Both are
methods of saving thought, the one in solving equations,
the other in deciding how to vote.

The modern arts of advertisement and of election-
eering, which is but a species of advertisement, are
the best examples of the application of psychological
principles in practice. In each case, simplicity of
association is of primary importance. The leading
English newspaper, to which the arts of advertise
ment have become by no means unfamiliar, in a
recent anniversary number, lays bare the psychology
of the method: — "The iterated appeal to the eye
stamps its form on the brain without any special
connotation, and in the absence of any opposi-
tion remains there until some favourable occasion
or recollection brings it into practical association
with the wants of some individual." If we are
continuously impressed with the simple connection
between Pulley's Moonshine Soap and Silver Purity,
some day we forget to make the mental effort needed
to realise that all the bills our eyes have seen bear the
impress of one man's desire — and order Moonshine.
If the political candidate, who appeals most to the
innate bent of our mind as modified by environment,
or to the hereditary political opinions bequeathed by
our forefathers, descends on our constituency but once
in a while to dispense lavish hospitality with the

260 SCIENCE AND THE HUMAN MIND

simple message of, " Tax the land and vote for Jones,"
or "Tax the foreigner and support Smith/' we shall
find ourselves much more enthusiastic in his support
than if he lives among us and confuses his election-
eering virtues with his qualities, perhaps his faults,
as a neighbour.

Then the psychology of a crowd has points of differ-
ence from those of a number of isolated individuals — the
management of a public meeting is not the same art
as that of the skilful canvasser. The speeches of
Brutus — the doctrinaire man of reason — and Mark
Antony — the astute and emotional opportunist — in
Shakespeare's Julius Ccesar are marvellous examples
of an inborn knowledge of crowd psychology. Every
would-be platform speaker should know them by
heart.

Now the nineteenth-century theory of democracy
was founded on the special varieties of intellectualism
then prevalent, reinforced by Lamarck's view of the
inheritance of acquired characters. Unfortunately,
we know now that, owing to the essential psychological
structure of the human mind, public opinion can be
manufactured, and is manufactured daily, without
any regard for reason. The long purse, the unscru-
pulous or misguided conscience, the oratorical appeal
to passion, prejudice and self-interest, have greater
power of creating public opinion than careful reason-
ing based on verified facts. Wherefore we cease to
wonder that in those countries which most pride
themselves on their democratic character the millen-
nium is no nearer than in others. The power of mere
benevolent stupidity in making history is a new
discovery. Stupidity is not necessarily due to evil

THE LATEST STAGE 261

intent or false reasoning. It is as often caused by
false associations, for which the intellect of the sufferer
is not primarily or even chiefly responsible.

In constitutional problems, too, we are passing away
from the purely intellectualist standpoint ; and once
more the change began before its psychological import
was understood. If we compare the attitude of mind
of 1860 with that of to-day, we mark the difference.
At that date the tendency was to a complete utili-
tarianism. A business-like constitution whose every
part had its direct economic use was the ideal. The
Monarchy was an interesting survival of a barbarous
past, which few wished forcibly to remove, but for
which few ventured to foretell a prolonged existence.
The colonies were somewhat useless and expensive
encumbrances, which might almost be encouraged to
" cut the painter." Colour and glow were passing
out of public life, and grey, useful uniformity was
spreading over all.

Slowly a change began. It can be traced back
through the " Oxford Movement " to the romantic
and historic inspiration of the novels of Sir Walter
Scott, an Anglian of the North British stock. Once
more the idea of Nationality was found to appeal
to sentiment, and to have driving force behind it.
It was discovered that " the golden link of the Crown "
stood for a corporate ideal of the State, which gained
real strength thereby. It was less easy to glorify
as the impersonation of the nation a bourgeois Pre-
sident in a frock-coat — still less was it easy to die at
his behest should the need arise. Colonies ceased
to be regarded as unprofitable branch establishments,
and became the Dominions Over Seas where lay the

262 SCIENCE AND THE HUMAN MIND

homes of our kith and kin. Coronations regained
their old splendour, and Jubilees were invented to
supplement them. Even towns begin to realize a
sense of corporate continuity, and pageants minister
to the newly recovered or newly acknowledged pro-
cessional instinct. We revive maypole dancing and
introduce acting and dramatic recitations into the
elementary schools — thereby returning to the educa-
tional ideals of the later Stuarts — and think we have
taken a step in advance.

Now all this movement has a real historical import-
ance in the development of the human mind. It
accompanied the contemporary change of attitude
in science, and was its representative in another field
of thought. The sages of 1860 had overlooked essential
psychological truths, and had made man a purely
intellectual being in their own fancied likeness. Since
then we have rediscovered his other faculties, and
have set to work, some of us to develop them,
others to find an equation which will express their
value in the corporate life of the community.

Meanwhile, the application of comparative, historical
Comparative anc^ evolutionary methods to the study of
Religion, religion has changed profoundly our ideas
of its course of development.

Even when the idea of evolution had been absorbed
and assimilated by theologians, the a priori method
reigned for a time supreme. Evolution had proceeded,
no doubt, but dispensation had followed dispensation,
till, in the fullness of time, the particular stage of
Catholic doctrine now authorized by the Holy Father,
or the particular tenets then emphasized by the

THE LATEST STAGE 263

Protestant sect favoured by the enquirer, had emerged
and proved their adaptation to the environment.
Heathen lands might still be painted black on the
missionary map, though it began to be realized that
there were shades of grey between black and white,
which required explanation and apology.

One underlying assumption made by theologian
and sceptic alike vitiated the whole conception of the
evolution of religion — an assumption inevitable till
the lesson of patient study of primitive peoples had
been learned. It was assumed that, at all stages, creed
and dogma were the essence of religion, and rite and
ritual but their expression.

Now the recent researches of anthropologists fail
to accord with this preconception — as, indeed, so often
facts do fail to accord with a priori theories.

Far earlier than definite theological beliefs or dogmas
are religious rites and ritual observances. It is a com-
parative advance to " bow down to wood and stone."
When the really primitive man wants rain or victory
he does not ask a god to give it to him, but goes and
tries to secure it himself. When it rains, the thunder
sounds or the frogs croak. If that be all, he can do it
too. So he whirls his bull-roarer to make thunder,
or hops and croaks like a frog to bring the rain. So
rises magic, " that spiritual protoplasm," as Miss Jane
Harrison calls it, " from which religion and science
ultimately differentiated." Then come ritual, magic
dance, and outpourings to fertilize the earth.

Social observances, necessary for the complicated
savage life, become inextricably mingled with these
nature-spells. A boy must leave the women who
tended his childhood and join the men in hunting

264 SCIENCE AND THE HUMAN MIND

and fighting. The break is essential, and must be
effectual for the social well-being of the tribe. Hence
spring initiatory ceremonies, often of cruel severity,
and revelations of tribal secrets and tabus. Here too
is a fertile source of ritual, acquiring all the sanctity
of custom. Leaders in ritual ceremonies tend to be-
come medicine men or priests. In time perhaps they
acquire divine attributes.

At this point another parallel development of ideas
is ready to join hands. To the savage, memory,
anticipation, dreams, give worlds as real as that which
alone is held by civilized man to be objective. All
things grouped under a common name become related
in blood — need a common origin. Tutelary deities,
divine ancestors, priests, spirits of wood, mountain
and stream emerge into vague consciousness. In
terms of these conceptions the familiar rites and
ritual tend to become explained. In a bewildering
variety of imagery religion rises for mankind.

It will be seen how far these facts of primitive life
are from the intellectualist theories of religious evolu-
tion current in the nineteenth century. In the light
of those theories, man believes, and therefore there
are rites and sacrifices. But primitive man, at all
events, has rites and sacrifices, and therefore believes.
Then, it is true, rite and sacrifice acquire an added
sanction, the process becomes cumulative.

Like politics, religion is seen to be affected pro-
foundly by the psychology of the race. The develop-
ment of the religious faculty in man is carried on by
his whole being, mental and emotional, not by his
intellect alone.

It is probable that, when the significance of the new

THE LATEST STAGE 265

knowledge of comparative religion is grasped by the
world at large, men, undeterred and unwarned by
experience, will feel their faith in danger and the
fountains of the deep unloosed upon them. When
they find how many cherished doctrines and how much
beloved ritual arose from magic and nature-worship
and were common possessions of many faiths ; when
they see that on those rites and doctrines Christianity
was merely grafted to supply a new interpretation
of the mysteries, they will feel religion itself is
crumbling before their eyes.

Yet, in truth, it is but the old story of the sun's
place in nature and the old story of evolution. When
natural selection gave a comprehensible theory of the
method of creation, some men rushed to the conclusion
that life and all existence were but the by-play of
materialistic mechanism. Slowly they came to see that
things stood much as they were, save that a fresh
revelation of How had been given to mankind.

So, in this new field of knowledge, a revelation of
the method and process of the development of the
religious experience of mankind does not alter the
fact of its existence, or make shallow the depths of the
soul's sea of awe and reverence for its own life and its
intuitive apprehension of the divine. The Kingdom
of Heaven is still within.

The words of Shakespeare are to be found in a
dictionary common to all mean books. That does not
destroy the genius of the poet. Though the ritual
and dogmas of Christianity, as of other religions, lie
scattered in a thousand creeds, the conception of the
Divine mind that reinterpreted and reinterprets them
to all ages is not less Divine. When we understand

266 SCIENCE AND THE HUMAN MIND

the origin of our Church, the derivation of its sacra-
ments, the history of its growth, the majesty of the
living structure is no whit diminished. Once more
we have learned something about methods. Though
the Church may have evolved by natural means, that
should teach us to see God in Nature, not to deny the
Church to the God of Nature. Though religion arose
naturally and inevitably by the psychology of man,
that should show us that man's whole nature is
essentially religious.

Attempts to support religion on an intellectual assent
to dogma alone are doomed to failure. They ignore the
essential psychological basis of the religious instinct.
Churches and ritual are a real need to most men, as the
Oxford Movement rediscovered. To one the gorgeous
but direct and simple imagery of Rome is necessary ;
another is best stirred by the more refined symbolism
of a plain white surplice and the majestic diction of
the Book of Common Prayer ; while to a third the pro-
found psychological device of the crowd-silence of a
Quakers' meeting is the most effective and impressive
as it is the most subtle, and psychologically the least
simple, form of ritual. An effective Church must be
able to enshrine the glamour of the past in continuity
of rite and tradition, to meet, by continual routine
of prayer and praise, man's psychological need of
association in the development of the religious sense ;
and to satisfy the artistic and emotional sides of man's
nature in dignified ritual, while maintaining its hold
on the best spirits of the age by an open-minded
receptivity to intellectual progress. A nation that
forsakes its Church, or suffers its Church to forget
traditions on the one side or to fall into unreasoning

THE LATEST STAGE 267

obscurantism on the other, a nation that ignores the
survival value of religion, will perish from off the face
of the earth.

Alongside the development of physical and biologi-
cal science which we have traced in the preceding
Theor of Pa£es> new attention has been devoted to
Scientific the fundamental concepts which lie at
Knowledge. the base of a]Q natural knowledge. Ernst

Mach in Germany and Karl Pearson in England have
modified and developed the doctrines of Mill and
Herbert Spencer.

In the laboratory, as in the practical life of the field
or the office, there is no time for philosophic doubt.
A naive realism is alone possible. We assume that
we know all about our spade or our pen, our test-tube
or our atom. Can we not see them, handle them, or,
at all events, trace their effects ? Yet if we think
carefully, we shall see that the case is not so simple as,
for practical convenience, unconsciously we assume.

A spade is to our eyes a long-shaped figure of a
brown colour, tipped with a flat blade of grey. The
stored impressions of memory enable us to say it is of
wood and iron, and thereby to endow it with the
qualities we associate with those materials. We
construct a mental image of the spade, partly by
sense-impression, partly by an unconscious act of
memory. Our image is real, we can reason about it,
develop it by trying experiments and adding to our
ideas of wood and iron an idea of the complete spade
as an implement useful for digging, or, at a push, as
a weapon of offence. We are not conscious of our
mental process of synthesis ; we regard the spade as

268 SCIENCE AND THE HUMAN MIND

a real " thing-in-itself " outside us, resembling in its
ultimate character our mental picture of it.

But what right have we to assume the real existence
of such an outside object ? What is it that we really
know when we observe the spade ? Nothing, in effect,
but impressions on our senses. Our optic nerves send
certain stimuli to the brain ; we call them sight of
a long brown object with a grey blade. We stretch
out our hand and seize the spade. Yet all that
we expect, and all that we experience, are certain
tactual sensations given to the brain by our sense of
touch.

Chemists have resolved the spade into atoms of
carbon, hydrogen, iron, etc. Physicists have gone
further, and pictured the atom as a system of whirling
electrons. All these attempts to get at a more ulti-
mate reality, merely mean that the sensations we
experience at first may be changed into others by
appropriate action, and that, to represent those new
sense-perceptions to our minds, new concepts are
needed. By putting the spade into the fire, or by
passing an electric discharge through the gases which
are thereupon evolved, new phenomena appear, arid a
new mental scheme is evolved. We cannot anyhow
get at the external "thing-in-itself"; we can but
modify our sense-impressions and our concepts in
certain limited ways.

Our brain has been likened to a telephone exchange
in which the operator sits for ever locked. His only
knowledge of the external world is derived from the
messages he gets or intercepts as they pass over the
wires. He may infer the existence of outside objects,
he cannot prove it, and he can only gain a picture of

THE LATEST STAGE 269

those objects as revealed by the limited number of
wires which enter the office, and by the kind of message
which can come over the wires. He can hear, but he
cannot see or feel. It is safe to predict that his
mental picture of the world would be incomplete, and
different from that which would be disclosed to him
could be unlock his door and pass outside into the
glory of the sunshine. How many more senses may
be possible than our poor five, and what picture of our
world would they reveal ? But still it would be a
phenomenal world, we could but obtain the record
of our senses, never could we apprehend directly the
" thing-in-insdf."

Similar caution is needed in dealing with what are
called laws of nature or natural laws. The word law
in the legal sense has a meaning different from that
which it ought to bear in science, where it should mean
simply a shortened or convenient way of describing
general routines in sense-impressions, or general
relations between different mental concepts. When
we say that the sun's visible rays are accompanied by
warmth, we mean that we always find one sense-
impression followed regularly by the other. When
we say that two similar electric charges repel each
other in the inverse ratio of the square of the distance,
we assert a certain relation between our mental con-
cepts of electricity, of force and of distance — concepts
which have been developed by our minds out of the
material of sense-impressions. The relation is sug-
gested by experiment, that is, by sense-perception,
but, once apprehended, it is used to develop a mathe-
matical theory of electric forces and their effects in
a purely mental or conceptual sphere. How far this

270 SCIENCE AND THE HUMAN MIND

complex scheme agrees with facts, i.e. with new sense-
impressions, is a matter of experiment again.

The universality of natural law may, says Pearson,
really be relative to the human minds involved,
which, like machines that work for no coin but a
penny, may sort out and analyse, all in practically
the same manner, the material they will alone accept.
This return to the doctrine of Kant — " the Ego pre-
scribes its own laws to nature " — would avoid the
assumption that these routines of sense-impressions,
these relations between mental concepts, are produced
by the unknowable, whether the unknowable take the
form of matter, the thing-in-itself of the materialist,
or the form of an immediate action of the Deity,
the idealist reality of Bishop Berkeley.

Thus, to these empiricists, " science — refusing to
infer wildly where it cannot know, and unwilling to
assume new causes where the old have not yet been
shown insufficient — treats the ' dead matter ' of the
materialist," the mind-stuff of the idealist metaphysi-
cian, the immanent Deity of the natural theologian,
" as a world of sense-impressions ; . . . the scientist
. . . recognizes that the so-called law of nature is
but a simple resume, a brief description of a wide
range of his own perceptions, and that the harmony
between his perceptive and reasoning faculties is not
incapable of being traced to its origin. . . . Our
groups of perceptions form for us reality, and the
results of our reasoning on these perceptions and the
conceptions deduced from them form our only genuine
knowledge."

On these lines the different sciences into which, for
convenience, our studies are divided are but different

THE LATEST STAGE 271

sections cut through the model of nature our minds
construct, or different aspects from which it may be
regarded, or, to vary the simile, different-coloured
flashlights thrown by our minds on the picture they
have to examine. Mechanic looks at the model from
one point of view, chemistry from a second, biology
from a third. None is necessarily more fundamental
in its essence than another, though mechanic may
give a wider view, and from historical and psychologi-
cal reasons seem to us more primary. Thus science
as such is not only not committed to materialism — a
belief in the dead matter of Moleschott and Biichner —
as the sole reality, but does not involve a mechanical
philosophy, as is so often supposed. Even should a
theory of life come to be expressed in mechanical
terms, and agree with observed phenomena, it would
only show that the human mind found it more con-
venient to express its perceptions and conceptions of
life in mechanical language. It would not show that
there was any objective reality corresponding to the
conceptual scheme, still less that that reality cor-
responded to the particular aspect of it which our
minds selected.

On the other hand, this empirical scheme of science
is equally far from lending support to an idealistic
or theistic belief. It simply has nothing to say on the
question of external reality, on the nature of " things-
in- themselves." It purchases its freedom from both
contending factions by a complete agnosticism, by a
strict attention to its own business as conceived by
itself — the attitude of the Liverpool Chinaman who,
as a measure of security in a time of riot between
Romanists and Orangemen, decked his shop-front

272 SCIENCE AND THE HUMAN MIND

with the legend, " Me no religion at all, me only wash
clothes."

What then becomes of the eternal, immutable laws
of nature, of which we have heard so often ? Are
such laws non-existent ? By no means. But they
are the logical laws of the conceptual world formed
by our minds. Mathematics is in its essence symbolic
logic, and mathematical and logical laws are of the
same nature, though that nature is still a matter of
dispute among philosophers. Some would hold here
too an empiricist view, and say we gain a knowledge
of such laws by experience. But, on the other hand,
a rational school hold that logical principles are
grasped by an intuitive action of the mind, and are
not proved, though usually suggested, by experience.
Once we understand the terms involved, we see
instinctively that two and two are four in all condi-
tions and at all times. Once we make the assumption
that every particle of matter attracts every other
particle with a force proportional to the product of
their masses and inversely proportional to the square
of the distance, the whole planetary theory follows
logically, though it may need a Newton first to work
it out.

Such relations follow from the structure of our
minds, they are laws of thought. Some hold that
they give us knowledge about a real world also — the
world of universals, and are laws of nature as well
as laws of thought. Such philosophers thus revive
Plato's doctrine of ideas in modern guise. But
however this may be, the laws enable us to build up
a logical and necessary structure in the conceptual
world once we have formed the conceptions and agreed

THE LATEST STAGE 273

on the definitions. How far this ideal world agrees in
substance and in fact with the real world of sense-
perception is an affair of experiment. Two and two
always are four, whether the two and two be apples,
or poets, or cats. Here the definitions are made to
agree accurately with the sense-perceptions. But
how far astronomical sense-perceptions will agree
with the deductions of the Newtonian scheme is purely
a matter of observation in the present and probability
in the past and future. The fact that concordance
exists over the period of two centuries during which
our observations extend gives us confidence in the
probability that we may extend our predictions back-
ward into the past and calculate the dates of ancient
eclipses, and forward into the future. But the farther
we go, the less the probability of concordance becomes.
To be of practical use, all our conceptual schemes
must thus enable us to predict the future behaviour
of our perceptions. What ground have we for con-
fidence that they will do so ? It is simply, as we have
said, an affair of probability. There is no certainty
in natural science. Because we have known the sun
rise for ten thousand yesterdays, we frame a concep-
tual sun which rises regularly each morning indefinitely,
and, as a matter of practice, we may bet ten thousand
to one that the perceptual sun also will rise to-morrow.
Because Newton's theory of gravity has met every
demand on it for two hundred years, we have great
confidence that the complicated conceptual astronomy
founded on it by mathematical logic will still continue
to agree with our observations of nature — that is, with
our sense-perceptions. Because all chemical elements
proved immutable for a hundred years, we assumed

18

274 SCIENCE AND THE HUMAN MIND

that no chemical element could ever change — and in
the surprising case of radium we proved to be wrong.

Let us return to the consideration of the empirical
or phenomenal view of science — the view that it deals
only with sense-perceptions and the concepts framed
from them, and has no message about aught beyond.
How far is that view right ? or, since we are here and
now only historians, how far is that view accepted in
the present, and likely to persist in the future ?

Probably most men of science who have thought
about the subject would agree that science itself was
thus limited ; that it could give of itself no certain
information about the nature of any external reality.
Its duty is to construct a consistent conceptual model,
and to examine by observation and experiment how far
that model conforms to sense-perceptions. But science,
though it should be kept clear of metaphysics, as
indeed our history abundantly shows, has much
metaphysical import. When we leave science and
take a metaphysical view, our science becomes one of
the most valuable, perhaps the most valuable, of our
sources of evidence. The empiricists are probably
right in restricting science to sense-perceptions and
mental concepts, but they are, perhaps, inconsistent
with their own doctrine in inferring from the evidence
of science that no other knowledge is possible, and
metaphysics an empty dream.

In the earlier chapters of this book, we have found

science treated as a branch of philosophy, with no

Science and independent existence. Gradually we

Philosophy. have traced its annexation of province

after province from the realm of philosophy, its libera-

THE LATEST STAGE 275

tion from philosophic bonds, and the establishment
of its right to sovereign jurisdiction within a kingdom
acknowledged as its own. Now, when we return to
the subject, we find, in a sense, the positions reversed.
Science stands on its own ground, alone, secure ;
philosophy has to frame its systems in conformity
with natural knowledge.

What, then, is the bearing of our present scientific
position, and of the tendencies we have traced in
recent scientific theories, on philosophic thought in
its most broad and general outlines, with which alone
we can deal.

And first let us consider, from this point of view, the
empirical or phenomenal theory of science described
in the last few pages. What is its metaphysical
import ? Does it impel us to philosophic agnosticism ?
Must we conclude that, if no scientific knowledge is
possible of any reality behind phenomena, no know-
ledge of any kind is there attainable ?

In reply, many philosophers would insist on the facts
that it is possible for us to construct a conceptual
model of nature consistent with itself, and consistent
to such an amazing extent with our sense-perceptions,
and hold that these facts are valid metaphysical
arguments that some reality exists outside our minds,
which conforms in some essential way to the picture
we frame of it. True that matter must be very
different from all our ideas of it, true the physical
nature, of energy is incomprehensible, still matter and
energy are probably somethings between which exist
real relations corresponding to the relations postulated
by our scheme of physics, and confirmed in the world
of sense-perceptions. Thus the relations at all events

276 SCIENCE AND THE HUMAN MIND

are realities. Electric current and electromotive
force may be purely conceptual quantities, but the
proportionality between them probably corresponds
to some real property of that external world about
which pure science may tell us nothing, but in which
metaphysical insight insists on belief, and to which
it calls science to witness in an alien court.

Many, too, would say that the fact that the human
mind finds reason in nature is not purely because it is
looking at itself projected there, not purely because,
itself being reasonable, it sorts out and classifies only
those relations in which it can find its own reason
reflected. A human mind can conceive of chaos ;
it can find chaos easily enough when it tackles a new
problem, and often leaves it in chaos at the last. Since
it finds reason and order in nature, then, it may fairly
conclude that nature itself is orderly, that perhaps
after all, in some faint way, natural law has points of
likeness to legal ordinance, and may denote a lawgiver.
This is not science, it is metaphysics once more calling
on science to witness. But metaphysically the argu-
ment has weight ; those who do not wish to see all
the wonders of creation concentrated in the human
mind may still hold, in the old realistic no less than in
the new conceptual sense, that " the heavens declare
the glory of God, and the firmament showeth his
handiwork."

During part of the nineteenth century, the idealistic
philosophies of such men as Kant and Hegel stood in
sharp contrast with the confident naturalism of those
who, like Herbert Spencer, took the impress of the
dominant school of scientific thought, and carried it
over to metaphysics.

THE LATEST STAGE 277

But, as the century drew to a close, the change in
science was paralleled by a corresponding change
in philosophy. The critical examination by Arthur
Balfour of the basis of knowledge, the passing over
of the majority of academic metaphysicians to the
idealistic camp, the constructive pragmatism of William
James with its idea of value as the criterion of truth,
the " creative evolution " of Henri Bergson, are in
one aspect but steps in the same direction, though not
upon the same road.

Bergson's philosophy of change, though unaccept-
able to most metaphysicians, corresponds closely to
the new vitalistic tendencies in biology. With his
wealth of illustration drawn from all our knowledge
of inorganic and organic nature, Bergson is far removed
from the purely a priori philosophers of the older
idealism, while his conclusions are even farther dis-
tant from those of the naturalistic philosophers who
took the typical science of the mid nineteenth century
as their source of inspiration.

The autonomy of life, the purposefulness of the
organism, which, as we have seen, have so impressed
themselves on some contemporary biologists, are to
Bergson the corner-stone of his system. Behind such
phenomena must lie a super-consciousness, free, in-
determinate and incalculable. Breaking into matter,
which is perhaps only a by-product of the creative
impulse, as and where it can, it endows it with some
share of its life — a share trammelled and enmeshed
in matter, but still preserving some of the attributes
of its free and unconfined source.

This process of becoming, this exaltation of the act
of change, abolishes the timeless absolute of older

278 SCIENCE AND THE HUMAN MIND

idealisms. To Bergson time is of supreme signifi-
cance. In it are duration and change, the present
ever eating into the future, the past persisting into
the present. Creative evolution is reality ; the vital
principle presses into new and ever new forms, failing
here and coming to a stop there, but ever pressing
onward, as far from teleology as from mechanical de-
terminism, with " no goal," according to Mr Balfour,
" more definite than that of acquiring an ever fuller
volume of free creative energy."

Life uses matter as its vehicle ; calls on the stored
energy of plant life to support the vital output of the
animal ; fires the explosive material by a touch of
the trigger, and directs the forces thus set at liberty ;
or times the action of the mechanism to take
advantage of the chance accumulations of molecular
energy in the manner of Maxwell's daemon. As
Lodge has pointed out, such action is in full accord
with the physical principle of the conservation of
energy. No work need be done in the processes of
timing and direction.

To Bergson, reason is chiefly concerned not with life
and freedom, but with the determinate mechanism
only introduced into the circle of life by its entangle-
ment with matter. Thus it is that reason is most
at home with material and mechanical conceptions.
It has been evolved to enable us to deal with matter,
the waste product of creation. Hence, in some ways,
instinct is nearer reality than reason. Man touches
reality in those rare moments of crisis when emotion
and insight are fused with intuitive judgment, and his
whole being is alive with the will to act. Then he
knows true freedom, " then he consciously sweeps

THE LATEST STAGE 279

along with the advancing wave of Time, which as it
moves creates."

Now, however fanciful this conception, however
dangerous the exaltation of instinct over calm reason,
it is impossible to overlook its analogy with the corre-
sponding tendency in psychology. There, too, the
reason of man has been found wanting as a complete
explanation of his conduct, his character or his beliefs.
Once more Bergson is in close touch with scientific
tendencies, though many will hold that he carries them
to an unwarranted extreme.

It is of interest to note that Bergson's philosophy is
used by some theologians as an instrument of attack
on rationalism, and by the revolutionary syndicalists
of the Continent as a justification for instinctive
attacks on the social order, when they have no reasoned
account to give of what could take its place. So close
in modern life are the cross-connections between
different branches of human endeavour.

It is possible that danger to science as to society
lies ahead. The dominance of the Universalist
Roman Church nearly stifled the incipient science
of the Northern race at the Renaissance; the
dominance of the Universal proletariat, which some
dread and others acclaim — a proletariat not dis-
similar in race to the Southern rulers of the Roman
Church— may threaten in the future the freedom of
enquiry, the fearless exercise of reason, the full de-
velopment of personality, that form the life-blood
of the Northern race and its scientific achievement.
The Roman Church saw its dogmas threatened by the
new learning, and invoked torture and stake in an
attempt to consolidate its forces. If the same race

280 SCIENCE AND THE HUMAN MIND

once more gains the ascendancy in Northern lands,
as, by the differential birth-rate and the downward
shift of political power, it seems destined to do, it is
difficult to believe that scientific results which threaten
its prejudices or are not in accord with its ideals will
be respected. Science, especially in its newly won
field of sociology, might find itself once more in an
environment where free and healthy growth was im-
possible. Indications are not altogether wanting to
remind us that reason is not always the mainspring
of human action, and that the reign of ignorance and
prejudice may yet again descend as a devastating
blight on the human mind.

We have reached the end of our journey ; we
stand at the frontier, where the country opened up

Science and an(^ Partly surveyed by science touches

the Human the dark forest of the unknown future.

Mind' What will the coming years disclose?

No man can say. He would be indeed bold who

would hazard more than a guess at the direction of

the next few steps.

Yet the story of the development of natural know-
ledge has an importance and a significance beyond
its mere historic interest, great though that may be.
The story of how discoveries were made in the past
throws light on the means by which further advance
becomes possible, and gives a clearer idea of the inner
meaning of what is already known than can be obtained
by non-historical methods.

Scientific laws and theories, when taken from the
conceptual sphere in which they may be rigidly
valid, and referred back to the interpretation of nature

THE LATEST STAGE 281

which suggested them, are essentially provisional.
They are but working hypotheses adapted to the needs
of the passing age. What part of the conceptual
model seemed better adapted to stand as a permanent
representation of nature than the immutability of
the chemical elements, what surer than the Newtonian
dynamics ? Yet, under the pressure of radio-active
phenomena, we have been forced to repudiate the one
as a universal law, and to modify the other to explain
the motion of bodies which approach too nearly the
velocity of light.

Again and again in the course of the preceding
chapters we have traced how a theory, put forward
at a definite stage in the development of a subject,
interprets adequately and successfully existing know-
ledge and points the way for future research. Yet,
a few pages later, we are driven to recount its failure
under the test of ever-advancing thought, and its
supersession by some other hypothesis more adapted
to the needs of the new time, and more fruitful in
suggestions for further work.

Moreover, we have had continually to acknowledge
that the later theory would have been less useful at
the previous stage than the outworn idea it replaced.
We come to see that the test of a successful theory is
not its concordance with absolute truth — with which
indeed we can never compare it — but the humbler and
more practically useful role of giving us a means of
co-ordinating conveniently and succinctly our existing
unconnected pieces of knowledge, and of enabling us
to frame experiments and enquiries calculated to open
up the greatest extent of hitherto unsurveyed territory
in the kingdom of nature. The test of a theory, then,

282 SCIENCE AND THE HUMAN MIND

is whether or no in its day it is a satisfactory " working
hypothesis."

The history of the caloric theory of heat is a good
instance of the successive changes in value of a
scientific idea. This theory of a weightless fluid gave
a vivid conception of heat as a quantity to be
measured, and was indispensable to the earlier
workers in calorimetry. It failed to explain the un-
limited development of heat by friction, and was
accordingly laid on one side during the investigation
of the mechanical aspect of heat studied in the form
of energy. But now that further research has
analysed the concept of energy into the two factors
of intensity and quantity, there are signs that, as
applied to the latter, a modification of the old caloric
theory may once more find a place in the modern
structure.

It is needless to repeat instances. Scientific theories
certainly " mount on stepping stones of their dead
selves to higher things." At our present stage, a
common basis of matter, energy as a quantity constant
in amount, evolution by means of natural selection,
are working hypotheses co-ordinating much of our
knowledge and underlying almost all our researches
into the unknown. They are suited to the age and to
the minds of present investigators, and we have not
yet exhausted their possibilities. But, in the light of
history, it would be rash to proclaim them as absolute,
eternal truth. We may hereafter discover new kinds
of corpuscles and again for a time have to give up the
idea of one basis of matter. Energy may prove to be
conserved only in the limited conditions hitherto
studied, and natural selection fail to explain all the

THE LATEST STAGE 283

wonders of creative evolution. Such a thought need
not hinder the fullest use of those conceptions in our
present stage ; for us, and now, they are true — true
enough, anyhow. But we must keep an open mind
in the future, and beware of blocking an advance by
a blind reliance on the authority of theories which,
by such treatment, are elevated or degraded into
dogmas.

So too with those wider philosophical questions that
for ever rise from scientific problems. The successive
oscillations of thought from mechanical to vitalistic
tendencies has been one of the features of our survey.
At recurrent times, the best work is done under the
inspiration of the hope of unifying the whole of nature
in one comprehensive scheme. The Greek atomists
extended their conceptions of the inorganic world to
cover the phenomena of life, unconscious of the
logical chasms in their reasoning. Some rash material-
ists thought that natural selection had solved all
problems. Once and again the explanation proved
insufficient, and the hope of reducing everything to
one science of nature, for the time at any rate, has
had to be abandoned. We have to be content with
regarding nature from several separate aspects, and
console ourselves for the loss of unity in the thought
of the greater fullness and richness of the manifold
prospect.

Considered mechanically, a man, for instance, is a
somewhat complicated piece of mechanism of certain
dimensions, containing levers of various kinds and
sizes, and conforming to all the conceptual laws of
mechanics, such as gravity, like any inorganic body.
To the chemist he is a chemical laboratory, in which

284 SCIENCE AND THE HUMAN MIND

many changes go on in various organs, to be repre-
sented ultimately by combinations and recombina-
tions among the atoms and molecules of the different
chemical elements which make up his frame. To the
physicist he illustrates processes such as osmosis or
electrolytic conduction, and the atoms of the chemist
are resolved into corpuscles or electrons, the vibrations
of which emit the electromagnetic radiation known as
radiant heat. By the physiologist he is resolved into
a collection of cells, and the changes studied by the
physicist and chemist are considered in their bearing
on the general life of the organism. To the anthropolo-
gist and zoologist the man is an individual of a certain
race which can be placed in its due class among the
other races of men and amid the long sequence of
geological specimens of other animals. To the psy-
chologist the man is primarily a mind, and his typical
product is a thought. To his doctor he is an obscure
and ill-understood piece of machinery, mechanical,
chemical and psychological ; while to his vicar he is
essentially an immortal soul to be saved or lost.

Each action of the man may be dealt with from
many points of view. One of his thoughts to the
parson may be a sin, to the psychologist an illustration
of the effect of suggestion, to the physiologist a func-
tion of the grey matter of his brain, while to the
physicist and chemist the thought may be represented
by electrical or chemical changes in those cerebral
cells.

In the present state of science, it is impossible
to say that any one of these aspects is more funda-
mental than the others, even if we reduce them to the
three main aspects of physics, biology and psychology.

THE LATEST STAGE 285

It is impossible to say which is the man or the thought.
The different aspects are on different planes, incom-
mensurable. A thought is represented by physical
and physiological changes, but it is none the less a
psychological phenomenon, part of the consciousness
of the man and part of his spiritual life.

If, in the distant future, science should approach
towards a complete explanation of a man regarded
from without, expressed in electrical, mechanical or
aethereal terms, it would be within sight of unity in
the scientific domain — of that unity which has been
the dream of so many philosophers and men of
science. Yet, inwardly, the consciousness of that
man would to himself remain an unconquered citadel,
a kingdom of heaven within him.

Without necessarily holding the view of Kant and
his modern followers that the Ego prescribes its own
laws to nature, and sees its own reason reflected in
natural phenomena, it is clear that the particular
scheme of theories in which modern science is ex-
pressed must be regarded as conditional on, and
indeed originated by, the constitution and peculiar-
ities of our minds. As we have said when dealing
with the history of these conceptions, the feeling that
an explanation is more satisfying and fundamental
when expressed in mechanical terms is probably a
consequence of the fact that our minds and bodies
possess a definite muscular sense, so that for us force
is a direct sense-perception. Did we, like the fish-
torpedo, possess a special electric sense, we might
regard electric conceptions as equally or more funda-
mental and satisfying than mechanics. Moreover,

286 SCIENCE AND THE HUMAN MIND

modern science in its essence has been formulated and
developed by the races of North- Western Europe. The
scientific conceptions suitable to interpret natural (and
indeed supernatural) phenomena to our race are not
necessarily suitable for other races. Modern science
might have worn a different guise had it developed in
other peoples, perhaps would never have developed at
all had not the Northern races been impelled to in-
vestigate nature experimentally at the right stage in
the history of the world.

But when all criticism is done, we cannot but pause,
wondering and amazed at the majesty of the temple
of science. Whether we stand within and gaze at
the beauty of its proportions and their concord one
with another, or whether we pass without and trace
the success with which it fits and interprets the spirit
of the landscape, we are equally fain to confess that
it is the grandest work of the human intellect. And,
like a cathedral that has been a shrine for many
generations of the sons of men, it can be altered to
changing needs. No rearrangement of parts of the
superstructure, no addition of mighty tower or soaring
spire, need endanger its foundations. Firm on the rock
of experience, free from the shifting sands of meta-
physical systems, with room on all sides for new aisles
and chapels and altars, it stands, a triumph of truth
and patient perseverance, and an eternal sanctuary for
the human mind.

BIBLIOGRAPHY

IT is impossible to give a complete account of the books
and papers to which the authors are indebted in the pre-
paration of this work. The following list is prepared
primarily as an indication where more detailed informa-
tion on special points may be found. Those works suitable
for the general reader are marked with an asterisk.

CHAPTER I

INTRODUCTION

Also for general reference throughout the book.

History of the Inductive Sciences. W. Whewell. 3 vols.,

1857-
History of Civilization in England. H. T. Buckle. 3rd

ed., 3 vols., 1871.

History of Philosophy. G. H. Lewes. 5th ed. , 2 vols. , 1880.
History of Materialism. F. A. Lange. Eng. trans. , 3 vols. ,

1877.
*The Foundations of the Nineteenth Century. H. S.

Chamberlain. Eng. trans., 2 vols., 1910.
History of the Philosophy of History. Robert Flint.

1893.

*The Races of Europe. W. L. Ripley. 1900.
"History of Mathematics. W. W. Rouse Ball. London,

1901.
Die Mechanik in ihre Entwickelung. E. Mach. 1883.

*Eng. trans., 2nd ed., 1902.
*History of Astronomy. A. Berry. 1898.
Geschichte der Physik. J. C. Poggendorff. 1879.

287

288 SCIENCE AND THE HUMAN MIND

*A History of Chemical Theories and Laws. M. M. Pattison

Muir. 1907.
The Study of Chemical Composition : Its Method and

Historical Development. Ida Freund. 1904.
Klassiker der exacten Wissenschaften. W. Ostwald.

1889, etc.
*Medical History from the Earliest Times. E. T. Withing-

ton. 1894.
*The Science of Life : an Outline of the History of Biology.

J. A. Thomson, (c. 1900.)
*The Cambridge Modern History, the Dictionary of National

Biography, and the *Encyclopsedia Britannica, loth

and nth editions, have been used freely throughout

the work. References are only given for some special

reason

CHAPTER II

SCIENCE IN THE ANCIENT WORLD

*The Dawn of Civilization. G. Maspero. Eng. trans.,

1896.
Religions of Ancient Egypt and Babylonia. A. H. Sayce.

1902.

Die Agyptologie. H. Brugsch. 1891.
The Religion of Ancient Egypt. W. M. Flinders Petrie.

1906.
*^Egean Civilisation. Crete. Encyclopaedia Britannica,

nth ed.
A History of Ancient Greek Literature. Gilbert Murray.

1897.

Early Age of Greece. W. Ridgway. 1901.
*The Greek View of Life. G. Lowes Dickinson. 1896.
History of Greek Philosophy. Ed. Zeller. Eng. trans.,

1881.
*Greek Thinkers. T. Gomperz. Eng. trans., 3 vols.,

1901-5.
Histoire de la Philosophic Atomistique. Mabilleau. 1895.

BIBLIOGRAPHY 289

The Atomic Theory of Lucretius. J. Masson. 1884.
De Rerum Natura. Lucretius. Ed. H. A. J. Munro.

2 vols., 1866.

The Works of Aristotle, translated into English. Claren-
don Press (now appearing).

The Works of Archimedes. T. L. Heath. 1897.
*Medicine. T. Clifford Allbutt. Encyclopaedia Britannica,

nth ed.
The Decline and Fall of the Roman Empire. E. Gibbon.

Ed. J. B. Bury. 7 vols... 1896.
La Cite Antique. F. de Coulanges. 1898.
The Greatness and Decline of Rome. G. Ferrero. Eng.

trans., 2 vols., 1907.

Letters of the Younger Pliny. Ed. J. D. Lewis. 1879.
*Astronomy. Encyclopaedia Britannica.
Foundations of the Nineteenth Century. H. S.

Chamberlain. 1910. Ch. V.: The Entry of the

Jews.
History of the Jews. H. H. Milman. 1830.

CHAPTER III

THE MEDIEVAL MIND

Cambridge Mediaeval History. I. Ch. XX. : Thought

and Ideas. H. F. Stewart.

"The Mediaeval Mind. H. O. Taylor. 2 vols., 1911.
La Connaissance de la Nature et du Monde au Moyen Age.

Ch. V. Langlois. 1911.
*The Universities of Europe in the Middle Ages. H.

Rashdall. 3 vols., 1895.
Illustrations of the History of Mediaeval Thought. R. L.

Poole. 1884.

A Mediaeval Garner. G. G. Coulton. 1911.
History of Christianity under the Empire. H. H. Milman.

1840.

History of Latin Christianity. H. H. Milman. 1855.

19

290 SCIENCE AND THE HUMAN MIND

Histoire des Origines du Christianisme. E. Renan. 8

vols., 1866-83.

*The Growth of Christianity. Percy Gardner. 1907.
The Making of Western Europe. Vol. I. — The Dark

Ages. C. R. L. Fletcher. 1912.
The Dark Ages (European Literature). W. P. Ker.

1894.

The Earthly Paradise. William Morris. 1868-1870.
Sigurd the Volsung. William Morris. 1876.
The Story of Burnt Njal. Sir George Dasent. 1900.
Mohammedanism. Article in Encyclopaedia Britannica.
Malaria and Greek History. W. H. S. Jones. 1909.
The Greatness and Decline of Rome. G. Ferrero. Eng.

trans., 2 vols., 1907.
Bede's Ecclesiastical History of England and the Anglo-

Saxon Chronicle. Bohn's Antiquarian Library.

1871.

*The Goths. H. Bradley. 1891.

*Italy and her Invaders. T. Hodgkin. 2nd ed., 1892.
L'Islamism et la Science. E. Renan. 1883.
Averroes et rAverroi'sme. E. Renan. 2nd ed., 1861.
Thomas Aquinas. Opera. Parma. 25 vols., 1852-73.
Thomas Aquinas. Of God and His Creatures. Abridged

trans, of Summa contra Gentiles. J. J. Rickaby,

SJ. 1905-
New Things and Old in Saint Thomas Aquinas. H. C.

O'Neill. 1909.

*Robert Grosseteste. F. S. Stevenson. 1899.
Roger Bacon. Opera. (Rolls Series.) Ed. J. S. Brewer.

1859.
Roger Bacon. Sa Vie, ses Ouvrages, ses Doctrines.

E. Charles. 1861.

Roger Bacon. Eine Monographic. Schneider. 1873.
Roger Bacon. Opus Magnus. Ed. by J. H. Bridges.

Martin Luther and the Reformation in Germany. Charles
Beard. 1889.

BIBLIOGRAPHY 291

CHAPTER IV

THE RENAISSANCE AND ITS ACHIEVEMENT

""Cambridge Modern History (1902-1911). Vol. I .

Ch. XVI. : The Classical Renaissance. R. C. Jebb.

Ch. XVII. : The Christian Renaissance. M. R. James.
*The Renaissance in Italy. J. A. Symonds. 1897.
Life of Leo X. W. Roscoe. 1805.
*L6onard de Vinci. Gabriel S£ailles. 1906.
Leonardo da Vinci's Note Books. Arranged and rendered

into English by Ed. M' Curdy. 1906.
La Philosophic de Leonard de Vinci. Peladan. 1910.
Giordano Bruno. J. L. M'Intyre. 1903.
Life of Giordano Bruno. T. Firth. 1887.
The Praise of Folly. Erasmus. New ed., 1870.
History of the Conflict between Religion and Science.

J. W. Draper. 1875.

*Galileo, his Life and Work. J. J. Fahie. 1903.
De Magnete. W. Gilbert. 1600. Eng. trans., ed. S. P.

Thompson. 1900.
Physiologia Epicuro-Gassendi-Charltoniana ; or, A Fabric

of Science Natural. Walter Charlton. 1654.
Bacon, Francis, Viscount St Albans. Letters and Life.

J. Spedding. 7 vols., 1861-74.

*Bacon's Essays and the Advancement of Learning. 1902.
Francis Bacon. Works. Ed. Ellis, Spedding and Heath.

1857-70.

Essaies de Montaigne. New ed., 7 vols., 1886-89.
Cartesianism. Encyclopaedia Britannica.
Port Royal. C. A. Sainte-Beuve. 6 vols., 1882.
Port Royal. Charles Beard. 2 vols., 1861.
Lettres Provinciales. Blaise Pascal. New ed., 1853.
Types of Ethical Theory. James Martineau. 2 vols.,

1886.
*Sir Isaac Newton. Life. D. Brewster. 2 vols., 1855.

Opera. Ed. S. Horsley. 5 vols., 1779-85.

292 SCIENCE AND THE HUMAN MIND

Essay on Newton's Principia. W. W. Rouse Ball.

1893-
"Cambridge Modern History. Vol. V., Ch. XXIIL:

European Science. W. W. Rouse Ball and Sir

Michael Foster. 1908.

The Sceptical Chemist. Robert Boyle. 1680.
Boyle, Hon. Robert. Works. Thomas Birch. 5 vols.,

1744.
"Principal Navigations, Voyages, Tramques and Discoveries.

R. Hakluyt. 3 vols., 1598-1600.
New Voyage round the World. By Captain Wm. Dampier.

4 vols., 1703.

Herbal. J. Gerard. 1597.

"History of the Rise and Influence of the Spirit of Rational-
ism in Europe. W. E. H. Lecky. 2nd ed., 2 vols.,

1865.

Christian Mysticism. W. R. Inge. 1899.
Select Discourses of John Smith. H. G. Williams. 1859.
The True Intellectual System of the Universe. Ralph

Cud worth. 3 vols., 1845.
Cambridge Modern History. Vol. VI., Ch. XXIIL:

English Political Philosophy in the Seventeenth and

Eighteenth Centuries. A. L. Smith. 1909.

CHAPTER V

THE PHYSICS OF THE NINETEENTH CENTURY

Lectures on the French Revolution. By Lord Acton.

Ed. J. N. Figgis and R. V. Lawrence. 1910.
Diderot and the Encyclopaedists. John Morley. 1878.
A History of Modern Philosophy from the Close of the

Renaissance to 1880. H. Hoffding. Eng. trans.,

1900.
A History of European Thought in the Nineteenth Century.

J. T. Merz. 2 vols., 1896.
Mechanics. J. Cox. 1904.

BIBLIOGRAPHY 293

*History of Astronomy during theJNineteenth Century.
Agnes M. Clerke. 4th ed., 1903.

The Electrical Researches of the Hon. Henry Cavendish.
Ed. by J. Clerk Maxwell. 1878.

The Theory of Experimental Electricity. W. C. D.
Whetham. 2nd ed., 1912.

The Principles of Chemistry. D. Mendeleeff. 1891.

Theory of Heat. J. Clerk Maxwell. 1880.

Theory of Light. T. Preston. 3rd ed., 1901.

Theory of Heat. T. Preston. 2nd ed., 1904.

Heat. J. H. Poynting and J. J. Thomson. 4th ed., 1911.

Thermodynamics. J. Parker. 1894.

Outline of the Theory of Thermodynamics. E. Bucking-
ham. 1900.

*Experimental Researches in Electricity. Michael Fara-
day. 3 vols., 1844-55.

Bakerian Lectures. Sir Humphry Davy. Philosophical
Transactions of the Royal Society of London. 1806,
1808 and 1809.

Electricity and Magnetism. J. Clerk Maxwell. 1873.

A History of the Theories of uEther and Electricity.
E. T. Whittaker. 1910.

Theory of Solution. W. C. D. Whetham. 1902.

CHAPTER VI

THE COMING OF EVOLUTION

*Darwin and Modern Science. Ed. A. C. Seward. 1909.
From the Greeks to Darwin. H. F. Osborn. 1894.
*The Coming of Evolution. J. W. Judd. 1910.
The Voyage of the " Beagle." Natural History, Geology,

etc. 1839-45.

Reports of Committees of the Royal Society of London.
*Principles of Geology. Sir Charles Lyell. I2th ed.,
2 vols., 1875.

294 SCIENCE AND THE HUMAN MIND

Synthetic Philosophy. Herbert Spencer. 9 vols. , 1860-93.
Principles of Population. T. R. Malthus. 1798.
*The Origin of Species. Charles Darwin. 2 vols., 6th

ed., 1891.

*The Descent of Man. Charles Darwin. 1871.
*Life and Letters of Charles Darwin. Ed. by Francis

Darwin. 3 vols., 1887.
*More Letters of Charles Darwin. Francis Darwin and

A. C. Seward. 1903.
*Life and Letters of Thomas Henry Huxley. Leonard

Huxley. 1900.

*Man's Place in Nature. T. H. Huxley. 1863.
Origin of Civilisation. Sir John Lubbock. 1870. 6th

ed., 1902.

*Primitive Culture. E. B. Tylor. 4th ed., 2 vols., 1903.
Anthropology. E. B. Tylor. 1881.
"•Hereditary Genius. Francis Galton. 1869.
Human Faculty. Francis Galton. 1883.
Natural Inheritance. Francis Galton. 1889.
The Laws of Heredity. G. Archdall Reid. 1911.
"Introduction to Eugenics. W. C. D. and C. D. Whetham.

1912.
*The Family and the Nation. W. C. D. and C. D. Whetham.

1909.
Thus spake Zarathustra. F. W. Nietzsche. Eng. trans.,

1902.

F. W. Nietzsche. Works. Eng. trans., 1896, etc.
The Riddle of the Universe. E. Haeckel. 1900.
Social Evolution. Benjamin Kidd. 1894.
Evidences of Christianity. W. Paley. 1794.

CHAPTER VII

THE LATEST STAGE

*The Recent Development of Physical Science. W. C. D.
Whetham. 4th ed., 1910.

BIBLIOGRAPHY 295

The Conduction of Electricity through Gases. J. J.

Thomson. 2nd ed., 1906.
Radioactivity. E. Rutherford. 2nd ed., 1905.
^Sther and Matter. J. Larmor. 1900.
Physical Optics. R. W. Wood. 1905.
Modern Electrical Theory. N. R. Campbell. 1907.
Zur Elektrodynamik bewegter Korper. Annalen der

Physik, xvii. A. Einstein. 1905.
The Common Sense of Relativity. Philosophical Magazine,

xxi. N. R. Campbell. 1911.

Mendel's Principles of Heredity. W. Bateson. 1909.
*Mendelism. R. C. Punnett. 3rd ed., 1911.
*Heredity and Society. W. C. D. and C. D. Whetham. 1912.
The Science and Philosophy of the Organism. H. Driesch.

1907.
*Is there One Science of Nature ? Hibbert Journal, Oct.

1911 and Jan. 1912. J. A. Thomson.
*The Theory of Life. Presidential Address to the British

Association. E. A. Schafer. 1912.
*Experimental Psychology. C. S. Myers. 1911.
A Manual of Psychology. G. F. Stout. 2nd ed., 1901.
Psychology. J. Ward. Encyclopaedia Britannica.
*Psychical Research. W. R. Barrett. 1912.
Proceedings of the Society of Psychical Research. 1882,

etc.
*Human Nature in Politics. Graham Wallas. 2nd ed.,

1910.
*The Problems of Philosophy. Hon. Bertrand Russell.

1911.

*Introduction to Mathematics. A. N. Whitehead. 1911.
A System of Logic. J. S. Mill, gth ed., 2 vols., 1875.
On Liberty. J. S. Mill. 1859.
On Representative Government. J. S. Mill. 3rd ed.,

1865.

The English Utilitarians. Leslie Stephen. 3 vols., 1900.
* Anthropology. R. R. Marett. 1911.
*The Golden Bough. J. G. Frazer. 2nd ed., 3 vols., 1900.

296 SCIENCE AND THE HUMAN MIND

Themis. Jane Harrison. 1911.

From Religion to Philosophy. F. M. Cornford. 1912.
Philosophy as Scientia Scientiarum. Robert Flint. 1904.
*The Grammar of Science. Karl Pearson. 2nd ed., 1900.
La Science et 1'Hypothese. Henri Poincare. 1902.
La Valeur de la Science. Henri Poincare. 1905.
Scientific Fact and Metaphysical Reality. R. B. Arnold.

1904.

*The Foundations of Science. W. C. D. Whetham. 1912.
Berkeley's Works. Ed. A. C. Frazer. 4 vols., 1901.
Naturalism and Agnosticism. James Ward. 2nd. ed.,

2 vols., 1903.

A Study of Religion. James Martineau. 2 vols., 1889.
A Defence of Philosophic Doubt. A. J. Balfour. 1879.
The Foundations of Belief. A. J. Balfour. 3rd ed., 1895.
The Will to Believe. William James. 1897.
*Varieties of Religious Experience. William James. 1908.
Creative Evolution. Henri Bergson. Eng. trans., 1911.
Matter and Memory. Henri Bergson. Eng. trans., 1911.
Philosophy of Bergson. A. D. Lindsay. 1911.
*Life and Consciousness. Hibbert Journal, October 1911.

H. Bergson.
* Creative Evolution and Philosophic Doubt. Hibbert

Journal, Oct. 1911. A. J. Balfour.
Treatise on Thermodynamics. M. Planck. Eng. trans.,

1903.

The Caloric Theory of Heat. Address to Section A, Brit.
Association. H. L. Callendar. 1912.

INDEX

ABELARD, 83.

Ability, distribution of, 151.

Academia Secretorum Naturae, 127.

Academic des Sciences, 128.

Academies, scientific, 127.

Accademia del Cimento, 127.

Adam, legend of, 26.

ADAMS, JOHN COUCH, 162.

.<ESCHYI us, 34.

^Ether, theory of, 131, 171, 174,

184, 241 et seq.
Age of man, 203.
Agriculture, 22, 23.
Ague, 199.
ALBERTI, 108.
ALBERTUS MAGNUS, 87.
ALCUIN, 71, 149.
Alexandria, 56, 57, 79.
ALFRED THE GREAT, 71.
Almagest, The, 56.
Alpine race, see tinder Race.
America, discovery of, 104.
AMERIGO VESPUCCI, 108.
AMMON, 230.
Anaesthetics, 200.
Anatomy, 53, 1 1 2, 133.
ANAXAGORAS, 35.
ANAXIMENES, 39.
ANSELM, 83.

Antarctic exploration, 194.
Anthropology, 222 et seq.
ANTONIO DELLA TORRE, 109.
Apothecaries, Society of, 138.
AQUINAS, THOMAS, 87 et seq., 125,

145, 146.
Arabia, 78.

Arabian science, 77 et seq.
ARCHIMEDES, 38, 51, 109.
Arian Church, 61, 67, 79.
ARISTARCHUS, 40, 47.
ARISTOPHANES, 35.
ARISTOTLE, 40, 45 et seq., 62. 80,

82, 85, 86, 88, 116, 204, 217,

251.

ARNOLD, MATTHEW, 143.
Asceticism, 63.
Asgard, 74.

Association, mental, 256.
Assyria, 25.

Astrology, 23, 28, 63, 127.
Astronomy, 4, 22, 28, 40, 56, 77,

89, in, 117, 126, 127, 161,

162, 175.
Athens, 38, 69.
Atomic weights, 170 et seq.
Atomists, the Greek, 43, 204, 217,

240, 283.

Atoms, theory of, 43, 53, 1 68, 240.
AUGUSTINE, 64.
Authority, 151.
Autonomy of life, 277.
AVEBURY, LORD, 213, 215.
AVERRHOES, 80, 89.
AVICENNA, 78, 132.
AVOGADRO, AMERICO, 8, 170.

Babylonia, 4, 223.

BACON, FRANCIS, LORD, 91, 120

et seq., 205, 221.
BACON, FRIAR ROGER, 80, 85, 90

et seq.

Bacteria, see Microbes.
Baghdad, 77, 78.
BALFOUR, ARTHUR}., 221, 277.
BATESON, WILLIAM, 246.
BEACONSFIELD, LORD, 225, 259.
" Beagle," Voyage of the, 193, 210.
BECQUEREL, HENRI, 238.
BEDE, THE VENERABLE, 71.
BELLARMINE, CARDINAL, 114.
Benedictine Order, 70.
BERENGARIUS OF TOURS, 83.
BERGSON, HENRI, 277, 279.
BERKELEY, BISHOP, 270.
Bestiary, The, 66.
BIFFEN, R., 248.
Biology, 53, 188, 277.
Birth-rate, 229, 280.
Black Death, the, 99.
BLACK, DR JOSEPH, 165, 167.
BOETIUS, 68, 71, 82.
Bologna, University of, 81.
BORCH, 164.
Botanic gardens, 137

298 SCIENCE AND THE HUMAN MIND

Botany, 137.

BOURGET, 230.

BOYLE, HON. ROBERT, 135, 144.

BOYLE, ROGER, 144.

BRAKE, TYCHO, 126.

British Association at Oxford, 214.

Bronze Age, 31.

BRUNO, GIORDANO, 115, 142.

Bubonic plague, 200.

BUCHNER, 198, 271.

Buddhism, 29, 222.

BUFFON, 139.

BUNSEN, DE, 174, 175.

Calculus, 130.

Caloric theory, 282.

Calorimetry, 168.

CALVIN, 134, 141.

Cambridge Christian Platonists,

144, 257.
Cambridge, University of, 82, 151,

202.

CAMERARIUS, 138.
Carbon, properties of, 194.
Carbonic acid, 165.
CARNOT, SADI, 179.
CARPENTER, W. B., 213.
Cartesian philosophy, 125.
CASSIODORUS, 71.
Caste, 29.

Cathode rays, 235, 238.
Cave men, 226.

CAVENDISH, HON. HENRY, 165.
Celibacy, effect of, 99.
Cell-structure, 196.
Cereals, 22.
Chaldea, 21, 24.
CHAMBERS, ROBERT, 208.
Change, philosophy of, 277.
Chaos, 14, 36, 69, 151.
CHARLEMAGNE, 71.
CHARLES I., 134, 135.
CHARLES II., 128.
Chartres, schools of, 84.
Chemistry, 133, 135, 165.
Chemistry, organic, 194, 251.
China, 10.

Cholera, chicken, 197.
Christianity, 64, 75, 265.
Church, development of, 67, 97,266.
Circulation of the blood, 133.
City life in Italy, 100.
Classification, Linnsean, 139.
Classification, meaning of, 257.

CLAUSIUS, R. J. E.. 179.
CLEMENT IV., 92.
CLEMENT VII., 114.
CLOVIS, 75.
Cnossus, 31.
Colloids, 196.

Colonial expansion, 31, 261.
COLUMBUS, CHRISTOPHER, 104.
Combining weights, 169.
Coming of the North, 72.
Comparative religion, 262.
Compass, mariner's, 119.
Compendium Theologies, 93.
Consciousness, subliminal, 257.
Conservation of energy, 177, 196,

282.

Conservation of matter, 166.
Constantinople, capture of, 101.
Constantinople, council of, 61.
COOK, CAPTAIN JAMES, 192.
COPERNICUS, 114, 218, 226.
CORNFORD, F. C., 5.
Corpuscles, 131, 235, 236, 238, 240,

282.

Cosmogonies, 4, 202.
Cosmogony, Norse, 73.
Council of Constantinople, 61.
Council of Nicsea, 67.
Creation and culture, 14.
Creative Evolution^ 27^.
Cremation, 31.

CROOKES, SIR WILLIAM, 235.
CURIE, M. and MME., 238.
CUVIER, GEORGES, 165, 191, 203.

DALTON, JOHN, 8, 169.

DAMPIER, WILLIAM, 137.

DANTE, 86, 89, 98.

Dark Ages, 68.

DARWIN, CHARLES, 194, 205, 208

et seq.t 226, 249, 251, 254.
DARWIN, ERASMUS, 160, 207,

209.

DARWIN, ROBERT WARING, 209.
DA VINCI, LEONARDO, 105 et seq.,

158, 202.
DAVY, SIR HUMPHRY, 172, 176,

182.

Deaf-mutism, 248.
De Generatione Animalium, 135.
Deists, the English, 146.
Deity, tutelary, 257.
DE LAPOUGE, 230.
De Magnete, 119.

INDEX

Democracy, theory of, 260.
DEMOCRITUS, 43, 44.
DESCARTES, 123 et seq., 128, 144,

145, 205.

Descent of man, 224.
Devil, the, 141, 143, 202.
Discourse of the Winds, 137.
Discovery, voyages of, 103, 104,

136, 192, 194.
DISRAELI, B., see Beaconsfield,

Lord.

Divine Comedy, 90, 98.
Dogma, 17, 19, 35, 220.
Dominants, 246.
Dominicans, So, 91.
DUNS SCOTUS, 80, 95, 145.

Edinburgh Review, 213.

Edinburgh, Royal Society of, 160.

Egypt, 25, 27, 28.

EINSTEIN, 243.

EL BATANI, 77.

Electric discharge through gases,

235;

Electricity, 120, 168, 181, 185.
Electro-magnetic waves, 183, 236.
Electro-magnetism, 183, 236.
Electro-plating, 182.
Electrons, 235.
Elements, 42, 170, 172.
ELGIN, EARL OF, 223.
ELLICOTT, BISHOP, 231.
Embryology, 47, 135, 189, 205.
EMPEDOCLES, 42, 204.
Encyclopaedists, the, 145, 147, 163,

218.

Energy, 42, 176.
Environment, modification through,

207, 250.
Enzymes, 198.
Equality of man, 149.
Equilibrium, theory of, 180.
ERASMUS, 19.

ERIGENA, SCOTUS, 19, 20, 83.
Essay on Population, 208, 210,

212.

Essays, Montaigne's, 122.
Ethnology, II, 216, 222.
EUCLID, 51.
EULER, 145.

Euphrates, valley of, 22, 25.
Europe, races of, see under Races.
Europe, reconstruction of nations,

7L

Evolution, 2Q^etseq., 212,216, 249.
Evolution Crtatrice, 277.
Exercitatio Anatomica, etc., 135.
Exorcism, 24, 52.
Experimental method, 109, 120,

221.

Exploration, scientific, 136, 192,

194.
Eye colour, 248.

Faith and reason, 80, 87, 145.

Faith healing, 144.

Falling bodies, 46, no, 117.

FARADAY, MICHAEL, 158, 182.

Fathers of the Church, 60.

Fermentation, 197.

Feudal system, 151.

FISCHER, 195.

Fittest, survival of the, 210, 221.

FITZGERALD, G. J. , 242, 244.

Fleas, 200.

Fluid theory of electricity, 168.

Fluid theory of heat, 167.

Fluids, imponderable, 167.

Fluxions, method of, 130.

" Force hyperme'canique," 195.

Fossils, in, 201, 202.

FOUCAULT, LEON, 175.

FRANCIS I., 106.

FRANCIS, ST, 16, 98, 226.

FRANKLIN, BENJAMIN, 168.

FRAUNHOFER, JOSEPH, 174, 175.

FRAZER, J. G., 228.

FRESNEL, 173, 241.

Friars, coming of the, 85.

GALKN, 55, 70, 132.

GALILEO, 46, no, 116, 126, 161.

GALLE, 162.

GALTON, SIR FRANCIS, 228.

GALTON, S. J., 160.

GALVANI, 181.

Galvanism, 181.

Galvanometers, 183.

Gardens, botanical, 137.

Gardens, zoological, 139.

Gases, properties of, 170.

Gases, electric discharge through,

235.
r-Li

GAY-LUSSAC, 170.
Geocentric theory, 39, 47, 114.
Geographical conditions, 10.
Geographical discovery, 40, 56, 103,
137, 192.

300 SCIENCE AND THE HUMAN MIND

Geology, in, 201.
Geometry, 22, 51, 124.
GERARD, JOHN, 138.
GIBBS, WILLARD, 180.
GILBERT, DR WILLIAM, 119.
GLADSTONE, W. E., 259.
GLANVILL, JOSEPH, 143.
GOETHE, 206.
Golden Bough, The, 228.
Goths, the, 72.
Gravity, laws of, 129, 162.
GRAY, ASA, 212, 213.
GREATRAKES, VALENTINE, 144.
Greece, 30, 32, 34, 36, 38, 62, 101.
Greek language, 90, 101.
Greek philosophy, 33, 38 et seq.
Greek religion, 32.
GREGORY OF NAZIANUS, 67.
GREGORY THE GREAT, 64, 71.
GREW, NEHEMIAH, 138.
GROSSETESTE, ROBERT, 85.
GUY DE FOULQUES, Q2.

HALES, 164.

HARRISON, FREDERIC, 231.

HARRISON, JANE, 263.

HARVEY, WILLIAM, 133, 195, 205.

Heat, theories of, 176, 179, 282.

HEGEL, 276.

HELMHOLTZ, 180, 196.

HENRIQUE, DOM, 103.

Herbals, 138.

HERODOTUS, 17.

HIPPARCHUS, 40.

HIPPOCRATES, 53, 70, 132.

HOBBES, THOMAS, 143.

HOMER, 31, 52.

HOOKER, SIRJOSEPH, 194,212,213.

HOOKER, SIR W. J., 194.

House of Commons, 227.

Humanists, the, 19.

HUMBOLDT, VON, 137, 192.

Hundred Years' War, 99.

HUNTER, ROBERT, 189.

HUTTON, JAMES, 202.

HUXLEY, T. H., 121, 194, 210, 213,

214 et seq., 224, 231.
HUYGENS, 130, 131, 164.

Hydrogen, 166.
Hymir, 73.

IAMBLICUS, 63.
IBN JUNIS, 77.
Icelandic Eddas, 72.

Idealism, 49, 144, 276.

Ideas, doctrine of, 49.

Imponderable fluids, 167.

Index, the Roman, 115, 125.

India, 10, 29, 77.

Inquisition, the, 133.

Intellectualism, 258.

"Interims Ethik," 65.

Ionia, 38, 41.

Ions, 185, 235, 240.

Ireland, 71.

ISODORE OF SEVILLE, 71.

Italy, 54, 69, 76, 81, 100, 102, 116.

Italy, secular schools, 70.

JAMES, WILLIAM, 277.

ansenism, 126.

ava, skulls from, 226.

ehovah, 4, 231.

ENNER, SIR WILLIAM, 198.

EROME, ST, 64.

EROME OF ASCOLI, 92.

esuits, the, 125, 126.

ewish schools at Alexandria, 58.

ews, the, 18, 58, 79.

OHN OF LONDON, 94.

OHN OF SALISBURY, 84.

OHN XXII., POPE, 96.

otunheim, 73.

OULE, J. P., 170, 176.
Julius Caesar, 260.
JUSTINIAN, EMPEROR, 69.

KANT, 165, 205, 270, 276, 285.
KELVIN, LORD, 179, 180, 243.
KEPLER, JOHN, 16, 126, 141.
KIRCHHOFF, 174, 175.
KNOWLES, JAMES, 231.
KNOX, JOHN, 141.
Kosmos, 193.

LAGRANGE, J. L., 161.
LAMARCK, 203, 207, 215, 249, 260.
Land measurement, 7, 22.
LAPLACE, MARQUIS DE, 161, 162,

201.

LARMOR, SIRJOSEPH, 236, 243.
Latent heat, 167.
Latin, 159.
LAVERAN, 199.
LAVOISIER, 166.
Laws of Nature, 269.
LEIBNIZ, 130, 145, 205.
LEO X., POPE, 1 02.

INDEX

301

LEO XIII., POPE, 87.
LEONARDO DA VINCI, 105 et seq.,

158, 202.

Lettres a un Provincial ', 1 26.
LEUCIPPUS, 43.
Lever, the, 51, no.
LEVERRIER, 162.
Light, wave theory of, 173, 241.
Linnsean Society, 212.
LINN^US, 139.
LISTER, LORD, 200.
LOCKE, JOHN, 146.
LODGE, SIR O. J., 185, 242, 278.
Logic, symbolic, 272.
Lombards, the, 72.
LORENTZ, 236, 242, 244.
Louis XIV., 128.
LUBBOCK, SIR JOHN, 213.
LUCA PACIOLI, 109.
LUCRETIUS, 43, 44.
Lunar Society, the, 160.
LUTHER, MARTIN, 19, 97, 141.
LYELL, SIR CHARLES, 203, 204,

211, 212, 215.

MACH, ERNST, 147, 267.

MAGALHAES, 104.

Magic, 4, 22, 24, 64, 141, 263.

Magnetic storm, 193.

Mahommedanism, 78, 79.

Malaria, 69, 199.

MALPIGHI, 135, 138.

Maltese fever, 200.

MALTHUS, T. R., 208, 209, 212.

Manichseism, 64.

MANNING, H.E. CARDINAL, 231.

MANSON, PATRICK, 199.

Man's Place in Nature^ 224.

MARCONI, 185.

MAKINUS OF TYRE, 56.

MARSH, ADAM, 90.

MARTINEAU, JAMES, 231.

Materialism, 160, 271.

Mathematics, 93, 117, 124, 130,

272.
Matter, problem of, 41, 42, 166,

1 68.

MAXWELL, SIR ANDREW, 144.
MAXWELL, J. CLERK, 241, 278.
MAYER, 196.
MAYOW, JOHN, 164.
Micanique Celeste, 161.
Mechanical theory of the Universe,

147, 153, 186, 220, 255.

Mechanics, 51, 117.
Mediseval mind, the, 35, 59.
Medicine, 28, 52, 55, 70, 77, 78,

132, 197, 198.
Mediterranean fever, 200.
Mediterranean race, see under Races.
MENDEL, G. J., 234, 245.
MENDKLEEFF, 172.
Mendelism, 172.
Metaphysics, 34, 62, 150, 276.
Meteorology, 137, 192.
MICHELSON and MORLEY, 242.
Microbes, 197, 199.
Middle Ages, 59, 217.
Milesian school of philosophy, 38.
MILL, JOHN STUART, 267.

MlNKOWSKI, 243.
Minoan civilization, 31.
Mithraism, 64.
MOHAMED EL BATANI, 77.
Molecules, 170.

MOLESCHOTT, 271.

Monarchy, 261.

MONTAIGNE, MICHEL DE, 122, 125.
MORE, HENRY, 143.
MORE, SIR THOMAS, 227.
MORLEY, JOHN, 231.
MORLEY and MICHELSON, 242.
Mosquitoes, 199.

Mysticism, 16, 18, 29, 39, 42, 83,
97, 126, 158, 218, 220, 231,
265.
Mythology, Chaldaean, 24.

Greek, 32.

Norse, 72.

NAPOLEON BONAPARTE, 163.

Nationality, 261.

Natural history, 191.

Natural History of Animals t 139.

Natural selection, 204, 210, 215,

221, 228, 249,254.
Naturalis Historia, 54.
Nature, experiments of, 221.

laws of, 269.

mechanical view of, 153, 220.
Nebular hypothesis, 162.
Neo-Platonism, 63, 85.
Neo- vitalism, 251.
Neptune, discovery of, 162.
NEWLANDS, 172.

NEWTON, SIR ISAAC, 16, 20, 128
et seq., 146, 173, 215, 218, 226.
Nicsea, Council of, 67.

302 SCIENCE AND THE HUMAN MIND

NICHOLAS IV., POPE, 93.
NIETZSCHE, 230.
Nile, the, 22, 25.
Nominalism, 50, 83, 96.
Northern race, see under Races.
Novum Organum, 122.
Numerals, Indian, 77.

OCCAM, WILLIAM OF, 19, 97, 100,

145-

OERSTED, H. O., 183.
OLAF TRYGGVASON, 74.
Optics, 131.
Opus Majus, 92.
Opus Minus, 92.
Opus Tertium, 92.
Organic Chemistry, 194.
ORIGEN, 20, 61, 102.
Origin of Species ; 206, 211, 212,

214, 216, 222, 224, 230.
OWEN, SIR RICHARD, 213.
Oxford, Meeting of the British

Association, 214.
Oxford Movement, 261, 266.
Oxford University, 82, 151.
Oxygen, 164, 165.

PALISSY, BERNARD, 202.
Paper, invention of, 103.
PARACELSUS, 16, 132, 164, 195.
Paris, University of, 81, 97.
Parthenon, sculptures of, 223.
PASCAL, BLAISE, 125.
PASTEUR, Louis, 158, 197, 198,

200.

Patristic Age, 60.
PEARSON, KARL, 243, 267, 270.
Periodic Law, 172.
Perpetual motion, no.
Persia, 17.

PETER DE MAHARN-CURIA, 94.
PETRARCH, 101.
Philosophica Teutonica, 18.
Philosophy, 6, 8, 33, 62, 69, 125,

150, 217, 219, 251, 274.
Philosophy of change, 277.
Phlogiston, 136, 163.
Physic gardens, 138.
Physiologus, 66.
Physiology, 47, H2, 133, 195,

253-

PICO DEL MlHANDOLA, IO2.

Pilgrim Fathers, 227.
Pisa, Leaning Tower of, 47.

Pitchblende, 238.

PLATO, 34, 48, 49, 62, 82, 88, 217,

272
Platonists, the Christian, 143, 144,

257.

PLINY THE ELDER, 54.
PLOTINUS, 63.
Polarization of light, 173.
POPES :

CLEMENT IV., 92.

CLEMENT VII., 114.

JOHN XXI I., 96.

LEO X. , 102.

LEO XIII., 187.

NICHOLAS IV., 93.
PORPHYRY, 63, 82.
Port Royal, 126.
Portugal, 103.
Pragmatism, 277.
Praise of Folly, 19.
PRIESTLEY, JOSEPH, 160, 165.
Primitive Culture, 228.
PRINCE HENRY THE NAVIGATOR,

103.

Principia, 161.
Principles of Geology > 203.
PROMETHEUS, 26.
Proteids, chemistry of, 196.
PROUT, 172.

Psychical research, 143, 144, 257.
PTOLEMY, 40, 56, 215.
PYTHAGORAS, 16, 39.
PYTHIAS, voyages of, 40.

Quadrivium, 82.

Rabies, 198.
Races :

Alpine, 13, 224.

Northern, 9, 13, 15, 17, 19, 30,
72, loo, 142, 148, 224, 279,
285.

Mediterranean, 12, 16, 17, 54,

74, 224, 279.

Radio-activity, 172, 237, 239.
Radium, 238, 239, 274.
Rationalism, 19, 83, 149, 279.
Realism, 83, 97.
Rats, 200.

"Rattlesnake," voyage of the, 194.
RAY, JOHN, 205.
" Recessive," 247.
REDI, FRANCESCO, 140.
Regne Animal, etc., 191.

INDEX

303

" Reign of Reason," 149.
Relativity, principle of, 243.
Religion, 4, 25, 33, 36, 60, 97, 145,

158, 217, 230, 262, 263, 265.
Renaissance, 99 et seq., 101, 102,

122, 132, 141.

Research, psychical, 143, 144, 257.
Revival of Learning, 81.
Revolution, the French, 149.
REYNOLDS, OSBORNE, 243.
R HAZES, 78.

ROGER BACON, see Bacon, Roger.
Roman Catholic Church, 18, 67, 87,

96, 100, 114, 115, 126, 145, 279.
Rome, 54, 67, 69, 87, 102.
Rontgen rays, 235, 238.
RONTGEN, W., 235.
ROSCELLINUS, 83.

Ross, SIR JAMES, 194.

Ross, SIR RONALD, 199.

ROUSSEAU, J. J., 149.

Royal Institution, 182.

Royal Society of London, 127, 160,

192, 213.

RUMFORD, COUNT, 176.
RUSKIN, JOHN, 231.
RUTHERFORD, E., 239, 241.

Sagas, Norse, 74.

ST AMBROSE, 66.

ST ANSELM, 83.

ST ANTHONY, 63.

ST ATHANASIUS, 63.

ST AUGUSTINE, 66.

ST BERNARD, 83, 98.

ST FRANCIS OF ASSISI, 16, 98, 226.

ST GREGORY OF NAZIANUS, 67.

ST GREGORY THE GREAT, 64, 71.

ST PAUL, 18.

ST PETER, 18.

ST THOMAS AQUINAS, 87 et seg.t

125, 145, 146.

SAINT-HILAIRE, E. G., 208.
Salerno, schools of, 70.
SALIMBENE OF PARMA, 100.
SALISBURY, MARQUESS of, 174.
Salvation, 60.

SAVONAROLA, GIROLAMO, 102.
Scandinavia, 72.
Scepticism, 19, 34.
SCHELLING, 206.
SCHLEIDEN, 196.

Scholar Gipsy, The, 143.
Scholasticism, 95.

Schoolmen, the, 84.
Schools, Arabian, 79.

cathedral, 81.

Dominican, 80.

secular, 81.

SCHWANN, 196, 197.

Science, natural, 6, 9, 10, 16, 29,
61, 76, 77, 80, 145, 150, 153,
159, 186, 1 88, 231, 233, 274,
280.

SCOTT, SIR WALTER, 261.
Secular schools in Italy, 70.
SELBORNE, EARL OF, 231.
SERVETUS, MICHAEL, 134, 142.
Sex-organs of plants, 138.
SHAKESPEARE, WILLIAM, 260.
SIDGWICK, HENRY, 231.
Signatures, doctrine of, 137.
Silkworm disease, 197.
SIMON, PIERRE, MARQUIS DE LA-
PLACE, 161.
Skeptical Chemist, 135.
Skulls, 12, 215, 224, 226.
SMITH, WILLIAM, 203.
SNORRI STURLESON, 72.
Societies :

Linnsean, 212.
Lunar, 160.
Metaphysical, 231.
Royal, 127, 160, 192, 213.
Royal, of Edinburgh, 160.
Sociology, 148, 149, 250.
SOCRATES, 35.
SODDY, F., 239.
Solutions, properties of, 185.
SOPHOCLES, 34.
Sorcerers, 24.
Spain, 79.

SPALLANZANI, ABBE, 140.
Spectrum analysis, 172, 174.
SPENCER, HERBERT, 206, 221, 267,

276

Spontaneous generation, 140.
Spy, skulls at, 226.
STAHL, G. E., 136, 195.
STANLEY, A. P., DEAN, 231.
Steam engine, 155.
STENSEN, NICOLAUS, 202.
STEPHEN, LESLIE, 231.
STEV|N, 126.
Stoics, the, 62.

STOKES, SIR GEORGE, 158, 174.
Subliminal consciousness, 257.
Sugar, preparation of, 195

304 SCIENCE AND THE HUMAN MIND

Summa Philosophica contra Gentiles ',

87.

Survival of the fittest, 221.
Symbolism, 64.
Syndicalism, 279.
System of Nature ', 139.
Sy steme dii Monde, 161.

Tabu, 257, 264.

TAFEL, 195.

TARTAGLIA, 109.

Teleology, 221, 278.

TENNYSON, ALFRED, LORD, 218,

231.

TERTULLIAN, 83.
Textual criticism, 61, 91.
THALES, 38.
Theology, 6, 34, 60, 80, 87, 93,

145, 150, 231, 262.
Theory of the Eartht 202.
Thermodynamics, 179.
THOMAS AQUINAS, see Aquinas,
THOMPSON, ARCHBISHOP, 231.
THOMSON, SIR WM., see Kelvin,

Lord.
Thot, 27.
Tigris, 25.
TITUS, 79.
TORRICELLI, 126.
TOSCANELLI, PAOLO, 108.
Totemism, 5.
Trigonometry, 56.
Trivium, 82.
TURGOT, 149.
Tutelary deities. 257, 264.
TYCHO BRAKE, 126.
TYLOR, E. B., 228.
TYNDALL, JOHN, 231.

UBALDI, no.
Universals, 82, 88, 272.
Universities, 81, 82, 151, 161.
Uranium, properties of, 238.
Uranus, 161.
Urea, 195.
Utilitarianism, 261.
Utopia, 227.

Vaccination, 198.
Venus, transit of, 192.
VESALIUS, ANDREAS, 133.
Vestiges of Creation, 208.

Vesuvius, eruption of, 55.

VIRCHOW, 216.

VIRGIL, 86.

Vis plastica, 202.

Vitalism, 277.

Vital principle, 136, 195.

VOLTA, 181.

VOLTAIRE, 19, 146.

VON BAER, 190.

VON HELMHOLTZ, 180, 196.

VON HUMBOLDT, 137, 192.

Vortex rings, 243.

Vortices, theory of, 126.

Voyage of the " Beagle," 193.

of the "Challenger," 194.

of the "Rattlesnake," 194.
Voyages of Wm. Dampier, 137.

WALLACE, ALFRED R , 205, 208,

212.

Watchers of the night, 28.
Water, analysis of, 166.
WATERSTON, 170.
Wave theory of light, 173.
Waves, electric, 183.
Waves, electromagnetic, 241.
WEDGWOOD, JOSIAH, 209.
Weights, combining, 169.
Weights and measures, 21.
WEISMANN, 250.
WESLEY FAMILY, 144.
West Goths, 79.
Wheat, properties of, 248.
WHICHCOTE, BENJAMIN, 144.
WHITEHEAD, DR A. N., 258.

WlLBERFORCE, BlSHOP SAMUEL,
214.

WILLIAM OF CHAMPEAUX, 83.
WILLIAM OF OCCAM, 96.
WILSON, C. T. R., 241.
Wireless telegraphy, 185.
Witchcraft, 141.
Wittenberg, University of, 97.
WOHLER, FRIEDRICH, 195.
WOLFF, C. F., 190
WOODWARD, JAMES, 202.

XENOPHANES, 33.

Yeast, properties of, 197.
YOUNG, THOMAS, 173, 241.

Zodiac, signs of, 23.

PRINTED BY KKILL AND CO., LTD., EDINBURGH

BOOKS BY THE SAME AUTHORS

THE RECENT DEVELOPMENT OF
PHYSICAL SCIENCE

AN ACCOUNT FOR THE GENERAL READER
OF THE PRESENT POSITION OF PHYSICS

John Murray, 1904. Fourth Edition, 1909. 53. net.

CONTENTS. — Introduction ; The Philosophical Basis of
Physical Science ; The Liquefaction of Gases ;
Fusion and Solidification ; The Problems of
Solution ; The Conduction of Electricity through
Gases ; Radio-activity ; Atoms and jEther ;
Astro-physics.

"Mr Whetham . . . has performed a difficult task with
conspicuous success. His exposition is as clear and simple as
the nature of the subject permits, and his language is felici-
tous."— Times.

"It is a welcome sign that Mr Dampier Whetham should
produce a work which can make a direct appeal to the educated
public by its lucid style and the unmistakable grasp of an original
investigator." — Standard.

"We cannot imagine a more helpful treatise for those
educated men who find a difficulty in keeping up with advances
along lines in which they are anxious to maintain an intellectual
interest," — Westminster Gazette.

BOOKS BY THE SAME AUTHORS

A HISTORY OF THE LIFE OF
COLONEL NATHANIEL WHETHAM

A FORGOTTEN SOLDIER OF THE
CIVIL WARS

Longmans, Green, and Co., 1907. 8s. 6d. net.

" The immediate purpose of this book is to record the career of a
typical soldier of high class, who, either in the field or in administration,
served continuously throughout the Civil War and up to the day of
the Restoration. But in pursuit of that purpose the authors have
established far wider claims to attention. They have made a real
contribution to a clear understanding of the conditions of the conflict,
from the first blow to the final stage, when, under Monck's consummate
guidance, the civil power triumphed over the rule of the sword ; and
their work should secure permanent recognition, not merely as a fine
result of patient and discriminating research, but also as a valuable
addition to the general literature of the subject. . . . Colonel Whetham
did nothing heroic or dashing on the great scale ; he did not even take
part in any of the more grandiose actions of the war. He was not
a Rupert or a Cromwell, a Hampden or a Falkland. He was not a
Monck, but * a man of the type of Monck — a soldier and administrator
loyal to his commission, and not meddling in politics or religion more
than he could help.' Of few words, but capable, vigilant, and prompt
of action, he was always sought after to fill positions of trust, made no
mistakes, took his own line with great effect at critical moments, and
left a life of incessant activity as unobtrusively as he had entered it.
To present such a figure attractively and, we may say, educatively,
from the meagre materials available, has been no light task ; and we
are sincerely grateful to those who have performed it. ...

" Rich in illustration, drawn in great measure from original sources,
this book is refreshingly free from superfluous matter ; and its style
presents the directness, and restraint regarding the intrusion of personal
sentiments, which belong to true scholarship. We scarcely think of its
authorship as we read, and the knowledge is so unobtrusively displayed
that we are apt to forget the industry by which alone it could have been
acquired." — Athenaum,

9

BOOKS BY THE SAME AUTHORS

THE FAMILY AND THE NATION

A STUDY IN NATURAL INHERITANCE
AND SOCIAL RESPONSIBILITY

Longmans, Green, and Co., 1909. 75. 6d. net.

" Those who wish to know what science has to say
on a subject of profound interest cannot do better
than study this book." — The Times.

"A quite excellent piece of exposition — the best
handbook we have seen for getting an accurate and
clear idea of the principal facts and hypotheses
current to-day." — Manchester Guardian.

" ' The Family and the Nation ' presents a broad,
and yet concise, summary of modern thought and
work on the subject, which is sound, judicial, and
yet easy of perusal." — The Lancet.

" The volume illustrates the growing tendency
among sociologists to think biologically. It is ably
done — evidently the product of long and careful
work — and ought to be provocative of very serious
thought." — Birmingham Post.

BOOKS BY THE SAME AUTHORS

HEREDITY AND SOCIETY

Longmans, Green, and Co., 1912. 6s. net.

" For sociology this is the most important book that
its authors have published ; indeed, it may rank as
one of the most remarkable contributions to social
and political theory in recent years. . . . Their
argument against women's suffrage strikes us as
almost the only one we ever encountered deserving
complete intellectual respect." — Manchester Guardian.

"One cannot summarize the essays, and most of
them are beyond criticism. They must be read." —
C. B. DAVENPORT in Science (U.S.A.).

" { Heredity and Society ' may be confidently re-
commended to all who wish to study Eugenics on
its broad applications — a recommendation given with
all the more confidence because the late Sir Francis
Galton, the founder of this science, . . . described
the authors' former work, 'The Family and the
Nation/ as c the best book out ' on the subject." —
Major LEONARD DARWIN in the Charity Organization
Review.

BOOKS BY THE SAME AUTHORS

BACK TO THE LAND

vt ^Medley

BY C2
Longmans, Green, and Co. 1910. 45. 6d. net.

" The book is certainly one to read, and we
proclaim him possessed of a dull wit who does
not thoroughly enjoy it, and concede to its authors
a soul of humour and other things that merit
human praise." — The World.

" Very clever, very sniffy, and very well-bred.
A very well-bred and tasteless book, so merely
clever as to be almost dull, which is a singular
achievement." — The Daily Chronicle.

"A wholly delightful and irresponsible story
of house-hunting. ... A vehicle for wise and
witty remarks on men and things." — The Church
Times.

"A book that has given me infinite amuse-
ment. They seem to have carried away from
their house-hunting some delicious reminiscences."
— The Sphere.

BOOKS BY THE SAME AUTHORS

AN INTRODUCTION TO
EUGENICS

Bowes and Bowes, Cambridge. Macmillan and Co.,
London, is. net. 1912.

"A useful introduction to the study of
eugenics. ... It contains the short and simple
annals of the subject, a statement as to what
constitute c racial qualities,' and an account of
the various methods by which knowledge has
been or may be acquired. It concludes with
a chapter on the construction of society and a
descriptive bibliography." — Nature.

THE FOUNDATIONS OF SCIENCE

THE PEOPLE'S BOOKS

Jack and Co., Edinburgh.
6d. 1912.

BOOKS BY THE SAME AUTHORS

STUDIES IN NATURE AND
COUNTRY LIFE

A BOOK FOR CHILDREN AND
THEIR PARENTS

Macmillan and Bowes, Cambridge, 1903. 25. 6d. net.

CONTENTS. — PART I. Chapter I. Nature and Obser-
vations ; II. Earth ; III. Air ; IV. Water ;
V. Heat ; VI. Sound ; VII. Light and Colour ;
VIII. The Weather. PART II. Chapter IX.
The Country and its Names ; X. Roads ;
XI. Springs and Streams ; XII. Soil ; XIII.
Fields and Hedgerows ; XIV. Trees and Woods ;
XV. Villages.

" This is a small but very admirable book, to be used by the
intelligent parent or teacher, directly or indirectly, or to be left
accessible to the inquiring mind . . . any properly constituted
child will take an interest in the contents of the book. It teaches
him that he is an observer and tells him what to look at, and it will
prove a most welcome refuge to many a child from the stupidity
of the male and the unscientific attitude of the female parent.
Here, at least, is some one who knows where the weather comes
from and what we may expect in normal seasons, what the ' Times '
map means, and why the dots are so often put in circles on it, and
the like points on which ' grown-ups ' evade the eager questioner.
The first part deals with earth, air, water, heat, sound, light, colour,
and weather ; the second with names, roads, springs, streams, soil,
fields, hedgerows, trees and woods, and villages. Any child who
can take its knowledge and its story separately will be charmed
with the volume." — Spectator.

BOOKS BY THE SAME AUTHORS

THE THEORY OF EXPERIMENTAL
ELECTRICITY

A TEXT-BOOK FOR UNIVERSITY
STUDENTS

Cambridge University Press. Second Edition, 1912. 8s. net.

" Mr Whetham's unique knowledge, not only of the most
advanced theory but also of all matter of experimental methods,
as well as his gift of clear exposition, admirably qualify him for
the task." — Electrical Review.

" Mr Whetham has written exactly the kind of book to inspire a
student with appreciation of what has been achieved by physicists,
and to suggest paths of research which might be followed with
reasonable probability of further discoveries." — Times.

" Mr Whetham's book is an admirable exposition of all that the
theorists have discovered so far. ' To some extent,' he writes in
the preface, { even a scientific text-book must be a piece of litera-
ture and a work of art.' ' Experimental Electricity ' can certainly
claim to be both ... we cannot conceive any earnest student
laying down the book without a desire to help, to the best of his
ability, in solving the riddle with which it closes." — Nature.

A TREATISE
ON THE THEORY OF SOLUTION

INCLUDING THE PHENOMENA OF
ELECTROLYSIS

Cambridge University Press, 1902. xos. net.

" This important work is a most noteworthy contribution to the
literature of physical chemistry, and is bound to rank as a classical
treatise on the subject. Both on account of its thorough and
exhaustive treatment of the subject, and its remarkably clear
and cautious exposition of it, the book is one of unsurpassed
excellence. " — Philosophical Magazine.

" Mr Whetham's book is probably the most complete and satis-
factory treatise on the subject in any language." — Athenaum.

rYNT

UNIVERSITY OF CALIFORNIA LIBRARY
BERKELEY

Return to desk from which borrowed.
This book is DUE on the last date stamped below.

DEC 1 1947

APK 28 1
JUN 16 1348

I5Jun'49GE
SEP 1 6 1949

(«SS

4Apr52DP
PR 12 1953 LU

6Apr'53IWA

23May'37PT

3 LD
JAN 2 9 1962
10 Mar'62LU
REC'D LD

MAR1 B62

LD 21-100m-9,'47(A5702sl6)476

•f?

HHi