UC-NRLF
491
o
i^
ON ARISTOTLE
AS A BIOLOGIST
WITH A
PROOEMION ON HERBERT SPENCER
;EING THE HERBERT SPENCER LECTURE
DELIVERED BEFORE THE UNIVERSITY OF
OXFORD, ON FEBRUARY 14, 1913
D'ARCY WENTWORTH THOMPSON
Price One Shilling net
OXFORD
AT THE CLARENDON PRESS
ON ARISTOTLE
AS A BIOLOGIST
WITH A
PROOEMION ON HERBERT SPENCER
BEING THE HERBERT SPENCER LECTURE
DELIVERED BEFORE THE UNIVERSITY OF
OXFORD, ON FEBRUARY 14, 1913
BY
D'ARCY WENTWORTH THOMPSON
OXFORD
AT THE CLARENDON PRESS
HENRY FROWDE
PUBLISHER TO THE UNIVERSITY OF OXFORD
LONDON, EDINBURGH, NEW YORK, TORONTO
MELBOURNE AND BOMBAY
ON ARISTOTLE AS A BIOLOGIST:
WITH A PROOEMION ON HERBERT SPENCER
HERBERT SPENCER was born when last century was
young, and this century was in its cradle when he passed
away. Ipse Epicurus obit, cried the poet of a philosophy
which of all the systems of antiquity was most kindred to
Spencer's own. A like thought passed through many
men's hearts when Herbert Spencer died men of all
nations and languages, for while Spencer lived his voice
reached far and wide, even to the ends of the earth.
He was a philosopher not speaking to the philosophers,
nor teaching in the schools ; but he had a gift and a
message, so in touch with the temper of his time, that it
made him a speaker, ex cathedra, to the world. No
philosopher of modern times, not Kant himself, has
exercised in his lifetime so wide a dominion. Only here
and there, among men of a very different stamp, in men
like Byron or Rousseau or Tolstoi, do we see that strange
power of captivating the imagination of an age, of speak-
ing with a voice that goes out into all lands. The
foundation under whose auspices we gather here, the gift
of an Indian scholar, reminds us of Spencer's influence
in the East : in still more distant Japan his counsel was
sought when the nation issued from its seclusion to join in
the labours and anxieties of the modern world ; he stirred
the restless blood of Russians and of Poles ; in America
his books were read far more sedulously than at home ;
and all this great influence was won without literary art
267230
4 ARISTOTLE AS A BIOLOGIST
or any charm of magic words, without the fire of Tolstoi,
the poetry of Heine or of Byron, the beauty of Rousseau's
prose. But Spencer had something in common with all
those men, as his popularity was commensurate with their
own. And that bond of likeness lay in the fact that to
men weary of old trammels and of old burdens he seemed
to point, he tried to offer, 1 a way of emancipation, a path
of deliverance from creeds outworn. By the world which
he addressed he was welcomed and acclaimed, in the
spirit in which Heine wished to be remembered, as a
gallant soldier, ein tapfrer Krieger, in the fight for freedom.
Let us recall, with all brevity, some few circumstances
of Spencer's life, that our minds may keep his memory
green.
Of that narrow, ascetic, and fiercely independent home
of his boyhood we have all read or heard with its
atmosphere of struggle, of criticism, of scientific and
political discussion, unrelieved by humour, by letters, or
by art. We remember how he went forth as a lad to
labour, at an age when men have not yet come up to the
University ; and how, as an engineer's assistant, he helped
to plan bridges and direct gangs of navvies on the great
new road to Birmingham and Crewe, and shared in all
the fever and haste of that great period of construction.
These were the years that he spoke of afterwards as ' the
futile part of his life ' ; but it is as plain as an open book
that they were years in which his mind was moulded and
his mechanical outlook on phenomena developed and
confirmed. Again, we remember his years of journalism,
during which, after the appearance of his first book, he
soon emerged from a lonely life, and with the friendship
1 Compare the opening passage of Social Studies (1864). ' " Give us
a guide," cry men to the philosopher. " We would escape from these
miseries in which we are entangled," ' &c.
ARISTOTLE AS A BIOLOGIST 5
of George Eliot and Lewes, Huxley, Tyndall, and many
more, found his place in the world of London. Hence-
forth, his life was so quiet, simple and retired, that we
might say of him, as Heine said of Kant, ' Er hatte weder
Leben noch Geschichte.'
In 1855, in the Principles of Psychology , Spencer affirmed
his belief in the ' development hypothesis ',* as account-
ing for the origin of species ; and as accounting also for the
successive association of ideas, and so, by their becoming
' innate ' and transmissible from generation to generation,
for the gradual development of mind: which latter
investigation, I need hardly say, has since been continued,
by a long line of evolutionary psychologists, in their
several and divergent ways. It is curious to learn from
his Autobiography that about this time, in his talks with
Huxley, it was the latter who still preserved a guarded
attitude, and Spencer who urged upon him, but with still
inadequate and unconvincing arguments, the hypothesis
of organic evolution.
Five years later, a year after the publication of the
Origin of Species, Spencer brought out the prospectus
of his Synthetic Philosophy, that heroic effort to combine,
in a Philosophy of Evolution, the whole range of physical,
mental, and social science. To discover and trace that
one identical phenomenon of Evolution, in the progress
of civilization, in the development of mind, in the course
of nature, in the history of the Universe, was his single
and life-long aim.
He found such tools as he worked with in the current
tendencies of political and economic thought, and in the
recent discoveries or generalizations of science. Of these
latter, on the physical side, the greatest was the principle
1 As already, in 1852, he had done in his essay on the Development
Hypothesis.
6 ARISTOTLE AS A BIOLOGIST
of the Conservation of Energy, the final result of the
doctrine of the correlation of the physical forces, in
establishing which Rumford had led the way ; while
on the biological side he drew inspiration from the fact,
indicated by Aristotle, developed by Wolff and Milne-
Edwards, made into an aphorism by Von Baer, that as
the organism grows it grows continually from the simple
to the complex, from the homogeneous to a greater and
greater heterogeneity. 1
But many years before Von Baer a greater than he had
enunciated the same truth, and had set it forth in even
plainer and better words. It was Goethe, in his Zur
^Morphologic, 2 who laid it down as a law that ' the more
imperfect a being is, the more do its individual parts
resemble each other, and the more do these parts resemble
the whole. The more perfect the being is, the more dis-
similar are its parts. In the former case the parts are
more or less a repetition of the whole ; in the latter case
they are totally unlike the whole. The more the parts
resemble each other, the less subordination is there of one
to the other ; and subordination of parts is the mark of
high grade of organization.' 3 Now these words are found
in the Life of Goethe, by Lewes, Herbert Spencer's closest
friend. We can scarce avoid the inference that it may have
been the poet's insight and the poet's words, quite as much
as Von Baer's, that crystallized in his famous formula of
evolution. And the inference is confirmed by the fact
that, though it was to Von Baer that Spencer was after-
wards in the habit of ascribing the law, yet, on the first
1 The ' law of differentiation ', or of ' organic progress ', was first
propounded by Spencer in his essay on Progress, its Law and Cause
(1857), where he argued that it was also the law of all progress what-
soever.
2 1807 (written in 1795). Republished in Goethe's Werke, xxxvi, p. 7.
3 Lewes, Life of Goethe (1855), 3rd ed. 1875, p. 358.
ARISTOTLE AS A BIOLOGIST 7
occasion when he mentions it, he speaks of it as having
been established ' by the investigations of Wolff, Goethe,
and Von Baer '.*
As in former days Descartes, and as Democritus and
Epicurus in days of old, so did Spencer find in matter and
in motion, or rather in matter and in force, the fabric of
a world. He draws a broad picture, confessedly of a
mechanical kind, of alternate cosmic rhythms of the Uni-
verse, in which as motion is dissipated, so matter cleaves^
from the dispersed and homogeneous into more coherent
and more segregated shapes ; until in the turn of the great
wheel, a new redistribution of matter and motion takes
place, and evolution is inevitably followed by dissolution
at its heels ; so the whole present order perishes, exitio
terras cum dabit una dies. Nevertheless, so vast is the
cosmic rhythm, that again the wheel turns, and the dust
and ashes of a Universe are co-ordinated and integrated
anew, to make ' another and another frame of things,
For ever ! '
All the while Spencer recognizes that Space, Time,
Motion, and Matter itself are remote from Absolute
Reality, and have their source in our own Empiricism.
The ' Persistence of Force ' is the only truth which
transcends experience ; and what we ultimately mean by
the persistence of force is a cause which transcends our
conception and our knowledge.
In his Biology Spencer takes for his keynote his concep-
tion of life, as having for its chief characteristic a con-
tinuous adjustment of the organism to its environment,
of its internal to its external relations. So structure
follows upon function and functional need, and hereditary
transmission hands on to the next generation the advances
1 Von Baer himself claimed no priority. ' Dieses Gesetz ist wohl nie
verkannt worden,' Zur Entwicklungsgesch. (i), p. 153.
8 ARISTOTLE AS A BIOLOGIST
that the past generation has made : life produces organi-
i zation, and not organization life. Again, in certain
- chapters which are by no means the least interesting of
the book, he shows, 1 after the fashion of the engineer,
and from the experience of the bridge-builder, 2 how the
principles of stress and strain are concerned in the fabric,
and in the physiology, of the organism ; how physical
and mechanical relations alter in the organism with
'increasing bulk; 3 and how incident forces of gravity,
growth, and pressure control or determine the shape of
leaf and bone and single cell. Under the guidance of
a wholesome restraint, a whole school of morphologists,
Roux's school of Entwickelungsmechanik, are now investi-
gating these self-same problems, and so bringing to the
help of morphology some of those physical concepts
which began to be the stock-in-trade of the physiologists
when Majendie wrote his Lemons sur les phenomenes
physiques de la Vie (1830).
In the Ethics, Spencer undertakes to establish ' rules of
right conduct ' on a scientific basis, and he does not mini-
mize the difficulty of getting rid of ' supernatural ethics ',
nor of forming a science of ' what ought to be '. Neverthe-
less, he does his best to connect absolute Ethics with his
universal formula of cosmic evolution and equilibration.
Ethics must be based on science, and not on metaphysics.
There is, he holds, not only an Ethic for all reasonable
beings, but a principle of Ethic for all living things ; life
1 As in an earlier essay on The Law of Organic Symmetry, 1859.
2 Even in his Sociology, where he discusses the place of the pontifices
in an archaic priesthood, he seems to dally with peculiar affection
over these old bridge-builders.
< * A curious corollary, or case in point, is found in the fact that
definite limits are set to the size of a terrestrial animal, and still more
to that of a flying bird, while the aquatic animal, comparatively im-
\ mune from gravity, increases in locomotive speed, as a ship does, the
bigger it becomes (Princ. of Biology (2nd ed.), i. 156).
ARISTOTLE AS A BIOLOGIST 9
and not reason is the essential thing. All conservation
implies evolution, and individuality is developed by the
inevitable changes of a changing world. 1 So Spencer
labours, but perhaps in vain, to make the best of the
bellum omnium contra omnes, to find in the biological
process of adjustment a continual tendency to happiness,
and in sociological evolution a tendency to ultimate
harmony ; in the which a somewhat complacent altruism
shall satisfy the egoist, and pleasure will consist in actions
which are salutary to the individual and the race. All
very much as Mr. Bridges puts it :
For Nature did not idly spend
Pleasure ; she ruled it should attend
On every act that doth amend
Our life's condition ;
Tis therefore not well-being's end
But its fruition.
So through all the circle of the sciences, Spencer tried
to satisfy that craving inherent in mankind for
a constructive system, which shall, in a single unity,
frame all the phenomena of the world : for such a unifica-
tion as in Aristotle's hands had endured unshaken for
nigh two thousand years. To bring the world of fact and
the world of Intelligence into the unity of a system is the
task which all philosophers essay, in the light of the
knowledge and the spirit of their time ; but as knowledge
grows, and men's ways and circumstances change, so does
Philosophy itself, like all else in the world, undergo its
own inevitable and endless evolution giving place, if
not to the better, to the new. 2
1 ' C'est la 1'idee capitale qu'il ajoute aux doctrines de Zenon, de
Spinoza et de Volney : ' Guyau, La Morale anglaise contemporaine,
1885, p. 268.
* The last words are quoted from Alden, A Study of Death (1895),
P- J 76; cf. North Amer. Review, January 1913.
B
io ARISTOTLE AS A BIOLOGIST
But let me not omit to say a word of Spencer's attitude
to ' the insoluble mystery ', of his confessio ignorantis, of
his share in that Agnosticism for which Huxley found a
name. ' At the utmost extent of his tether/ to borrow
words from Locke, ' he sat down in quiet ignorance of those
things which he found to be beyond the reach of his
comprehension . '
By a bold abstraction Spencer puts asunder things that
our thought insists shall be conjoined. And, through
relation, association, and causation, he carried to their
bitter end those theories of empiricism, and of the
relativity of knowledge, that were no new thing in
philosophy, but had percolated down to him through
Mansel and through Hamilton, from Locke and Hume
and Kant, through all those who had discussed the
possibility of knowledge in itself ; carried them to their
bitter end, and stripped them bare of the garments of the
old philosophy, of intuition, or of faith, wherewithal they
were wont to be clothed. And in so doing it may seem
to many of us that he stopped short but a little way along
that steep and narrow road, that parvus trames, which is
the Pathway from Appearance to Reality.
Ipse Epicurus obit, decurso lumine vitae ' when the
lamp of life ran low'. And so too Spencer died as it
were but yesterday full of years and of honour.
And to the multitude of friends, disciples, mourners,
gathered at his grave, a wise and eloquent man spoke
a few noble words. He spoke of Spencer's deep affec-
tions and lasting friendships, of the houses that he
entered as an habitual guest and honoured friend ; of
the magnitude of his task, of his unwearied struggle, and
of his joy when his work was done ; of his ' coherent,
luminous, conception of the evolution of the world ' ; of
his exaltation of man's individual freedom, of the ethical
ARISTOTLE AS A BIOLOGIST n
purpose that underlay his quest of truth. And, lastly,
Lord Courtney spoke of Spencer's last brave effort, in the
Riddle of the Universe, to face and scrutinize the im-
placable facts of life : of how in the end he had confessed
himself overawed by the vastness of the unknowable,
appalled by the great vision of Everlasting Law, and
silent in the contemplation of the Infinite and the
Eternal.
And now that I have tried to pay, in not ungrateful
words, our annual tribute to Spencer's memory, as to one
who has been a great influence in our world, whose words
have become part of our familiar speech, and whose
thought has interpenetrated and commingled with our
own, let me proceed for what time remains towards
another, but I hope a cognate, theme.
In passing from Spencer to Aristotle, we turn from the
one philosopher of our own times who has made biology
an intrinsic part of his sociology and his psychology, to
the great biologist of antiquity, who is maestro di color
che sanno, in this science as in so many other departments
of knowledge. And by the analogy of contrast, we can
scarce think of Herbert Spencer's biology without recur-
ring to that of Aristotle, so reverting from a great teacher
of mechanical causation to him who taught us our first
clear lessons of the phenomena of Life. But, save only by
repeating what I have said, that Spencer came to the study
of biology in the spirit and with the equipment of the
engineer, and by declaring that Aristotle seems to me to
have been first and foremost a biologist, by inclination
and by training, I will not attempt to pursue the com-
parison. Let us simply glance at some parts of Aristotle's
Natural History, and attempt to show, in a partial and
elementary way, the influence of that study upon his mind.
12 ARISTOTLE AS A BIOLOGIST
The naturalist is born a naturalist, and we may be sure
that Aristotle was a lover and a student of nature from
a boy ; but it would help us to trace the relation of his
biological studies to his philosophical work if we could
ascertain when his chief biological work was done. It
has often been held that Aristotle devoted himself to
biology as an old man's recreation, after his retirement to
Euboea. This theory is not adequate, and I do not think
it is true. Another legend, that Alexander sent his pupil '.
specimens from his campaigns, Cuvier accepted and
Humboldt denied ; there is no evidence for it, direct or
indirect, in Aristotle's writings, and this tradition also
I believe to be worthless. But there is evidence, of
a geographical kind, that helps us to answer our pre-
liminary question.
Among the isles of Greece there is a certain island,
insula nobilis et amoena, which Aristotle knew well. It lies
on the Asian side, between the Troad and the Mysian
coast, and far into its bosom, by the little town of Pyrrha,
runs a broad and sheltered lagoon. It is the island of
Lesbos. Here Aristotle came and spent two years of
his life, in middle age, bringing his princess-bride from the
petty court of a little neighbouring state where he had
already spent three years. It was just before he went to
Macedon to educate Alexander ; it was ten years later that
he went back to Athens to begin teaching in the Lyceum.
Now in the Natural History references to places in
Greece proper are very few indeed ; there is much more
frequent mention of places on the northern and eastern
coasts of the Aegean, from Aristotle's own homeland
down to the Carian coast ; and to places in and round
that island of Lesbos, or Mitylene, a whole cluster of
Aristotle's statements and descriptions refer. Here, for
instance, Aristotle mentions a peculiarity of the deer on
ARISTOTLE AS A BIOLOGIST 13
a neighbouring islet, of the weasels by the wayside near
another island town. He speaks of the big purple Murex
shells at Cape Lectum, and of the different sorts of
sponges found on the landward and the seaward side of
Cape Malia. But it is to the lagoon at Pyrrha that
Aristotle oftenest alludes. Here were starfish in such
abundance as to be a pest to the fishermen ; here the
scallops had been exterminated by a period of drought, *s
and by the continual working of the fishermen's dredge ;
here the sea-urchins come into season in the winter time,
an unusual circumstance. Here among the cuttlefishes
was found no octopus, either of the common or of the
musky kind ; here was no parrot-wrasse, nor any kind
of spiny fish, nor sea-crawfish, nor the spotted nor the
spiny dog-fish ; and, again, from this lagoon, all the
fishes, save only a little gudgeon, migrated seaward to
breed. And though with no special application to the"
island, but only to the Asiatic coast in general, I may
add that the chameleon, which is the subject of one of
Aristotle's most perfect and minute investigations, is
here comparatively common, but is not known to occur
in Greece at all.
I take it then as probable, or even proven, that an
important part of Aristotle's work in natural history
was done upon the Asiatic coast, and in and near to
Mitylene. 1 He will be a lucky naturalist who shall go
some day and spend a quiet summer by that calm lagoon,
find there all the natural wealth uvaov AeV/3os . . . e^ro?
ee'pyei, and have around his feet the creatures that
Aristotle loved and knew. Moreover, it follows for certain,
if all this be true, that Aristotle's biological studies
preceded his more strictly philosophical work ; and it is
of no small importance that we should be (as far as
1 Perhaps it was here also that Aristotle found his ' Lesbian rule '.
14 ARISTOTLE AS A BIOLOGIST
possible) assured of this, when we speculate upon the
influence of his biology on his philosophy. 1
Aristotle -is no tyro in biology. When he writes upon
Mechanics or on Physics we read him with difficulty :
his ways are not our ways ; his explanations seem
laboured ; his science has an archaic look, as it were
coming from another world to ours, a world before
Galileo. Speaking with all diffidence, I have my doubts
as to his mathematics. In spite of a certain formidable
passage in the Ethics, where we have a sort of ethica more
geometrico demonstrata, in spite of his favourite use of the
equality of the angles of a triangle to two right angles as an
example of proof indisputable, in spite even of his treatise
De Lineis Insecabilibus, I am tempted to suspect that he
sometimes passed shyly beneath the superscription over
Plato's door.
But he was, and is, a very great naturalist. When he
treats of Natural History, his language is our language,
and his methods and his problems are wellnigh identical
with our own. He had familiar knowledge of a thousand
varied forms of life, of bird and beast, and plant and
creeping thing. He was careful to note their least details
of outward structure, and curious to probe by dissection
into their parts within. He studied the metamorphoses
of gnat and butterfly, and opened the bird's egg to find
the mystery of incipient life in the embryo chick. He
1 Pursuing my geographical inquiries a very little further, I have
discovered that of the very large number of place-names mentioned
in the Problems, by far the greater number are situated in Southern
Italy, that is to say in Magna Graecia, or in Sicily ; and I live in
hopes of seeing this work, or a very large portion of it, expunged, for
this and other weightier reasons, from the canonical writings of
Aristotle. In the treatise De Plantts, which is already acknowledged
to be spurious, only three or four geographical names, I think, occur ;
but they likewise are every one of them situated within the bounds of
Magna Graecia.
ARISTOTLE AS A BIOLOGIST 15
recognized great problems of biology that are still ours
to-day, problems of heredity, of sex, of nutrition and
growth, of adaptation, of the struggle for existence, of
the orderly sequence of Nature's plan. Above all he was
a student of Life itself. If he was a learned anatomist,
a great student of the dead, still more was he a lover of
the living. Evermore his world is in movement. The
seed is growing, the heart beating, the frame breathing.
The ways and habits of living things must be known :
how they work and play, love and hate, feed and pro-
create, rear and tend their young ; whether they dwell
solitary, or in more and more organized companies and
societies. All such things appeal to his imagination and
his diligence. Even his anatomy becomes at once an
anatomia animata, as Haller, poet and physiologist,
described the science to which he gave the name of
physiology. This attitude towards life, and the knowledge
got thereby, afterwards helped to shape and mould
Aristotle's philosophy.
I have no reason to suppose that the study of biology
4 maketh a man wise ', but I am sure it helped to lead
Aristotle on the road to wisdom. Nevertheless he takes
occasion to explain, or to excuse, his devotion to this
study, alien, seemingly, to the pursuit of philosophy.
' Doubtless,' he says, 1 ' the glory of the heavenly
bodies fills us with more delight than we get from
the contemplation of these lowly things ; for the sun
and stars are born not, neither do they decay, but are
eternal and divine. But the heavens are high and afar off,
and of celestial things the knowledge that our senses give
us is scanty and dim. On the other hand, the living
creatures are nigh at hand, and of each and all of them
we may gain ample and certain knowledge if we so desire.
1 De Part. Anim. i. 5.
16 ARISTOTLE AS A BIOLOGIST
If a statue please us, shall not the living fill us with
delight ; all the more if in the spirit of philosophy we
search for causes and recognize the evidences of design.
Then will Nature's purpose and her deep-seated laws be
everywhere revealed, all tending in her multitudinous
work to one form or another of the Beautiful.' In some-
what similar words does Bacon, 1 retranslate a familiar
saying : ' He hath made all things beautiful according
to their seasons ; also he hath submitted the world to
man's inquiry.' On the other hand, a most distinguished
philosopher of to-day is struck, and apparently per-
plexed, by ' the awkward and grotesque, even the
ludicrous and hideous forms of some plants and animals '. 2
I commend him, with all respect, to Aristotle or to that
Aristotelian verity given us in a nutshell by Rodin,
1 II n'y a pas de laideur ! '
To be sure, Aristotle's notion of beauty was not
Rodin's. He had a philosopher's comprehension of the
Beautiful, as he had a great critic's knowledge and under-
standing of Poetry ; but wise and learned as he was, he
was neither artist nor poet. His style seldom rises, and
only in a few such passages as that which I have quoted,
above its level didactic plane. Plato saw philosophy,
astronomy, even mathematics, as in a vision ; but Aristotle
does not know this consummation of a dream. The
bees have a king, with Aristotle. Had Plato told us
of the kingdom of the bees, I think we should have
had Shakespearian imagery. The king would have had
his ' officers of sorts ', his magistrates, and soldiers, his
' singing masons building roofs of gold '. Even Pliny,
arid encyclopaedist as he is, can now and then throb
and thrill us as Aristotle cannot do for example, when
1 De Sapientia Veterum (Eccles. iii. u).
2 Ward, op. cit., p. 85.
ARISTOTLE AS A BIOLOGIST 17
he throws no little poetry and still more of music into his
description of the nightingale's song. 1
But let us now come, at last, to exemplify, by a few
brief citations, the nature and extent of Aristotle's zoologi-
cal knowledge. And here, brevity bids me choose between
two ways : either to deal with Aristotle's theories or
his facts, his insight or his erudition. The former are of
the highest possible interest to us, and their treatment
partly includes the latter. But it would take more than
all the time I have, to deal with any one of Aristotle's
theories of generation, for instance, or of respiration
and vital heat, or those still weightier themes of
variation and heredity, the central problems of biology,
or again the teleological questions of adaptation and
r design.
Let me therefore confine myself, almost wholly, to a few
fragments out of his storehouse of zoological and embryo-
logical facts.
Among the bloodless animals, as Aristotle called what
we call the Invertebrates, he distinguishes four great
genera, and of these the Molluscs are one. These are the
cuttle-fish, which have now surrendered their Aristotelian
name of ' molluscs ' to that greater group, which is seen
to include them with the shell-fish, or * ostracoderma '
of Aristotle. These cuttle-fishes are creatures that we
seldom see, but in the Mediterranean they are an article
of food, and many kinds are known to the fishermen.
All, or wellnigh all, of these common kinds were known
to Aristotle, and his account of them has come down
to us with singular completeness. He describes their
form and their anatomy, their habits, their development,
all with such faithful accuracy that what we can add
to-day seems of secondary importance. He begins with
1 H. N. x. 43 (29).
c
i8 ARISTOTLE AS A BIOLOGIST
a methodical description of the general form, tells us of
the body and fins, of the eight arms with their rows of
suckers, of the abnormal position of the head. He points
out the two long arms of Sepia and of the Calamaries,
and their absence in the octopus ; and he tells us, what
was only confirmed of late, that with these two long arms
the creature clings to the rock and sways about like a ship
at anchor. He describes the great eyes, the two big teeth
forming the beak ; and he dissects the whole structure
of the gut, with its long gullet, its round crop, its stomach
and the little coiled caecal diverticulum ; dissecting not
only one but several species, and noting differences that
-, were not observed again till Cuvier re-dissected them.
He describes the funnel and its relation to the mantle-sac,
and the ink-bag, which he shows to be largest in Sepia of
all others. And here, by the way, he seems to make one
of those apparent errors that, as it happens, turn out
to be justified : for he tells us that in Octopus the funnel
is on the upper side ; the fact being that when the
creature lies prone upon the ground, with all its arms
spread and flattened out, the funnel-tube (instead of
being flattened out beneath the creature's prostrate body)
is long enough to protrude upwards between arms and
head, and to appear on one side or other thereof, in a
position apparently the reverse of its natural one. He
describes the character of the cuttle-bone in Sepia, and
of the horny pen which takes its place in the various
Calamaries, and notes the lack of any similar structure in
Octopus. He dissects in both sexes the reproductive
organs, noting without exception all their essential and
complicated parts ; and he had figured these in his lost
volume of anatomical diagrams. He describes the various
kinds of eggs, and, with still more surprising knowledge,
shows us the little embryo cuttle-fish, with its great
ARISTOTLE AS A BIOLOGIST 19
yolk-sac, attached (in apparent contrast to the chick's)
to the little creature's developing head.
But there is one other remarkable structure that he
knew, centuries before it was rediscovered almost in our
own time. In certain male cuttle-fishes, in the breeding
season, one of the arms develops in a curious fashion
into a long coiled whip-lash, and in the act of breeding
may then be transferred to the mantle-cavity of the female.
Cuvier himself knew nothing of the nature or the function
of this separated arm, and indeed, if I am not mistaken,
it was he who mistook it for a parasitic worm. But
Aristotle tells us of its use and its temporary development,
and of its structure in detail, and his description tallies
closely with the accounts of the most recent writers.
Among the rarer species of the group he knew well the
little Argonaut, with its beautiful cockle-shell, and tells
how it puts up its two broad arms to sail with, a story
that has been rejected by many, but that after all may
perhaps be true.
Now in all this there is far more than a mass of frag-"
mentary information gleaned from the fishermen. It is
a plain orderly treatise, on the ways and habits, the
varieties, and the anatomical structure of an entire
group. Till Cuvier wrote there was none so good, and
Cuvier lacked knowledge that Aristotle possessed.
Not less exact and scarcely less copious is the chapter
in which Aristotle deals with the crab and lobster, and
all such crustacean shell-fish, nor that in which he
treats of insects, after their kind. Most wonderful of all,
perhaps, are those portions of his books in which he
speaks of fishes, their diversities, their structure, their
wanderings, and their food. Here we may read of fishes
that have only recently been rediscovered, 1 of structures
1 e.g. Parasilurus A ristotelis, a siluroid fish of the Achelous.
20 ARISTOTLE AS A BIOLOGIST
only lately reinvestigated, of habits only of late made
known. 1 And many such anticipations of our knowledge,
and many allusions to things of which we are perhaps still
ignorant, may yet be brought to light ; for we are still
far from having interpreted and elucidated the whole
mass of Aristotle's recorded erudition : which whole
recorded mass is only, after all, tanquam tabula nau-
fragii.
There is perhaps no chapter in the Historia Animalium
more attractive to the anatomist than one which deals
with the anatomy and mode of reproduction of the cartila-
ginous fishes, the sharks and rays, a chapter which moved
to admiration that prince of anatomists Johannes Miiller. 2
The latter wrote a volume on the text of a page of
Aristotle, a page packed full of a multitude of facts, in
no one of which did Johannes Miiller discover a flaw.
The subject is technical, but the gist of the matter is this :
that among these Selachians (as, after Aristotle, we still
sometimes call them) there are many diversities in the
structure of the parts in question, and several distinct
modes in which the young are brought forth or matured.
For in many kinds an egg is laid, which eggs, by the way,
Aristotle describes with great minuteness. Other kinds
do not lay eggs, but bring forth their young alive, and
these include the Torpedo and numerous sharks or dogfish.
The eggshell is in these cases very thin, and breaks
before the birth of the young. But among them there
are a couple of sharks, of which one species was within
1 e.g. the reproduction of the pipe-fishes (Syngnathi), the hermaphro-
dite nature of the Serrani, the nest-building of the Wrasses, &c., &c.
2 Cf. Cavolini, in his classical Mem. sulla Generazione dei Pesci,
Naples, 1787 : ' E quando io . . . scorro la Storia degli Animali di
Aristotile, non posso non essere da stupore preso, in esse leggendo
veduti quei fatti, che a noi non si son potuti che a stento manifestare :
e rilevati poi con tutta la nettezza, e posti in parallelo coi fatti gia
riconosciuti nel feto del gallo ; ' &c.
ARISTOTLE AS A BIOLOGIST 21
Aristotle's reach, where a very curious thing happens.
Through the delicate membrane, which is all that is left
of the eggshell, the great yolk-sac of the embryo becomes
connected with the parental tissues, which infold and inter-
weave with it ; and by means of this temporary union the
blood of the parent becomes the medium of nourishment
for the young. And the whole arrangement is physio-
logically identical with what obtains in the higher animals,
the mammals, or warm-blooded vivipara. It is true that
the yolk-sac is not identical with that other embryonic
membrane which comes in the mammals to discharge the
function of which I speak ; but Aristotle was aware of the
difference, and distinguishes the two membranes with
truth and accuracy.
It happens that of the particular genus of sharks to
which this one belongs, there are two species differing by
almost imperceptible characters ; but it is in one only of
the two, the yaAeo? Aetos of Aristotle, that this singular
phenomenon of the placenta vitellina is found. It is
found in the great blue shark of the Atlantic and the
Mediterranean ; but this creature grows to a very large
size before it breeds, and such great specimens are not
likely to have come under Aristotle's hands. Cuvier
detected the phenomenon in the blue shark, but paid little
attention to it, and, for all his knowledge of Aristotle, did
not perceive that he was dealing with an important fact
which the Philosopher had studied and explained. In*
the seventeenth century, the anatomist Steno actually
rediscovered the phenomenon, in the yaAeo? Aaos, the
Mustelus laevis itself, but he was unacquainted with
Aristotle. And the very fact was again forgotten until
Johannes Miiller brought it to light, and showed not only
how complete was Aristotle's account, but how wide
must have been his survey of this class of fishes to enable
22 ARISTOTLE AS A BIOLOGIST
him to record this peculiarity in its relation to their many
differences of structure and reproductive habit. I used
to think of this phenomenon as one that Aristotle might
have learned from the fishermen, but, after a more careful
study of Johannes Miiller's book, I am convinced that this
is not the case. It was a discovery that could only have
been made by a skilled and learned anatomist.
In a lengthy and beautiful account Aristotle describes
the development of the chick. It is on the third day
that the embryo becomes sufficiently formed for the
modern student to begin its study, and it was after just
three days (a little earlier, as Aristotle notes, in little
birds, a little later in larger ones) that Aristotle saw the
first clear indication of the embryo. Like a speck of
blood, he saw the heart beating, and its two umbilical
blood-vessels breaking out over the yolk. A little later
he saw the whole form of the body, noting the dispropor-
tionate size of head and eyes, and found the two sets of
blood-vessels leading, the one to the yolk-sac, the other to
the new-formed allantois. In the tiny chick of the tenth
day, he saw the stomach and other viscera ; he noted the
altered position of the heart and great blood-vessels ; he
traced clearly and fully the surrounding membranes ; he
opened the little eye to seek, but failed to find, the lens.
And at length he describes in detail the appearance and
attitude of the little chick, the absorption of the yolk, the
shrivelling of the membranes, just at the time when the
little bird begins to chip the shell, and before it steps out
into the world. While this epitome contains but a part
of what Aristotle saw (and without a lens it would be
hard to see more than he), it includes the notable fact of
the early appearance of the heart, the punctum saliens of
later writers, whose precedence of all other organs was
a chief reason for Aristotle's attributing to it a common,
ARISTOTLE AS A BIOLOGIST 23
central, or primary sense, and so locating in it the central
seat of the soul. And so it was held to be till Harvey's
time, who, noting the contemporaneous appearance of
heart and blood, held that the contained was nobler than*?
that which contained it, and that it was the blood that was (
' the fountain of life, the first to live, the last to die, the
primary seat of the soul, the element in which, as in a
fountain-head, the heat first and most abounds and
flourishes ' ; so harking back to a physiology more
ancient than Aristotle's ' for the blood is the life thereof.' 7 )
All students of the Timaeus know that here Aristotle
parted company with Plato, who, following Hippocrates,
and Democritus, and others, placed the seat of sensation,
the sovereign part of the soul, in the brain. Right or
wrong, it was on observation, and on his rarer use of
experiment, 1 that Aristotle relied. The wasp or the
centipede still lives when either head or tail is amputated,
the tortoise's heart beats when removed from the body,
and the heart is the centre from which the blood-vessels
spring. To these arguments Aristotle added the more
idealistic belief that the seat of the soul, the ruling force
of the body, must appropriately lie in the centre : and he
found further confirmation of this view from a study of
the embryo plant, where in the centre, between the seed-
leaves, is the point from which stem and root grow. And
Ogle reminds us how, until a hundred years ago, botanists
still retained an affectionate and superstitious regard for
that portion of the plant, calling it now cor, now cerebrum,
the plant's heart or brain.
And now is it possible to trace directly the influence of
Aristotle's scientific training and biological learning upon
1 Aristotle's experiments were akin to Voltaire's, who employed
himself in his garden at Ferney in cutting off the horns and heads of
snails, to see whether, or how far, they grew again.
24 ARISTOTLE AS A BIOLOGIST
his sociology, his psychology, or in general on his philo-
sophy ? That such an influence must have been at work
is, prima facie, obvious. The physician who becomes
a philosopher will remain a physician to the end ; the
engineer will remain an engineer ; and the ideas of pure
mathematics, Roger Bacon's ' alphabet of philosophy ',
will find issue and expression in the philosophy of such
mathematicians as Plato, Leibnitz, Spinoza, or Descartes.
Moreover, it is not only the special training or prior
avocation of the philosopher that so affects his mind.
In divers historical periods the rapid progress or the
diffused study of a particular science has moulded the
philosophy of the time. So on a great scale in the present
day does biology ; so did an earlier phase of evolutionary
biology affect Hegel ; and in like manner, in the great days
after Lavoisier, the days of Dalton, Davy and Berzelius, did
chemistry help, according to John Stuart Mill, to suggest a
' chemistry of the mind ' to the ' association ' psychologists.
A certain philosopher, 1 in dealing with this theme, begins
by telling us that ' Mathematics was the only science that
had outgrown its merest infancy among the Greeks '. Now
it is my particular purpose to-day to show, from Aristotle,
that this is not the case. Whether Aristotle's biological
forerunners were many or few, whether or not the Hippo -
cratics (for instance) had failed to raise physiology and
anatomy to the dignity of a science, or having done so,
had only reserved them, as a secret cult, to their own
guild ; in short, whether Aristotle's knowledge is in the
main the outcome of his solitary labours, or whether, as
Leibnitz said of Descartes, praeclare in rem suam vertit
aliorum cogitata, it is at least certain that biology was in
his hands a true and comprehensive science, only second
to the mathematics of his age.
1 Ritchie, Darwin and Hegel, p. 39.
ARISTOTLE AS A BIOLOGIST 25
The influence, then, of scientific study, and in particular
of Biology, is not far to seek in Aristotle's case,. / It has
ever since been a commonplace to compare the state, the
body politic, with an organism, but it was Aristotle who
first employed the metaphor. Again, in his exhaustive
accumulation and treatment of political facts, his
method is that of the observer, of the scientific student,
and is in the main inductive. Just as, in order to under-
stand fishes, he gathered all kinds together, recording
their forms, their structure, and their habits, so he did
with the Constitutions of cities and of states. Those two
hundred and more TroAireuu which Aristotle laboriously
compiled, after a method of which Plato would never have
dreamed, were to form a Natural History of Constitutions
and Governments. And if we see in his concrete, objective
treatment of the theme a kinship with Spencer's Descrip-
tive Sociology, again, I think, a difference is soon apparent,
between Spencer's colder catalogue of facts and Aris-
totle's more loving insight into the doings and into the
hearts, into the motives and the ambitions, of men.
,. But whatever else Aristotle is, he is the great Vitalist,
the student of the Body with the Life thereof, the historian
of the Soul/
Now we have already seen how and where Aristotle
fixed the soul's seat and local habitation. But the soul
has furthermore to be studied according to its attributes,
or analysed into its ' parts '. Its attributes can be
variously analysed, as in his Ethics Aristotle shows.
But it is in the light of Biology alone that what amounts
to a scientific analysis, such as is developed in the De
Anima, becomes possible ; and in that treatise it is only
after a long preliminary physiological discussion that
Aristotle at length formulates his distinctive psychology.
There is a principle of continuity, a wvtytia, that runs
D
26 ARISTOTLE AS A BIOLOGIST
through the scale of structure in living things, and so, little
by little, by imperceptible steps, does Nature make the
passage from plant, through animal, to man. It is with
all the knowledge, summarized in a great passage of the
Natural History, and embodied in this broad generaliza-
tion, that Aristotle afterwards proceeds to indicate the
same gradation in psychology, and to draw from it
a kindred classification of the Soul.
There is a soul which presides over the primary physio-
logical requirement of nutrition, a soul already inherent in
the plant and inseparable from life itself ; it is ?/ TT/)(UTT?
X/O>XT}. Common likewise to all living things are the
physiological functions of growth and reproduction, and
the psychical agencies directing these are concomitant
with, and in fact identical with, the nutrient soul. Sensa-
tion or sensibility, whereby the animal essentially differs
from the plant, distinguishes the atV^rtKr/ ^vxn f the
sentient soul ; and the soul of movement, undisplayed in
the very lowest of animals, presently accompanies the
soul of sensibility. At length the reasoning soul, the
biavorjriKri ^vyji, or vov<s, emerges in man, as the source of
his knowledge and his wisdom. 1 In a brief but very
important passage, 2 with a touch of that Platonic
idealism never utterly forgotten by him (and so apt to
bring Wordsworth to our own minds), Aristotle tells us
that this soul ' cometh from afar ' povov OvpaOev fircuri&ai,
KOL 6tiov clvai fiovov. Yes, in very plain Greek prose,
this is no less than to assert that ' trailing clouds of glory ',
' it cometh from afar.'
But however glorified be the reasoning soul, yet these
parts, these subdivisions of the soul, do not stand apart in
1 I have here borrowed some words from a former address, and from
my notes on the Histona Animalium.
* De Gen. An. ii. 3, 736 b 27. Cf. Brentano, Aristoteles' Lehre vom
Ursprung des menschlichen Geistes, 1911, p. 18.
ARISTOTLE AS A BIOLOGIST 27
mutual exclusiveness, but just as we may discern a triangle
within a square, so is each lower grade of 'tyvyji implicit
in the higher. And as the higher organisms retain the
main physiological faculties of the lower, so do they retain
such psychological qualities as these possess : and
gradually (more and more as we ascend the ladder) do we
find adumbrations of the psychical qualities that will be
perfected in the higher forms. Among the higher
animals, at least, a comparative psychology may be
developed ; for just as their bodily organs are akin to one
another's and to man's, so also have we in animals an
inchoate intelligence, wherein we may study, in one or
another, the psychology of such things as fear, anger,
courage, and at length of something which we may
call sagacity, which stands not far from reason. And,
last of all, we have a psychology of childhood, wherein
we study in the child, at first little different from the
animal, the growing seeds of the mind of man.
But observe before we leave this subject that, though
Aristotle follows the comparative method, and ends by
tracing in the lower forms the phenomena incipient in the
higher, he does not adopt the method so familiar to us all,
and on which Spencer insisted, of first dealing with the
lowest, and of studying in successive chronological order
the succession of higher forms. The historical method^
the realistic method of the nineteenth century, the
method to which we so insistently cling, is not the only
one. Indeed, even in modern biology, if we compare
(for instance) the embryology of to-day with that of thirty
years ago, we shall see that the pure historical method
is relaxing something of its fascination and its hold.
Rather has Aristotle continually in mind the highest of
organisms, in the light of whose integral and constituent
phenomena must the less perfect be understood. So was
28 ARISTOTLE AS A BIOLOGIST
it with one whom the Lord Chancellor of England has
called ' the greatest master of abstract thought since
Aristotle died '. For Hegel, 1 as surely for Aristotle also,
Entwicklung was not a ' time-process but a thought-
2 process'. To Hegel, an actual, realistic, outward, his-
torical evolution seemed but a clumsy and materialistic
philosophy of nature. In a sense, the ' time- difference
has no interest for thought '. And if the lower animals
help us to understand ourselves, it is in a light reflected
from the study of Man.
So grows up, upon a broad basis of Natural History,
the whole psychology of Aristotle, and in particular that
great doctrine of the tripartite soul, according to which
created things ' by gradual change sublimed, To vital
spirits aspire, to animal, To intellectual ! '
In this \j/vx^ of Aristotle there was (in spite of the
passage which I have quoted) a trace of the concrete
and the all but material, which later Greek as well
as Christian thought was not slow to discern and to
modify. But, as a philosopher of our own day reminds
us, it was in relation to a somewhat idealized Body
that Aristotle described that somewhat unspiritual Soul.
Such as it is, it has remained at the roots of our
psychology, even to this day.
/Bergson only partially gets rid of it when he
/recasts Aristotelian psychology on the lines of that
\ branching tree which modern evolutionary biology sub-
\stitutes for the scala Naturae of Aristotle : ./and when he
sees, for instance, in psychological evolution, not the
successive grades of continuous development, through
sensibility and instinct to intelligence, but rather the
splitting up of an original activity, of which instinct
1 Ritchie, op. cit. Cf. Hoffding, in Darwin and Modetn Science.
Cambridge, 1909, p. 449.
ARISTOTLE AS A BIOLOGIST 29
and intelligence are not successive, but separate and
diyrging, outgrowths.
,/In our recent science the Aristotelian doctrine is not
dead. For but little changed, though dressed in new
garments, this Aristotelian entelechy, 1 which so fascinated
Leibnitz, 2 enters into the Vitalism of Hans Driesch ; and
of those who believe with him, that far as physical laws
may carry us, they do not take us to the end : that the
limitations of induction forbid us to pass in thought and
argument from chemistry to consciousness, or (as Spencer
well knew) from Matter to Mind ; 3 that Life is not merely
' an outstanding difficulty, but a veritable exception to
the universal applicability of mechanical laws ' ; that not
to be comprehended under the category of physical cause,
but to be reckoned with apart, is the fundamental con-
ception underlying Life and its Teleology. 4
It is easy so to sketch in simple words the influence of
Aristotle's biological studies upon his method of work,
or to see in his Psychology and his Ethics the results of
his biological analysis of the soul. But his natural science
seems to send a still deeper influence running through the
whole of his philosophy, for better or for worse, which
H ioriv
* Cf. Jacoby, De Leibnitii studiis Aristotelicis, Berlin, 1867.
/ * Cf. Spencer, Princ. of Psychology (para. 63) : ' Though of the two it
' seems easier to translate so-called Matter into so-called Spirit, than to
/ translate so-called Spirit into so-called Matter (which latter is indeed
wholly impossible) ; yet no translation can carry us beyond our
/ symbols. Such vague conceptions as loom before us are illusions con-
i jured up by the wrong connotations of our words.'
* Cf. Kant's views in the Kritik der Urteilskraft and elsewhere, on the
teleological aspect of living organisms, with (for instance) Schleiden
in the Preface to his Grundziige der Botanik (1860) : ' . . . durch die
Darwinsche Lehre die Teleologie aus der Naturwissenschaft voll-
standig heraus, und in die erbauliche oder poetische Rede, wo sie
hingehort, verwiesen wurde 1 ' Cf. also Professor Sidgwick's remarks
on Spencer's ' avoidance of teleological explanation ', in the Ethics
of T. H. Green, &c., p. 141.
30 ARISTOTLE AS A BIOLOGIST
influence I lack the needful learning to fathom and to
describe. I can only see dimly, and cannot venture to
explain, how his lifelong study of living things led to his
rejection of Plato's idealistic ontology, and affected his
whole method of classification, his notion of essentials and
accidents, his idea of ' Nature ' that ' makes nothing in
vain ', his whole analysis of causation, his belief in,
and his definition * of, Necessity, his faith in design, his
particular form of teleology, his conception and appre-
, hension of God.
And now, to close my story. It is in no derogation
of Spencer's commemorative honour that I have spoken
of him together with a greater Philosopher, and one of
the greatest of men. So I have used my hour of Oxford
to speak, and to salute, the name of Aristotle, here where
his spirit has dwelt for six hundred years I who have
humbly loved him since my day began.
We know that the history of biology harks back to
Aristotle by a road that is straight and clear, but that
beyond him the road is broken and the lights are dim.
And we have seen that biology was no mere by-play of
Aristotle's learned leisure, but was a large intrinsic part
of the vast equipment of his mind.
This our science is no petty handicraft, no narrow
discipline. It was great, and big, in Aristotle's hands,
and it is grown gigantic since his day.
It begins in admiration of Nature's handiwork, as she
strews it by the way. It bids us seek through the land, and
search the deep places of the sea. It toils for the health
and wealth of men. It speaks of things humble; it
whispers of things high. It tells (if I dare use the old
theologian's word 2 ) of Laws, ' whose Voice is the harmony
of the World, and whose Seat is the bosom of God.'
s ex (iv - * Hooker.
ARISTOTLE AS A BIOLOGIST 31
Sometimes, as to-day, it brings us by a by-way to the
study of the history of human thought and knowledge,
and introduces us to a company of great men, dwellers
in the ' clear air ' of Athens.
The little Greek I know, first learnt at my Father's
knee, is but a child's plaything to that of many a scholar
here. But I hear, now and then, a welcome given, in
old Hellenic speech, to men who call at that Interpreter's
House wherein Plato and Aristotle show us ' excellent
things, such as will be a help to us in our journey '.
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