University of Virginia Library

BIOLOGICAL CONCEPTIONS
IN ANTIQUITY

The ancients did not distinguish between being alive
and having a soul, which was conceived in various ways
as something that organizes and controls the body.
Lacking optical instruments, they had no concept of
the living cell, nor did they think of flesh or wood as
possibly different from the constituents of nonliving
things. Life was given by the soul, both in animals and
in plants. Biology, as the study of the living, is a modern
concept; when we speak of ancient biology, we mean
the study of the ensouled. At the same time, the differ-
ence between living and nonliving things was less
marked, because the ancients tended to assume that
all matter possesses power and mobility and is quasi-
alive (the assumption that the material world is alive
is known as “hylozoism”).

The early biological conceptions seem to originate
in pre-philosophical reflection upon everyday experi-
ence. A great deal of data was available concerning
husbandry, stockbreeding, hunting, nutrition, medicine
and poisons, childbirth and dying, to which was added
special information from Persian game reserves, from
the wild animals of India, Egypt, and Libya, from the
Babylonian gardens where the fertilization of fig and

palm was practiced, from augury and sacrifices, and
from ritual crafts like root-cutting for drugs. From this
variety of data there arose certain common ideas which
can be conveniently grouped under the topics of the
four elements (Earth, Air, Fire, Water), the mysterious
extra element (aether), heredity, species, classification,
and teleology. But these ideas did not acquire precision
until philosophical argument came to sharpen them.
Agriculture and medicine were conducted by tradi-
tional rule of thumb. It was the early philosophers who
used these data to illustrate and justify their own cos-
mological arguments, and thereby evolved biological
theories which were then taken over by the agricultural
and medical writers (especially the Hippocratics). The
theoretical influence therefore ran mostly from philos-
ophy to biology rather than the other way. Zoology
and botany were not separated from cosmology until
Aristotle departmentalized the sciences; and even he
did not set up autonomous principles in biology, but
applied a conceptual framework from his general phi-
losophy. The earlier biological theories therefore need
to be understood in the context of larger physical
theories. Inevitably Greek philosophy is the best place
to study these ideas. Not that the other ancient civili-
zations lacked biological speculation; but we do not
find there any major biological idea that does not also
appear in the richer and fuller Greek discussions.

I. THE FOUR ELEMENTS

The soul was traditionally associated with blood,
breath, semen, the warmth of life, and the persona.
Each of these retained significance as theorizing de-
veloped. The most universal was the conception of vital
warmth, which was regarded as one aspect of the role
played by heat in the cosmos. Here the early cosmol-
ogists combined three traditional ideas: vital warmth;
the seasonal powers of hot, cold, wet, and dry; and
the four world-masses of fire, air, water, and earth.
Vital warmth was extended from warm-blooded ani-
mals to all animals and even to plants. It clearly meant
more than temperature, for pine wood (which is not
hotter to touch than other timber) was thought to
contain more heat and therefore to burn better. Hotter
plants have better fruit; hotter animals are more intel-
ligent. Animal droppings may still contain the warmth
of life, enabling them to generate maggots. This is the
concept of heat as a stuff, not merely a quality and
not necessarily perceptible, which survived into the
eighteenth-century theory of phlogiston. It was com-
mon ground among ancient scientists, even those who
did not consider heat to be an element. The atomist
Democritus, for instance, who argued that heat is
merely a sensation, nevertheless gave it an objective
basis by saying that it is the round atoms that feel
hot and that form the soul; that the heart contains the
fire of life; that stags grow horns because their bellies
are hot and send the nourishment upwards; that the
owl sees in the dark because she has fire in her eyes.
These views are typical of the age.

As heat is necessary to life, so cold brings death:
it is not mere absence of heat, but a stuff with its own
powers. Wet and dry also figure in early theorizing,
more commonly than other powers, as being necessary
in various forms of liquid and solid. These four were
assimilated to fire, air, water, and earth. The two sets
do not exactly match, but Aristotle eventually recon-
ciled them by a formula of cross-pairing: fire is hot
plus dry, air is hot plus wet, and so on. He held that
hot, cold, wet, and dry are the primitive qualities of
matter but cannot exist in isolation, while fire, air,
water, and earth are the simplest separable elements,
capable of transformation into each other.

Some medical theorists at first opposed the concept
of four elements, arguing that there are other equally
basic powers in the body, such as the sweet, bitter,
salty, acid, astringent, insipid, and that the body con-
tains separate essential liquids (later “humours” from
the Latin translation). After controversy the humors
were agreed to be four—blood, black bile, yellow bile,
phlegm—which were accommodated to Aristotle's ele-
ments by similar cross-pairing: blood is hot plus wet
plus sweet, phlegm is cold plus wet plus salty.... Each
humor was associated with a season and a human
temperament. This systematization lasted through the
Middle Ages.

Heat always seemed the chief active force. Its char-
acteristic action was to concoct materials, to bring
them to fruition, to energize, sometimes to volatilize
or dissolve. Cold caused condensing, coagulation, so-
lidifying. When Aristotle called hot and cold the chief
instruments of nature, he was expressing a universal
view, whose details clearly originated from kitchen and
garden. Water and earth were the materials upon
which hot and cold worked; Aristotle analyzed them
into various kinds of liquid and solid.

The importance of a fruitful balance among ele-
ments, a harmony of opposites, impressed the Greeks
perhaps more than other peoples, and came from them
into medieval European thought. The idea of symmetry
and proportionate blending dominated their medicine,
their art and architecture, their social and political
thinking. The cosmologist Alcmaeon, who was also a
physician, made it his first cosmic principle under the
political metaphor isonomia (“equality of rights”).
When applied to mixtures of materials, it led the way
from a qualitative assessment towards a quantitative
chemistry. But the ancients did not go far in that
direction. Aristotle held that if the proportions of a

mixture were upset, one ingredient could master
(kratein) the others. Wine and water can form a mix-
ture; but a single drop of wine, put into an ocean,
would be overcome and would lose its nature entirely.
Both concepts, proportion and mastery, are important
in his biology, particularly in genetics.

II. PNEUMA

The notion of a mysterious extra element in the
living body began to appear in Aristotle's time, espe-
cially among those inclined towards a materialistic
explanation. Aristotle believed in a special fifth ele-
ment, the aether, but he confined it to the heavens.
In biology he uses a concept of innate breath (pneuma),
which is mingled with vital heat and is present even
in nonbreathing animals. It transmits sensation, and is
the conveyor of soul in the semen. At one point he
compares its generative power with the aether, but
otherwise he defines it as warmed air, which the body
replenishes by respiration.

After Aristotle the pneuma concept spread widely,
with different applications according to the different
philosophical positions. Among medical writers it was
the residuary legatee of unattributed functions, psychic
and sensory. The Stoics equated it with the divine
Logos that permeates nature, identifying pneuma and
aether (which remain confused in the medieval concept
of the fifth element or quinta essentia). Even the atom-
ists posited a special kind of atom to account for the
soul, which Epicurus said consists of atoms of fire, air,
wind, and a nameless fourth kind—thus reducing his
opponents' pneuma to wind but replacing its mysteri-
ous functions with a new mystery.

Aristotle's predecessors had debated whether the
brain or the heart is the center of sensation, and
whether the heart or the liver is the source of the blood.
He decided for the heart in both cases. But in the third
century B.C. the Alexandrian anatomists distinguished
arteries from veins, and isolated the nervous system
with the brain as its base. This led to an elaboration
of pneuma theory: venous blood is formed in the liver,
where it is charged with the lowest grade of pneuma
(Latin spiritus naturalis, “natural spirits” in Renais-
sance medicine); some venous blood flows to the heart,
where it is mixed with “pneuma necessary for life”
(“vital spirits”) and so becomes arterial blood; this flows
to the brain, where its pneuma is purified into “pneuma
used by the soul” (spiritus animalis, “animal spirits”).
To explain the blood's route, Galen in the second cen-
tury A.D. postulated minute passages leading from right
to left ventricle in the heart, for which later anatomists
searched in vain. After Harvey had demonstrated the
circulation of the blood, the whole hypothesis of
pneuma was gradually discarded.

III. GENETICS

It was an ancient question whether the male or the
female contributes the seed which grows into the em-
bryo; the answer to it partly determined a society's
view of blood-kinship and legal inheritance. In classical
Greece the father was thought to be the primary con-
tributor, but they disputed whether the mother pro-
vides merely nutrition (as in the dramatic decision in
Aeschylus' Oresteia) or a second seed which unites with
the father's. Aristotle's analysis of current theories in
his Generation of Animals shows that discussions were
particularly lively in this field, where much evidence
was quoted, some seriously misleading—for example,
that fishes swallow the milt, or that wound-scars have
been inherited (G.A. I. 17-18, III. 5, IV. 1). He himself
opposed the concept of female seed, but it was ac-
cepted by Galen, Avicenna, and the Renaissance scien-
tists, until finally it was superseded by Von Baer's
demonstration of the mammalian ovum. Among many
diverse theories held by the atomists, “pangenesis”
was important: that seed is drawn from every part of
both parents' bodies, to account for resemblances. An-
other was “preformationism”: that every part of the
embryo must preexist in the seed (“for how could hair
grow from non-hair?” said Anaxagoras). Some argued
that males must develop from the father's seed and
females from the mother's; others attributed sex-
differentiation to differences of heat or position in the
uterus. Multiple births, monstrous growths, superfeta-
tion, sterility, were regularly quoted in evidence: to
some they suggested disproportion between two seeds,
to others they suggested excess or deficiency of heat.

A Persian tradition connecting the semen with the
brain and spinal marrow was followed by those who
held the brain to be the center of psychic activity.
Those who held the heart to be the center argued that
semen must come from the blood. A Greek tradition
associated it with foam (aphros, as in Aphrodite). Aris-
totle rationalized this idea in terms of pneuma, which
emulsifies the semen, being present in it as the vehicle
of soul.

Aristotle gathered together these trains of thought
in a formulation based on his own theory of matter
and form. The male seed transmits soul, which is form
and movement; but its somatic part is sloughed away.
The female contributes only the material (the cata-
menia). Among his arguments, he points out that fishes'
eggs do not develop unless sprinkled with the milt,
yet this does not change them quantitatively; and that
certain insects (as he thought) can receive the male
impulse without a transmission of seed. Using his con-
cept of “mastery” he argues that family likeness de-
pends upon the extent to which the male impulse
controls the female material. Malformations, redun-

dancies, sterility, are due to disproportion of materials.

After Aristotle, the concept of female seed was re-
vived by the Alexandrian anatomists, who demon-
strated the genital connections of the ovaries and con-
cluded that these are channels for seeds coming from
the blood. Later Galen demonstrated the oviduct in
sheep; but instead of moving to a concept of mam-
malian ovum, he tried to reconcile this new datum with
Aristotle's view, arguing that the female seed contrib-
utes only nutrition and the allantois, while the male
seed forms the other embryonic membranes (chorion,
amnion) and bodily parts.

It was a universal belief (until Pasteur) that many
insects and plants grow out of rotting materials without
seed. The early cosmologists used this to argue that
life must have begun in that way. A typical account
occurs in the History of Diodorus Siculus in the first
century B.C. In the primeval mud (that is, cold dry earth
mixed with wet rain and the sun's heat) there appear
membranes containing embryo animals of every kind,
which grow up and then reproduce themselves sexu-
ally. There was no ancient theory of evolution out of
simpler forms, and therefore one problem was to ex-
plain how young animals, having appeared sponta-
neously, could survive in the mud long enough to
become mature.

Those like Aristotle, who held that the universe had
no beginning, still had to account for spontaneity. He
argued that pneuma containing vital warmth is some-
times present in water and earth mixed; a foamy bubble
is then formed, out of which may arise eels and certain
of the fishes, testaceans and insects. He would not
however allow that rottenness is a cause, for rottenness
is disintegration whereas only concoction by heat can
generate new life.

IV. SPECIES

In folklore the animals and plants had clear-cut
natures, including moral characterizations such as we
find in Aesop and in the Oriental and African fables.
The ancients believed that some types regularly meta-
morphose into each other, for example, cuckoo hawk
and hoopoe interchange, and wheat can become darnel.
By this they meant a change of identity, not an ambi-
guity between these types, nor a seasonal change (as
stoat to ermine).

Plato was the first to apply a philosophical technique
to the conception of animal types. According to his
theory of Forms, we identify natural qualities by com-
paring them with ideal qualities which may not appear
exactly in nature but are known directly to the mind.
The animal type is an aggregate of characters which
approximate to ideal Forms. The Forms therefore are
an absolute reference point.

Aristotle inverts this analysis, by taking the animal
type as the exact object of knowledge, while its char-
acters vary in precision. Some characters are essential,
some not (for instance, the eye may be essential, and
an eye must have a color, but its actual color is ines-
sential and imprecise). The animal type, namely its
species, is a unified pattern of essential characters and
functions. It is identical in all members of the species.
The variations between individuals are due to their
material makeup, not to their form.

There have been so many conceptions of species in
modern times that it is perhaps useful to say what
Aristotle's conception is not. It is not a statistical aver-
age, not a population, not an approximation, not an
arbitrarily selected type-specimen. On the other hand,
it is not a form imposed by God. It is a type-pattern
that exists in nature as an objective datum: it is there
to be detected within individuals. It differs from any
one individual as absolutely as the mathematical circle
differs from a drawing of a circle. It is this species-
pattern that Aristotle believes to be eternally repro-
duced in nature, for that is the nearest that sublunary
beings can get to the eternal cyclic movement of the
stars. The fact that it may never be exactly reproduced
does not affect his point, which is that nature tends
to reproduce it.

This conception could easily become a belief in fixed
species, but Aristotle did not consider that point; there
was in fact nothing in his biology that was incompatible
with an evolutionary theory, had the question ever
arisen. He accepted reports of new species resulting
from miscegenation (he quotes dog and fox, dog and
wolf, several fishes and birds). He makes only the pro-
viso that interbreeding is limited to animals that are
alike in species, size, and length of gestation, and that
in any case there could not be indefinite production
of new species, because that would defeat nature's
teleology (meaning that there would be no goals, for
the goal is the reproduction of the parent's form). He
emphasizes that the ladder of nature is continuous, and
that many types overlap the borders of classifications.
Moreover his theory of reproduction is aimed at ex-
plaining how the father's form is transmitted and how
the family likeness may come to be disturbed: the
precise goal is that the animal should “beget another
like itself,” and its specific form is something wider
that is only latent in it. There is a contradiction in
his doctrine here: for he says theoretically that species
is the object of science while individual differences are
due to matter and are unknowable, but in practice he
brings to scientific account many characters that are
below specific level—not only family likeness but ines-
sential attributes such as coloration and voice. Just
occasionally he suggests that individuals differ not only

in matter but in form too, since the materials that
individualize them could be stated generally; but he
does not follow this up. (It was followed up by some
medieval scholastics, who thereby removed this diffi-
culty from his theory of individuation.)

Aristotle therefore could have accommodated an
evolutionary theory of species; but he had no need of
it. He had no paleontology, no obsolete species to
consider; similarity of species could be covered by his
theory; and believing that the world had no beginning,
he had no problem of the origins of species. By the
third century A.D. some Stoic and Neo-Platonist theo-
logians had developed the idea that forms and species
are thoughts in the mind of God. It was this idea, rather
than Aristotle's theory, that led later scientists like
Linnaeus to posit the fixity of species.

V. CLASSIFICATION

Animals were traditionally grouped into Birds,
Beasts, and Fishes, air, land, and sea creatures, and
some of them into subgroups like cloven-hoofed,
horned, carnivorous. Plants were grouped as trees,
shrubs, fruiting, leguminous, and others that Theoph-
rastus reports. Popular classification did not go far, and
was unsystematic in that some classes cut across each
other.

Plato developed in several dialogues the logical
technique of “Division,” whereby a large concept is
analyzed into its varieties—for example, the concept
“living on land” is divisible into walking and flying,
and walking is further divisible into quadruped, biped,
and polypod. With it he combined the complementary
technique of “Collection,” whereby data are sorted
into groups by common concepts, and these groups are
further grouped under more general concepts; for ex-
ample, biped and quadruped share the concept walk-
ing, and walking, flying, and swimming share the con-
cept locomotion. Collection is the inductive process
which Division follows and confirms deductively.
Plato's aim was to “track down” and identify concepts
by showing their relationships in a Division.

Plato intended his method to reveal the actual divi-
sions in nature, but when applied to animal characters
it split up natural groups. Aristotle therefore took as
initial data not characters but animal types (which have
multiple characters). Class the species by likeness, then
class the classes by more general likenesses, until you
arrive at the class Animal itself. Then reconsider what
are the most significant distinguishing characters, and
re-divide the classes accordingly down to the individual
species again. You now have an orderly hierarchy of
genera and species, enabling you to define species by
group-characters, to classify new species as they ap-
pear, and to predict characters not yet observed. This
is the same conception that Ray and Linnaeus success-
fully developed, but Aristotle lacked enough data to
make it workable. He also handicapped it unnecessarily
by laying down that within a genus the member-species
must have characters differing only in degree (for ex-
ample, wings of various shapes), whereas between
genera the comparison must be one of “analogy” (as
wing to fin). He began with a division of Animal into
“blooded” (that is, red-blooded) and “bloodless,” and
divided these into (1) man, viviparous quadrupeds,
oviparous quadrupeds, cetaceans, birds, fishes and (2)
crustaceans, testaceans, mollusks, insects. But he points
out that this scheme omits some types (snakes, sponges),
and that below this level the natural subgroups cut
across each other: for example, the classes solid-hoofed,
hornless, ruminant are defeated by the “overlapping”
types pig and camel.

He therefore preferred to arrange the species in an
order of “perfection.” This too was inspired by Plato,
who had set out a rough scala naturae running down-
wards from man, through bipeds, quadrupeds,
polypods, serpents, to fishes; his indices were intelli-
gence and posture. Aristotle took vital heat as his index
of perfection, as shown not only by intelligence and
posture but also by respiration, method of repro-
duction, and state at birth. This method better suited
his view that nature is continuous from plant to animal
(the testaceans and sponges being in both categories).
In his actual practice he often argues from this order
of perfection, but makes almost no use of genus-species
classification.

VI. TELEOLOGY

Teleological explanations in ancient biology are of
several kinds. They have in common the basic meaning
that natural processes occur for the sake of their conse-
quences; they tend towards goals. Traditional religion
ascribed this tendency to the gods, who send rain to
make the crops grow. This conception of providential
teleology could vary from its strong form in Judaic
monotheism to the quite unsystematic religious beliefs
of the Greeks. Opposing the popular ideas of provi-
dence, the early Greek cosmologists claimed to account
for all phenomena by “necessity,” that is by automatic
causes like the hot and the cold. But within their
naturalistic theories there was room for teleology of
another kind, no longer implying providence or pur-
pose. Anaxagoras included “Mind” among his natural
causes, to account for nature's orderliness; Empedocles
included “Love and Strife” to account for complexity;
Diogenes held that the cosmic Air is intelligent, to
account for nature's tendency towards goals. They
were opposed by the atomists, who held that all three
features—orderliness, complexity, and directiveness—

could be explained by random movements of atoms.
These features have remained the chief talking-points
in the debate over teleology, which has continued into
modern times.

Plato argued that the cosmologists merely analyzed
the material constituents of things, and failed to ac-
count for the characters of whole entities as such: for
a whole has a character which is not found by adding
together the characters of its parts. He also criticized
Anaxagoras for not making proper use of his concept
of Mind, for he did not explain how things tend towards
“the best,” nor what “the best” means. Plato's own
concept was a world-soul distinct from the material
elements. He believed in an overall teleology, namely
that nature is coordinated so that the “best” for an
individual cannot be distinguished from the good order
of the cosmos; but control by the world-soul is not
complete, for there is much failure and evil due to
irrational material.

This dualism disappears in Aristotle's analysis. He
still uses Plato's double explanation—material necessity
on the one hand, directiveness or “the final cause” on
the other hand—but he emphasizes that both coexist
in natural movements. Living things contain their own
sources of motion and directiveness. There is no
world-soul or divine providence outside them. The
“Unmoved Mover” (God) which he posits as the sus-
taining cause of motion in the universe, does not elicit
the individual “beginnings of motion” which are all
the time occurring in nature; nor does God originate
or comprehend nature's forms and species. Again,
within nature itself there is no overall design nor coor-
dinating agency, no quasi-conscious purpose. In his
explanations of animal structures the goal is the ani-
mal's own complete state, nothing beyond. For con-
venience he personifies “nature who does nothing at
random, but always does what is best out of the avail-
able possibilities,” and speaks of it as a prudent house-
wife who “apportions” the materials and “uses” the
necessary movements of the elements. In so speaking,
he formulated several principles of nature's economy
which were adopted by later teleologists, such as: one
function to one organ, no duplication of defenses, use
of by-products from one tissue in another. But if taken
literally, these expressions would have to imply an
overall purposiveness in nature, for which there is no
foundation in his philosophy. They must therefore be
rhetorical. His frequent comparison between nature
and craftsman helps to analyze teleological sequences
but does not imply a craftsman in nature. Lucretius
the atomist uses even more colored language about
natura creatrix, which he could not possibly mean. The
one or two occasions when Aristotle seems to suggest
that one animal's advantage is sacrificed to the good
of other species probably mean no more than a general
balance of nature. He never speaks of “purpose” in
nature. His expression for the final cause is “the end
for the sake of which the development occurs,” and
this end is the individual's perfection and reproduction.

The source of directiveness in an animal or plant
is its soul. Aristotle did not agree with Plato that the
soul is a separable entity, but argued that it is the form
of the single body-soul entity. It is both the structural
pattern of the living body, and the motive force which
makes it grow into that pattern. This difficult concep-
tion is closely related with his conception of directive
nature. It is natural for the elements to act according
to their simple properties; but it is equally natural for
them to combine and become organized in complexes,
and in so doing to act against the simple properties.
He takes this development from simple to complex as
a datum, for which he offers no extra-physical cause.
Even where he posits the soul as the cause of develop-
ment, this soul is not something over against the com-
plex of materials: it is the form of the whole complex,
its essential nature as a unity. Where Plato regarded
necessity and directiveness as arising from separate
sources, Aristotle regarded them as arising simulta-
neously within nature. An animal is a process (a “road
to nature” in his words) consisting of many movements,
all natural, which by natural coordination tend towards
the animal's complete form.

There is therefore no “extra factor” such as modern
teleologists posit, no “conatus” (innate striving) irreduc-
ible to the laws of physics. Aristotle's physics no doubt
made it easier to accommodate directiveness, for he
was some way from the concept of an exactly quanti-
tative science, nor had he the theory that bodies are
naturally inert. He may also have been unconsciously
influenced by traditional hylozoism, which represented
nature as behaving like a living being. At any rate,
soul is not enough to account for all of nature's direc-
tiveness, for Aristotle explicitly says that nature pro-
ceeds without a break from the soulless to the ensouled
(P.A. 681a 12, H.A. 588b 4).

When he defends teleology he does not argue pri-
marily from directiveness, like later teleologists, but
from the fact that forms and species exist; from this
fact he then infers directiveness. The object to be
explained is a living animal and its structures. If it were
an artifact—for example a chair—it would not be
enough to define it as “something made of wood,” but
its form must be included. In an animal there is the
further point that it is able to function (for a dead man's
hand is no longer strictly a hand). Therefore the first
thing to grasp is the form and function of the whole
living animal, and only then can one understand its
growth. The parts are “for the sake of the whole”; and

just as a whole differs from the sum of its parts, so
an end differs in kind from the process leading to it.
From the fact that nature regularly produced these
forms, he infers that natural processes tend towards
them.

After Aristotle the Epicurean atomists produced a
counter-theory to make teleology unnecessary. Atoms
have all kinds of shapes, and those that happen to fit
together must tend to interlock when they meet in
random collisions. In this way complexes can be
formed, which may grow very large. Within them
movements will necessarily become restricted to cer-
tain patterns. Having been formed by pure chance,
such a system will become stabilized, so long as it does
not conflict with neighboring systems. For as atoms
continually flow in and out of it, a successful system
will automatically perpetuate itself by rejecting atoms
of incompatible shape, while retaining those that fit.
Furthermore, if a complex part of the system comes
away, it will consist of atoms linked in the same con-
formation as in the parent system. One such system
will be an animal. Innumerable unsuccessful animals
will doubtless be formed, lacking essential organs and
so unable to feed or defend themselves. But sometimes
a successful one will appear, able to survive. Its off-
spring will naturally be of the same conformation.
Teleological explanations are therefore vacuous: the
eye is not produced for the sake of sight, but having
been produced by chance it then creates its own use.

This hypothesis of course could not be an inference
from data; spontaneous generation was the only sup-
porting evidence available. It was a theoretical con-
struction designed to show that random atomic move-
ments would originate complex and stable systems,
which would then reproduce themselves. The atomists'
explanation of the survival of the fittest systems was
indeed a conception of random natural selection. It
was not, however, linked with an evolutionary theory,
though it would have readily lent itself to one if it
had been suggested.

A new kind of teleology appeared in Stoicism, which
was a materialistic theory of divine providence. The
divine pneuma, consisting of warm air, is a continuum
that permeates the whole of nature. Not only souls,
but all forms and abstract constructions, are parts of
the divine, and are somatic; they penetrate natural
objects and hold them in tension. Hence every detail
in nature is continuously controlled by providence,
which coordinates all goals in a predestined design.
In such a conception Aristotle's primary defense of
teleology (that forms cannot be explained by material
causes) is irrelevant. The Stoics based their case on
directiveness, and it was therefore important to ac-
count for every detail teleologically. Galen's exhaustive
treatise On the Use of the Parts (second century A.D.)
shows the difference from Aristotle's conception.
Writing under Stoic influence, Galen analyzes bodily
structures to the smallest detail of tissue and arrange-
ment, to show their uses. Where some detail carries
a disadvantage, he shows that it is for an ulterior
advantage (for example, the skull's thinness aids the
brain's efficiency); positive evils, like disease, are there
for moral training. Aristotle on the other hand depends
upon conceiving the animal as a coherent pattern of
activity, not upon piecemeal explanations of utility,
and he recognizes that “while many things are for the
sake of ends, much else occurs of necessity”: if you
have bone for the sake of rigidity, you must expect
it also to be breakable.

In this way the Stoics contributed the first thorough-
going conception of providential teleology, within a
naturalistic philosophy. This at once creates a problem
of evil; in biology it means that all the inessentials and
imperfections which Aristotle could attribute to “ne-
cessity” must now be shown to be purposed. The Stoic
answer to this problem was unsatisfactory (as were
their answers to the allied ethical problems of free will
and wrongdoing). They confused the issue by trying
to equate providence and nature. And by trying to treat
immaterial things (such as abstract ideas) as if they
were material, they confused design and directiveness.
Subsequent developments, however, clarified the real
issues in the teleological arguments.

The first step was the return of Stoicism to a non-
materialistic theology. With the Neo-Platonists of the
third century A.D., they held that forms are thoughts
in God's mind, from which they emanate into matter
or are imposed upon it. Hence nature exhibits a ra-
tional design which is blurred by matter's intractability.
This was a return to Plato's view and restored the
distinction between abstract and material. The next
step was due to the impact of Judeo-Christian theology,
which introduced the idea (not found in Greek philos-
ophy) that God is not part of the universe, is omnip-
otent, and has created the universe out of nothing.
From this it follows that matter of itself is inert, and
its motion is imparted to it. Natural and supernatural
were now categorically distinguished. Providential
design could no longer be confused with a natural
directiveness. At first indeed Aristotle's conception of
natural teleology seemed impossible, for all movements
in nature must be imparted by God alone. The problem
of evil now became critical, but was answered at this
stage by theological doctrines (such as the Fall of Man)
which do not concern teleology. But as the concept
of inertia developed in physics during the later Middle
Ages, a contrast came to be drawn between the auto-
matic orderly movements of physical bodies and the

supernatural guidance leading to goals. This brought
out a distinction which had been latent but obscure
in Greek physics, between orderliness and directive-
ness. The orderliness of nature had been claimed in
evidence both by Aristotle and by his opponents, the
atomists. But now, and especially after Newton, it
seemed to support only the anti-teleologists: they now
developed a concept of nature working like a machine
by the “laws” of physics, while teleologists had to
produce evidence of God's interference in the causal
nexus. Then in the nineteenth century the Epicurean
conception of random natural selection appeared anew
in association with the Darwinian theory of evolution.
The concept of rigid laws of nature became modified
into a concept of statistical probability. Teleologists
opposed the notion of randomness, but began to argue
less from design and more from directiveness, so mov-
ing closer to Aristotle's natural teleology. But modern
teleology still differs from his insofar as it relies upon
directiveness first, rather than upon forms, and insofar
as it posits an “extra factor” that is not reducible to
physics and chemistry. It is therefore less simple, and
to that extent less rational, than Aristotle's. But al-
though teleology has taken so many different forms,
and has been opposed on different grounds, never-
theless the debate has in a way always been between
the same contestants.

BIBLIOGRAPHY

A. L. Peck's editions (Loeb Classical Library, London and
Cambridge, Mass.) of Aristotle's Parts of Animals (1955),
Generation of Animals (1953), and Historia Animalium
(1965) contain expository introduction, English translation
and notes, including a short bibliography of modern sec-
ondary literature on ancient Greek biology. E. Lesky, Die
Zeugungs- und Vererbungslehren der Antike und ihr
Nachwirken (Vienna, 1950) describes ancient genetic theo-
ries. O. Keller, Die antike Tierwelt, 2 vols. (Leipzig, 1909-13)
collects information under each animal. Ernest H. F. Meyer,
Geschichte der Botanik, 4 vols. (Königsberg, 1854-59) dis-
cusses authors chronologically from classical times. E. L.
Greene, Landmarks of Botanical History, Smithsonian Mis-
cellaneous Collections 54 (Washington, D.C., 1909) and A.
Arber, The Natural Philosophy of Plant Form, (Cambridge,
1950) analyze Greek views, especially of Theophrastus.
F. S. Bodenheimer, The History of Biology (London, 1958)
includes English translations of ancient non-Greek texts.

D. M. BALME

[See also Atomism; Causation; Chain of Being; Classification
of the Sciences; Evolutionism; Genetic Continuity; God;
Platonism; Stoicism.]