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Parts of Animals

Aristotle

c. 350-322 BC · Ancient · Philosophy · Greek

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Summary

Parts of Animals is Aristotle's treatise on why living things are built as they are. Where the History of Animals collects the facts (which creatures have lungs, horns, gills or teeth), this work asks for the causes, and especially for the cause Aristotle thought biologists must look to first: what each part is for. William Ogle's 1911 Oxford translation is attached. Book I is a short essay on biological method. Aristotle argues that in nature, as in the crafts, the end for which a thing comes to be is prior in explanation to the matter it is made of; a house exists for shelter, and bricks and timber are arranged for that end. He criticizes earlier thinkers, Empedocles above all, for explaining bodies by material necessity alone, and he criticizes dividing animals by simple dichotomies. Then he defends the study of animals against those who prefer the heavens. The stars are nobler, but animals are near at hand and can be known more completely, and no creature is too humble to study. He recalls Heraclitus telling hesitant visitors to come into his kitchen because there were gods there too, and says that every kind of animal reveals something natural and something beautiful. Books II to IV apply the method. Aristotle distinguishes the uniform parts (blood, fat, marrow, bone, flesh) from the non-uniform organs built out of them (heart, lung, face, hand) and explains both by the work they do. The heart is the first part to form in the embryo, the source of the blood and the seat of sensation; the brain, cold and moist, exists to temper the heart's heat and brings on sleep. The lungs cool, the diaphragm separates the nobler upper body from the region of nutrition, and laughter at tickling is traced to the warming of the midriff, which is why only man laughs. Horns, tusks, teeth and beaks are compared across species, with the rule that nature makes nothing in vain and does not give the same defensive weapon twice. The fourth book treats bloodless animals (cephalopods, crustaceans, insects), the parts of birds, fish and seals, and man, whose upright posture fits his divine nature and whose hands are many tools in one. Against Anaxagoras, who said man is wisest because he has hands, Aristotle answers that man has hands because he is wisest. Many of its particular claims are wrong; Aristotle located thought in the heart, not the brain. Yet its insistence on comparing structures across species, on dissection and observation, and on asking what a part does made it a founding text of biology. Galen built his own anatomy on its plan and quarrelled with its cardiocentrism, Harvey still argued with it, and Darwin later praised Aristotle as an observer. For students it raises a lasting question: is purpose a real feature of living things or only a way of speaking about them?

Plot or Argument

Book I: the canons of natural science
An educated person should be able to judge a method. Aristotle sets the final cause before the material cause, rejects explanation by necessity alone, criticizes classification by dichotomy, and defends the study of humble animals as a source of wonder and knowledge.
Book II: uniform parts and the head
Hot and cold, solid and fluid are defined; blood, fat, marrow, bone, cartilage and flesh are explained by function. The brain is treated as a cooling counterweight to the heart, followed by the senses, the face, teeth, mouth and tongue.
Book III: horns, teeth and the internal organs
Horns and tusks as weapons; the neck, windpipe and oesophagus; the heart as origin of the vessels and sensation; lung, liver, spleen, kidneys and bladder; the diaphragm and the explanation of laughter; the stomachs of ruminants.
Book IV: bloodless animals and external parts
The internal organs of insects, crustaceans, cephalopods and shellfish; then the external parts of the blooded animals: the legs and wings of birds, the fins of fishes, the seal and the ostrich as intermediates, and man's upright posture, breast, arms and hands.

Lessons

Even the kitchen has its gods
Aristotle urges students not to recoil from studying worms, shellfish or the inside of the body. Every animal shows design and beauty to someone who looks for causes. The passage is an early defence of curiosity about the ordinary world.
- Why does Aristotle say a picture of an animal can please us more easily than the animal itself?
- What is the point of the Heraclitus story?
- How does this passage compare with Psalm 104 on the creatures?
Related across the library
- Generation of Animals, Lesson: Eternal in the only way possible
  Eternal in the only way possible. Book II opens with a philosophical reason for reproduction: since individual animals must die, they share in the eternal by producing others like themselves. For Aristotle this explains why there are always men, animals and plants. Christian readers can compare this natural longing for permanence with Scripture's account of mortality and of a life that does not depend on the species alone.
- Poetics, Lesson: Pity, fear and catharsis
  Pity, fear and catharsis. Aristotle says tragedy works through pity and fear to bring about catharsis of those emotions, and that the effect should come from the story itself, so that even hearing the tale of Oedipus makes one shudder. He never explains catharsis in the Poetics, and readers have taken it as purgation, purification, or clarification. The treatise treats emotion as something art can educate rather than simply excite.
- The Expression of the Emotions in Man and Animals, Chapter XI. Disdain—contempt—disgust-Guilt—pride
  In the accompanying Plate VI figs and Mr Rejlander has successfully acted the gesture of shrugging the shoulders Englishmen are much less demonstrative than the men of most other European nations and they shrug their shoulders far less frequently and energetically than Frenchmen or Italians do The gesture varies in all degrees from the complex movement just described to only a momentary and scarcely perceptible raising of both shoulders or as I have noticed in a lady sitting in an arm-chair to the mere turning s...
- The Expression of the Emotions in Man and Animals, Chapter V. Special Expressions of Animals
  Of the above points the stiff gait and upright tail alone require further discussion Sir C Bell remarks that when a tiger or wolf is struck by its keeper and is suddenly roused to ferocity every muscle is in tension and the limbs are in an attitude of strained exertion prepared to spring This tension of the muscles and consequent stiff gait may be accounted for on the principle of associated habit for anger has continually led to fierce struggles and consequently to all the muscles of the body having been violen...
- Brave New World, Lesson: The uses of art and suffering
  The uses of art and suffering. Shakespeare gives John a language for love and grief that the World State lacks. The novel suggests that great art depends on conflict, loss and longing.
What a part is for
Book I places the final cause first: to understand a hand or a horn, ask what it does, then ask what matter and process make that possible. Aristotle does not deny material necessity; he denies that it is enough.
- Explain the house analogy for final causes in your own words.
- Where does Aristotle admit that some features exist by necessity rather than for an end?
- Is it legitimate for a modern biologist to ask what an organ is for?
Related across the library
- History of Animals, Lesson: Inquiry begins with collecting differences
  Inquiry begins with collecting differences. Historia means an organised gathering of facts. Aristotle insists on first establishing what is the case about animals, their parts and habits, before explaining why, and he keeps that task separate from his causal treatises. Students learn that careful description is not inferior to theory but its necessary foundation.
- On the Motion and Gait of Animals, Lesson: The body as a well-governed city
  The body as a well-governed city. At the end of chapter 10 Aristotle compares the organism to a commonwealth where, once order is established, no separate ruler is needed at each task; the soul resides centrally and the parts do their work by natural structure. The image describes a hierarchy in which order is distributed rather than micromanaged. Students can test it against what he says about involuntary movements, which happen without the ruler's command.
- Generation of Animals, Lesson: Building an embryo part by part
  Building an embryo part by part. Against those who thought all parts are present from the start, Aristotle argues that the embryo forms in sequence, beginning with the heart, and that nature outlines before it colours, like a painter. This view, later called epigenesis, was argued over until the nineteenth century. It also shaped long debates in Christian thought about when the soul is present in the unborn child, debates the book itself does not settle.
- History of Animals, Lesson: Traces of character in animals
  Traces of character in animals. Book VIII opens by noting that animals show traces of gentleness or ferocity, courage or cowardice, and that nature passes by small steps from lifeless things to plants and animals. Aristotle sees continuity without erasing the difference reason makes. The passage invites careful thought about how creatures resemble us and how they do not.
- On the Motion and Gait of Animals, Motion of Animals, ch. 8
  Pleasure and pain, courage, panic and erotic feeling are each accompanied by a change of temperature; memories and anticipations cause the same changes in weaker form.
Hands follow intelligence
Aristotle reverses Anaxagoras: nature gives the flute to the flute-player, so man has hands because he is intelligent, not intelligent because he has hands. The hand is many instruments in one because the mind that uses it can do many things.
- Restate the flute-player argument.
- What does it imply about how nature distributes organs?
- Does the argument still persuade you?
Related across the library
- Discourse on Method, Lesson: Language marks the difference between mind and mechanism
  Language marks the difference between mind and mechanism. Part V's two tests, flexible speech and general-purpose reason, are Descartes's criteria for telling a thinking being from an automaton. They anticipate debates about artificial intelligence and animal minds.
- Body and Mind, Lesson: Body and Mind teaches historical caution
  Body and Mind teaches historical caution. Body and Mind rewards readers who keep its categories in their own century before translating them into ours. It can sharpen modern judgment precisely because its insights and errors are both visible.
- Dialogues Concerning Natural Religion, Part 10
  they are nothing in comparison of those which arise within ourselves, from the distempered condition of our mind and body Demea moves from external dangers to disease and mental suffering, introducing a quotation from Milton's description of the lazar-house.
- Ethics, Part II, Props. XI–XIII and Note
  The mind as idea of the body; the more a body is capable of many actions, the more its mind is capable of many perceptions.
- Description of the Retreat, Lesson: Description of the Retreat teaches historical caution
  Description of the Retreat teaches historical caution. Description of the Retreat rewards readers who keep its categories in their own century before translating them into ours. It can sharpen modern judgment precisely because its insights and errors are both visible.
Brilliant and mistaken
Aristotle's comparative method was sound, yet he held that the brain cools the heart and that sensation begins in the heart. Students can admire a great observer while noticing how conclusions depend on the evidence and instruments available.
- What observations led Aristotle to think the heart was the origin of the blood?
- Why might he have thought the brain was cold?
- What should we learn from a great scientist's errors?
Related across the library
- An Introduction to the Study of Experimental Medicine, Lesson: Chance favours the prepared observer
  Chance favours the prepared observer. Bernard's discovery of sugar formation in the liver began when an experiment gave a result he did not expect. Instead of discarding it, he formed a new hypothesis and tested it. He presents the unforeseen fact as a gift that only an attentive and well-trained mind can use.
- My First Summer in the Sierra, Chapter I: Through the Foothills with a Flock of Sheep
  those scattered along the ragged sides of the main body hastily explored nooks in the rocks and bushes for grass and leaves the lambs and feeble old mothers dawdling in the rear were called the tail end About noon the heat was hard to bear the poor sheep panted pitifully and tried to stop in the shade of every tree they came to while we gazed with eager longing through the dim burning glare toward the snowy mountains and streams though not one was in sight The landscape is only wavering foothills roughened here...
- Philebus, Summary
  The Philebus begins in the middle of an argument. Philebus, a young hedonist who worships pleasure as the goddess Aphrodite, has grown tired of defending his claim that enjoyment and delight are the good for every living creature, and hands the position to his friend Protarchus. Socrates maintains that wisdom, intelligence, memory, right opinion and true reasoning are better than pleasure for all who can share in them. Before deciding between the two, he insists on a method: pleasure and knowledge are each one a...
- The Expression of the Emotions in Man and Animals, Chapter XI. Disdain—contempt—disgust-Guilt—pride
  In the accompanying Plate VI figs and Mr Rejlander has successfully acted the gesture of shrugging the shoulders Englishmen are much less demonstrative than the men of most other European nations and they shrug their shoulders far less frequently and energetically than Frenchmen or Italians do The gesture varies in all degrees from the complex movement just described to only a momentary and scarcely perceptible raising of both shoulders or as I have noticed in a lady sitting in an arm-chair to the mere turning s...
- On the Motion of the Heart and Blood in Animals (De Motu Cordis), Chs. II–V
  Observations from vivisection of cold-blooded and warm-blooded animals establish that the heart's active phase is contraction.

Context

Aristotle's biological works (History of Animals, Parts of Animals, Generation of Animals and shorter treatises) make up about a quarter of his surviving writings. Much of the observation probably dates from his years at Assos and on Lesbos (c. 347-343 BC), where he and Theophrastus studied marine life, and was organized later at the Lyceum in Athens.

Composition

The treatise cannot be precisely dated; it presupposes the History of Animals and was probably revised over years of teaching. Book I may have been composed separately as an introduction to the whole biological course. Ogle's translation first appeared in 1882 and was revised for the Oxford Works of Aristotle in 1911.

Reception

Galen's On the Usefulness of the Parts follows the plan of this treatise while arguing for the brain and nerves against Aristotle's heart-centred account. Arabic and Latin translations spread it through the medieval schools, Harvey's work on the heart engaged its claims, and Darwin, after reading Ogle's translation, wrote that Linnaeus and Cuvier were mere schoolboys to old Aristotle.

Science / Knowledge Animals Nature / Landscape Illness / Body

Comparisons

History of Animals
The History of Animals gathers the facts of anatomy and behaviour; Parts of Animals explains them by function, so the two are best read as data and theory.
Generation of Animals
The companion treatise applies the same causes to reproduction and embryology, extending the claim here that the heart forms first.
Galen: Selected Works
Galen adopted Aristotle's teleology but answered his cardiocentrism with dissections of nerves and brain; set the two on the seat of sensation.
On the Motion of the Heart and Blood in Animals (De Motu Cordis)
Harvey, an admirer of Aristotle, kept the heart at the centre of the body but overturned the account of blood formed in it and carried outward without return.
On the Origin of Species
Darwin explains the fit between organ and function by natural selection rather than by nature acting for an end; compare how each accounts for horns, teeth and vestigial parts.

Quotes

“Every realm of nature is marvellous”

— Aristotle, Parts of Animals, Book I, Part 5, trans. William Ogle (1911, Oxford).Quote card

On the Motion and Gait of Animals, Gait of Animals, ch. 2
Nature creates nothing without a purpose, but always the best possible in each kind of living creature by reference to its essential constitution The first of the principles Aristotle lays down before explaining the number and bending of limbs.
Generation of Animals, Book II, Ch. 6 (743b)
exactly as if Nature were a painter producing a work of art On the order of development: outlines come first, colour and hardness later.
On the Motion and Gait of Animals, Motion of Animals, ch. 1
each animal as a whole must have within itself a point at rest The conclusion of the opening argument from joints: the elbow, shoulder, knee and hip each stay fixed while the limb below them moves.
Euthydemus, 291b
we were like children after larks, always on the point of catching the art, which was always getting away from us Socrates tells Crito how the search for the art of happiness slipped away as they approached the kingly art.
Galileo: The Starry Messenger, Letter to the Grand Duchess Christina, and Two New Sciences (First Day), Letter to the Grand Duchess Christina
That it is both piously spoken, and prudently affirmed, That the Sacred Scripture can never lye, when ever its true meaning is understood Galileo grants his critics' premise that Scripture cannot err and then turns attention to the difficulty of its true meaning.

“for each and all will reveal to us something natural and something beautiful”

— Aristotle, Parts of Animals, Book I, Part 5, trans. William Ogle (1911, Oxford).Quote card

Julius Caesar, Act I, Scene I
all Exeunt Citizens See whether their basest metal be not mov d They vanish tongue-tied in their guiltiness Go you down that way towards the Capitol This way will I Disrobe the images If you do find them deck d with ceremonies MARULLUS May we do so You know it is the feast of Lupercal FLAVIUS It is no matter let no images Be hung with Caesar s trophies I ll about And drive away the vulgar from the streets So do you too where you perceive them thick These growing feathers pluck d from Caesar s wing Will make him...
On the Motion and Gait of Animals, Gait of Animals, ch. 2
Nature creates nothing without a purpose, but always the best possible in each kind of living creature by reference to its essential constitution The first of the principles Aristotle lays down before explaining the number and bending of limbs.
Generation of Animals, Book I, Ch. 22 (730b)
just so no material part comes from the carpenter to the material, i.e. the wood in which he works The craft analogy for the male contribution: form and movement are imparted without any bodily part passing over.
Julius Caesar, Act III, Scene I
curtsies and base spaniel fawning Thy brother by decree is banished If thou dost bend and pray and fawn for him I spurn thee like a cur out of my way Know Caesar dost not wrong nor without cause Will he be satisfied METELLUS Is there no voice more worthy than my own To sound more sweetly in great Caesar s ear For the repealing of my banish d brother BRUTUS I kiss thy hand but not in flattery Caesar Desiring thee that Publius Cimber may Have an immediate freedom of repeal CAESAR What Brutus CASSIUS Pardon Caesar...
History of Animals, Full Text
as well as corrects their errors there can be no doubt that Aristotle had the advantage of many works which have perished in the lapse of ages In the Appendix to the present Translation will be found the Essay of Schneider on the sources whence Aristotle derived his knowledge of the animals he describes and these sources together with his own accurate observations are probably sufficient to account for the correct knowledge of the history of animals displayed throughout the work It is right perhaps to observe in...

“The brain, then, tempers the heat and seething of the heart”

— Aristotle, Parts of Animals, Book II, Part 7, trans. William Ogle (1911, Oxford).Quote card

History of Animals, Book I, Ch. VI-XVII
Systematic description of the human body, head to foot and then internal organs, used as the standard for comparing other animals; includes the claim that the occiput is empty.
Letters from a Farmer in Pennsylvania, Medical lens
The letters have no medical subject. Their bodily images are political metaphors: Letter IX says the ax is laid to the root of the tree and the whole body must perish, and Letter XII warns that a speck of decay on a remote limb should alarm the whole body and compares British restrictions to the spear of Telephus, which could heal the wound it made. These belong to the long tradition of the body politic rather than to the medicine of the period.
A History of Philosophy, Vol. IV: Descartes to Leibniz, Medical lens
The volume is a standard map of the seventeenth-century debates from which modern talk of mind and brain descends. Descartes's mechanical physiology and his account of the passions, Spinoza's treatment of the emotions as confused ideas that understanding can master, and Leibniz's unnoticed 'little perceptions' are each expounded. A reader in psychiatry or the history of medicine can use the relevant chapters as a reliable orientation before turning to the primary texts; Copleston himself writes as a philosopher,...
A History of Philosophy, Vol. I: Greece and Rome, Medical lens
This is a history of philosophy, not of medicine, but several of its chapters bear on how the ancients understood soul and body. Early Greek cosmology overlapped with medical theory: Empedocles was remembered as a healer, and the Pythagorean circle produced physicians who speculated about health as balance. The chapters on Plato's psychology and Aristotle's De Anima describe the two classic Greek accounts of how soul relates to body, which later shaped medieval and early modern medicine. The Hellenistic chapters...
On the Motion and Gait of Animals, Lesson: Every push needs a place to stand
Every push needs a place to stand. Aristotle's first claim is physical and easily tested: a joint moves only because one point in it is still, and an animal advances only by pressing on something that resists. The sand, the heaped grain and the boat give students experiments they can perform. The principle then grounds his argument that the universe itself depends on a mover outside it.

“For nature never makes anything superfluous or in vain”

— Aristotle, Parts of Animals, Book III, Part 1, trans. William Ogle (1911, Oxford).Quote card

The Critique of Judgement, Part I, § 46
Genius_ is the innate mental disposition (_ingenium_) _through which_ Nature gives the rule to Art Kant's definition of genius, which makes original art a gift of nature that the artist cannot reduce to explicable rules.
On Generation and Corruption, Lesson: Experience before system
Experience before system. In I.2 Aristotle says that lack of experience narrows our view of the facts, and that those who live close to nature form better principles than those who dogmatize from a few observations. He uses this to prefer Democritus's physical arguments to the Platonists' geometrical ones, even while rejecting Democritus's conclusion. The passage is an ancient statement of the duty to look before theorizing.
Generation of Animals, Book II, Ch. 6 (743b)
exactly as if Nature were a painter producing a work of art On the order of development: outlines come first, colour and hardness later.
Generation of Animals, Book III, Ch. 11 (762a)
in a sense all things are full of soul Part of Aristotle's explanation of spontaneous generation from enclosed vital heat, a theory later disproved.
Principles of Literary Criticism, Full Text
the best order The whole soul of man in activity Unity in variety The synthetic and magical power of the imagination The eye on the object The disimprisonment of the soul of fact The identification of content and form A criticism of Life Empathy favourable to our existence Significant form The expression of impressions etc etc Such are the pinnacles the apices of critical theory the heights gained in the past by the best thinkers in their attempt to reach explanations of the value of the arts Some of them many o...

“we must conclude that man does not owe his superior intelligence to his hands, but his hands to his superior intelligence”

— Aristotle, Parts of Animals, Book IV, Part 10, trans. William Ogle (1911, Oxford).Quote card

Hamlet, Act 4, Scene 5
There’s rosemary, that’s for remembrance In her madness Ophelia distributes flowers whose meanings comment on the court's grief and guilt.
History of Animals, Book I, Ch. VI, §5
And of necessity, man must be the best known to us of all animals Aristotle justifies beginning his survey of animal parts with the human body, the familiar standard against which others are measured.
The Story of a Soul, Chapter I
I understood that if all the lowly flowers wished to be roses, nature would lose its springtide beauty, and the fields would no longer be enamelled with lovely hues. Explaining why God creates both great and lesser saints, as He creates both roses and daisies.
Coriolanus, Act 5, Scene 3
As if a man were author of himself, And knew no other kin As his family approaches, he resolves to resist the pull of nature, the resolution that his mother's plea is about to break.
Galileo: The Starry Messenger, Letter to the Grand Duchess Christina, and Two New Sciences (First Day), Letter to the Grand Duchess Christina
But that that self same God who hath indued us with Senses, Discourse, and Understanding hath intended, laying aside the use of these, to give the knowledg of those things by other means, which we may attain by these The opening of Galileo's argument that God does not ask human beings to abandon sense and reason in natural questions.

Medical Lens

A foundational text for the history of anatomy and physiology. Aristotle appeals to dissection and embryology to argue that the heart is the origin of the blood vessels, the first organ formed and the seat of sensation, and he gives the brain the subordinate role of cooling the heart and inducing sleep. Galen's anatomy was built in dialogue with this work, and the dispute between heart and brain as the seat of mind ran from Alexandria to the Renaissance. The account of laughter as the warming of the midriff and of morbid changes in the hearts of diseased animals are early physiological explanations, now superseded.

Ancient Medicine Anatomy Dissection Mind Body Sleep Insomnia

Book II, Part 7
The brain as a cold, moist counterweight that tempers the heat of the heart and produces sleep by chilling the blood that rises after food.
Ancient Medicine Mind Body Sleep Insomnia
Book III, Part 4
The heart as the first part formed and the fountain of the blood, demonstrated by dissection and embryology; animals dying of disease show morbid changes of the heart.
Anatomy Dissection Ancient Medicine
Book III, Part 10
The diaphragm separates the upper and lower body; tickling warms it and causes involuntary laughter, which Aristotle says is peculiar to man.
Mind Body Ancient Medicine

Creative Prompts

Classroom
Choose one animal part (a woodpecker's beak, a cat's claw) and write two explanations, one Aristotle's 'what is it for' and one 'what is it made of and how did it form'.
Essay
Defend or attack Aristotle's claim that man has hands because he is intelligent, using the flute-player argument and one example of your own.
Dialogue
Write a conversation between Aristotle and Galen over a dissected heart and brain about where sensation begins.