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Aristotle (384-322 BC)
History of Animals
translated by Richard Cresswell

In Book I, Aristotle lays out his method: comparing similarities and differences, both in the “parts” (organs, extremities, skin and scales, etc.) and in “manner of life…actions and dispositions” in order to classify living things into groups. Book VII, mixing shrewd observation with wrongheaded theorizing, demonstrates the limits of the method.

The beginning of the final book, Book VIII, contains the clearest statement of scala naturae, the seed of the medieval Great Chain of Being.

About this translation

Richard Cresswell, scholar and clergyman, translated Aristotle’s biological compendiums in the nineteenth century; his translations of these texts are still the most commonly used.

Book I

Some animals have all these parts the same, in others they are different from each other. Some of the parts are the same in form, as the nose and eye of one man is the same as the nose and eye of another man, and flesh is the same with flesh, and bone with bone. In like manner we may compare the parts of the horse, and of other animals, those parts, that is, which are the same in species, for the whole bears the same relation to the whole as the parts do to each other. And in animals belonging to the same class, the parts are the same, only they differ in excess or defect….

…Animals also differ in their manner of life, in their actions and dispositions, and in their parts. We will first of all speak generally of these differences, and afterwards consider each species separately. The following are the points in which they vary in manner of life, in their actions and dispositions.

Some animals are aquatic, others live on the land; and the aquatic may again be divided into two classes, for some entirely exist and procure their food in the water, and take in and give out water, and cannot live without it–this is the nature of most fishes. But there are others which, though they live and feed in the water, do not take in water but air, and produce their young out of the water….

Different aquatic animals are found in the sea, in rivers, in lakes, and in marshes….Some land animals take in and give out air, and this is called inhaling and exhaling ; such are man, and all other land animals which are furnished with lungs; some, however, which procure their food from the earth, do not inhale air, as the wasp, the bee, and all other insects. By insects I mean those animals which have divisions in their bodies, whether in the lower part only, or both in the upper and lower….

There are also carnivorous animals, herbivorous, omnivorous, and others which eat peculiar food, as the bee and the spider ; the former eats only honey and a few other sweet things, while spiders prey upon flies and there are other animals which feed entirely on fish. Some animals hunt for their food, and some make a store, which others do not. There are also animals which make habitations for themselves, and others which do not. The mole, the mouse, the ant, and the bee, make habitations, but many kinds both of insects and quadrupeds make no dwelling.

…Some kinds of animals burrow in the ground, others do not; some animals are nocturnal, as the owl and the bat, others use the hours of daylight….Some animals utter a loud cry, some are silent, and others have a voice….There are also noisy animals and silent animals, musical and unmusical kinds, but they are mostly noisy about the breeding season….

Again, there are classes of animals furnished with weapons of offence, others with weapons of defence ; in the former I include those which are capable of inflicting an injury, or of defending themselves when they are attacked; in the latter those which are provided with some natural protection against injury….

The following are the principal classes which include other animals, birds, fishes, cetacea. All these have red blood. There is another class of animals covered with a shell, and called shell fish, and an anonymous class of soft-shelled animals….and another of mollusca….All these are without blood….

We have now treated of these things in an outline, for the sake of giving a taste of what we are afterwards to consider, and of how many. Hereafter we will speak of them more accurately, in order that we may first of all examine into their points of difference and agreement…

Book VII

The circumstances attending on the growth of man, from his conception in the womb even to old age, derived from his peculiar nature, are after this manner…

The male begins to have semen at about the age of fourteen complete. At the same time hair begins to appear on the pubes. As Alcmaeon of Crotona says that flowers blossom before they bear seed, about the same period the voice begins to become more harsh and irregular. It is neither quite harsh, nor deep, nor all alike, but it resembles a discordant and harsh instrument. This is called “to have a voice like a goat”….Until twenty-one years of age the semen is unproductive, afterwards it becomes fertile, though boys and girls produce small and imperfect children: this is also the case with other animals. Young girls conceive more readily, but after conception suffer more in parturition, and their bodies frequently become imperfect.

Men of violent passions, and women that have borne many children, grow old more rapidly than others; nor does there appear to be any increase after they have borne three children. Women of violent sexual desires become more temperate after they have borne several children.

Women who have attained thrice seven years are well adapted for child-bearing, and men also are capable of becoming parents. Thin seminal fluid is barren. That which is lumpy begets males; what is thin and not clotted, females.

…[A]fter conception the [menstrual] discharge no longer takes its usual course, but is turned towards the mammae, in which the milk begins to make its appearance.

Pregnant women are apt to have all sorts of fancies, which change very rapidly. Some persons call this longing. These fancies are strongest when a female is conceived, and there is but little pleasure in their gratification….

Other animals have a single exact period for parturition, for one time is appointed for them all. The human subject alone varies in this particular, for the period of gestation is seven, eight, or nine months, or ten at the outside, though some have even advanced as far as the eleventh month….

Maimed parents produce maimed children; and so also lame and blind parents produce laine and blind children; and, on the whole, children are often born with anything contrary to nature, or any mark which their parents may have, such as tumours and wounds. Such marks have often been handed down for three generations; as if a person had a mark on their arm which was not seen in the son, but the grandson exhibited a dark confused spot on the same place. The
circumstances, however, are rare; and sound children are generally produced from lame parents; nor is there any complete certainty in these matters; and children resemble their parents or their grandparents, and sometimes they resemble neither….


The nature of animals and their mode of reproduction has now been described. Their actions and mode of life also differ according to their disposition and their food. For almost all animals present traces of their moral dispositions, though these distinctions are most remarkable in man. For most of them, as we remarked, when speaking of their various parts, appear to exhibit gentleness or ferocity, mildness or cruelty, courage or cowardice, fear or boldness, violence or cunning ; and many of them exhibit something like a rational consciousness, as we remarked in speaking of their parts. For they differ from man, and man from the other animals, in a greater or less degree ; for some of these traits are exhibited strongly in man, and others in other animals.

Others differ in proportion. For as men exhibit art, wisdom, and intelligence, animals possess, by way of compensation, some other physical power. This is most conspicuous in the examination of infants, for in them we see, as it were, the vestiges and seeds of their future disposition; nor does their soul at this period differ in any respect from that of an animal; so that it is not unreasonable for animals to present the same, or similar, or analogous appearances.

Nature passes so gradually from inanimate to animate things, that from their continuity their boundary and the mean between them is indistinct. The race of plants succeeds immediately that of inanimate objects; and these differ from each other in the proportion of life in which they participate; for, compared with other bodies, plants appear to possess life, though, when compared with animals, they appear inanimate.

The change from plants to animals, however, is gradual, as before observed. For a person might question to which of these classes some marine objects belong; for many of them are attached to the rock, and perish as soon as they are separated from it….Some of them appear to have no sensation ; in others it is very dull. The body of some of them is naturally fleshy…and the acalephe and the sponge entirely resemble plants; the progress is always gradual by which one appears to have more life and motion than another.

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