History of Animals (Historia Animalium)

And of such as these, some are called not parts merely, but limbs or members. Such are those parts that, while entire in themselves, have within themselves other diverse 10 parts: as, for instance, the head, foot, hand, the arm as a whole, the chest; for these are all in themselves entire parts, and there are other diverse parts belonging to them.¹

All those parts that do not subdivide into parts uniform with themselves are composed of parts that do so subdivide, for instance, hand is composed of flesh, sinews, and bones. 15 Of animals, some resemble one another in all their parts, while others have parts wherein they differ.² Sometimes the parts are identical in form or species, as, for instance, one man’s nose or eye resembles another man’s nose or eye, flesh flesh, and bone bone; and in like manner with a horse,

¹ P. A. i. 5. 645^b 35.
² ἔχει δὲ τῶν ζῳῶν. The succeeding passage is not easy to translate, but its meaning seems to me to be exquisitely clear, and its statements to be ordered with an admirable logic. Of animals, some have all their parts alike, each to other, alike in one horse and in another horse, in one man and in another man. Such animals are alike in form or species, and differ only as individuals. Some, again, have the same parts, but the properties or accidents thereof are contrary or opposite, or at least differ in degree. Such animals are alike in kind, or genus, as fishes are or birds, but differ specifically. Moreover, in certain cases, some part altogether new may supervene in one species though lacking in others, like the cock’s comb, which is something singular and unmatched among birds; but we must not unduly estimate the importance of such minor accretions, which leave the totality of the organism insignificantly changed. Thirdly, we may have animals under observation whose parts neither are identical nor differ only by accident or in degree; but which, on the contrary, have an essential unlikeness, and only resemble one another in the way of analogy: for analogy might be described as the likeness between things essentially different, or as being no more than that resemblance which is conferred by similarity of place, use, or general significance. For instance, a bird’s feather is not the same thing as a fish’s scale, nor is the difference one of accident or of degree; but they are separate things, included under no single concept, and such resemblance as they possess one to another is best described as an analogy; and the creatures that bear them are not of the same genus, but of different genera. While these matters are of chief importance, there is a sort of difference not to be altogether overlooked, the difference of position, in parts that are still manifestly the same: as in the case of teats, that are pectoral in one animal and inguinal in another. Lastly, passing from animals in their integrity to the tissues of which they are composed, these may be classified according to the simpler classifications of elementary things, which fall into such simple categories as solid and fluid, or hard and soft, or wet and dry. Of such simple contrasts, flesh and bone, or blood and artery, are simple instances.