The Politics of Aristotle

by Aristotle

  The question of this perception raises a difficulty: for if the windpipe alone has perception, does it perceive by means of the wind which passes through it, or by its [25] bulk or by its bodily constitution? Or if the air comes first below soul, may it perceive by means of this air which is superior and prior in origin?

  What then is the soul? They make it out to be a potentiality which is the cause of such a motion as this. Or is it clear that you will not be right in impugning those who say it is the rational and spirited faculty? for they too refer to these as potentialities.

  [30] But if the soul resides in this air, the air is at any rate a neutral substance. Surely, if it becomes animate or becomes soul, it suffers some change and alteration, and so naturally moves towards what is akin to it, and like grows by the addition of like. Or is it otherwise? for it may be contended that the air is not the whole of soul but is something which contributes to this potentiality or in this sense makes it,12 and that which has made it is its principle and foundation.

  In the case of non-respiring creatures, where the internal air is not mixed with [483b1] the external13—or is this not the case, is it rather mixed in some other way than by respiration?—what is the difference between the air in the air-duct and the outside air? It is reasonable—perhaps inevitable—to suppose that the former surpasses the latter in fineness.

  Again, is it warm by its inherent nature or by the influence of something else? [5] For it seems that the inner air is just like the outer, but it is helped by the cooling. But which is really the case? for when outside it is soft, but when enclosed the air becomes breath, being as it were condensed and in some manner distributed through the vessels. Or must it be mixed in some way, when it moves about in the fluids, and among the solid particles of the body? It is not, therefore, the finest of substances, if it is mixed. We may, however, reasonably expect that the substance [10] which is first capable of receiving soul should be the finest, unless, indeed, soul is something such as has been described, i.e. something not pure nor unmixed: and that the air-duct should be capable of receiving the breath, while the sinew is not.

  There is this difference too, that the sinew is tensible, but the air-duct is easily broken, just like a vein.

  The skin contains veins, sinews, and air-ducts—veins because when pricked it [15] exudes blood, sinews because it is elastic, air-ducts because air is breathed through it—for only an air-duct can admit air.

  The veins must have pores in which resides the bodily heat which heats the blood as if in a cauldron; for it is not hot by nature, but is diffused like molten [20] metals. For this reason too the air-duct becomes hardened, and has moisture both in itself and in the coats which surround its hollow passage.

  It is also proved both by dissection and by the fact that the veins and air-ducts, [25] which apparently conduct the nutriment, connect with the intestines and the belly. From the veins the nutriment is distributed to the flesh—not sideways from the veins but out at their mouths, as it were through pipes. For fine veins run sideways14 from the great vein and the windpipe along each rib, and a vein and an air-duct [30] always run side by side.

  The sinews and veins form the connexion between the bones, joining them with the centre of the body, and also form the meeting-place between the head and the body, through which fishes receive nutriment and breathe; if they did not respire, they would die immediately on being taken out of the water.

  But it is plain even from observations of sense that the veins and air-ducts [484a1] connect with each other; but this would not occur if the moisture did not require breath and the breath moisture,—because there is warmth both in sinew, in air-duct, and in vein, and that which is in the sinew is hottest and most similar to [5] that of the veins. Now the heat seems unsuited to the space where the breath is located, especially with a view to refrigeration: but if the animal produces and as it were re-kindles the heat by heat from without, then there may well be heat there. Besides this, permanence is in a sense natural to all things which have warmth, [10] provided that nothing resists or cools it;15 for that all things require refrigeration is practically proved by the fact that the blood retains its heat in the veins and as it were shelters it there; so when the blood has flowed out it loses its heat, and the creature dies, through the liver having no air-duct.

  6 · Does the seed pass through the air-duct? Is its passage due also to [15] pressure, and does this take place only in process of emission? Through this we have evidence of the transformation of the blood into flesh—through the fact that the sinews are nourished from the bones; for they join the bones together. Or is this not true? For sinew is found in the heart, and sinews are attached to the bones: but those in the heart do not connect with anything else, but they end in the flesh. Or does this [20] amount to nothing, and would those which connect the bones be nourished from the bones? But we might say, that rather the bones themselves get their nutriment from the sinew. For this too is strange—since the bone is dry by nature and has no ducts for fluid;16 while the nutriment is fluid. But we must consider first, if the nutriment of the sinews is from the bones, what is the nutriment of the bone. Do the ducts [25] carry it both from the veins and from the air-duct into the bone itself? In many parts these ducts are visible, particularly those leading to the spine, and those leading from the bones are continuous, e.g. in the case of the ribs; but how do we suppose that these ducts lead from the belly, and how does the drawing of the nutriment take place?

  Surely most bones are without cartilage like the spine, in no way adapted to [30] motion. Or are they designed to form connexions? And similarly, if bone is nourished from sinew, we must know the means by which sinew is nourished. We say that it is from the fluid surrounding the sinew, which is of a glutinous nature: but we must determine whence and how this arises. To say that the flesh is nourished from vein and air-duct, on the ground that blood comes from any point [35] where you prick it, is false in the case of the other animals, e.g. birds, snakes, and fishes, and oviparous creatures in general. The universal dispersion of the blood is a peculiarity of creatures with a large blood-supply: for e.g. even when a small bird’s breast is cut, not blood but serum flows.

  Empedocles says that nail is formed from sinew by a hardening process. Is the [484b1] same true of skin in relation to flesh?

  But how can hard and soft-shelled creatures get their nutriment from outside? On the contrary it seems that they get it from inside rather than out. Again, how and by what course does the passage of foods from the belly take place, and again [5] their return into the form of flesh, unaccountable as it is? For this process seems extraordinary and absolutely impossible.

  Do different things, then, have different nutriment, not all things being nourished by the blood except indirectly?

  7 · We must then consider the nature of bone, whether it exists with a view to motion or to support, or covering and surrounding, and further, whether some bones [10] are as it were originators of motion, like the axis of the universe.

  By motion I mean, e.g. that of the foot, the hand, the leg, or the elbow, both the bending motion and motion from place to place—for the latter cannot take place either without the bending, and usually the supporting functions belong to these same bones. And by covering and surrounding I mean as e.g. the bones in the head [15] surround the brain; and those who make the marrow the originator of motion treat the bones as primarily meant to protect it. The ribs are for the purpose of locking together; the originator of motion, itself immovable, is the spine, from which spring the ribs for the purpose of locking the body together: for there must be something of this kind, since everything that is in motion depends on something that is in a state of rest.

  At the same time a final cause must exist—under which head some class the [20] originator of motion; i.e. the spinal marrow and the brain.

  Besides these there are others which are at a joining17 and whose purpose is locking together, e.g. the collar-bone, which perhaps is named the ‘key-bone’ f
rom its functions. Every one is well adapted for its purpose, for there could be no flexion either of whole or parts, if the parts were not such as they are: e.g. the spine, foot, [25] and elbow: for the bending of the elbow must be inwards to serve our purpose. Similarly, the bending of the foot and the other parts must be such as it is. All exist for a purpose, and so do the smaller bones contained in these larger ones—e.g. the radius in the fore-arm to enable us to twist the fore-arm and the hand; for we should not be able to turn the palm down or up nor lift nor bend the feet if there were not [30] the two radii which are used in these motions. Similarly we must investigate the other details, e.g. whether the motion of the neck is due to only one bone or more. Also we must examine all that are for the purpose of gripping or knitting together, e.g. the patella over the knee; and why other parts have no such bone.

  Now all parts which are capable of motion are connected with sinews—and [35] perhaps those concerned with action in a positive way are especially so—thus we find sinews in the elbow, the legs, the hands, and the feet; the other sinews are for the purpose of fastening together all those bones which require fastening; for perhaps some, e.g. the spine, have little or no function except that of bending,18 for the substance which connects the vertebrae is a serum or mucous fluid; others are [485a1] bound together by sinews—thus we find sinews in the joints of the limbs.

  8 · The best description of everything may be obtained by an investigation like the present; but we must adequately investigate the final causes. We must not [5] suppose that the bones are for the sake of movement; that is rather the purpose of the sinews or what corresponds to them, viz. the immediate receptacle of the breath which causes motion, since even the belly moves and the heart has sinews—but only some, not all parts have bones: every part must have sinews appropriate for [10] performing such motion or for . . . 19 For the octopus walks little and walks badly. We must take as a starting-point the fact that all animals have different organs for different purposes with a view to the peculiar motion of each, e.g. terrestrial animals have feet—those that are upright having two; others which move altogether upon the earth, the material of whose bodies is more earthy and colder, have several.

  [15] Some creatures again may be entirely without feet, for it is possible for them under these conditions to be moved only by external force. Similarly, flying creatures have wings, and their shape is appropriate to their nature. The parts differ in proportion as they are to fly faster or slower. They have feet for the purpose of seeking food and to enable them to stand; bats are an exception; as they cannot use [20] their feet, they get their food in the air, and do not need to rest for the purpose; for they certainly do not need to do so for any other reason.

  The hard-shelled aquatic animals have feet on account of their weight; thus they are enabled to move from place to place: all that concerns their other needs is as ordered by the individual requirements of each, even if the principle is not [25] clear—e.g. why many-footed creatures are the slowest, and yet quadrupeds are swifter than bipeds. Is it because the whole of their body is on the ground or because they are naturally cold and hard to move, or for some other reason?

  9 · We cannot agree with those who say that it is not the heat-principle which is active in bodies, or that fire has only one kind of motion and one [30] power—the power to cleave. For in the case of inanimate things the action of fire is not universally20 the same on all—some it condenses, others it rarefies; some it dissolves, others it hardens; and so we must suppose that in the case of animate creatures the same results are found, and we must investigate the fire of nature by comparing her processes to those of an art; for different results are achieved by fire [35] in the work of the goldsmith, the coppersmith, the carpenter, and the cook—though, perhaps, it is truer to say that the arts themselves achieve these different results, for [485b1] that by using fire as an instrument they soften, liquefy, and desiccate substances, and some they temper.

  Individual natures work in the same way, and so they differ one from another; so that it is ridiculous to judge by externals; for whether we regard the heat as [5] separating or refining, or whatever the effect of warming or burning is, the results will be different according to the different natures of the agencies which employ it. But while the crafts use the fire merely as an instrument, nature uses it as a material as well.

  Certainly no difficulty is involved in this; but rather it is remarkable that nature, who employs the instrument, is herself an intelligent agent, who will assign to objects their proper symmetry together with the visible effects of her action: for [10] this is no longer a function either of fire or of breath, so it is remarkable that we should find such a faculty combined with these two bodies. Again, with regard to soul we find the same cause of wonder, for it must be assumed in the functions of these two, and therefore there is some sense in referring to the same agent—either generally or to some particular creative part—the fact that its motion always operates21 in the same way; for nature, from which they are generated, is always [15] constant. But now what variation can there be in individual heat, whether we regard it as an instrument or material, or both? The variations in fire are simply quantitative; but this is practically a question of whether it is mixed with other substances or unmixed, for the purer substance has the proper qualities of its kind in a higher degree.

  The same statement applies in the case of all other simple things; for whereas [20] there is a difference between the bone and flesh of a horse and those of an ox,22 this must be the case either because they are produced from different materials, or because the materials are used differently. Now if they are different, what are the distinctive characteristics of each of the simple things and what is . . .?23 for it is these that we are seeking.

  But if they are the same in nature, they may be different in their proportions: for one or the other must be the case—as holds good with other things—for the consistencies of wine and honey are different on account of the difference of [25] substance; difference in wine itself, if there is any, is a matter of proportion.

  And so Empedocles stated the nature of bone too simply;24 for,25 on the supposition that all bones follow the same proportion in the mixture of elements, the bones of a lion, a horse, and a man ought to be indistinguishable; whereas they actually differ in hardness and softness, density, and other qualities. Similarly with [30] the flesh and other parts of the body.

  Further, the various parts in the same creature differ in density and rarity, and in other qualities, so that the blending of their constituents cannot be identical; for, granted that coarseness and fineness, greatness and smallness are quantitative differences, hardness, density, and the opposites certainly depend on the qualitative nature of the mixing. But those who give this account of it must know how the creature element can vary, by excess or deficiency, by being in isolation or in [486a1] combination or heated in something else, like food that is boiled or baked,—which last is perhaps the true explanation; for in the process of mixing it produces the effect designed by nature.

  So I suppose we must give the same account of flesh; for the variations are the [486b1] same; and practically the same observations apply to the veins and air-ducts and the rest; so that, in conclusion, either the proportion observed in their mixture is not constant, or the definitions must not be stated in terms of hardness, density, and their opposites.

  **TEXT: W. W. Jaeger, Teubner, Leipzig, 1913

  1Reading τὸ περιέχoν.

  2Reading ἐί τε.

  3Reading αὐτό (and ὄν in line 6).

  4Reading λoγoδεέστερoν.

  5Retaining oὔτι γε.

  6Reading αὐτὸ ὃ ςητεῖαι.

  7Reading oὔτως γε.

  8Reading γoῦν.

  9Omitting ὥσπερ.

  10Omitting the comma after μή (line 26) and the full stop after κίνησιν (line 28).

  11Jaeger excises this sentence.

  12Reading
ἀήρ,ἢ o꜎ τω ταύτην.

  13Placing ἤ oὐ…μειγνύμενoς in parentheses.

  14Omitting φλεβῶν.

  15Reading σύμφυτόν πως…καταψύχντoς•ὄτι.

  16Reading ꜑γρoῦ.

  17Reading ἐπὶ συναφῆς.

  18Reading ἄλλ’ ἢ κάμψις.

  19Jaeger marks a lacuna here.

  20Reading ὅλως.

  21Retaining ἐνέργειαν.

  22Reading ‴ ἵππoυ καὶ ‴ βoός.

  23Jaeger marks a lacuna here.

  24Reading λίαν ¬πλῶς.

  25Reading ἐπεὶ εἴπερ.

  HISTORY OF ANIMALS**

  d’A. W. Thompson

  BOOK I

  [486a5] 1 · Of the parts of animals some are simple: to wit, all such as divide into parts uniform with themselves, as flesh into flesh; others are composite, such as divide into parts not uniform with themselves, as, for instance, the hand does not divide into hands nor the face into faces.

  [10] And of such as these, some are called not parts merely, but members. Such are those parts that, while entire in themselves, have within themselves other 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 parts belonging to them.

  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. Sometimes the parts are identical in form, 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, and with all other animals which we [20] reckon to be of one and the same species; for as the whole is to the whole, so each to each are the parts severally. In other cases the parts are identical, save only for a difference in the way of excess or defect, as is the case in such animals as are of one and the same genus. By ‘genus’ I mean, for instance, Bird or Fish; for each of these is subject to difference in respect of its genus, and there are many species of fishes and of birds.