No fish has testicles either externally or internally; as indeed have no footless [10] animals, among which of course are included the serpents. One and the same orifice serves both for the excrement and for the generative secretions, as is the case also in all other oviparous animals, quadrupeds included, inasmuch as they have no bladder and form no fluid excretion.
Such then are the characters which distinguish fishes from all other animals. [15] But dolphins and whales and all such Cetacea are without gills; and, having a lung, are provided with a blow-hole; for this serves them to discharge the sea-water which [20] has been taken into the mouth. For, feeding as they do in the water, they cannot but let this fluid enter into their mouth, and, having let it in, they must of necessity let it out again. Gills are useful here, as has been explained in the treatise on Respiration, to such animals as do not breathe; for no animal can possibly possess gills and at the same time be a respiratory animal. In order, therefore, that these Cetacea may discharge the water, they are provided with a blow-hole. This is placed in front of [25] the brain; for otherwise it would have cut off the brain from the spine. The reason for these animals having a lung and breathing, is that animals of large size require more heat to enable them to move. A lung, therefore, is placed within their body, and is fully supplied with blood-heat. These creatures are after a fashion land and [30] water animals in one. For so far as they are inhalers of air they resemble land-animals, while they resemble water-animals in having no feet and in deriving [697b1] their food from the sea. So also seals and bats are ambivalent, the former between land and water animals, and the latter between animals that live on the ground and animals that fly; and so they belong to both kinds or to neither. For seals, if looked [5] on as water-animals, are yet found to have fins. For their hind feet are exactly like the fins of fishes; and their teeth also are sharp and saw-like as in fishes. Bats again, if regarded as winged animals, have feet; and, if regarded as quadrupeds, are without them. So also they have neither the tail of a quadruped nor the tail of a bird; [10] no quadruped’s tail, because they are winged animals; no bird’s tail, because they are terrestrial. This absence of tail is the result of necessity. For they are skin-winged; but no animal, unless it has barbed feathers, has the tail of a bird; for a bird’s tail is composed of such feathers. As for a quadruped’s tail, it would be an actual impediment, if present among the feathers.
14 · Much the same may be said also of the Libyan ostrich. For it has some [15] of the characters of a bird, some of the characters of a quadruped. It differs from a quadruped in being feathered; and from a bird in being unable to soar aloft, and in having feathers that resemble hair and are useless for flight. Again, it agrees with quadrupeds in having upper eyelashes, and the parts about the head and the upper [20] portion of the neck are bare—so that its eyelashes are more hairy; and it agrees with birds in being feathered in all the parts posterior to these. Further, it resembles a bird in being a biped, and a quadruped in having a cloven hoof; for it has hoofs and not toes. The explanation of these peculiarities is to be found in its bulk, which is that of a quadruped rather that of a bird. For speaking generally, a bird must [25] necessarily be of very small size. For a body of heavy bulk can with difficulty be raised into the air.
Thus much then as regards the parts of animals. We have discussed them all, and set forth the cause why each exists; and in do doing we have severally considered each group of animals. We must now pass on, and in due sequence must [30] next deal with the question of their generation.
**TEXT: A.L. Peck, Loeb, London/Cambridge, Mass., 1937
1See On Generation and Corruption II 9–11.
2Excised by Peck.
3Excised by Peck.
4Excised by Peck.
5Excised by Peck.
6Excised by Peck.
7Omitting, with Peck, oἷoν τί ἦν αὐτῷ τò αἵματι εἶναι.
8Reading καὶ α꜎ τη ˦σπερ α꜊ ἐργασίαι.
9Excised by Peck.
10‘πρόσωπoν’ (‘face’) is connected with ‘πρόσωθεν ὄπωπε’ (‘he looks directly in front’).
11Excised by Peck.
12‘φρένες’ (‘diaphragm’) and ‘φρoνεῖν’ (‘think’).
13See Iliad X 457; Odyssey XXII 329.
14Excised by Peck.
15Reading στόμαχoν.
16Excised by Peck.
17Reading κατὰ ταύτας.
18The Greek text of the next two sentences is corrupt: Peck’s text, which is translated here, draws heavily on the Arabic version.
19Transposing ʭνα … πoλλoῖς to follow τὴν ἰσχύν.
20Reading παραπλησίαν τoîς πτερυγίoις.
MOVEMENT OF ANIMALS**
A. S. L. Farquharson
1 · Elsewhere we have investigated the movement of animals after their [698a1] various kinds, the differences between them, and the causes of their particular characters (for some animals fly, some swim, some walk, others move in various other ways); there remains an investigation of the common cause of any sort of [5] animal movement whatsoever.
Now we have already determined (when we were discussing whether eternal [10] motion exists or not, and what it is, if it does exist) that the origin of other motions is that which moves itself, and that the origin of this is the immovable, and that the prime mover must of necessity be immovable. And we must grasp this not only generally in theory, but also by reference to individuals in the world of sense; for with these in view we seek general theories, and with these we believe that general theories ought to harmonize. Now in the world of sense too it is plainly impossible [15] for movement to be initiated if there is nothing at rest, and before all else in our present subject—animal life. For if one of the parts of an animal be moved, another must be at rest, and this is the purpose of their joints; animals use joints like a centre, and the whole member, in which the joint is, becomes both one and two, both straight and bent, changing potentially and actually by reason of the joint. And [20] when it is bending and being moved one of the points in the joint is moved and one is at rest, just as if on a diameter AD were at rest, and B were moved, and AC were generated. However, in the geometrical illustration, the centre is held to be altogether indivisible (for in mathematics the motion they speak of is a fiction, no [25] mathematical entity being really moved), whereas in the case of joints the centres become potentially and actually now one, now divided. But still the origin of movement, qua origin, always remains at rest when the lower part of a limb is [698b1] moved; for example, the elbow joint, when the forearm is moved, and the shoulder, when the whole arm; the knee when the tibia is moved, and the hip when the whole leg. Accordingly it is plain that each animal as a whole must have within itself a point at rest, whence will be the origin of that which is moved, and supporting itself [5] upon which it will be moved both as a complete whole and in its members.
2 · But the point of rest in the animal is still quite ineffectual unless there is something outside it which is absolutely at rest and immovable. Now it is worth [10] while to pause and consider what has been said; for it involves a speculation which extends beyond animals even to the motion and march of the universe. For just as there must be something immovable within the animal, if it is to be moved, so even more must there be without it something immovable, by supporting itself upon [15] which that which is moved moves. For were that something always to give way (as it does for tortoises walking on mud or persons walking in sand) advance would be impossible, and neither would there be any walking unless the ground were to remain still, nor any flying or swimming were not the air and the sea to resist. And this which resists must needs be different from what is moved, the whole of it from [20] the whole of that, and what is thus immovable must be no part of what is moved; otherwise there will be no movement. Evidence of this lies in the problem why it is that a man easily moves a boat from outside, if he push with a pole, putting it
against the mast or some other part, but if he tried to do this when in the boat itself [25] he would never move it, no not even Tityus himself nor Boreas blowing from inside the ship, if he really were blowing in the way painters represent him; for they paint [669a1] him sending the breath out from himself. For whether one blew gently or so stoutly as to make a very great wind, and whether what were thrown or pushed were breath or something else, it is necessary in the first place to be supported upon one of one’s own members which is at rest and so to push, and in the second place for this [5] member, either itself, or that of which it is a part, to remain at rest, fixing itself against something external to itself. Now the man who is himself in the boat, if he pushes, fixing himself against the boat, does not move the boat, because what he pushes against must remain at rest. Now what he is trying to move, and what he is [10] fixing himself against is in his case the same. If, however, he pushes or pulls from outside he does move it; for the ground is no part of the boat.
3 · Here we may ask the question whether if something moves the whole heavens this mover must be immovable, and moreover be no part of the heavens, nor in the heavens. For either it is moved itself and moves the heavens, in which case it [15] must touch something immovable in order to cause movement, and then this is no part of that which cause movement; or if the mover is from the first immovable it will equally be no part of that which is moved. In this point at least they argue correctly who say that as the sphere is carried round in a circle no single part remains still; for then either the whole would necessarily stand still or its continuity [20] be torn asunder; but they argue less well in supposing that the poles have a certain power, though they have no magnitude, but are merely termini or points. For besides the fact that no such things have any substantial existence it is impossible for a single movement to be initiated by what is twofold; and yet they make the poles [25] two. From a review of these difficulties we may conclude that there is something so related to the whole of nature, as the earth is to animals and things moved by them.
And the mythologists with their fable of Atlas setting his feet upon the earth appear to have based the fable upon intelligent grounds. They make Atlas a kind of diameter twirling the heavens about the poles. Now as the earth remains still this would be reasonable enough, but their theory involves them in the position that the [30] earth is no part of the universe. And further the force of that which initiates movement must be made equal to the force of that which remains at rest. For there is a definite quantity of force or power by dint of which that which remains at rest does so, just as there is of force by dint of which that which initiates movement does [35] so; and as there is a necessary proportion between contrary motions, so there is between states of rest. Now equal forces are unaffected by one another, but are overcome by a superiority of force. And so Atlas, or whatever similar power initiates [699b1] movement from within, must exert no more force than will exactly balance the stability of the earth—otherwise the earth will be moved out of her place in the centre of things. For as the pusher pushes so is the pushed pushed, and with equal [5] force. But that which initiates movement is to begin with at rest, so that its force is greater, rather than equal and like to the stability. And similarly also than the stability of what is moved but does not initiate movement. Therefore the power of the earth in its immobility will have to be as great as that of the whole heavens, and of that which moves the heavens. But if that is impossible, it follows that the [10] heavens cannot be moved by anything of this kind inside them.
4 · There is a difficulty about the motions of the parts of the heavens which, as akin to what has gone before, may be considered next. For if one could overcome by power of motion the immobility of the earth he would clearly move it away from [15] the centre. And it is plain that the force from which this power would originate will not be infinite; for the earth is not infinite and therefore its weight is not. Now things are called impossible in several ways; for when we say it is impossible to see a sound, and when we say it is impossible to see the men in the moon, we use the word in different ways: the former is of necessity, the latter, though their nature is to be [20] seen, will not actually be seen by us. Now we suppose that the heavens are of necessity impossible to destroy and to dissolve, whereas the result of the present argument would be to do away with this necessity. For it is natural and possible for a motion to exist greater than that by dint of which the earth is at rest, or than that by dint of which fire and the upper body are moved. If then there are superior [25] motions, these will be dissolved by one another; and if there actually are not, but might possibly be (for they cannot be infinite because not even body can be infinite), there is a possibility of the heavens being dissolved. For what is to prevent this coming to pass, unless it be impossible? And it is not impossible unless the opposite [30] is necessary. This difficulty, however, we will discuss elsewhere.1
Must there be something immovable and at rest outside of what is moved, and no part of it, or not? And must this necessarily be so also in the case of the universe? Perhaps it would be thought strange were the origin of movement inside. And to those who so conceive it the words of Homer2 would appear to have been well [35] spoken: ‘Nay, ye would not pull Zeus, highest of all, from heaven to the plain, no not even if ye toiled right hard; come, all ye gods and goddesses! Set hands to the chain’. [700a1] For that which is entirely immovable cannot possibly be moved by anything. And herein lies the solution of the difficulty stated just now, the possibility or [5] impossibility of dissolving the system of the heavens, in that it depends from an origin which is immovable.
Now in the animal world there must be not only an immovable without, but also within those things which move in place, and initiate their own movement. For one part of an animal must be moved, and another be at rest, and against this the [10] part which is moved will support itself and be moved; for example, if it moves one of its parts; for one part supports itself against another as though it were at rest.
But about things without life which are moved one might ask the question whether all contain in themselves both that which is at rest and that which initiates [15] movement, and whether they also, for instance fire, earth, or any other inanimate thing, must support themselves against something outside which is at rest. Or is this impossible and must it not be looked for rather in those primary causes by which they are set in motion? For all things without life are moved by something other, and the origin of all things so moved are things which move themselves. And out of these we have spoken about animals (for they must all have in themselves that which is at rest, and without them that against which they are supported); but [20] whether there is some higher and prime mover is not clear, and an origin of that kind involves a different discussion. Animals at any rate which move themselves are all moved supporting themselves on what is outside them, even when they breathe in and out; for there is no essential difference between casting a great and a small weight, and this is what men do when they spit and cough and when they breathe in [25] and breathe out.
5 · But is it only in that which moves itself in place that there must be a point at rest, or does this hold also of that which causes its own qualitative changes, and its own growth? Now the question of original generation and decay is different; for [30] if there is, as we hold, a primary movement, this would be the cause of generation and decay, and probably of all the secondary movements too. And as in the universe, so in the animal world this is the primary movement, when the creature attains maturity; and therefore it is the cause of growth, when the creature becomes the cause of its own growth and the cause too of alteration. Otherwise, the point at rest is not necessary. However, the earliest growth and alteration in the living creature [700b1] arise through another and by other channels, nor can anything possibly be the cause of its own generation and decay; for the mover must exist before the moved, the begetter before the begotten, and nothing is prior to itself.
6 · Now whether the soul is moved or not, and how
it is moved if it be moved, [5] has been stated before in our treatise concerning it.3 And since all inanimate things are moved by some other thing—and the manner of the movement of the first and eternally moved, and how the first mover moves it, has been determined before in our work on first philosophy,4 it remains to inquire how the soul moves the body, and [10] what is the origin of movement in a living creature. For, if we except the movement of the universe, things with life are the causes of the movement of all else, that is of all that are not moved by one another by mutual impact. And so all their motions have a limit, inasmuch as the movements of things with life have such. For all living things both move and are moved for the sake of something, so that this is the limit of [15] all their movement—that for the sake of which. Now we see that the living creature is moved by intellect, imagination, purpose, wish, and appetite. And all these are reducible to thought and desire. For both imagination and sensation are on common ground with thought, since all three are faculties of discrimination though differing [20] according to distinctions stated elsewhere. Wish, however, impulse, and appetite, are all three forms of desire, while purpose belongs both to intellect and to desire. Therefore the object of desire or of intellect first initiates movement—not every object of intellect, but only the end in the domain of conduct. Accordingly it is goods [25] of this sort that initiate movement, not everything fine. For it initiates movement only so far as something else is for its sake, or so far as it is the end of that which is for the sake of something else. And we must suppose that a seeming good may take the room of actual good, and so may the pleasant, which is itself a seeming good. From these considerations it is clear that in one regard that which is eternally [30] moved by the eternal mover is moved in the same way as every living creature, in another regard differently, and so while it is moved eternally, the movement of living creatures has a limit. Now the eternally fine, and the truly and primarily good (which is not at one time good, at another time not good), is too divine and precious to be relative to anything else. The prime mover then moves, itself being unmoved, whereas desire and its faculty are moved and so move. But it is not necessary for the [701a1] last in the chain of things moved to move something else; wherefore it is plainly reasonable that motion in place should be the last of the movements in things that come into being; for the living creature is moved and goes forward by reason of desire or purpose, when some alteration has been set going on the occasion of [5] sensation or imagination.
The Complete Works of Aristotle Page 190