Aristotle · a new plain-English translation from the original language
1| ON BREATH.
2| What is the persistence of the innate breath, and what is its growth? For we see that it becomes greater and stronger both with change of age and with the condition of the body. Or, as with the other parts, this happens by something being added. Nourishment is added to ensouled things, so we must consider what this nourishment is and where it comes from. There are two ways by which it occurs: either through breathing, or through the concoction that comes with the taking in of food, as with the other parts. Of these, one might think it seems no less to be not this way through nourishment: for body is nourished by body, and breath is a body. What then is the way? Clearly, by a kind of drawing and concoction from the vein. For blood is the final nourishment, and it is the same for all things. So then, just as it takes nourishment into its own vessel, so also it takes nourishment into what is contained, for the sake of the heat. Air conducts this, producing the activity, and by adding the power of concoction to itself, it grows and nourishes itself. There is perhaps nothing strange in this itself, but rather in the claim that it first came to be from nourishment. For what is connatural with the soul is purer — unless one should also say that the soul comes to be later, once the seeds are differentiated and come into their nature. And if it is a residue of all nourishment, by what route is this sent off? Not by exhalation, for that is not reasonable, since it takes in again immediately. It remains, then, clear that it is through the passages of the windpipe. What is excreted is either finer or coarser. Either way it is strange, if this is to be the purest of all things. And if coarser, there will have to be some larger passages. And if it takes in and sends out through the same passages, this itself is unreasonable and strange. This, then, is roughly the account of growth and persistence from nourishment.
3| The growth from breathing, as Aristogenes thinks (for he thinks that breath too, once concocted, is nourishment — not the air within the breath; and that this is distributed into the vessels, while the residue is sent out again) has more difficulties. For by what is the concoction performed? It is likely by the breath itself, as with the other cases. But this itself is strange, if it does not differ from the air outside; for in that case it would be the heat that does the concocting. And indeed it is also reasonable that it is coarser, mixed as it is with moisture from the vessels and from the mass of the body as a whole, so that the concoction would tend toward the bodily. But that the residue, if it comes about, is finer, is not plausible. The speed of the concoction is also unreasonable. For exhalation follows immediately after inhalation. What then is it that changes and alters so quickly? One would suppose it is above all the heat, and perception bears this out: for the exhaled breath is warm. Further, if what is concocted is in the lung and the windpipe, then the power of the heat is in these — but this is not what they say; rather, they say that the nourishment is heated in the motion of the breath. And if it draws the nourishment in from something else, as it were, or receives it from what moves it, this is more astonishing still.
4| At the same time, this is also not itself the first mover. Further, breathing reaches only as far as the lung, as they themselves say, while the innate breath extends through the whole. And if it is distributed from this both to the lower parts and to the others, how is the concoction so quick? For this is more astonishing still and a greater difficulty, since it does not send the air down to the lower parts immediately once concocted. And yet this would seem necessary, given that the concoction occurs in the lung, and the lower parts too share in the breathing. What follows is thus even greater and more paradoxical: the concoction occurs, as it were, only by a kind of passage and contact. This too is unreasonable, and still more so, if the account of the nourishment and of the residue is the same. And if it is through some other of the internal parts, the same accounts apply as before — unless one should say this: that a residue does not occur from all nourishment, nor in all cases, just as it does not for plants either, since it is not possible to get one from each of the parts of the body either. But if not, at least not from every part. But perhaps the growth of the vessels is the same as that of the other parts, and as these widen and separate, more air flows in and out.
5| But if there is something necessary present in it, this very thing is what is being sought — what the natural amount is, and how it becomes greater in a healthy way; from this it would become clear. But for creatures that do not breathe, what is the nourishment of the innate breath, and what is its growth? For it is no longer from outside for these. But if it is from the internal parts and the common nourishment, this is reasonable for them too; for like things come from the same things, and in the same way. Unless, then, for these too it is from outside, just as they also perceive smells. But in that case a kind of breathing occurs. About this one might well raise a difficulty as to whether it is really so, both putting forward this very point and the drawing-in of nourishment (for there is a drawing of breath at the same time), and further disputing on the score of cooling, on the ground that these creatures too need it. And if it occurs in them through the diaphragm, then clearly the entry of air is by this route too, so that it is something like breathing. Except that it is not determined what the drawing is, and by what. Or if it is not a drawing, how does entry occur? Unless, then, it happens automatically. This, then, is itself also a matter for separate consideration. But for water-creatures, what is the nourishment and growth of the innate breath?
6| For apart from the fact that they do not breathe, we also say that there is no air present at all in the moist element. It remains, then, that it is through nourishment — either not in the same way for all, or these water-creatures too grow through nourishment; for one of these three must be the case. This, then, is our account concerning the growth and nourishment of breath.
7| Concerning breathing, some do not say for the sake of what it occurs, but only the way in which it occurs — Empedocles and Democritus, for instance; others do not even say the way at all, but treat it as something obvious. But it is necessary to make clear this very point too: whether it is for the sake of cooling. For if the heat is in the upper parts, it would no longer need cooling in the lower parts. But the innate breath extends through the whole, and its starting point is from the lung. And it seems that breathing too is distributed into all the parts by continuity, so that this must be shown not to be so. And it is strange if it does not need some motion and, as it were, nourishment. But if it breathes through to everything, it would no longer be for the sake of cooling. And indeed the distribution is, besides, imperceptible, as is its speed. And again, the matter of the ebb-and-flow, if it is indeed from all the parts, is astonishing, unless it happens in some other way from the extremities. The primary and proper ebb-and-flow is from the region around the heart. In many cases the relation of actualities and potentialities is like this. It is strange, all the same, if it is also distributed into the bone; for indeed they say this too comes from the arteries. For this reason, as has been said, we must inquire concerning breathing — both for the sake of what, and in which parts, and how. Further, the conveyance of nourishment does not appear in all cases to occur through arteries, for instance to the vessels themselves and to certain other parts; yet plants live and are nourished. These matters, however, belong more properly to the discussion of nourishment.
8| Since there are three motions of the breath in the windpipe — respiration, pulse, and a third, the one that draws in and processes nutriment — we must speak about each: where it occurs, how, and for the sake of what. Of these, the motion of the pulse is evident even to perception, to those touching any part whatever; the motion of respiration is evident up to a point, but for the most part known by reasoning; the motion of nutriment is, so to speak, entirely known by reasoning, though from what happens it is also grasped by perception. Respiration, then, clearly has its principle from within — whether we should call this a capacity of soul, or soul itself, or some other mixture of bodies which of itself produces such a drawing. The nutritive motion would seem to derive from respiration; for this is given back in return, and resembles the true motion. But if not, the body evens everything out in its timing by such motion. Or, if the simultaneity makes no difference, all the parts must be examined. The pulse is something peculiar, distinct from these — in one respect it might seem to be accidental, if indeed, whenever there is an abundance of heat in moisture, what is turned to vapor must, because it is trapped within, produce a pulse; but it seems present at the origin and first, if indeed it is innate in the first parts —
9| for it is in the heart most of all and first, and from there it passes to the other parts as well. Perhaps this necessarily accompanies the underlying substance of the animal, arising from its activity. A sign that the pulse has nothing to do with respiration: whether someone breathes rapidly or evenly, forcefully or gently, the pulse remains alike and the same; rather, its irregularity and intensification occur in certain bodily affections and in the soul's fears, hopes, and agonies. Whether the pulse is also present in the arteries, and whether, being the same in rhythm, it is regular, must be examined; it does not, at least, resemble that in the parts far removed. It appears least of all to occur for the sake of something, as has been said. For, on the other hand, respiration and the intake of nutriment — whether as wholly distinct from one another or as one related to the other — appear to occur for the sake of something and to have some rational account. But of the three, is it reasonable that the pulsatile and the respiratory motions come first? For nutriment belongs to what already exists. Or not? For breathing occurs once the creature has been released from the one carrying it, while the influx and nourishment occur both while it is being formed and once it has been formed; but the pulse occurs immediately at the beginning, as the heart is being formed, as is evident in eggs.
10| So this — the pulse — is first, and it seems to belong to some activity and not to a trapping of breath, unless indeed this trapping contributes to the activity. The breath from respiration is carried into the stomach — not through the gullet (for this is impossible) — but there is a passage alongside the loin, through which the breath is carried by respiration from the gill into the stomach and out again; this is evident to perception. The matters concerning perception also present a difficulty. For if only the windpipe perceives, is it by the breath passing through it, or by its bulk, or by its body? Or, if air is the first thing subject to the soul, is it by the more authoritative and prior thing? What, then, is the soul? They say it is the capacity that is the cause of such motion. But clearly one would not be right to censure those who speak of the calculative part and the spirited part; for they too speak of them as capacities. But if indeed the soul is in this air, this air being common, or being affected somehow and altered, then reasonably the soul, being ensouled, would be carried toward its kindred, and like grows by like. Or not? For the whole is not air, but air is something contributing to this capacity — or rather, it is not the thing that produces this capacity; and what produced it is the principle and the underlying basis.
11| In creatures that do not breathe, it is so that the internal breath remains unmixed with what is outside. Or is that not so, but rather it is mixed in some other way? What, then, is the difference between the breath in the windpipe and the breath outside? It is reasonable that they differ, and perhaps necessarily so, in fineness. But further, is it hot in its own right, or by something else? For the internal breath appears just like the external; but it is helped by cooling. Which is it, then? Outside it is mild, but once enclosed as breath, it is as if condensed and distributed in some way. Or must it necessarily take on some admixture, since it moves about amid moisture and bodily masses? It is not, then, the finest, if indeed it is mixed. And yet it is reasonable that the first receptacle of soul — unless indeed the soul too is of such a kind, and not something pure and unmixed — is the windpipe alone, which is receptive of breath, and not the sinew. They differ also in that the sinew has tension, while the windpipe tears easily, as does the vein too. The skin is composed of vein, sinew, and windpipe — of vein, because when pricked it gives off blood; of sinew, because it has tension; of windpipe, because it has the capacity for transpiration. For the windpipe alone is receptive of breath. The veins have passages, in which the heat, being present as though in a forge, heats the blood —
12| for the blood is not by nature hot, but is melted down like fusible substances; hence the windpipe also solidifies, and has moisture both in itself and in the coats that surround its cavity. This is evident both from dissections, and from the fact that both the veins and the windpipes connect into the intestine and into the stomach — vessels which it is likely draw in the nourishment. From the veins the nourishment is distributed into the flesh, not through the sides but through the mouth of the vessel, as though through pipes. For from the great vein and the windpipe, along each rib, fine little veins stretch out from the lateral veins, and windpipe and vein lie alongside each other; and the sinews and veins attach to the bones both at their midpoints and at the joints of their heads, through which fish receive their nourishment and breathe; and if they did not breathe, they would die immediately once taken out of the water. That the veins and windpipes connect into one another is also evident to perception. This would not happen unless the moist needed breath and breath needed moisture, since heat exists in sinew, windpipe, and vein — but the heat in the sinew is the hottest and, as it were, most vein-like.
13| It would be strange, then, for heat to occupy the place of breath, especially since that place exists for the sake of cooling. But if heat produces something and, as it were, rekindles heat by heat, this could happen. Further, for all things possessing innate heat, its persistence is in some way natural, so long as nothing opposes or cools it. That all things need cooling is nearly evident from the fact that the blood in the vein holds in the heat as though sealing it off; hence, whenever the blood flows out, the heat is released and the creature dies, because the liver has no windpipe at all.
14| Is the seed carried through the windpipe, as also being compressed, and is this true only at the moment of emission? In these creatures the transformation from blood also appears to occur through the fact that the sinews are nourished from the bones; for they attach to them. Or is this not even true? For there is a sinew in the heart too, and yet the sinews are attached from the bones. It does not connect at another point, but terminates in flesh. But this proves nothing; for the nourishment could just as well come from the bone. Rather, the bones themselves get their nourishment from the sinew. For this too would be strange, the bone being by nature dry and not having moist passages; but nourishment is moist. We must examine, if indeed the sinew is nourished from the bones, what the nourishment of the bone itself is — or whether passages carry it into the bone both from the vein and from the windpipe. In many places these passages are quite evident, especially into the spine. Those from the bones are continuous, as in the case of the ribs; but in what way these come from the stomach, or how the drawing takes place. Or is it that most bones are cartilage-free, as the spine is — but this is not for the sake of motion, but for the sake of connection.
15| But we must also know, if bone is nourished from sinew, what nourishes the sinew. We say it is from the moisture around it, which is viscous. We must say where this moisture comes from and how. The claim that flesh comes from vein and artery, on the ground that blood comes out everywhere when the body is pricked, is false, at least in the case of other animals — birds, snakes, fish, and egg-laying animals generally. This is peculiar to animals rich in blood, since even in small birds, when the breast is cut, what appears is serum, not blood. Empedocles says the nail comes from sinew by solidification. Is skin related to flesh in the same way, then? But in shell-covered animals and soft-shelled animals, how does nourishment come from outside? For the opposite seems rather to be the case — that it comes more from within than from outside. Further, what is the passage from the stomach, and by what means does it occur? And again, the conversion of these into flesh, unaccountable though it is. For this appears something quite astonishing, and altogether impossible. Is it, then, that different animals have different nourishment, and blood is not the nourishment for all — except that the rest come from this?
16| We must therefore examine the nature of bones either in relation to motion or to support, and to covering and enclosing, and further, whether some serve as starting-points, as the pole does. I mean, in relation to motion — of foot, hand, leg, or elbow — both bending motion and locomotion alike; for locomotion is not possible without bending either. And support, too, lies more or less in these same bones. As for covering and enclosing: for instance, the bones in the head enclose the brain, and — for those who hold that marrow is a starting-point — enclose the marrow as well. The ribs serve the function of enclosing. The spine is both a starting-point and a fixed part, from which the ribs too extend for enclosure. For there must necessarily be something of this sort, since everything that moves does so from something at rest. And at the same time there must also be that for the sake of which motion occurs. In this connection some indeed place the starting-point in both the spinal marrow and the brain. And besides these, there are bones for the sake of joining and enclosing, such as the collarbone — whence perhaps also its name. And each is well suited to its use. For bending would not occur, neither of the whole nor of the parts, without such bones as these — the spine, the foot, the elbow.
17| For the bending must be inward, for the sake of use. And likewise that of the foot and of the other joints must be of this kind too. Everything is for the sake of something, including the bones within these joints — for instance the bone in the elbow, for the sake of the rotation of the elbow and the hand. For we would not be able to move the hand prone and supine without this bone, nor to raise and bend the feet, unless there were two such bones involved in the motion. In the same way the other cases must be examined too — for instance the motion of the neck, and whether its bone is one single bone. We must also consider whatever bones serve for grasping or for binding together, such as the kneecap at the knee — but also why other joints do not have one. Now all the bones that serve motion do so together with sinews, but perhaps especially those most concerned with practical action, such as those around the elbow, legs, hands, and feet. The others serve for the sake of binding, wherever it is needed. For in some cases perhaps there is none, or only a little — the spine, for instance — and yet there is bending. For indeed the bonding of the vertebrae to one another is by serum and a mucous moisture. And some bones are also bound together by sinews, such as those around the joints.
18| For all these matters there is a better account, such as we are now seeking; but we must examine the starting-points sufficiently, and for the sake of what they exist. It would not seem that the bones exist for the sake of motion, but rather the sinews, or their analogue, in which the motive breath is present first, since even the stomach moves, and the heart has sinews; but these are not present in all animals, only in some, and it is necessary that they also have sinews for this kind of motion, or else for [text breaks off] — for the octopus walks only a little, and badly. For we must take this as a starting-point: that either it belongs to all, or it exists for the sake of something else — but in relation to each animal's own proper motion, feet belong to land-animals; and of these, two belong to the upright ones, but more to those entirely upon the ground, whose matter is more earthy and colder. And it is possible for some to be entirely footless. For flying creatures move by force in this way, having wings, and the form of these is proper to their nature. And these differ between the more strongly-flying and the shorter-winged. They have feet for the sake of feeding and for rising up, except the bat — which is why its food too comes from the air. And it has no need of rest; for they do not need it by any other means. The shelled water-animals are somewhat-footed because of their weight. These, then, serve for change of place. As for whatever serves other uses, the inquiry itself indicates the particular features of each, including whatever is not obvious — for instance, why the many-footed creatures are the slowest, even though the four-footed are faster than the two-footed: is it because their whole bodies lie close upon the ground? Or because they are cold by nature and hard to move? Or for some other cause?
19| Those who deny that heat is what is at work in bodies, or who hold that the cutting motion and power of fire is some single, uniform thing, are not speaking correctly. For indeed it does not do the same thing to all inanimate things alike; rather, it condenses some, rarefies and melts others, and solidifies others. In the case of ensouled things, then, we must suppose it works in just this way, thinking of the fire of nature by analogy with that of craft. For indeed in the crafts too, the goldsmith's fire produces a different result from the bronzesmith's and the carpenter's, and so does the cook's fire. But perhaps it is truer to say it is the crafts that do this; for they use fire as an instrument, softening, melting, and drying things, and some also giving them shape. And natures do this same thing too — which is indeed the source of their differences from one another. So it is absurd to judge the matter by looking only at what is external. For whether being heated and set afire is a separating, or a thinning, or whatever else it may be, the results will differ according to those that make use of it. But the crafts use it as an instrument, whereas nature uses it at once also as matter. This part is not the difficult one; rather, the difficult thing is to grasp in thought the nature itself that makes use of it, which, along with the perceptible affections, will also account for the resulting form. For this is no longer a matter of fire, nor of breath.
20| That such a power should be mixed in with these is astonishing. And this same astonishing thing holds also concerning the soul; for it is present in these. For this reason it is not wrong to hold that the same thing — whether the soul as a whole, or some part of it — is what does the making, and that the motion, being always alike, constitutes an actuality; for so too does nature, from which coming-to-be also proceeds. But then what is the difference between the heat in each particular case? Whether we take it as instrument, or as matter, or as both. For the differences among fires are a matter of more and less. And this is more or less as in mixture and non-mixture; for the purer fire is more so. And the same account holds also for the other simple bodies. For necessarily, since the bone and flesh of a horse are different from those of an ox, they must differ either by being composed of different materials or by their use. If, then, they are different materials, what are the differences of each of the simple bodies, and which are they? For these are what we are seeking. But if they are the same materials, they would differ in their ratios of mixture. For necessarily it is one or the other of two options, just as in other cases: the blend of wine and honey differs because of the underlying ingredients, whereas differences within wine itself, if indeed there are differences, are because of the ratio. This is why, for Empedocles too, the cause of the nature of bone is a simple one: since if all bones have the same ratio of mixture, then those of horse, lion, and man ought to be indistinguishable.
21| But as things stand, it differs in hardness, softness, density, and the rest. Likewise flesh too, and the other parts. Further, the parts within the same animal differ in density and looseness and the rest, so that the blend is not the same. For being quick and fine and large and small would belong to quantity, while being hard and dense, and their opposites, belong to the quality of the mixture. But those who speak this way must know how the thing that produces this could be different. And yet this is a matter of more or less, both in what exists in its own right and in what is mixed in, or else of being fired within something else, the way things that are boiled and roasted are. And this is perhaps true: for the agent is mixed in at the same time and produces the effect that belongs to nature. So the same account holds for flesh as well; for the differentiae are the same. And much the same holds for vein and artery and the rest. So one of two things follows: either the account of these is not single with respect to the mixture, or the accounts must not be taken in terms of hardness and density and their opposites.