Aristotle · a new plain-English translation from the original language
1| But none the less, in each of the two parts all the parts of the soul are present, and they are uniform in kind with one another and with the whole—with one another as not being separable, and with the whole soul as the whole being divisible. And the principle found in plants also seems to be a kind of soul, for this is the only one that animals and plants share; and this is separable from the perceptual principle, whereas nothing has perception without this. B.
2| Let what has been handed down by our predecessors about soul be stated in this way; and let us now go back again, as it were from the beginning, and try to determine what soul is and what would be the most general account of it. We say, then, that one genus of things that are is substance, and of substance one part is as matter, which in its own right is not a this-something, another is shape and form, in respect of which it is already called a this-something, and a third is what is composed of these. And matter is potentiality, while form is actuality, and this in two ways, one as knowledge, the other as the act of contemplating. Bodies seem to be substances most of all, and among these the natural bodies, for these are the principles of the others. And of natural bodies, some have life and some do not; and by life we mean self-nourishment and growth and decay through itself. So every natural body that shares in life would be a substance, and a substance in the sense of a composite. Since, then, it is a body of a certain kind—namely, one having life—the body cannot be the soul; for the body is not something said of a subject, but rather is as a subject and matter.
3| It is necessary, then, that soul be a substance as the form of a natural body that has life in potentiality. But substance is actuality. Soul, then, is the actuality of a body of this kind. And actuality is spoken of in two ways, one as knowledge, the other as the act of contemplating. It is clear, then, that it is actuality in the sense of knowledge; for both sleep and waking depend on the presence of the soul, and waking is analogous to contemplating, while sleep is analogous to having knowledge without exercising it. And in the same subject, knowledge is prior in coming-to-be. Hence soul is the first actuality of a natural body that has life in potentiality. And such a body is one that is equipped with organs. The parts of plants too are organs, though altogether simple ones—for example the leaf is a covering for the pericarp, and the pericarp is a covering for the fruit. And the roots are analogous to the mouth, for both draw in nourishment. If, then, one must state something common to every soul, it would be the first actuality of a natural body equipped with organs. Hence one need not ask whether the soul and the body are one, any more than whether the wax and the shape are one, or in general whether the matter of each thing and that of which it is the matter are one; for while unity and being are spoken of in many ways, that which is so in the strict sense is the actuality.
4| We have, then, stated in general terms what the soul is: it is substance in accordance with the account or essence. And this is the essence of a body of this kind, just as if one of the tools were a natural body—an axe, for instance; for its being an axe would be its substance, and this would be its soul; and if this were separated from it, it would no longer be an axe, except homonymously. As it is, however, it is an axe; for the essence and the account that is soul does not belong to a body of that sort, but to a natural body of a certain kind, one having within itself a principle of motion and rest. What has been said must also be examined in the case of the parts. For if the eye were an animal, sight would be its soul; for this is the substance of the eye in accordance with the account. And the eye is the matter of sight, and when sight is lacking it is no longer an eye, except homonymously, like an eye made of stone or a painted one. Now what holds for the part must be applied to the whole living body; for as part stands to part, so proportionately the whole of perception stands to the whole perceptive body, as such. And it is not that which has lost the soul that is the thing potentially such as to live, but that which has it.
5| The seed and the fruit are what is potentially a body of this sort. Now just as cutting and seeing are actualities, so too is waking an actuality, while as sight and the capacity of the organ are, so is the soul; and the body is what is potentially ensouled. But just as the eye is the pupil and the sight together, so there the soul and the body are the animal. That the soul is not separable from the body, then, or that certain parts of it are not, if it is naturally divisible into parts, is not unclear; for of some parts the actuality is of the parts themselves. Still, nothing prevents some parts from being separable, because they are the actuality of no body at all. Further, it is unclear whether the soul is an actuality of the body in the way a sailor is of a ship. Let this stand, in outline, as our determination and sketch concerning the soul.
6| Since what is clear and more knowable in point of definition comes to be out of what is unclear but more evident, we must try again to go over the subject in this way; for the definitional account ought not merely to make clear the fact, as most definitions state it, but the cause too should be present in it and made evident. As things stand, the accounts given in definitions are like conclusions. For example: what is squaring? Making an equilateral right-angled figure equal in area to an oblong. Such a definition is an account of the conclusion. But the one who says that squaring is the finding of a mean proportional states the cause of the thing. Taking, then, as our starting point for inquiry, we say that the ensouled is marked off from the unsouled by living. But since living is spoken of in several ways, we say a thing lives even if only one of these belongs to it: intellect, perception, motion and rest with respect to place, and further the motion involved in nutrition, and decay and growth. Hence all growing things too are held to live; for they evidently have in themselves a power and a principle of this kind, through which they undergo growth and decay in contrary directions; for they do not grow upward only and not downward, but alike in both directions and every way, and they are nourished and continue to live throughout, as long as they are able to take in nourishment.
7| This power can be separated from the others, but the others cannot be separated from it in mortal things. This is evident in the case of growing things; for no other power of soul belongs to them. Living, then, belongs to living things because of this principle, but being an animal belongs to them primarily because of perception; for even things that do not move or change place, but have perception, we call animals and not merely living. And of perception, touch is present first in all of them. Just as the nutritive power can be separated from touch and from every perception, so touch can be separated from the other perceptions. We call nutritive that part of the soul in which plants too share; but all animals evidently have the perception of touch. For what cause each of these facts holds we will say later. For now let this much only be said: that the soul is the principle of the things we have mentioned, and is marked off by these: the nutritive, the perceptive, the intellective, and motion. Whether each of these is a soul or a part of a soul, and if a part, whether separable only in account or also in place, is on some points not hard to see, but on others it presents difficulty.
8| For just as in the case of plants some are seen to live and to be separated from one another when divided, on the ground that the soul in them is in actuality one in each plant but in potentiality many, so too we see this happening with respect to another difference of soul in the case of insects, in those that are cut in two; for each of the parts has perception and motion with respect to place, and if perception, also imagination and desire; for where there is perception there is also pain and pleasure, and where these are, desire follows of necessity. But concerning intellect and the power of contemplation nothing is yet clear, though it seems to be a different kind of soul, and this alone admits of being separated, as the eternal is separated from the perishable. But it is clear from these considerations that the remaining parts of the soul are not separable, as some say; that they are different in account is clear, for being perceptive and being given to opinion are different, if indeed perceiving is different from forming an opinion. And likewise for each of the other capacities mentioned. Further, in some animals all of these are present, in some only certain of them, and in others only one. This is what makes the difference among animals;
9| the cause of this we must examine later. Something similar holds with respect to the perceptions too; for some animals have all of them, some have certain of them, and some have only the most necessary one, touch. Since that by which we live and perceive is spoken of in two ways, just as that by which we know is—we call the one knowledge, the other soul; for we say we know by each of these—and likewise that by which we are healthy, the one being health, the other some part of the body, or even the whole of it. Of these, knowledge and health are a shape and a certain form and account, and as it were an activity of what is receptive—the one of what is capable of knowing, the other of what is capable of being made healthy (for the activity of the productive factors is held to belong to what is acted on and disposed); but the soul is that by which we live and perceive and think, primarily, so that it would be a kind of account and form, and not matter and the substrate. For substance is spoken of in three ways, as we said: one is form, one is matter, and one is what is composed of both; and of these, matter is potentiality, and form is actuality; and since what is composed of both is the ensouled thing, the body is not the actuality of the soul, but soul is the actuality of a certain body.
10| And for this reason those judge well who hold that the soul neither exists without a body nor is itself a body; for it is not a body, but belongs to a body, and for this reason it is present in a body, and in a body of a certain sort—and not, as those before us did, fitting it into a body without further determining in what and of what sort, even though it is evident that not just anything receives just anything. This is also how it turns out to be in accordance with reason; for the actuality of each thing naturally comes to be present in what is potentially that thing, and in its own proper matter. That the soul, then, is a certain actuality and account of what has the capacity to be of this sort is clear from these considerations.
11| Of the powers of the soul just mentioned, all belong to some things, as we said, while to others only some of them belong, and to some only one. The powers we spoke of are the nutritive, the desiderative, the perceptive, the locomotive, and the intellective. To plants only the nutritive belongs; to others this and also the perceptive. And if the perceptive, then also the desiderative; for desire is appetite, spirit, and wish, and all animals have at least one of the perceptions, namely touch; and whatever has perception has pleasure and pain, and the pleasant and the painful, and whatever has these has also appetite; for appetite is desire for what is pleasant. Further, animals have perception of their food; for touch is the perception of food; for all animals are nourished by what is dry and moist and hot and cold, and the perception of these is touch, while of the other perceptibles they have perception only incidentally; for neither sound nor color nor smell contributes anything to nourishment. Flavor is one of the tangible qualities. Hunger and thirst are appetite—hunger for what is dry and hot, thirst for what is cold and moist; and flavor is, as it were, a kind of seasoning of these.
12| We must make these points clear later, but for now let it be said this much: that appetite belongs to those animals that have touch. About imagination it is unclear, and it must be examined later. In addition to these, some animals also have the capacity for motion from place to place, and others also have the capacity for thought and intellect — for example, human beings, and any other such being there may be, or one even more honorable. It is clear, then, that in the same way there would be one account of soul as there is of figure. For in the case of figure there is no figure over and above the triangle and those that follow it in order, nor in this case is there any soul over and above the ones mentioned. There could indeed be, in the case of figures too, a common account, one that will fit all of them but will be the proper account of none of them. And likewise with the souls just mentioned. That is why it is absurd, both here and elsewhere, to look for a common account that will be the proper account of none of the things there are, nor correspond to the peculiar and indivisible species, while setting aside the proper account of each. What holds for figures holds in much the same way for the parts of the soul. For always, in the case of both figures and ensouled things, the prior member is present potentially in the one that follows in the series — for example, the triangle is present in the square, and the nutritive capacity is present in the perceptive.
13| So one must inquire in each case what the soul of each thing is — for example, what the soul of a plant is, and what the soul of a human being or of an animal is. And we must consider for what cause they stand in this order, one after another. For without the nutritive capacity there is no perceptive capacity; but the nutritive is separated from the perceptive in plants. Again, without the capacity for touch none of the other senses is present, but touch is present without the others; for many animals have neither sight nor hearing, nor any perception of smell at all. And among things that have perception, some have the capacity for motion from place to place, and others do not have it. Last, and belonging to the fewest, is reasoning and thought. For those perishable things to which reasoning belongs, all the rest belong as well; but not all things to which each of those other capacities belongs have reasoning — indeed some of them do not even have imagination, and others live by that alone. As for the theoretical intellect, that is a different discussion. It is clear, then, that this account of each of these capacities is the one most proper to them, and likewise concerning the soul.
14| Anyone who intends to conduct an inquiry into these matters must grasp what each of them is, and only then go on to investigate what is connected with them, or the other matters as well. And if we must state what each of them is — for example, what the intellective capacity is, or the perceptive, or the nutritive — we must first state, still earlier, what thinking is and what perceiving is; for the activities and actions are prior in account to the capacities. And if that is so, and prior even to these one must have studied their objects, then for the same reason it would be necessary to determine those first — for example, nourishment, the perceptible, and the intelligible. So we must speak first about nourishment and generation; for the nutritive soul belongs to the other kinds as well, and it is the first and most common capacity of soul, the one in virtue of which living belongs to all of them. Its functions are to generate and to make use of nourishment. For the most natural of the functions belonging to living things — those that are complete and not maimed, or that do not have spontaneous generation — is to make another thing like itself, an animal producing an animal, a plant producing a plant, so that they may share, so far as they are able, in the everlasting and the divine. For all things desire that, and it is for the sake of that that they do whatever they do by nature.
15| That for the sake of which is twofold: the thing for the sake of which, and the being for whose sake. Since, then, a thing is unable to share continuously in the everlasting and the divine — because nothing among perishable things admits of remaining the same and one in number — each thing shares in that in the way it is able to, some more, some less; and what persists is not the thing itself but something like itself, one not in number but one in species. Now the soul is the cause and principle of the living body. These terms are used in many ways. And likewise the soul is a cause in the three ways that have been distinguished: for it is a cause both as that from which motion comes, and as that for the sake of which, and as the substance of ensouled bodies. That it is a cause as substance is clear: for substance is the cause of being for all things, and for living things, being is living, and the cause and principle of this is the soul. Further, the actuality of what exists potentially is its account. And it is evident that the soul is also a cause as that for the sake of which; for just as intellect acts for the sake of something, in the same way nature does too, and this is its end. Such is soul in animals, in accordance with nature also;
16| for all natural bodies are instruments of the soul, and just as it is with the bodies of animals, so too with those of plants, since they exist for the sake of the soul. That for the sake of which is twofold: the thing for the sake of which, and the being for whose sake. But further, that from which motion in place first proceeds is also the soul; not all living things, however, possess this capacity. Alteration and growth too occur in accordance with soul; for perception seems to be a kind of alteration, and nothing perceives that does not have soul. And the same holds concerning growth and decay; for nothing decays or grows naturally unless it is nourished, and nothing is nourished that does not share in life. Empedocles did not speak well on this point, when he added that growth occurs in plants — downward, because their roots grow together with the earth on account of the earth's being carried that way by nature, and upward on account of fire behaving in the same way. For he does not take up-and-down correctly: for up and down are not the same for all things and for the universe, but rather, as the head is for animals, so the roots are for plants — if indeed the organs are to be called different and the same according to their functions. Besides this, what is it that holds together fire and earth, which are carried toward opposite places?
17| For they will be torn apart, unless there is something to prevent it; and if there is, this is the soul, and the cause of growing and being nourished. Some think that the nature of fire is, simply and without qualification, the cause of nourishment and growth; for fire alone, among bodies or elements, appears to be nourished and to grow. That is why one might suppose that this is what is doing the work both in plants and in animals. But fire is in a way a joint cause, yet not the cause without qualification — rather the soul is more so. For the growth of fire goes on without limit, so long as there is fuel to burn, but of all things constituted by nature there is a limit and a ratio of both magnitude and growth; and these belong to soul, not to fire, and to the account rather than to the matter. Since the same capacity of the soul is nutritive and generative, we must first determine the matter of nourishment; for it is by this function that the nutritive capacity is marked off from the other capacities. Nourishment seems to be the contrary by the contrary — not every contrary by every contrary, but only those contraries that have not only generation from one another but also growth from one another; for many things come to be from one another, but not all of them in a quantitative way — as, for example, a healthy thing from a sick one.
18| It appears that not even those things are food for one another in the same way; rather, water is food for fire, but fire does not nourish water. So among the simple bodies, it seems that this relation holds most of all — one being food, the other being nourished. But there is a difficulty here: some say that like is nourished by like, just as it also grows by like, while others hold the opposite, as we said — that the contrary is nourished by the contrary — on the ground that the like is unaffected by the like, whereas food changes and is concocted; and change, for everything, is into its opposite or into an intermediate. Further, the food is acted on in some way by what is nourished, but the latter is not acted on by the food — just as the carpenter is not acted on by his material, but the material by him; the carpenter only changes from inactivity into activity. Whether the food is what is added last or what is added first makes a difference. But if it is both — one unconcocted, the other concocted — then it would be possible to speak of food in both ways: insofar as it is unconcocted, the contrary is nourished by the contrary; insofar as it is concocted, the like by the like. So it is clear that both sides speak in a way that is both right and not right.
19| Since nothing is nourished that does not partake of life, what is nourished would be the ensouled body, insofar as it is ensouled; so that food too is relative to the ensouled, and not accidentally so. But being food and being productive of growth are different: insofar as the ensouled thing is a certain quantity, food is productive of growth; but insofar as it is a this and a substance, it is food — for food preserves the substance, and the thing exists just so long as it is nourished; and food is productive of generation, not of the thing that is nourished, but of something like the thing that is nourished — for the substance already exists, and nothing generates itself, but only preserves itself. So this principle of soul is a capacity of such a kind as to preserve what possesses it, insofar as it is such a thing, while food equips it to be active. That is why, deprived of food, it cannot exist. Since there are three things — what is nourished, that by which it is nourished, and what nourishes — what nourishes is the primary soul, what is nourished is the body that possesses it, and that by which it is nourished is the food. And since it is right to name everything from its end, and the end is to generate another thing like itself, the primary soul would be generative of another thing like itself. And that by which a thing is nourished is twofold, just as that by which one steers is twofold — the hand and the rudder — the one both moving and moved, the other only moving.
20| All food must be capable of being concocted, and heat produces the concoction; that is why every ensouled thing has heat. So in outline it has been said what food is; it must be made clear later, in the discussions proper to it. Now that these matters have been distinguished, let us speak generally about perception as a whole. Perception occurs in being moved and being acted on, as has been said; for it seems to be a kind of alteration. Some say that like is acted on by like. How this is possible or impossible we have stated in the general discussions about acting and being acted on. There is a difficulty as to why there is no perception of the senses themselves, and why, without external objects, they do not produce perception, though fire and earth and the other elements are present in them, of which — or of whose accidents — perception is. It is clear, then, that the faculty of perception is not in actuality but only in potentiality. That is why, just as the combustible does not burn by itself apart from what is capable of burning it — for otherwise it would burn itself, and would have no need of a fire actually existing — so too with perceiving. And since we speak of perceiving in two ways (for we say that what is capable of hearing and seeing hears and sees, even if it happens to be asleep, and also that what is already actively doing so hears and sees), perception too would be spoken of in two ways, the one as potentiality, the other as actuality. Likewise also perceiving, both what exists potentially and what exists actually.
21| First, then, let us speak as though being acted on, being moved, and being active were the same thing; for motion is indeed a kind of actuality, though an incomplete one, as has been said elsewhere. Now everything is acted on and moved by what is productive and exists in actuality. That is why in one sense it is acted on by the like, and in another sense by the unlike, as we said; for what is unlike is acted on, but having been acted on it is made like, and is such as the other. We must also draw a distinction concerning potentiality and actuality — for so far we have been speaking of them simply. In one sense something is a knower in the way we would call a man knowing, because man is one of those who know and possess knowledge; in another sense we call knowing the one who already possesses grammar. Each of these two is capable in a different way — the one because his kind and matter are of such a sort, the other because, if he wishes, he is capable of contemplating, provided nothing external prevents it; while the one who is already contemplating is in actuality and, strictly speaking, knows this particular A. Now both of the first two are knowers in virtue of potentiality, but the one has been altered through learning, changing often from a contrary state, while the other, from possessing perception or grammar, has done so without being active — moves into activity in another way.
22| Being acted on, too, is not simple; rather, in one sense it is a kind of destruction by the contrary, and in another sense it is rather the preservation of what exists potentially by what exists in actuality and is like it, standing to it as potentiality stands to actuality. For what possesses knowledge becomes one who is contemplating — which is either not a case of being altered at all (since the advance is into itself and into actuality) or is a different kind of alteration. That is why it is not right to say that what is thinking, when it thinks, is being altered — any more than the builder is altered when he builds. So the process that leads from what exists potentially into actuality, in respect of intellect and thought, deserves not the name "being taught" but some other name; while for the one who, starting from what exists potentially, learns and acquires knowledge from what exists actually and is capable of teaching, we must either say — as has been said — that he is not even acted on, or else that there are two kinds of alteration: the change into privative dispositions, and the change into states and into nature. In the case of the faculty of perception, the first change comes about through the parent; and once the thing is generated, it already possesses perceiving in the way it possesses knowledge. And "in actuality" is spoken of in a like way to "contemplating"; but it differs in that the objects productive of the activity are external — the visible and the audible — and likewise the rest of the perceptibles.
23| The reason is that perception in actuality is of particulars, while knowledge is of universals; and these are in a way within the soul itself. That is why it is up to oneself to think, whenever one wishes, but it is not up to oneself to perceive — for the perceptible object must be present. It is the same way, too, in the case of the branches of knowledge that deal with perceptible things, and for the same reason — that perceptible things are particulars and external things. But it would be an opportunity to clarify these matters on another occasion as well. For now let this much be determined: that what is called potential is not simple, but just as we might say that a child is capable of commanding an army, and also one who has reached the proper age, so it stands with the faculty of perception. And since the differentia between them has no name, though it has been determined that they are different, and how they are different, we must use "being acted on" and "being altered" as the proper terms; and the faculty of perception is potentially such as the perceptible object already is in actuality, as has been said. So it is acted on while not being like, but having been acted on it has been made like and is such as that object.
24| We must speak of each perception in turn, and first about the objects of perception. The perceptible is spoken of in three ways: of these, two we say we perceive in their own right, and one accidentally. Of the two, one is peculiar to each perception, the other common to all. By peculiar I mean what cannot be perceived by another perception, and about which the perception cannot be deceived — as sight is of color, hearing of sound, taste of flavor. Touch has more differentiae; but each of these still discriminates about its objects, and is not deceived that there is color or that there is sound, but only about what the colored thing is or where it is, or what the sounding thing is or where it is. Such things, then, are called peculiar to each sense, while the common objects are motion, rest, number, shape, magnitude; for such things are peculiar to no one sense, but common to all — for motion, for instance, is perceptible both by touch and by sight. A thing is called perceptible accidentally when, for example, the white thing happens to be the son of Diares: for one perceives this accidentally, since this — the thing perceived — is an accidental attribute of the white thing. And that is why the perceiver is in no way affected by the perceptible object insofar as it is such a thing. Of the things perceptible in their own right, the peculiar objects are the perceptible objects in the strict sense, and it is to these that the substance of each perception is naturally directed.
25| What sight is of, that is the visible. And the visible is color, and also something that can be stated in an account but happens to have no name; this will become clearer as we go on. For the visible is color. And this is what belongs to what is visible in its own right — in its own right not by the account given of it, but because it has in itself the cause of being visible. Every color is capable of setting in motion what is transparent in actuality, and this is its nature. That is why it is not visible without light, but the color of each thing is visible only in light. Hence we must first say what light is. There is, then, something transparent. And by transparent I mean what is visible, yet not visible in its own right, simply speaking, but through the color belonging to something else. Air and water are of this kind, and many solid bodies too; for it is not qua water or qua air that they are transparent, but because there is a nature present in both of these, and also in the eternal body above, which is the same in all of them. Light is the actuality of this transparent thing qua transparent. And where this is present only potentially, there is darkness.
26| Light is, as it were, the color of the transparent, whenever the transparent is transparent in full actuality through the agency of fire or something of the kind, such as the body above; for one and the same thing belongs to that body too. What the transparent is, then, and what light is, has been stated: light is neither fire, nor body generally, nor an effluence from any body (for it would then itself be a kind of body), but the presence of fire or something of that kind in the transparent; for it is not possible for two bodies to be in the same place at once. Light seems to be the opposite of darkness; and darkness is the privation of this kind of state in the transparent, so that clearly the presence of that state is what light is. And Empedocles was not right, nor was anyone else who has said as much, in holding that light travels and at a given moment comes to be between the earth and what surrounds it, without our noticing it; for this runs counter both to the truth as reasoned out and to the observed facts. Over a small distance it might escape notice, but that it should escape notice from sunrise to sunset is too great a claim to ask us to accept. What is receptive of color is what is colorless, and what is receptive of sound is what is soundless.
27| Colorless is the transparent, and also the invisible, or what is barely visible, as the dark seems to be. Of this latter kind is the transparent, but not when it is transparent in full actuality — rather when it is so potentially; for the same nature is at one time darkness and at another light. Not everything visible is visible in light, but only each thing's own proper color; for some things are not seen in light, yet produce a perception in darkness — for instance things that appear fiery and gleaming (these have no single name), such as fungus, horn, the heads, scales, and eyes of fish; yet in none of these is the thing's own proper color seen. For what reason these things are seen is another discussion; for the present it is clear only this much, that what is seen in light is color. That is also why it is not seen without light; for this was what being color meant for it — being capable of setting in motion what is transparent in actuality; and the actuality of the transparent is light. Here is a clear sign of this: if one places the colored thing directly on the eye itself, it will not be seen; rather color sets the transparent — the air, for instance — in motion, and by this, being continuous, the sense organ is set in motion.
28| Democritus is wrong in this, in thinking that if the space between were to become a void, one would see with perfect precision — even an ant in the sky; for this is impossible. For seeing occurs because the sense organ is in some way affected; and this cannot happen through the agency of the very color seen itself, so it remains that it happens through the medium between; hence there must necessarily be something between. And if it becomes a void, not merely will nothing be seen with precision, but nothing will be seen at all. The reason, then, why color must necessarily be seen in light has been stated. Fire, however, is seen in both conditions, both in darkness and in light, and this of necessity; for it is by fire that the transparent becomes transparent. The same account holds also for sound and smell; for none of these produces perception by touching the sense organ itself, but the medium is set in motion by the smell and the sound, and by this medium each of the two sense organs is set in motion in turn; and whenever one places the sounding or smelling thing directly on the sense organ itself, it will produce no perception at all. With touch and taste the case is the same in fact, though it does not appear so; the reason for this will become clear later. The medium of sounds is air, that of smell has no name.
29| For there is some affection common to air and water alike — just as the transparent is common to color, so there is something present in both of these that belongs to what has smell; for the aquatic animals too are plainly seen to have a perception of smell. But man, and such land animals as breathe, are unable to smell without breathing. The reason for this too will be stated later. For now let us first give an account of sound and hearing. Sound is spoken of in two ways: one is an actuality, the other a potentiality; for we say some things do not have sound, for instance a sponge or wool, and others do, for instance bronze and whatever is solid and smooth, because they are capable of sounding. This capacity is to produce actual sound between the sounding body and the hearing. Sound in actuality always occurs as of something against something and in something; for it is a blow that produces it. Hence it is also impossible for sound to arise from one thing alone; for the thing striking and the thing struck are different, so that what sounds, sounds against something. And a blow does not occur without locomotion. As we said, sound does not come from a chance blow; for wool, if struck, produces no sound at all, but bronze does, and whatever is smooth and hollow — bronze because it is smooth; hollow things, because by reflection they produce many blows after the first one, since what has been set in motion is unable to escape. Further, sound is heard in air and in water, though less distinctly. Neither air nor water is what governs sound; rather there must occur a collision of solid bodies against one another and against the air.
30| This happens when the air, having been struck, holds its ground and is not dispersed. Hence if it is struck quickly and forcefully, it makes a sound; for the motion of the thing striking it must outrun the crumbling of the air, just as if someone were to strike a heap or a string of sand while it is moving fast. Echo occurs when, after the air has become a single mass because of the container that has bounded it and prevented it from crumbling, the air is pushed back again, like a ball. Echo seems always to occur, but not distinctly, since what happens with sound is just as with light; for light too is always reflected (otherwise there would not be light everywhere, but darkness outside the sunlit spot), but it is not reflected in the way it is from water or bronze or some other smooth thing, so as to produce a shadow, by which we mark off light. The void is rightly said to be decisive for hearing. For air seems to be what is meant by the void, and it is this that causes hearing, when it is moved as a continuous single mass. But because it is friable, it does not resound clearly unless what is struck is smooth. In that case it becomes one all at once, because of the flat surface; for the surface of a smooth thing is one.
31| That which is capable of moving a single mass of air continuously as far as the organ of hearing is capable of producing sound, and hearing is naturally joined to air. And because the organ is in air, when the air outside is moved, the air inside is moved. That is why an animal does not hear in every part, nor does the air pass through everywhere; for not every part that can be moved and is ensouled contains air. In itself, then, air is soundless because it crumbles easily; but when it is prevented from crumbling, its motion is sound. The air in the ears has been built in so as to be immovable, so that it may perceive accurately all the differences of the motion. And this is also why we hear in water too, because the water does not get in to the air that is naturally joined to us; nor does it get into the ear, because of its coils. But when this does happen, one does not hear; nor does one hear if the membrane is damaged, just as one does not see when the skin over the pupil is damaged. And a sign of whether one is hearing or not is that the ear always rings, like a horn; for the air in the ears is always moved with a motion of its own; but the sound one hears is foreign to it and not its own. And this is why they say we hear by means of what is void and resounding, because we hear by means of what has air bounded within it. Does what is struck make the sound, or what strikes?
32| Or both, but in different ways? For sound is the motion of what is capable of being moved in the way that things rebound from smooth surfaces, when someone strikes them. Not everything, as has been said, makes a sound when struck and striking, for instance if a needle strikes a needle; but what is struck must be even, so that the air rebounds and is shaken as a mass. The differences among things that produce sound are made evident in the actual sound; for just as colors are not seen without light, so too the high-pitched and the low-pitched are not perceived without sound. These terms are used metaphorically, taken from the objects of touch; for the high-pitched moves perception a great deal in a short time, while the low-pitched moves it a little in a long time. So the high-pitched is not itself fast, nor the low-pitched slow, but the motion of the one comes to be of that character because of speed, and of the other because of slowness. And it seems to be analogous to the sharp and the blunt in the sphere of touch; for the sharp, as it were, pricks, while the blunt, as it were, pushes, because of the way each moves something, the one in a little space, the other in much, so that it turns out that one is fast and the other slow.
33| Let sound, then, be defined in this way. Voice is a certain sound of an ensouled being; for none of the soulless things has a voice, but they are said to have a voice only by resemblance, for instance the pipe and the lyre and all the other soulless things that have range and melody and articulation; for it seems that voice too has these features, but many animals do not have voice, for instance the bloodless animals, and among the blooded, fish. And this is reasonable, if indeed sound is a certain motion of air. But the fish said to have a voice, for instance those in the Achelous, make sound with their gills or with some other such part. Voice is the sound of an animal, and not made with any random part. But since everything makes a sound when something strikes something in something, and this medium is air, it is reasonable that only those things that take in air should have voice. For nature already puts what is breathed to use for two functions, just as it does the tongue for both taste and speech, of which taste is necessary (and that is why it belongs to more animals), while expression is for the sake of well-being; so too with breath, for the internal heat, as something necessary (the cause of which will be stated elsewhere), and for voice, so that well-being may obtain.
34| The organ of breathing is the windpipe; and the part for the sake of which this windpipe exists is the lung; for it is by means of this part that land animals have more heat than the others. And the region around the heart is the first to need breathing. Hence it is necessary, when breathing occurs, for the air to go in inside. So voice is the striking of the breathed-in air, by the soul residing in these parts, against what is called the windpipe. For not every sound made by an animal is voice, as we said (for it is possible to make a sound with the tongue too, and as those coughing do), but what strikes must be ensouled and act with some imagination; for voice is indeed a sound with meaning, and not simply a sound of the breathed air, as coughing is; but with this air it strikes the air in the windpipe against the windpipe itself. A sign of this is that one cannot produce voice while breathing in, nor while breathing out, but only while holding the breath; for the one holding the breath moves it in this way. It is also clear why fish are voiceless; for they do not have a windpipe. And they do not have this part because they do not take in air nor breathe. The reason why, however, is a matter for a different discussion.
35| Concerning smell and the object of smell, it is less easy to give a clear account than of what has been discussed; for it is not clear what sort of thing smell is, in the way sound or color is. The reason is that we do not have this perception in a precise form, but worse than many animals have it; for a human being smells poorly, and perceives none of the objects of smell apart from what is painful or pleasant, as if the sense organ were not precise. And it is reasonable that hard-eyed animals also perceive colors in this way, and that the differences among colors are not distinct to them except in terms of the frightening and the unfrightening. And the human race is in the same condition with respect to smells; for smell seems to stand in analogy to taste, and the species of flavors correspond to those of smell, but we have a more precise sense of taste, because it is a kind of touch, and this is the sense that the human being has most precisely; for in the other senses he falls far short of other animals, but in respect of touch he is distinctively more precise than many of the others. That is why he is also the most intelligent of animals. A sign of this is that even within the human race, people are well-endowed or poorly-endowed by nature according to this sense organ, and by no other;
36| For those with hard flesh are ill-endowed in intellect, while those with soft flesh are well-endowed. And just as flavor is, in one case sweet and in another bitter, so too are odors. But some things have odor and flavor in proportion to each other — I mean, for example, a sweet odor along with a sweet flavor — while others have the opposite. Likewise there is a pungent, an astringent, a sharp, and an oily odor. But, as we said, because odors are not as sharply distinguishable as flavors are, they have taken their names from these by resemblance of the things involved: the sweet odor from saffron and honey, the pungent from thyme and things of that sort; and the same way for the others. And smell is like hearing and each of the other senses: as hearing is of the audible and the inaudible, and sight of the visible and the invisible, so smell is of the smellable and the unsmellable. A thing is unsmellable either because it is wholly incapable of having odor, or because it has only a small and poor odor. The same is said of the tasteless. And smelling, too, occurs through a medium, such as air or water; for aquatic animals too are held to perceive odor.
37| The same holds both for animals with blood and for those without, just as for those in the air; for even among these, some meet their food from a distance because they get wind of it. Hence it appears puzzling: if all creatures smell in the same way, how is it that a human being, while breathing in, does smell, but while not breathing in — either breathing out or holding the breath — does not smell, whether near or far, not even if the object is placed right inside the nostril? Now that a thing placed directly on the sense organ itself is imperceptible is common to all the senses; but failing to perceive without breathing is peculiar to human beings — and this is clear if one tries it. So bloodless animals, since they do not breathe, would have to possess some other sense distinct from the ones named. But that is impossible, if indeed they perceive odor; for the perception of the smellable, whether foul-smelling or sweet-smelling, is smelling. Moreover, they are evidently harmed by the same strong odors that harm a human being, such as bitumen and sulfur and things of that kind. It is necessary, then, that they smell, but not by breathing. It seems that in human beings this sense organ differs from that of other animals, the way human eyes differ from those of hard-eyed creatures: human eyes have a barrier and, as it were, a covering in the eyelids, which one does not see without moving or lifting;
38| whereas hard-eyed creatures have nothing of the kind, but see at once whatever occurs in the transparent medium. So too, then, the organ of smell is in some creatures uncovered, like the eye of the hard-eyed animals, while in those that take in air it has a covering, which is uncovered when they breathe in, as the little veins and passages are widened. And this is why creatures that breathe do not smell in a liquid medium; for smelling necessarily requires having breathed in, and this is impossible to do in a liquid. Odor belongs to the dry, just as flavor belongs to the moist; and the organ of smell is potentially of that same character.
39| What is tastable is a kind of tangible object; and this is the reason it is not perceptible through a medium that is a body other than the organ itself — for neither is touch. And the body in which the flavor resides, the tastable thing, is in moisture as its matter; and this moisture is itself something tangible. Hence, even if we were in water, we would perceive something sweet thrown in, but our perception of it would not come through a medium, but rather by the sweet thing's mixing with the moisture, as happens with a drink. Color, by contrast, is not seen this way, by mixing, nor by effluences. So in the sense that there is a medium, there is none here; but as color is the visible object, so flavor is the tastable object. Now nothing produces perception of flavor without moisture, but it has moisture either in actuality or in potentiality, as with what is salty; for salt is itself easily dissolved and dissolves the tongue along with it. And just as sight is of both the visible and the invisible (for darkness is invisible, and sight judges this too), and also of the excessively bright (for this too is invisible, though in a different way from darkness), so likewise hearing is of both sound and silence, of which the one is audible and the other not, and also of loud sound, just as sight is of the bright;
40| for just as a small sound is in a sense inaudible, so too is a loud and violent one; and something is called invisible either in the unqualified sense, as with what is impossible in other cases too, or in the sense that, though naturally fit to have it, it lacks it or has it poorly, as with the footless or the stoneless. So too taste is of both the tastable and the tasteless; and this latter is what has a small or poor flavor, or one destructive of taste. It seems that the drinkable and undrinkable are a starting point here; for both are a kind of taste, but the one is poor and destructive of the taste, the other in accordance with nature. What is common to touch and taste is the drinkable. Since what is tastable is moist, its sense organ too must necessarily be neither actually moist nor incapable of being moistened; for taste is in some way affected by the tastable object, insofar as it is tastable. It is necessary, then, that the organ of taste be moistened — being capable of being moistened while remaining preserved, yet not itself moist. A sign of this is that the tongue perceives neither when it is completely dry nor when it is excessively moist; for in the latter case there occurs contact with the primary moisture already present, as when someone tastes another flavor after having first tasted a strong one; and it is like the case of the sick, to whom everything appears bitter, because they perceive with a tongue full of that kind of moisture.
41| The kinds of flavors, as with colors, are, in their simple form, the opposites — the sweet and the bitter — and, closely allied to these, the oily to the one and the salty to the other; and between these come the pungent, the astringent, the harsh, and the sharp; for these pretty much appear to be the differentiae of flavors. So the faculty of taste is that which is potentially of this character, while the tastable is what actually produces it.
42| Concerning the tangible and touch, the same account applies. For if touch is not a single sense but several, then the tangible objects of perception must also be several. There is a puzzle here as to whether they are several or one, and what the sense organ is that is capable of touch: whether it is the flesh — and in other animals whatever is analogous to it — or not, but this is rather the medium, while the primary sense organ is something else, internal. For every sense is held to be of a single pair of contraries — for example, sight of white and black, hearing of high-pitched and low-pitched, taste of bitter and sweet — whereas in the case of the tangible there are present many contrarieties: hot and cold, dry and moist, hard and soft, and other such pairs. There is, however, some solution available at least to this puzzle: that in the other senses too there are several contrarieties — for example, in sound not only high pitch and low pitch, but also loudness and softness, and smoothness and roughness of sound, and other such qualities. And there are similar further differentiae in the case of color as well. But what the single underlying thing is that stands to touch as sound stands to hearing is not evident.
43| Is the organ of touch internal, or is it not, but flesh itself immediately the organ? It seems to be no sign either way that perception occurs the moment things are touched. For even now, if one were to stretch something around the flesh, making it like a membrane, we would signal perception in the same way, immediately upon contact; and yet it is clear that the organ of perception is not in this membrane. And if the membrane grew naturally attached, perception would get through even faster still. This is why this part of the body seems to be in the same condition as it would be if air had grown around us in a circle: we would then seem to perceive sound and color and smell by one single thing, and sight, hearing, and smell would seem to be one single perception. But as things stand, because the medium through which the movements occur is distinct in each case, the perceptual organs mentioned are plainly different from one another. In the case of touch, though, this is at present unclear: for it is impossible for the ensouled body to be composed out of air or water alone, since it must have something solid in it. What is left, then, is that it be a mixture of earth and these, of the sort that flesh and its analogue tend to be; so that the body must necessarily be something situated between the tangible object and what is naturally attached, through which the perceptions—being more than one—occur. That they are more than one is shown by the sense of touch on the tongue:
44| for it perceives all tangible qualities and also flavor by the same part. If the rest of the flesh likewise perceived flavor, taste and touch would seem to be the same, single perception; but as it stands they are two, because they do not convert into one another. One might raise a difficulty here: every body has depth, and this is the third dimension; and where there is some body between two bodies, it is not possible for those two to touch one another. Now the wet cannot exist apart from body, nor can the moist, but there must necessarily be water, or something that has water in it. And things that touch one another in water, if their extremities are not dry, must necessarily have water between them, with which their outer surfaces are soaked through. And if this is true, it is impossible for one thing to touch another in water. The same holds in air as well: for air stands to things in it the same way water stands to things in water. But this escapes our notice more, just as it escapes the notice of water-animals, whether one moist thing touches another moist thing. So then, is perception the same in all cases, or is it different in different cases, as it now seems: taste and touch by actual contact, the other senses from a distance?
45| That is not so; rather, we perceive hard and soft too through something else in between, just as we perceive the audible, the visible, and the smellable—only in these latter cases the medium acts from far off, and in the former from close by. That is why it escapes notice, since in fact we perceive everything through a medium; but in these cases it escapes notice. And yet, as we said before too, even if we perceived all tangible things through a membrane without noticing that it was separating us from them, we would be in the same condition as we now are in water and in air—for we seem to touch these things directly and think there is nothing between. But the tangible differs from the visible and the audible in this: we perceive those by the medium's doing something to us, while we perceive tangible things not by the medium's agency but together with the medium, the way a man struck through his shield is struck—for it is not the shield, once struck, that struck him, but both happened to be struck at once. In general, it seems that flesh and tongue stand to the organ of touch just as air and water stand to sight, hearing, and smell, each of the media standing to its own sense. If the organ of perception itself is touched, no perception would occur in that case or in the other—as if someone were to place a white body right on the surface of the eye.
46| This also makes it clear that the organ that perceives the tangible is internal. For then the very thing that happens with the other senses would happen here too: when objects are placed on the organ of perception itself, no perception occurs, but when they are placed on the flesh, perception does occur; so that flesh is the medium of the tactile power. The tangible qualities, then, are the differentiae of body as body; I mean the differentiae that mark off the elements—hot, cold, dry, wet—about which we have spoken earlier in our treatise on the elements. The organ that perceives them is the organ of touch, and the part in which what is called touch first resides is the part that is such potentially: for to perceive is to be acted on in some way. So that whatever acts, being such actually, makes the part such which is such potentially. This is why we do not perceive what is equally hot or cold as ourselves, or equally hard or soft, but only the extremes, on the ground that perception is a kind of mean state relative to the opposition present in perceptible qualities. And this is why it discriminates the perceptible qualities. For the mean is what does the discriminating: it becomes, relative to each of the two extremes, the other extreme; and just as what is going to perceive white and black must be neither of the two actually, though both potentially, so too in the other cases, and in touch it must be neither hot nor cold.
47| Further, just as sight was in a way of both the visible and the invisible, and likewise the other senses of their opposed pairs, so too touch is of the tangible and the untouchable; and untouchable is what has only a very slight differentia among tangible qualities, such as is the condition of air, and also the extremes of tangible qualities, such as things that are destructive. So then, concerning each of the senses, the account has been given in outline.
48| But concerning every sense in general, one must grasp that sense is what is receptive of perceptible forms without the matter, as wax receives the imprint of the ring without the iron or the gold, and takes the imprint that is gold or bronze, but not insofar as it is gold or bronze; and likewise sense is acted on in each case by what has color, or flavor, or sound, but not insofar as each of those things is called what it is, but insofar as it is of such-and-such a quality, and according to its ratio. The primary organ of sense is that in which such a power resides. The organ and the power are the same thing, but their being is different: for what perceives would be some magnitude, yet its being what is capable of perceiving is not a magnitude, nor is perception itself a magnitude, but rather a certain ratio and power of that thing. And from this it is also clear why excesses of the perceptible qualities destroy the sense organs: for if the movement is too strong for the organ, the ratio is dissolved—and this ratio was what perception was—just as both the concord and the pitch are dissolved when the strings are struck too hard. And it is also clear why plants do not perceive, even though they have some part that belongs to soul and are affected by tangible qualities:
49| for indeed they are cooled and heated. The cause is that they do not have a mean state, nor a principle of the sort that is able to receive the forms of perceptible objects, but are acted on together with the matter. One might raise the difficulty whether something incapable of smelling could be affected by an odor, or something unable to see by a color, and likewise in the other cases. If the smellable is odor, then if odor produces anything, it produces smelling. So none of the things incapable of smelling could be affected at all by odor; and the same account holds in the other cases too—nor indeed can things capable of perceiving be affected by it except insofar as each is capable of perceiving. And this is also clear in the following way. Neither light and darkness, nor sound, nor odor do anything at all to bodies, but rather the things in which they occur do—for instance, the air that accompanies thunder splits wood apart. But tangible qualities and flavors do act: for if not, by what would lifeless things be affected and altered? Will odor and sound, then, act on those things too? Or is it rather that not every body is capable of being affected by odor and sound; and the things that are affected by them are indeterminate and do not stay fixed, like air—for it comes to smell, as though it had been affected in some way. What, then, is smelling, over and above being affected in some way?