Aristotle · a new plain-English translation from the original language
1| ON SENSE AND SENSIBLE OBJECTS. [section 1] Since the soul has been marked off in its own right, and the capacities of each of its parts have been discussed, the next task is to undertake an inquiry about animals and all things that have life, as to what activities are peculiar to them and what activities are common to them. Let what has been said about the soul be taken as established, and let us speak of what remains, and first of the first things. [section 2] Now the greatest and most common as well as the most peculiar features of animals appear to belong in common to soul and body—for example perception and memory and spirit and appetite and desire generally, and besides these, pleasure and pain; for these belong, one may say, to practically all animals. [section 3] Beyond these, some things are common to everything that shares in life, while others belong only to some animals. The greatest of these happen to fall into four pairs in number, namely waking and sleeping, youth and old age, inhaling and exhaling, and life and death; about these we must examine what each of them is, and through what causes it comes about. [section 4] It belongs to the student of nature to observe the first principles of health and disease as well; for neither health nor disease can occur in things deprived of life. That is why nearly all students of nature, and those doctors who pursue their craft in a more philosophical way, the former end up dealing with matters of medicine, while the latter begin from matters of nature in their treatment of medicine.
2| [section 5] That the things mentioned belong in common to soul and body is not unclear. For all of them either occur along with perception or occur through perception; and some of them happen to be affections of it, others states, others safeguards and preservations of it, and others destructions and privations of it. That perception comes to the soul through the body is clear both by argument and apart from argument. [section 6] But about perception and perceiving, what it is and why this affection occurs in animals, this has been said before in the works on the soul. For animals, insofar as each is an animal, it is necessary that perception belong to it; for it is by this that we mark off being an animal from not being an animal. [section 7] But taking each sense separately now: touch and taste follow of necessity in all animals—touch on account of the cause stated in the works on the soul, and taste on account of nourishment; for taste discriminates the pleasant and the painful in nourishment, so that the animal avoids the one and pursues the other, and in general flavor is an affection of the nutritive part.
3| [section 8] The senses that operate through external objects, in animals capable of locomotion—such as smell and hearing and sight—belong to all that possess them for the sake of preservation, so that by perceiving in advance they may pursue their nourishment and avoid what is bad and destructive; but in those animals that also attain practical wisdom, these senses serve the good life as well; for they report many differences, out of which arises both the practical wisdom concerned with objects of thought and that concerned with things to be done. [section 9] Of these senses themselves, sight is superior for necessities, and superior in its own right, while hearing is superior with a view to intellect, though only accidentally. [section 10] For the power of sight reports many differences of every kind, because all bodies share in color, so that it is especially through sight that we perceive the common sensibles as well (I mean by common sensibles shape, size, motion, number); whereas hearing reports only differences of sound, and in few animals also differences of voice. [section 11] But accidentally, hearing contributes the greatest part toward practical wisdom. For speech, being audible, is a cause of learning—not in its own right, but accidentally; for speech is composed of names, and each of the names is a symbol.
4| [section 12] That is why those blind from birth are more practically wise than the deaf and dumb, who are deprived of the other of the two senses. Now concerning the power that each of the senses has, this has been discussed earlier. [section 1] As to the parts of the body in which the sense organs naturally arise, some inquirers look to the elements of bodies; and finding it difficult to bring the sense organs, which are five, into correspondence with the four elements, they reach eagerly for a fifth. [section 2] All make sight to be of fire, because they do not know the cause of a certain affection; for when the eye is pressed and moved, fire appears to flash out from it; and this naturally happens in darkness, or when the eyelids are closed—for darkness occurs then too. This raises another difficulty as well. [section 3] For if it is impossible for one who perceives and sees to escape notice of some object seen, then it must follow that the eye sees itself. Why then does this not happen when the eye is at rest? [section 4] The causes of this—both of the difficulty and of the appearance that sight is fire—must be grasped from the following. Smooth things naturally shine in the dark, though they do not produce light; and the part of the eye called the black, the middle part, appears smooth. This appearance occurs when the eye is moved, because it happens that the one thing seems, as it were, to become two. This is caused by the speed of the motion, so that the seeing part and the part seen seem to be different.
5| [section 5] That is why this does not occur unless it happens quickly and in the dark; for the smooth naturally shines in the dark, as do the heads of certain fish and the ink of the cuttlefish; and when the eye changes slowly, it does not happen that the seeing part and the part seen seem to be at once one and two. [section 6] In that other way the eye sees itself, just as in reflection—since if sight really were fire, as Empedocles says and as is written in the Timaeus, and seeing came about by light going out as if from a lantern, why would sight not also see in the dark? [section 7] But to say that the light is quenched as it goes out into the dark, as Timaeus says, is utterly empty; for what is a quenching of light? What is hot and dry is quenched by what is moist or cold, as seems to be the case with the fire in glowing coals and with flame, and neither of these appears to belong to light. [section 8] But if it does belong, and only escapes our notice because it is gentle, then light ought to be quenched by day as well and in water, and darkness ought to occur more in frost—since flame and things set on fire do undergo this; but as it is, nothing
6| of the kind occurs. [section 9] Empedocles seems to think that we see at one time by light going out, as has been said before; at any rate he speaks as follows: As when someone planning a journey fits out a lantern, a gleam of blazing fire through a wintry night, fastening lamp-guards against all sorts of winds, which scatter the breath of the blowing winds, and the light, springing out—as much of it as is finer—shines across the threshold with unyielding rays; so then the primeval fire, confined within the membranes and fine tissues, lay in wait for the round-eyed maiden; and these held back the deep of the surrounding water, but the fire sprang forth outside, as much of it as was finer. [section 10] So at one time he says we see in this way, and at another time by effluences coming from the things seen. Democritus says correctly that sight is water, but not correctly that seeing consists in the reflected image; for this occurs because the eyeball is smooth, and the image is not in the eye but in the one who sees—for the affection is reflection. [section 11] But about reflected images and reflection in general, nothing had yet, it seems, been made clear. It is also strange that it did not occur to him to ask why the eye alone sees, and none of the other things in which images are reflected. Now it is true that sight is of water, but seeing does not occur to it insofar as it is water but insofar as it is transparent—which is also common to air.
7| [section 12] But water is easier to keep pure and easier to freeze than air; and this is why the pupil and the eye are made of water. This is clear also from the facts themselves: for what flows out when eyes decay appears as water, and in embryos altogether this is exceedingly cold and bright. [section 13] And the white of the eye in blooded animals is fat and oily; and this is for the sake of keeping the fluid from congealing. And this is why the eye is the least liable to chill of all parts of the body: for no one has ever felt the inside of the eyelids go numb with cold. In bloodless animals the eyes are hard-skinned, and this provides the protection instead. [section 14] It is altogether unreasonable to suppose that sight sees by something going out from the eye and stretching as far as the stars, or that it goes out to some point and there fuses with the object, as some say. For it would be better than this for the fusion to occur at the very start, in the eye itself. But even this is silly: for what would it mean for light to fuse with light? Or how could this even happen? For not anything fuses with anything at random. [section 15] And how does what is inside the eye fuse with what is outside? For the membrane lies between. Now the question why nothing is seen without light has been discussed elsewhere; but whether what lies between the object seen and the eye is light or air, it is the motion through this that produces seeing. And reasonably the inside is made
8| of water; for water is transparent. [section 16] But just as seeing outside does not happen without light, so too seeing inside: the inside must be transparent, then. And it must be water, since it is not air. For the soul, or the perceptual organ of the soul, is not situated at the outer surface of the eye, but clearly inside; and so the inside of the eye must be transparent and receptive of light. [section 17] And this is clear also from what actually happens: for before now men have been struck in war near the temple in such a way that the passages of the eye were cut through, and it seemed to them that darkness fell as if a lamp had been put out, because the transparent part, the so-called pupil, had been cut off like a kind of lantern. [section 18] So if any of these things happens as we say, it is clear that each of the sense organs must be accounted for and attached in this way to one of the elements. The visual part of the eye should be supposed to be of water, the part perceptive of sounds of air, and smell of fire. [section 19] For what smell is in actuality, the organ of smell is in potentiality: for the object of perception makes the perception actual, so that the perception must exist beforehand in potentiality. And odor is a kind of smoky exhalation, and the smoky exhalation comes from fire.
9| [section 20] This is also why the organ of smell is located in the region around the brain: for the matter of what is cold is hot in potentiality. And the formation of the eye follows the same pattern: for it is formed from the brain, since the brain is the moistest and coldest of the parts in the body. [section 21] And the organ of touch is of earth. Taste is a kind of form of touch. And this is why their organ, that of taste and of touch, is near the heart: for the heart is opposite to the brain, and is the hottest of the parts. Let this, then, be our account of the perceptive parts of the body. [section 1] Concerning the objects perceived by each sense organ - I mean color and sound and smell and flavor and touch - it has been said in general in the work On the Soul what their function is and what it is for each sense organ to be active; but what one ought to say each of them actually is - for instance what color is, or what sound is, or what smell or flavor is, and likewise concerning touch - must now be examined, and first concerning color. [section 2]
10| Each of these is spoken of in two ways, the one in actuality, the other in potentiality. Now how actual color and actual sound are the same as, or different from, the perceptions that correspond to their actuality, such as sight and hearing, has been said in the work On the Soul; what each of them is in itself that produces the perception and its actuality, let us now say. [section 3] As has been said there concerning light, that it is the color of the transparent, accidentally: for whenever something fiery is present in the transparent, its presence is light, and its privation is darkness. [section 4] What we call transparent is not a property peculiar to air or water or any of the other bodies so called, but is a certain common nature and power, which is not separable but exists in these, and is present in the other bodies too, more in some, less in others. Just as there must be some outer limit of bodies, so too there must be one of this transparent nature. [section 5] Now the nature of light exists in the transparent when the latter is indeterminate; but as for the limit of the transparent that is in bodies - that this is something is clear; that this is color is evident from the facts. For color is either in the limit or is a limit; and this is why the Pythagoreans called the surface color.
11| [section 6] For color is in the limit of the body, but it is not the limit of the body; rather one must suppose that the same nature which is colored on the outside is also colored on the inside. And both air and water appear to be colored; for the beam of light too is of this kind. [section 7] But there, because the transparent is indeterminate, air and sea do not have the same color when approached from close up and from far off; whereas in bodies, unless the surrounding medium causes the change, the appearance of the color is fixed. It is clear, then, that the same thing is receptive of color both there and here. [section 8] The transparent, then, insofar as it is present in bodies - and it is present, more or less, in all of them - makes them share in color. And since color is in a limit, color would be in the limit of this transparent. So color would be the limit of the transparent in a bounded body. [section 9] And in the transparent things themselves - water, for instance, and anything else of this kind - and in all things that appear to have a color of their own at their outer surface, color belongs to them all in the same way. Now it is possible for that which produces light in air to be present in the transparent, or not to be present but instead to be lacking; so, just as there in air there is on the one hand light, on the other darkness, so in bodies white and black come to be.
12| [section 10] Concerning the other colors, we must now distinguish and state in how many ways they can come to be. For it is possible for white and black to be placed side by side, so that each is invisible because of its smallness, while what results from both becomes visible in this way. [section 11] For this can appear neither white nor black; and since it must have some color, and neither of these two is possible, it must be a mixture, a different species of color. [section 12] It is possible, then, to suppose in this way that there are more colors than white and black, and many according to ratio: for three to two, and three to four, and according to other numbers, colors can be juxtaposed, while others are altogether in no ratio, but in some incommensurate excess and deficiency; and colors stand in the same relation as musical consonances do: for the colors in well-proportioned numbers, just as with the consonances there, are thought to be the most pleasant of colors - for instance purple and crimson, and a few others of this kind - for the same reason that the consonances too are few - while the other colors are not in proportional numbers; or else all colors are in numbers, some ordered, some disordered, and these latter, whenever they are not pure, become so because they are of this kind through not being in proportional numbers.
13| [section 13] This, then, is one way colors come to be; another is their appearing through one another, as sometimes painters do it — laying a more vivid color over another, as when they want to make something appear as if in water or in air; and as the sun itself, seen directly, appears white, but through mist and smoke appears crimson. [section 14] And in this way too there will be many colors, by the same manner as was said before; for there would be a certain ratio of the surface colors to the ones underneath, though in some cases there is no ratio at all. [section 15] Now to say, as the ancients did, that colors are effluences and are seen because of a cause of that kind is absurd; for on their view perception must in every case occur through touch, so that it is far better to say straightaway that perception occurs by the medium between the sense and the sensible object being moved, by contact, and not by effluences. [section 16] In the case of things lying side by side, it is necessary to take, just as an invisible magnitude, so too an imperceptible time, so that the motions arrive unnoticed and seem to be one because they appear together. But here there is no such necessity; rather the surface color, being unmoved yet moved by what underlies it, will not produce a motion like that one. That is why it appears different, and neither white nor black.
14| [section 17] So if it is not possible for any magnitude to be invisible, but everything is visible from some distance, then this too would be a certain mixture of colors. And in that way nothing prevents some common color from appearing to things seen from far off; for whether there is no invisible magnitude at all must be examined later. [section 18] But there is a mixture of bodies not only in the way some people suppose — the smallest parts being placed side by side, imperceptible to us because of our perception — but also, wholly and in every way, as has been said generally about all mixture in the treatise on mixture. [section 19] For on that first view, only those things mix which admit of being divided into smallest parts, as men, horses, or seeds; for of men the smallest is a man, of horses a horse; so that by the juxtaposition of these the multitude of both together is called a mixture — but we do not say one man has been mixed with one horse. [section 20] But things that are not divided into a smallest part cannot come to be mixed in this way, but only by being mixed through and through — which is in fact the way things are most naturally mixed. How this is possible has been stated earlier in the treatise on mixture.
15| [section 21] But that when things are mixed the colors too must be mixed is clear, and that this cause is the decisive one for there being many colors, and not the superposition nor the side-by-side placing; for it is not the case that from far off one color of the mixed things appears but from near it does not — rather it appears one from every distance. [section 22] There will be many colors because the things that mix can mix with one another in many ratios, some in numerical ratios and some only by way of excess. [section 23] And the rest can be said in the same way about mixed colors as was said about colors placed side by side or on the surface. For what cause the kinds of colors are determinate and not infinite, and likewise of flavors and sounds, we will say later. [section 1] What color is, then, and for what cause there are many colors, has been stated; about sound and voice it has been stated earlier, in the treatise on the soul; about odor and flavor we must now speak. For it is nearly the same affection, though each of the two does not occur in the same subjects. [section 2] The kind belonging to flavors is more evident to us than that of odor. The cause of this is that we have the worst sense of smell of all the animals, and the worst among the senses in ourselves, but the most exact touch of all
16| the animals. And taste is a kind of touch. [section 3] Now the nature of water wants to be flavorless; and it is necessary either that water contains in itself the kinds of flavors, imperceptible because of their smallness, as Empedocles says, or that there is in it a matter of that kind, a sort of seed-mixture of flavors, and that everything comes to be from water, but different things from different parts of it; or that, water having no differentiation at all, the efficient cause is something else — as if one were to say the hot, and the sun. [section 4] Of these, as Empedocles states it, the falsehood is all too easy to see; for we observe flavors changing under the action of heat when the rinds are removed and exposed to the sun and scorched, showing that they do not come to be such by drawing them out of the water, but change within the rind itself; and further, when dried out and left lying, in the course of time things become astringent instead of sweet, and bitter, and all sorts of things, and when boiled they change into practically every kind of flavor. [section 5] And likewise it is impossible for water to be a matter that is a seed-mixture; for we observe different flavors coming to be from the same thing, as from the same nourishment. It remains, then, that water changes by being affected in some way.
17| [section 6] That water, then, does not acquire this power which we call flavor from the power of heat is clear; for water is the thinnest of all liquids, thinner even than oil itself. But oil spreads further than water because of its viscosity. Water is crumbly; that is why it is harder to keep water in the hand than oil. [section 7] Since water when heated shows no thickening by itself alone, it is clear that there must be some other cause; for all flavors have thickness to a greater degree, and heat is a contributing cause. And the flavors that appear in the rinds of fruit are found to be present in the earth as well. [section 8] That is why many of the ancient natural philosophers say that water is of whatever kind the earth is through which it passes. And this is clearest of all in the case of salty waters; for salt is a kind of earth. And water filtered through ash, since the ash is bitter, produces a bitter flavor. [section 9] There are also many springs, some bitter, some sharp, and some having all sorts of other flavors. And it is reasonable that the kind belonging to flavors should occur above all in growing things. For the moist is by nature affected, like other things, by its contrary; and the contrary is the dry. That is why it is also affected by fire; for fire's nature is dry.
18| [section 10] But what is proper to fire is the hot, and to earth the dry, as has been said in the treatise on the elements. So, insofar as a thing is fire and insofar as it is earth, it is not naturally suited to act or be acted upon at all, nor is anything else; but insofar as contrariety belongs to each, in that respect all things both act and are acted upon. [section 11] Just as those who rinse colors and flavors out into a liquid make the water take on such a quality, so too does nature make the dry and earthy element, and by filtering through the dry and earthy and moving it with heat, prepares the moist as having a certain quality. [section 12] And this affection coming to be in the moist, under the action of the dry just spoken of, is flavor — an affection capable of altering the taste's capacity into actuality; for it brings what is perceptive, existing potentially, into this actuality; for perceiving occurs not by way of learning but by way of contemplating. [section 13] That flavors are an affection, or a privation, not of everything dry but of what is nutritive, one must grasp from this: that neither the dry occurs without the moist nor the moist without the dry; for neither of them by itself is nourishment for animals, but only what is mixed of the two.
19| [section 14] Of the nourishment brought to animals, the tangible sensible qualities produce growth and decay; for the cause of these is that what is brought is hot or cold, since these produce both growth and decay; but what nourishes is that what is brought is tasteable, for all things are nourished by the sweet, either simply or in combination. [section 15] These matters need to be determined precisely in the works on generation, but here we need only touch on them so far as is necessary. For heat increases and produces the nourishment, and draws off what is light, while it leaves behind what is salty and bitter on account of its weight. Now what external heat does in bodies outside, this the internal heat does in the nature of animals and plants; that is why they are nourished by the sweet. [section 16] The other flavors are mixed into nourishment in the same way as the salty and the sharp, serving as seasoning. This is because they counteract the sweet's being too nourishing and apt to rise to the surface. And just as colors arise from a mixture of white and black, so flavors arise from the sweet and the bitter. [section 17] And indeed each flavor exists according to a ratio of more and less,
20| whether according to certain numbers of the mixture and motions, or in an indeterminate way. But those flavors that produce pleasure when mixed do so only when they are in numerical ratios. So the oily is a flavor akin to the sweet, the salty and the bitter are practically the same, while the astringent, the pungent, the harsh, and the sharp lie in between. [section 18] For the species of flavors and the species of colors are practically equal in number. There are seven species of each, if one posits, as is reasonable, that gray is a kind of black; for then yellow remains as a species of white, just as the oily is a species of the sweet, while crimson, purple, leek-green, and deep blue lie between white and black, and the rest are mixtures of these. [section 19] And just as black is the privation of white in what is transparent, so the salty and the bitter are the privation of the sweet in nourishing moisture. That is why the ash of all burned things is bitter, for the potable element has been evaporated out of them. But Democritus and most of the natural philosophers who discuss perception do something quite absurd, for they make all sensible objects tangible. [section 20]
21| Yet if this is so, it is clear that each of the other senses too would be a kind of touch; and it is not hard to see that this is impossible. Moreover, they treat what is common to all the senses as though it were peculiar to one; for magnitude and shape, and the rough and the smooth, and further the sharp and the blunt found in solid bodies, are common to the senses -- if not to all of them, at least to sight and touch. [section 21] That is why we are deceived about these common qualities, but not deceived about the objects peculiar to each sense, as sight is not deceived about color, nor hearing about sounds. But some thinkers reduce the objects peculiar to a sense to these common qualities, as Democritus does; for he says white is rough and black is smooth, and he reduces flavors to shapes. Yet it is either no sense at all, or sight more than any other, that discerns the common qualities. [section 22] But if in fact taste discerns them better, still it belongs to the most exact sense to distinguish the smallest differences within each genus, so that taste ought to perceive the other common qualities best of all as well, and be the most discriminating with respect to shapes. [section 23] Further, all sensible objects admit of contrariety, as in color white is contrary to black, and in flavors bitter is contrary to sweet; but one shape does not seem to be contrary to another -- for to which of the many-sided figures is the circle contrary?
22| [section 24] Further, since shapes are infinite in number, flavors would necessarily be infinite as well; for why should one shape produce a sensation and another not? So much, then, has been said about the tasteable and flavor; the other affections of flavors have their own proper inquiry in the natural science concerning plants. [section 1] We must think about odors in the same way. For what the dry produces in the moist, the flavored moisture produces in another genus, in air and water alike. What is common to both of these we are now calling the transparent, but a thing is smellable not insofar as it is transparent, but insofar as it is capable of washing out or rinsing off a flavored dryness; for the object of smell exists not only in air but also in water. [section 2] This is clear in the case of fish and shellfish; for they evidently smell even though there is no air in the water (for air, when it gets in, rises to the surface) and even though they themselves do not breathe. If, then, one posits that both air and water are moist, the nature of a flavored dryness in a moist medium would be odor, and what is such would be smellable.
23| [section 3] That this affection belongs entirely to flavor is clear from things that have and do not have odor. For the elements are odorless -- fire, air, water, earth -- because both their dry and their moist components are without flavor, unless something mixed in produces one. [section 4] That is why the sea has odor, for it has flavor and dryness. And salt is more odorous than natron; this is shown by the oil that can be extracted from it, whereas natron is more earthy. Again, stone is odorless, since it is without flavor, while wood is odorous, since it has flavor; and among woods, the watery ones are less odorous. [section 5] Again, among the mined substances gold is odorless, since it is without flavor, while bronze and iron are odorous. When the moisture has been burned out, the slag of all of them becomes less odorous. Silver and tin are more odorous than some metals and less than others, since they are watery. [section 6] Some think that odor is a smoky exhalation, common to earth and air. And everyone is drawn toward this view about odor; that is why Heraclitus too has said that if all existing things became smoke, the nostrils would distinguish them. [section 7]
24| Everyone is drawn to explain odor either as vapor, or as exhalation, or as both together. But vapor is a kind of moisture, while smoky exhalation, as has been said, is common to air and earth; and from the one water is formed, and from the other some form of earth. [section 8] But odor seems to be neither of these; for vapor belongs to water, while smoky exhalation cannot occur in water. Yet things in water do smell, as has been said before. Further, exhalation is spoken of in the same way as effluences. So if that account is not correct, this one is not correct either. [section 9] That the moisture in breath and the moisture in water can partake of and be affected by a flavored dryness is not unclear, for air too is moist by nature. And that the dry, as it were washed out, acts in the same way in moist bodies and in air is evident. Further, odors must be analogous to flavors. [section 10] And indeed this does hold in some cases; for there are pungent and sweet odors, and astringent, harsh, and oily ones, and one might say that putrid odors are analogous to bitter flavors. That is why, just as bitter flavors are hard to swallow, putrid odors are hard to breathe in. It is clear, then, that what flavor is in water, odor is in air and in water.
25| [section 11] And for this reason cold and congealing both dull flavors and destroy odors; for cooling and congealing destroy the heat that moves and produces them. There are two species of the object of smell; for it is not the case, as some say, that there are no species of the object of smell — rather there are. [section 12] We must distinguish in what sense there are and in what sense there are not: one kind is ranked according to the flavors, as we said, and these have the pleasant and the painful only accidentally; for since they are affections of the nutritive faculty, the odors of these things are pleasant to those who desire them, but not pleasant to those who are sated and need nothing, nor again to those for whom the food that has these odors is not itself pleasant either. [section 13] So these odors, as we said, have the pleasant and the painful only accidentally, and that is why they are common to all animals; but there are odors that are pleasant in their own right, such as those of flowers — for these neither summon one to food any more nor less, nor contribute anything at all to appetite, but rather the opposite; for what Strattis said in mockery of Euripides is true: when you boil lentil soup, don't pour perfume into it.
26| [section 14] Those who nowadays mix such powers into their drinks force pleasure by habituation, until the pleasant, though it arises from two senses, comes to be felt as one thing and from a single sense. [section 15] This kind of object of smell, then, is peculiar to man, while the kind ranked according to flavors belongs to the other animals too, as was said before; and in their case, because they have the pleasant only accidentally, the species are divided according to the flavors, but this is no longer so for the other kind, because its nature is pleasant or painful in its own right. The cause of this kind of odor being peculiar to man is the cooling around the brain. [section 16] For since the brain is by nature cold, and the blood around it in the small vessels is fine and pure, but easily cooled (which is why the exhalation from food, being cooled because of this region, produces the diseased discharges), this kind of odor has come to exist in humans for the aid of health; for it has no other function than this. [section 17] And it does this evidently; for food that is pleasant, both the dry and the moist,
27| is often unhealthy, while what comes from an odor that is fragrant in its own right is beneficial, one might say always, whatever condition people are in. [section 18] And for this reason this effect comes about through breathing — not in all animals, but in humans, and among the blooded animals in the four-footed ones, and in those that partake more of the nature of air; for as the odors are carried up toward the brain because of the lightness of the heat in them, the region around this place is in a healthier condition; for the power of odor is by nature hot. [section 19] Nature has employed breathing for two purposes: as its main work, for aid to the chest, and as a by-product, for smell; for in the act of breathing it produces, as it were incidentally, the motion through the nostrils. [section 20] This kind of odor is peculiar to human nature because man has the largest and moistest brain of the animals in proportion to size; for this is why man, one might say alone among animals, perceives and delights in the odors of flowers and of things of this sort; for their heat and motion are commensurate with the excess of moisture and coldness present in that region.
28| [section 21] To the other animals that have lungs, because they breathe, nature has given perception of the other kind of odor only, so as not to make two organs of sense; for it is enough, since they too breathe, that perception of only the one kind belongs to them, whereas for humans it belongs to both kinds of object of smell. [section 22] That the animals that do not breathe have perception of the object of smell is evident; for fish and the whole class of insects perceive precisely and from far off, by means of the nutritive kind of odor, even when far removed from their proper food — as bees do in relation to honey, and the class of small ants that some call gnats, and among sea creatures the purple-fish, and many of the other such animals perceive their food sharply through its odor. [section 23] But by what organ they perceive it is not equally evident. Hence one might raise the puzzle of what they perceive odor by, if indeed smelling occurs only for those that breathe — for this appears to hold of all animals that breathe — while none of those other animals breathes, yet they do perceive it, unless there is some other sense besides the five. [section 24]
29| This is impossible; for smelling belongs to the object of smell, and those animals do perceive this object — though perhaps not in the same way. Rather, in animals that breathe, the breath removes what lies over the organ like a kind of lid (which is why they do not perceive when they are not breathing), while in animals that do not breathe, this lid has been removed from the start — just as, in the case of the eyes, some animals have eyelids, which must be uncovered before they can see, while the hard-eyed animals do not have them, and so need nothing to uncover the organ, but see straightaway, from the moment they are able to see. [section 25] Likewise, none of the other animals whatsoever is troubled by the odor of things that are foul-smelling in their own right, unless the thing happens to be destructive. And by such things they are destroyed in the same way that humans too are made heavy-headed and often destroyed by the vapor of charcoal; so also the other animals are destroyed by the power of sulfur and of bituminous substances, and flee because of this affection. [section 26] But they take no notice at all of foulness of smell in its own right, even though many growing things have foul odors, unless it contributes something to their taste or their eating. [section 27] The sense of smelling seems — since the senses are odd in number and an odd number has a middle term — itself to be the middle between the senses that operate by contact, such as touch and taste, and those that perceive through something else, such as sight and hearing.
30| [section 28] That is why the object of smell is both an affection of the nutritive things (and these belong to the class of the tangible), and also of the audible and the visible, which is why animals smell both in air and in water. So the object of smell is something common to both of these, belonging both to the tangible and to the audible and the transparent; for this reason it has reasonably been compared to a kind of dyeing and washing of dryness in moisture and in what is fluid. [section 29] As to in what sense one should speak of species of the object of smell and in what sense not, let this much be said. But what some of the Pythagoreans say is not reasonable; for they say that some animals are nourished by odors. [section 30] For first, we observe that food must be composite; for the things that are nourished are not simple either, which is why residues of the food are also produced, either within them or outside them, as in the case of plants. Further, water by itself alone, unmixed, is not able to nourish; for what is to be constituted into body must have some bodily character. And it is far less reasonable still that air should become body. [section 31] Besides this, all animals have a place receptive of food, from which the body draws and takes it; but the organ of smell is in the head, and smell enters along with a vaporous exhalation, so that it would go to the region used for breathing.
31| [section 32] That the object of smell, as such, does not contribute to nourishment is clear; but that it does contribute to health is evident both from perception and from what has been said, so that what flavor is in the nutritive process and in relation to what is nourished, that is what the object of smell is in relation to health. Let this, then, be the manner in which we have distinguished the several senses one by one. [section 1] One might raise the difficulty whether, if every body is divisible without limit, the sensible affections too are so divisible - color, for instance, and flavor and odor and weight and sound and cold and hot and light and hard and soft - or whether this is impossible. For each of these is productive of perception; indeed they are all said to be what they are through their capacity to move perception. [section 2] So it would be necessary both that perception be divisible into infinitely many parts and that every magnitude be perceptible; for it is impossible to see white without seeing it as having some quantity. For if this were not so, it would be possible for there to be some body having no color nor weight nor any other such affection at all - and so it would not be perceptible at all, since these are precisely what the perceptible things are. [section 3] The perceptible thing, then, will turn out to be composed of things that are not perceptible. But that is necessary - for it is certainly not composed of mathematical points. Further, by what shall we judge or come to know these parts? By the intellect? But they are not intelligible, and the intellect does not think external things except in company with perception. And at the same time, if this is how things stand, it appears to bear witness for those who posit indivisible magnitudes; for it is in this way that the argument would be resolved.
32| [section 4] But this is impossible; the point has been discussed in our treatises on motion. As for the resolution of these difficulties, it will become clear at the same time, and also why the forms are limited in number - of color, of flavor, of sounds, and of the other perceptible objects. For wherever there are extremes, the things between them must be limited; and the contraries are the extremes. [section 5] Every perceptible thing has a contrariety - in color, for instance, white and black, in flavor, sweet and bitter; and in all the others likewise the contraries are the extremes. Now the continuous is divided into unequal parts without limit, but into equal parts only a limited number of times; but what is not continuous in its own right is divided into a limited number of forms. [section 6] Since, then, the affections must be spoken of as forms, and continuity always belongs to them, one must grasp that potentiality and actuality are different things; and this is why the ten-thousandth part of a millet seed escapes notice when the seed is seen, even though sight has already reached it, and the quarter-tone in a musical interval escapes notice, even though, being continuous, one hears the whole melody. [section 7] The interval that lies between the extremes escapes notice too. And likewise with the other perceptible things, the very small parts escape notice; for they are visible potentially, but not actually, when they are separated out. For indeed the foot-length is present potentially in the two-foot length, but only actually once it has been divided off.
33| [section 8] When such excesses are separated off, it would be reasonable for them to dissolve away into their surroundings, just as a mere drop of flavor poured out into the sea dissolves away. [section 9] Nevertheless, since the excess in perception is not perceptible in its own right nor separable either - for the excess is present potentially in the more precise perception - so too such a small perceptible thing will not be separable so as to be perceived actually; but all the same it will be perceptible, for it already exists potentially, and will exist actually once it is added on. [section 10] That some magnitudes and affections escape notice, then, and for what cause, and how they are perceptible and how not, has been stated. But whenever things present in this way are such as to be perceptible actually, and are limited not only within the whole but also apart from it, then colors and flavors and sounds must be limited in number. [section 11] One might raise the difficulty whether it is the perceptible objects themselves, or the motions coming from the perceptible objects - whichever way it turns out that perception comes about - that first arrive at the intervening medium when the objects are acting; for instance, both odor and sound appear to act in this way. For the person nearby perceives the odor sooner, and sound arrives later than the blow that produces it.
34| [section 12] Is this the case, then, also with the visible object and with light? Just as Empedocles says that the light from the sun arrives first into the intervening medium before it reaches sight or the earth. [section 13] It would seem reasonable that this should happen; for what is moved is moved from one place to another, so that there must be some time in which it moves from the one to the other; and every time is divisible, so that there was a time when the ray was not yet seen but was still being carried through the intervening medium. [section 14] And even if everything hears at once and has heard, and in general perceives at once and has perceived, and there is no coming-to-be of these, but they exist without coming-to-be nonetheless - just as the sound, once the blow has already occurred, is not yet at the ear. [section 15] The reshaping of the letters shows this too, as evidence that the motion occurs within the intervening medium; for people evidently have not heard what was said, on account of the air being reshaped as it travels. Is this the case, then, also with color and with light? [section 16] For it is surely not by being in a certain state that the one sees and the other is seen, as though they were things made equal;
35| for there would be no need for either to be anywhere in particular; for things that become equal, it makes no difference whether they are near or far from one another. [section 17] Rather it is reasonable that this should happen in the case of sound and odor; for just as air and water are continuous, yet the motion of both is nonetheless divided into parts. Hence in one sense the one who hears or smells first and the one who does so later perceive the same thing, and in another sense they do not. [section 18] Some think there is a difficulty about these cases too; for some say it is impossible for one person to hear or see or smell the very same thing as another, since it is not possible for many people, being apart from one another, to hear or smell the same thing - for then the one thing would be apart from itself. [section 19] But as regards what first produced the motion - the bell, say, or the frankincense, or the fire - all perceive that very same thing, one in number; but as regards what is peculiar to each perceiver, that is different in number, though the same in form; and that is why many people see and smell and hear at the same time. And these are not bodies, but an affection and a certain motion - for otherwise this could not happen - nor yet are they without body. [section 20]
36| As for light, the account is different; for light exists by being something, and is not a kind of motion. And in general the case is not the same with alteration as with locomotion; for it is reasonable that locomotions should arrive first at the intervening medium - and sound seems to be a motion of something being carried - but with things that undergo alteration, this is no longer so in the same way; for it is possible for something to be altered all at once, and not the half of it first, as when water freezes all at once, entirely. [section 21] Nevertheless, if what is being heated or frozen is extensive, the part in contact is affected by the part in contact with it, while the parts nearest to what causes the alteration change first, and it is not necessary that alteration occur simultaneously and all at once. [section 22] And tasting would be like smelling, if we were in a liquid and perceived the object further off, before touching it. It is reasonable that, of the things that lie between the object and the organ of perception, not all are affected at once - except in the case of light, for the reason stated. And for the same reason this also holds for seeing; for it is light that produces seeing. [section 1] There is also another difficulty of the following kind about perception: whether it is possible to perceive two things at once, in the same indivisible time, or not - given that the greater motion always drives out the lesser; which is why, when things are brought toward the eyes, people do not perceive them, if they happen to be thinking intently about something, or afraid, or listening to a loud noise.
37| [section 2] Let this be laid down, and also that each thing is more perceptible when it is unmixed than when it is blended — for example, unmixed wine rather than mixed wine, and honey, and color, and the topmost note by itself rather than within the full octave — because they obscure one another. [section 3] This happens with things out of which some single thing comes to be. If, then, the greater motion drives out the lesser, it is necessary, when they occur together, that the greater itself also be less perceptible than if it were alone; for the lesser motion, being mixed in, takes something away from it, given that all simple things are more perceptible. If then two different motions are equal, there will be perception of neither; for each will equally obscure the other. And it is not possible to perceive either as simple. [section 4] So either there will be no perception at all, or a different perception arising out of both. And this is indeed what seems to happen with things that are blended, in whatever medium they are mixed. [section 5] Since, then, from some things a single thing comes to be, but from others it does not — and the things of this latter kind are those falling under different senses (for things blend whose extremes are one; but from white and sharp in pitch a single thing cannot come to be except accidentally, not the way a concord comes to be from a sharp and a low note) — it follows that it is not possible to perceive such things simultaneously either.
38| [section 6] For if the motions are equal, they will obscure one another, since a single motion does not arise out of them. But if they are unequal, the stronger will produce the perception, since the soul would perceive two things together more readily by the one perception whose object is a unity — sharp and low pitch, for instance — than by two, sight and hearing; for the motion of that single perception occurs more together than that of the two. [section 7] But it is not possible to perceive two things at once by the one perception unless they have been blended; for the blend wants to be one, and of one thing there is one perception, and the one perception operates together with itself. So it follows necessarily that one perceives the blended things together, because one perceives them by a single perception in actuality; for the perception that is one in actuality belongs to what is one in number, while the perception that is one in potentiality belongs to what is one in species. And so, if the perception in actuality is one, it will pronounce those things one. [section 8] They must, therefore, have been blended. When, then, they are not blended, there will be two perceptions in actuality. But by one capacity and in an indivisible time the actuality must be one; for of one thing there is, on a single occasion, one motion and one exercise, and the capacity is one. It is not possible, therefore, to perceive two things at once by the one perception.
39| [section 9] But surely if it is impossible to perceive at once two things falling under the same sense, when there are two, it is clear that it is even less possible to perceive at once things falling under two different senses — white and sweet, for example. For it appears that the soul calls a thing one in number by nothing other than the fact that it is simultaneous, while it calls a thing one in species by the discriminating perception and by the manner. [section 10] I mean this: that presumably white and black, though different in species, are discriminated by the same sense, and sweet and bitter likewise, the same sense discriminating itself, though a different sense from that one — but it discriminates each of the pair of contraries differently, while it discriminates the things in the same column with itself in the same way: as taste discriminates the sweet, so sight discriminates the white; and as the latter discriminates the black, so the former discriminates the bitter. [section 11] Further, if the motions of contraries are contrary, and it is not possible for contraries to belong at once to the same indivisible thing, and under the one sense there are contraries — sweet, for instance, as against bitter — it would not be possible to perceive these at once. [section 12] And likewise it is clear that neither is it possible to perceive the things that are not contraries; for some belong to white, others to black, and similarly in the other cases — of flavors, for instance, some belong to sweet, others to bitter. Nor is it possible to perceive the blended things at once; for they are ratios of opposites, as the octave and the fifth are, unless one perceives them as one.
40| [section 13] It is in this way that a single ratio of the extremes comes to be, and not otherwise; for there would then be at once a ratio of much to little, or of odd to even, and also a ratio of little to much, or of even to odd. [section 14] If, then, things said to be in the same column but belonging to a different genus are further apart from and differ more from one another than things in the same genus (I mean, for example, that I call sweet and white things "in the same column," though different in genus; and sweet differs still more in species from black than white does), then it would be still less possible to perceive these together than things that are the same in genus. [section 15] So that if not even the latter can be perceived together, neither can the former. Now what some writers on musical concords say — that sounds do not in fact arrive simultaneously, though they appear to, and this escapes notice when the interval of time is imperceptible — is this said correctly or not? [section 16] For perhaps someone would say that even now it is for this reason that we seem to see and hear at once — because the intervening times escape notice. But is this not true? Is it in fact not possible for any time to be imperceptible or to escape notice, but rather is it possible to perceive every interval of time? [section 17]
41| For if, when someone perceives himself or something else in continuous time, it is not possible at that time for its existing to escape his notice, and yet there is, within the continuum, some interval, however long, that is altogether imperceptible, then clearly it would escape his notice at that time whether he himself exists, and whether he sees, and he would not perceive; and if he does perceive, then again there would be neither time nor any object at all that he perceives, or in which he perceives, unless it is thus: that he sees something within a part of it, or that he sees a part of it — if indeed there is some magnitude, both of time and of the object, that is altogether imperceptible because of smallness; for if he sees the whole, he also perceives the same continuous time, not merely some part of these "nows." [section 18] Let the segment GB be taken away, the segment within which he was not perceiving. Then it is within some part of this whole, or of some part of this, that he perceives — just as he sees the whole earth because he sees this part of it, and he walks throughout the year because he walks in this part of it. But indeed within BG he perceives nothing. It is, then, by perceiving within some part of AB that he is said to perceive the whole, and to perceive it as a whole. [section 19] And the same account holds also for AG; for it is always within some part, and of some part, that he perceives, and it is not possible to perceive the whole as such. All things, then, are perceptible, but they do not appear to be as large as they are; for one sees the sun's size, and sees the four-cubit object from a distance, but its size does not appear as it is — rather sometimes it appears undivided, though one sees it as in fact not undivided.
42| [section 20] The cause of this has been stated earlier, in the discussion of this topic. That, then, no time is imperceptible is clear from these considerations. But concerning the difficulty stated earlier, we must inquire whether it is possible to perceive several things at once, or not possible. And by "at once" I mean at one and the same indivisible time, relative to one another. [section 21] First, then, is it possible in this way — that one perceives at once, but by a different part of the soul, and not by what is indivisible, though this part is indivisible in the sense of being a single continuous whole? Or is this impossible because, first of all, in the case of things falling under one sense — sight, say — if it is to perceive different colors by different parts, it will also have several parts that are the same in species? [section 22] For indeed the things it perceives are within the same genus. But if someone should say that it is like two eyes, nothing prevents its being so also in the soul — that presumably out of these a single thing comes to be, and their activity is one; whereas in the other case, if what comes from both is one, that will be the perceiving subject, but if they are separate, it will not be so. [section 23] Further, the supposedly same perceptions will be several, as if one were to call different branches of knowledge really different; for the actuality will not exist apart from the capacity in its own right, nor will there be perception apart from this. But if
43| perceives several of these in one and indivisible time, it is clear that it also perceives the others; for it was more possible for several of these to be perceived together than several of the things differing in genus. [section 24] If, then, the soul perceives sweet by one part and white by another part, what results from these is either some one thing or not one. But it must be one; for the perceiving part is some one thing. Of what one thing, then, is that part percipient? For nothing composed out of these is one. It is necessary, therefore, that there be some one thing belonging to the soul by which it perceives all of them, as has been said before, though a different genus is perceived through a different part. [section 25] Is it, then, that insofar as it is undivided in actuality, the faculty that perceives sweet and white is some one thing, but when it becomes divided in actuality, it is a different thing? Or perhaps what holds for the things themselves holds likewise for the soul: numerically the very same thing is both white and sweet, and many other things besides, provided the affections are not separable from each other, though each has a distinct being. [section 26] So likewise it must be laid down, in the case of the soul as well, that the faculty that perceives all things is the same and one in number, though different from case to case in its being -- different in genus for some, in species for others. So it would perceive several things at once by the same and one faculty, but not by the same account. And it is clear that every sensible object is a magnitude, and that there is no indivisible sensible object.
44| [section 27] For there is a distance from which a thing would not be seen, and this distance is unlimited, while there is a distance from which it is seen, and this is limited. And likewise for what is smelled and heard, and for everything that is perceived without being touched. And and a first point from which it is seen. [section 28] This point, then, must necessarily be indivisible: beyond it, while the thing remains there, it is not possible to perceive it, but on this side of it, it must be perceived. If, then, there is some indivisible sensible object, then when it is placed at that furthest point from which it is, as the last point, not perceived, but as the first point, perceived, it will follow that it is at the same time visible and invisible; and this is impossible. Concerning the sense organs, then, and the sensible objects, in what way things stand, both in common and for each sense organ taken separately, has now been stated.