Theophrastus

“ Anaxagoras holds that sense perception comes to pass by means of opposites, for the like is unaffected by the like. He then essays to review each sense separately. Accordingly he maintains that seeing is due to the reflection a in the pupil, but that nothing is reflected in what is of like hue, but only in what is of a different hue. Now with most [creatures] this contrast of hue [with that of the pupil] occurs by day, but with some by night, and this is why the latter are keen of vision by night. But, in general, night the rather is of the eye's own hue. ”

“ And yet even here one might entertain a doubt whether sense perception actually is an alteration, and whether an opposite is cognizant of its opposite. But as for the thesis that sense perception is universally conjoined with pain, this finds no warrant in experience, inasmuch as some objects are actually perceived with pleasure, and most of them at least without pain. Nor is it reasonable. For sense perception is in accord with nature, and no such process does violence and brings pain, but the rather it has pleasure as its accompaniment,—a law whose operation is quite manifest. ”

“ Secondly, it is silly to assert that those have the keenest sense of smell who inhale most; for if the organ is not in health or is, for any cause, not unobstructed, mere breathing is of no avail. It often happens that a man has suffered injury [to the organ] and has no sensation at all. Furthermore, persons 'short of breath or at hard labour or asleep —since they inhale most air—should be most sensitive to odours. Yet the reverse is the fact. For in all likelihood respiration is not of itself the cause of smell, but is connected with it incidentally ”

“ For reason does not have its seat in all our members—in our legs and feet, for instance—but in determinate parts, even those by whose means, at the proper age, we exercise memory and the power of thought. Childlike, too, is his idea that men differ from animals— not in their essential nature, as animate things differ from inanimate,—but because they breathe purer air. ”

“ Vision is keenest in such animals as have their [internal] air and their ducts refined—as is true of the other [senses] ,—and have an exceedingly lustrous eye. But since the eye reflects better a colour that stands in contrast with it, black-eyed " persons have a vision superior by day and for brilliant objects, while those with eyes of opposite hue see better by night. That the internal air, however, is the real agent of perception —being a tiny fragment of divinity—is proved by this, that when our minds are engrossed in other things we often neither see nor hear. ”

“ When Anaxagoras says that larger animals have better powers of sense, and that sense perception varies in general with the size of the organs of sense, one of these propositions raises the question whether small animals or large animals have better powers of sense. For it would seem to be essential to keener sense perception that minute objects should not escape it. And we might reasonably suppose, too, that an animal with power to discern smaller objects could also discern the larger. ”

“ His own statement is that colours are reflected in one another, but particularly the strong in the weak; consequently each of these—but especially black and the weaker colours generally—should possess the power of sight., For the reason just given, he holds that the organ of vision is of the same colour as the night, and that light is the cause of the visual reflection. But in the first place, we see light itself, without any image of it whatsoever; and in the second place, black objects and white objects alike lack light. ”

“ The tongue, he holds, is pre-eminently the judge of pleasure, for it is exceedingly soft and of open texture and all the ducts lead into it. Very many symptoms with the sick are consequently found here in the tongue. And in other animals [the tongue] reveals the colours [of their skin] , for the variety and character [of these colours] are [there] reflected. Such is the manner and occasion, then, of perception's rise. Thinking, as was said, is due to pure dry air; for moisture clogs the intellect. Thought is at a low ebb consequently in sleep and in one's cups and in repletion. ”

“ And it is indeed quite ridiculous to suppose that we think with the blood: for many animals are bloodless; and of those that have blood, the parts about the organs of sense are the most deficient in blood. ”

“ Hearing is by means of the ears, he says, because within them is an empty space, and this empty space resounds. & A kind of noise is produced by the cavity, and the internal air re-echoes this sound. Smelling is by means of the nostrils in connection with the act of respiration when one draws up the breath to the brain. By the tongue we discern tastes. For since it is warm and soft, the tongue dissolves [substances] with its heat; and because of its loose and yielding texture it readily receives and transmits [the savours] . ”

“ When set in motion [this organ] drives the air against the solid parts and produces there a sound.
Smell, according to Empedocles, is due to the act of breathing. As a consequence, those have keenest smell in whom the movement of the breath is most vigorous. The intensest odour emanates from bodies that are subtile and light. Of taste and touch severally he offers no precise account, telling us neither the manner nor the means of their operation,—save the [assertion he makes with regard to all the senses in] common, that perception arises because emanations fit into the passages of sense. ”

“ Now if green be added to white and red, there results the most beautiful colour; but the green component must be small, for any large admixture would not comport with the union of white with red. The tint will vary according to the amount [of green] that is introduced.
Crimson comes from white, black, and red,—the largest ' portion ' being red, that of black small, and of white midway; for thus it makes an appearance delightful to the sense. That black and red are present in it is patent to the eye: its brilliance and lustre testify to the presence of white; for white pro duces such effects. ”

“ But if there be no objective reality in sensory objects because they do not appear the same to all, there is manifestly none in animals or other bodies; for men disagree about these things, too. And yet even if the cause of sweet and bitter is not the same for us all, at least the bitterness l and sweetness appear the same for all. Democritus himself seems a witness to this; for how could that which is bitter for us be sweet or astringent for others, unless these very qualities had a definite nature? ”

“ And further, to assume straight passages in substances that are white, and passages zig-zag in those that are black, implies that the very structure of the object enters [our sense organ] . Vision, he says, is due to an emanation and to the reflection in the organ of sight. But if this be so, what difference does it make whether the passages [in the object] lie end to end or zig-zag? Nor is it easy to believe that an emanation can by any possibility arise from the void. The cause of this, therefore, should be stated. For he seems to derive whiteness from light or something else ”

“ The other investigators confine themselves to the statement that white and black are the fundamental colours and that the rest are derived from these by mixture. For even Anaxagoras treats of the [colours] in only a loose and general way.
Democritus and Plato, however, are the investigators who go into the question most fully, for they define the object of each sense; although [Plato] never robs these objects of their external reality, whereas Democritus reduces them one and all to effects in our sensuous faculty. Where the truth itself lies, is not the question we are now discussing. ”

“ Possibly, however, the reflection in the eye is caused by the sun, in sending light in upon the visual sense in the form of rays,—as Democritus seems to mean. For the idea that the sun "drives the air from itself and, in thus repelling, condenses it", as he says,—this is in defensible; since the sun by its very nature disperses the air. He is unfortunate, too, in regarding visual perception as a function not only of the eyes but of the rest of the body as well ”

“ Pleasure and pain, he holds, arise in the following way. Whenever the air mingles in large quantities with the blood and sublimates it,—since the air is now in its normal state and pervades the entire body,—there is pleasure. ”

“ Now since, for him, the eye is composed of fire and of its opposite, it might well recognize white and black by means of what is like them; but how could it become conscious of gray and the other compound colours? For he assigns [their perception neither to the minute passages of fire nor to those of water nor to others composed of both these elements together. Yet we see the compound colours no whit less than we do the simple.
Odd, too, is [his account of] the fact that certain animals see better by day, and others by night. For a weaker fire is extinguished by a stronger ”

“ For these are present in all things, of whatsoever figures they are composed. He should have given some distinctive [figure] to green, as he has to the other colours. And if he holds [green] to be the opposite of red, as black is of white, it ought to have an opposite shape; but if in his view it is not the opposite, this itself would surprise us that he does not regard his first principles as opposites, for that is the universally accepted doctrine. Most of all, though, he should have determined with accuracy which colours are simple, and why some colours are compound and others not ”

“ Accordingly animals with less of light in their eyes ought to have had poorer vision by day. Or if what is qualitatively similar does in fact supplement, and what is qualitatively different tends to destroy and thwart, as he says, then all creatures—both those that had less light and those that had more—should have seen white things better by day; and black, by night. Yet in fact all but a few animals see every manner of object better by day. ”

“ In the case of smell, however, there is a special difficulty: for he asserts that rarefied air is the more odorous; and yet that the animals which inhale the dense air have a keener sense of smell than those inhaling the subtile.
Anaxagoras' doctrine of the visual image is one some- what commonly held; for nearly everyone assumes that seeing is occasioned by the reflection in the eyes. They took no account of the fact, however, that the size of objects seen is incommensurate with the size of their reflection ”

“ Nor does the effect of excessively intense stimuli and of stimulation long continued prove that perception is [invariably] conjoined with pain, but rather that sense perception implies a certain correspondence and a composition suited to the object. And this perhaps is why a deficient stimulation passes unperceived, and an excessive one causes pain and is destructive. Now our author, we see, arrives at his interpretation of what is normal and according to nature, from what is exceptional and contrary to nature; for excess is contrary to nature. ”

“ Hearing is keenest, he maintains, when the outer tunic is tough and the ducts are empty and unusually free from moisture and are well-bored in the rest of the body as well as in the head and ears; when, too, the bones are dense and the brain is well-tempered and that which surrounds it is exceedingly dry. For the sound thus enters compact, since it traverses a cavity large and dry and with good orifices, and swiftly the sound is "sent broadcast" impartially through the body and does not again escape. ”

“ Those particles yield that have a small base. Heavy and light should not be defined, he maintains, by resort to the relations ' up ' and 'down '; for these have no objective reality. But anything is light when it is with ease drawn to a place opposed to its own nature; it is heavy when this is done with difficulty. Of rough and smooth he has nothing to say, passing them by as of a character clear enough. With regard to pleasure and pain, he explains pleasure as a sudden and violent experience of return to the natural state ”

“ But, in general, night the rather is of the eye's own hue. Furthermore, there is reflection by day, he holds, because the light is a contributing cause of reflection, and because the stronger of two colours is regularly reflected better in the weaker. Touch and taste, according to Anaxagoras, perceive their objects after this same manner. ”

“ Woad hue is composed of deep black and golden green, but with the major 'portion' black. Leek green is of crimson and woad, or of golden green and purplish. . . . For sulphur colour is of this character, with a dash of brilliance. Indigo is a mixture of woad and fiery red, with round figures and figures needle-shaped to give a gleam to the colour's dark ness.
Brown is derived from golden green and deep blue; but if more of the golden green be mixed, flame-colour is the result; for the blackness is expelled because [the golden green] is shadowless. ”

“ And similarly of smell: for rarefied air has a stronger odour, since it is odorous when heated and rendered less dense. A large animal when breathing, accordingly, inhales the dense along with the subtile, while the small animal inhales merely the subtile; large animals as a consequence have the more perfect sensory power. For an odour near by is more intense than one remote, he holds, because it is denser, and in scattering becomes faint. Roughly, then, his view is, that large animals perceive no ' subtile odour ', and small animals no odour that is dense. ”

“ Plants are entirely bereft of thought because they are not hollow and consequently do not receive the air.
The same principle explains also why young children lack understanding; for they are excessively moist, and in consequence [the air] cannot make its way through out the body but is set apart in the breast, leaving them sluggish and witless. They are passionate and impetuous in general and flighty because the air in large quantities is excreted from their tiny bodies. ”

“ By some investigators it is ascribed to similarity, while by others it is ascribed to contrast: Parmenides, Empedocles, and Plato attribute it to similarity; Anaxagoras and Heraclitus attribute it to contrast.
The one party is persuaded by the thought that other things are, for the most part, best interpreted in the light of what is like them; that it is a native endowment of all creatures to know their kin; and furthermore, that sense perception takes place by means of an effluence, and like is borne toward like. ”

“ Those in whom these mingled elements are of the same or nearly the same [amount] , being neither widely separated nor too small nor of excessive size,—such persons are most intelligent and keen of sense; and others are intelligent and keen of sense according as they approach to such a mixture; but those whose condition is the very reverse are the least intelligent. Again, persons in whom the elements lie loose and rare are slow and laborious ”