In lieu of an abstract, here is a brief excerpt of the content:

CHAPTER 4 438B2–439A5 438b2 That it is impossible to see without light was said elsewhere. But whether it is light or air that is between the thing seen and the eye, the movement through it causes seeing. 438b5 It is reasonable that what is inside be made of water, for water is transparent. And it seems that, as what is outside is not without light, so also what is inside. Therefore it must be transparent. Therefore it is necessarily water, because it is not air. 438b8 For the soul, or the sensitive part of soul, is not at the limit of the eye, but clearly inside. Hence the inside of the eye needs to be transparent and receptive of light. 438b11 This is also clear from what happens. For when some are wounded in war about the temples in such a way that the passages of the eye are cut off, they experience a darkening as when a lamp is extinguished, because the transparent thing called the pupil is, like a torch, cut off. 438b16 If, then, what happens in these cases is as we have said, it is clear that, if one must, following this method, attribute and assign each one of the sensitive parts to one of the elements, one should think that eyesight is of water, what is perceptive of sounds is of air, and smelling is of fire. 438b21 For what smelling is in actuality the olfactory part is in potentiality. For a sensible object makes a sense-power act, and so the latter necessarily exists first in potentiality. But odor is smoky evaporation. But smoky evaporation is from fire. 438b25 For this reason the proper sensitive part of smell is in a place around the brain: for the potentially hot is the matter of what is cold. 438b27 And the generation of the eye also has the same mode: for it stems from the brain, and the brain is coldest and moistest of all parts of the body. 438b30 But the tactile part is of earth, and the tasting part is a kind of touch. 439a1 And so the sensitive part for these, namely taste and touch, is near the heart: for the heart is opposite the brain, and is the warmest of the parts. 439a4 Let it be determined in this way about the sensitive parts of the body. 45 Commentary 438b2 After the Philosopher has disproved the opinion of those who hold that vision occurs by extromission, here he determines the truth. On this point he does three things. First he makes clear how vision occurs according to his own thought. Second, on this basis, he gives the cause of something mentioned above concerning the organ of sight, where he says It is reasonable (438b5). Third he shows the cause by a sign, where he says This is also clear (438b11). Accordingly he first takes up something that was said in the book On the Soul, that it is impossible to see without light.1 For because vision occurs through a medium that is transparent, vision requires light, which makes a body be transparent in actuality, as was said in the book On the Soul.2 And so, whether the medium that is between the thing seen and the eye is air that is illuminated in actuality, or whether it is light—light existing not in itself, since it is not a body, but in something else that is a body, such as glass or water—the movement that occurs through this medium causes vision. ) _ This movement should not be taken to be local movement, as if, as Democritus and Empedocles held, it were a movement of bodies emanating from the thing seen to the eye, because then it would follow that the bodies that are seen would be reduced by this emanation until they were totally worn away. It would also follow that the eye would be injured by the continuous striking of these bodies. Again, it would not be possible for a whole body to be seen by anyone, but only as much as could be taken in by the pupil. Rather, this is “movement” according to alteration: the alteration is a movement towards a form that is a quality of the thing seen. Inasmuch as it is bright in actuality, the medium is in potentiality to this form; the medium is an unbounded transparent (color is a quality of a bounded transparent, as will be said below),3...

Share