On Sense And The Sensible   

case is different. For Light has its raison d'etre in the being [not

becoming] of something, but it is not a movement. And in general, even

in qualitative change the case is different from what it is in local

movement [both being different species of kinesis]. Local movements,

of course, arrive first at a point midway before reaching their goal

(and Sound, it is currently believed, is a movement of something

locally moved), but we cannot go on to assert this [arrival at a point

midway] like manner of things which undergo qualitative change. For

this kind of change may conceivably take place in a thing all at once,

without one half of it being changed before the other; e.g. it is

conceivable that water should be frozen simultaneously in every

part. But still, for all that, if the body which is heated or frozen

is extensive, each part of it successively is affected by the part

contiguous, while the part first changed in quality is so changed by

the cause itself which originates the change, and thus the change

throughout the whole need not take place coinstantaneously and all

at once. Tasting would have been as smelling now is, if we lived in

a liquid medium, and perceived [the sapid object] at a distance,

before touching it.

Naturally, then, the parts of media between a sensory organ and

its object are not all affected at once- except in the case of Light

[illumination] for the reason above stated, and also in the case of

seeing, for the same reason; for Light is an efficient cause of

seeing.

7



Another question respecting sense-perception is as follows:

assuming, as is natural, that of two [simultaneous] sensory stimuli

the stronger always tends to extrude the weaker [from

consciousness], is it conceivable or not that one should be able to

discern two objects coinstantaneously in the same individual time? The

above assumption explains why persons do not perceive what is