On Sense And The Sensible   

such time, be unaware of his own existence, as well as of his seeing

and perceiving; [this assumption must be false].

Again, if there is any magnitude, whether time or thing,

absolutely imperceptible owing to its smallness, it follows that there

would not be either a thing which one perceives, or a time in which

one perceives it, unless in the sense that in some part of the given

time he sees some part of the given thing. For [let there be a line

ab, divided into two parts at g, and let this line represent a whole

object and a corresponding whole time. Now,] if one sees the whole

line, and perceives it during a time which forms one and the same

continuum, only in the sense that he does so in some portion of this

time, let us suppose the part gb, representing a time in which by

supposition he was perceiving nothing, cut off from the whole. Well,

then, he perceives in a certain part [viz. in the remainder] of the

time, or perceives a part [viz. the remainder] of the line, after

the fashion in which one sees the whole earth by seeing some given

part of it, or walks in a year by walking in some given part of the

year. But [by hypothesis] in the part bg he perceives nothing:

therefore, in fact, he is said to perceive the whole object and during

the whole time simply because he perceives [some part of the object]

in some part of the time ab. But the same argument holds also in the

case of ag [the remainder, regarded in its turn as a whole]; for it

will be found [on this theory of vacant times and imperceptible

magnitudes] that one always perceives only in some part of a given

whole time, and perceives only some part of a whole magnitude, and

that it is impossible to perceive any [really] whole [object in a

really whole time; a conclusion which is absurd, as it would logically

annihilate the perception of both Objects and Time].

Therefore we must conclude that all magnitudes are perceptible,

but their actual dimensions do not present themselves immediately in

their presentation as objects. One sees the sun, or a four-cubit rod

at a distance, as a magnitude, but their exact dimensions are not