On Sense And The Sensible   

figure, magnitude, motion, number: while hearing announces only the

distinctive qualities of sound, and, to some few animals, those also

of voice. indirectly, however, it is hearing that contributes most

to the growth of intelligence. For rational discourse is a cause of

instruction in virtue of its being audible, which it is, not directly,

but indirectly; since it is composed of words, and each word is a

thought-symbol. Accordingly, of persons destitute from birth of either

sense, the blind are more intelligent than the deaf and dumb.

2



Of the distinctive potency of each of the faculties of sense

enough has been said already.

But as to the nature of the sensory organs, or parts of the body

in which each of the senses is naturally implanted, inquirers now

usually take as their guide the fundamental elements of bodies. Not,

however, finding it easy to coordinate five senses with four elements,

they are at a loss respecting the fifth sense. But they hold the organ

of sight to consist of fire, being prompted to this view by a

certain sensory affection of whose true cause they are ignorant.

This is that, when the eye is pressed or moved, fire appears to

flash from it. This naturally takes place in darkness, or when the

eyelids are closed, for then, too, darkness is produced.

This theory, however, solves one question only to raise another;

for, unless on the hypothesis that a person who is in his full

senses can see an object of vision without being aware of it, the

eye must on this theory see itself. But then why does the above

affection not occur also when the eye is at rest? The true explanation

of this affection, which will contain the answer to our question,

and account for the current notion that the eye consists of fire, must

be determined in the following way: Things which are smooth have the

natural property of shining in darkness, without, however, producing

light. Now, the part of the eye called 'the black', i.e. its central