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CH. I.] properties than, as has just been said, we see that an individual is the son of Cleon. The senses, however, do perceive, casually, the special qualities of each other; but then they do so, not as distinct senses but, as becoming one sense, as when double impressions may be made simultaneously upon the same organ, as by bile, which is bitter and yellow. But as it belongs not to either sense to say that both qualities belong to one substance, we are exposed to error, and led to think that if a fluid be yellow it must be bile.

Should any one inquire why we have been furnished with several senses in place of having only one, it might be answered, " that we have so been constituted in order that the sequences and common properties of bodies, as motion, magnitude, and number, may the less readily escape our notice." If vision, in fact, were our only sense and it perceptive only of whiteness, then all other qualities would more readily escape our notice and seem to be identical, on account of colour and magnitude being in an invariable sequence to one another. But as here common properties are manifested in different bodies, it is evident that each of those properties (colour and magnitude) must also be different.