This page has been validated.
CH. VII.]
ARISTOTLE ON THE VITAL PRINCIPLE.
165

to flee from or pursue after something; and perceptions of pain and pleasure emanate from the sentient medium in its relation to good or evil, in so far as things may be one or other. So actual flight from something is identical with actual appetite, as the fugitive impulse does not differ from the appetitive stimulus, for they differ neither from one another nor from the sentient medium; and yet they do differ in mode of being. Images belong, naturally, to the thinking, as sensations do to the sentient principle; and as it may affirm or deny that anything is good or bad, it bids to flee from or pursue after it. The Vital Principle, therefore, never thinks without an image; as the air has made the pupil what it is, the pupil something else, and so with the hearing; but the last term is one, as the mean, to which belong several modes of being, is one.

It has already been said by what faculty the mind discerns that sweet differs from hot, but yet it may be spoken of again here. It is then an unit of some kind; and an unit in the sense of a limit, for it is as an unit and a limit in the relation, considered analogically and numerically, which the unit bears to the limit. What matters it, besides, whether our doubt is as to how the faculty judges of things, generically, the same, or opposite, as white and black ?

Let A = white be in relation to B = black, and let C be to D as A is to B, and so reciprocally; if C, D be