totle indicates, without fully explaining, his doctrine of the relation of the mind to external things in a celebrated passage (‘Soul,’ iii. v.), where he says that there are two kinds of Reason in the soul—the one passive, the other constructive. “The passive Reason becomes all things by receiving their impress; the constructive Reason creates all things, just as light brings colours into actual existence, while without light they would have remained mere possibilities.” Aristotle, then, appears to be removed from the “common-sense” doctrine of “natural realism,” which believes that the world would be just what we perceive to be, even if there were no one to perceive it; for, by his analogy, the mind contributes as much to the existence of things as light does to colour; and he is equally removed from that extreme idealism which would represent things to be merely the thoughts of a mind, for he evidently considers that there is a “not-me”—a factor in all existence and knowledge—which is outside of the mind, and which may be taken to be symbolised by all the constituents of colour, except light: the mind, according to him, contributes only what light does to colour; all else is external to the mind, though without the mind nothing could attain to actuality. The external world, then, according to Aristotle, is a perfectly real existence, but it is the product of two sets of factors—the one being the rich and varied constituents of the universe, the other being Reason manifested in perceiving minds; and, without the presence and co-operation of this perceptive Reason, all things would be at once condemned to virtual annihilation.
