reality with which alone he is concerned, and each state of consciousness is a real fact in that world — a fact occurring at a definite time and in a definite set of connections with other psychical facts. The interconnections of this factual world, the laws of the happening of psychical events, are what the psychologist has to investigate.
It is only for the psychologist, however, that mental states are interesting on their own account, as subjective realities or facts. To every one else they are interesting only for what they mean, for the knowledge they give us of a world beyond themselves. Viewed in themselves, the mental states are, as it were, only instrumental; by them, as Locke says, the understanding hath knowledge. They are merely a mechanism by which a world of men and things is somehow revealed to me. It is only for the psychologist, I say, that the investigation of this mechanism, as a mechanism, has an interest. To all the rest of mankind ideas or presentations are interesting only for the knowledge they give us of a reality beyond themselves. In point of fact, we never pause to consider them as what they are in themselves, — we treat them consistently as significant, as ideas of something, as representative or symbolic of a world of facts. Now it is from this latter point of view that epistemology considers ideas.
Of course this distinction, even the manner of stating it, is far from being new. Not to go further back, it is drawn with great clearness in the writings of Descartes and his followers. In fact, considerable emphasis is laid upon it in the Cartesian philosophy, and a special terminology is employed to designate it. "Ideas," says Descartes himself, [1] "may be taken in so far only as they are certain modes of consciousness," and so regarded, "they all seem in the same manner to proceed from myself." That is to say, they are all subjective functions or psychical events. But they may also be considered "as images, of which one represents one thing and another a different." So far as the idea is taken simply as an act or function of the mind,
- ↑ Third Meditation.
