I believe--as I shall try to prove in a later lecture--that desire, like force in mechanics, is of the nature of a convenient fiction for describing shortly certain laws of behaviour. A hungry animal is restless until it finds food; then it becomes quiescent. The thing which will bring a restless condition to an end is said to be what is desired. But only experience can show what will have this sedative effect, and it is easy to make mistakes. We feel dissatisfaction, and think that such and-such a thing would remove it; but in thinking this, we are theorizing, not observing a patent fact. Our theorizing is often mistaken, and when it is mistaken there is a difference between what we think we desire and what in fact will bring satisfaction. This is such a common phenomenon that any theory of desire which fails to account for it must be wrong. What have been called "unconscious" desires have been brought very much to the fore in recent years by psycho-analysis. Psycho-analysis, as every one knows, is primarily a method of understanding hysteria and certain forms of insanity*; but it has been found that there is much in the lives of ordinary men and women which bears a humiliating resemblance to the delusions of the insane. The connection of dreams, irrational beliefs and foolish actions with unconscious wishes has been brought to light, though with some exaggeration, by Freud and Jung and their followers. As regards the nature of these unconscious wishes, it seems to me--though as a layman I speak with diffidence--that many psycho-analysts are unduly narrow; no doubt the wishes they emphasize exist, but others, e.g. for honour and power, are equally operative and equally liable to concealment. This, however, does not affect the value of their general theories from the point of view of theoretic psychology, and it is from this point of view that their results are important for the analysis of mind. * There is a wide field of "unconscious" phenomena which does not depend upon psycho-analytic theories. Such occurrences as automatic writing lead Dr. Morton Prince to say: "As I view this question of the subconscious, far too much weight is given to the point of awareness or not awareness of our conscious processes. As a matter of fact, we find entirely identical phenomena, that is, identical in every respect but one-that of awareness in which sometimes we are aware of these conscious phenomena and sometimes not"(p. 87 of "Subconscious Phenomena," by various authors, Rebman). Dr. Morton Price conceives that there may be "consciousness" without "awareness." But this is a difficult view, and one which makes some definition of "consciousness" imperative. For nay part, I cannot see how to separate consciousness from awareness.