I must point out here that the analogy with the law of the conservation of energy is very close. In both cases the question arises when an effect of energy disappears, where is this energy meanwhile, and where will it reemerge? Applying this point of view as a heuristic principle to the psychology of human conduct, we shall make some astonishing discoveries. Then we shall see how the most heterogeneous phases of individual psychological development are connected in an energic relationship. Every time we see a person who is splenetic or has a morbid conviction, or some exaggerated mental attitude, we know here is too much libido, and the excess must have been taken away from somewhere else where there is too little. From this standpoint, psychoanalysis is that method which discovers those places or functions where there is too little or too much libido, and restores the just proportions. Thus the symptoms of a neurosis must be considered as exaggerated and correspondingly disturbed functional manifestations overflowing with libido. The energy which has been used for this purpose has been taken away from somewhere else, and it is the task of the psychoanalyst, to restore it whence it was taken, or to bestow it where it was never before given. Those complexes of symptoms which are mainly characterized by lack of libido, for instance, the so-called apathetic conditions, force us to reverse the question. Here we have to ask, where did the libido go? The patient gives us the impression of having no libido, and there are occasionally physicians who believe exactly what the patients tell them. Such physicians have a primitive way of thinking, like the savage who believes, when he sees an eclipse of the sun, that the sun has been swallowed up and put to death. But the sun is only hidden, and so it is with these patients. Although the libido is there, it is not get-at-able, and is inaccessible to the patient himself. Superficially, we have here a lack of libido. It is the task of psychoanalysis to search for that hidden place where the libido dwells, and where it is as a rule inaccessible to the patient. The hidden place is the non-conscious, which may also be called the unconscious, without ascribing to it any mysterious significance. The Conception of Unconscious Phantasy