this phenomenon of reactivation or secondary exaggeration of infantile reminiscences "regression." But in Freud's conception it appears as if the incestuous desires of the Œdipus-complex were the real cause of the regression to infantile phantasies. If this were the case, we should have to postulate an unexpected intensity of the primary incestuous tendencies. This view led Freud to his recent comparison between the so-called psychological "incest-barrier" in children and the "incest-taboo" in primitive man. He supposes that a real incestuous desire has led the primitive man to the invention of a protective law; while to me it looks as if the incest-taboo is one among numerous taboos of all sorts, and due to the typical superstitious fear of primitive man, a fear existing independently of incest and its interdiction. I am able to attribute as little particular strength to incestuous desires in childhood as in primitive humanity. I do not even seek the reason for regression in primary incestuous or any other sexual desires. I must state that a purely sexual ætiology of neurosis seems to me much too narrow. I base this criticism upon no prejudice against sexuality, but upon an intimate acquaintance with the whole problem. Therefore I suggest that the psychoanalytic theory should be liberated from the purely sexual standpoint. In place of it I should like to introduce an _energic view-point_ into the psychology of neurosis. All psychological phenomena can be considered as manifestations of energy, in the same way as all physical phenomena are already understood as energic manifestations since Robert Mayer discovered the law of the conservation of energy. This energy is subjectively and psychologically conceived as _desire_. I call it _libido_, using the word in the original meaning of this term, which is by no means only sexual. Sallustius applies the term exactly in the way we do here: "_Magis in armis et militaribus equis, quam in scortis et conviviis libidinem habebant._"