If this were so, the withdrawal of erotic interests in the neuroses would lead to a loss of reality—a loss of reality indeed that could be compared with that in dementia præcox. But, as I said before, this is not the case. These facts have made it impossible for me to transfer Freud’s libido theory to dementia præcox. Hence, my view is, that the attempt made by Abraham, in his article “The Psycho-Sexual Differences Between Hysteria and Dementia Præcox,” is from the standpoint of Freud’s conception of libido theoretically untenable. Abraham’s belief, that the paranoidal system, or the symptomatology of dementia præcox, arises by the libido withdrawing from the external world, cannot be justified if we take “libido” according to Freud’s definition. For, as Freud has clearly shown, a mere introversion or regression of the libido leads always to a neurosis, and not to dementia præcox. It is impossible to transfer the libido theory, with its sexual definition, directly to dementia præcox, as this disease shows a loss of reality not to be explained by the deficiency in erotic interests. It gives me particular satisfaction that our master also, when he placed his hand on the fragile material of paranoiac psychology, felt himself compelled to doubt the applicability of his conception of libido which had prevailed hitherto. My position of reserve towards the ubiquity of sexuality which I allowed myself to adopt in the preface to my “Psychology of Dementia Præcox”—although with a complete recognition of the psychological mechanism—was dictated by the conception of the libido theory of that time. Its sexual definition did not enable me to explain those disturbances of functions which affect the indefinite sphere of the instinct of hunger, just as much as they do those of sexuality. For a long time the libido theory seemed to me inapplicable to dementia præcox. The Genetic Conception of Libido With greater experience in my analytical work, I noticed that a slow change of my conception of libido had taken place. A genetic conception of libido gradually took the place of the descriptive definition of libido contained in Freud’s “Three Contributions.” Thus it became possible for me to replace, by the expression “psychic energy,” the term libido. The next step was that I asked myself if now-a-days the function of reality consists only to a very small extent of sexual libido, and to a very large extent of other impulses. It is still a very important question, considered from the phylogenetic standpoint, whether the function of reality is not, at least very largely, of sexual origin. It is impossible to answer this question directly, in so far as the function of reality is concerned. We shall try to come to some understanding by a side-path.