The prerequisite of obsessions is also a sexual infantile experience, but of a different nature than that of hysteria. The etiology of both defense neuropsychoses now shows the following relation to the etiology of both simple neuroses, neurasthenia and anxiety neurosis. As I have shown above, both the latter neuroses are the direct results of the sexual noxas alone, while both defense neuroses are the direct results of sexual noxas which acted before the appearance of sexual maturity, that is, they are the results of the psychic memory remnants of these noxas. The actual causes producing neurasthenia and anxiety neurosis simultaneously play the rôle of inciting causes of the defense neuroses, and on the other hand, the specific causes of the defense neuroses, the infantile traumas, may simultaneously prepare the soil for the later developing neurasthenia. Finally it not seldom happens that the existence of a neurasthenia or anxiety neurosis is only preserved by continued recollection of an infantile trauma rather than by actual sexual injuries. II. THE ESSENCE AND MECHANISM OF COMPULSION NEUROSIS. Sexual experiences of early childhood have the same significance in the etiology of the compulsion neurosis as in hysteria, still we no longer deal here with sexual passivity but with pleasurably accomplished aggressions, and with pleasurably experienced participation in sexual acts, that is, we deal here with sexual activity. It is due to this difference in the etiological relations that the masculine sex seems to be preferred in the compulsion neurosis. In all my cases of compulsion neurosis I have found besides a subsoil of hysterical symptoms which could be traced to a pleasurable action of sexual passivity from a precedent scene. I presume that this coincidence is a lawful one, and that premature sexual aggression always presupposes an experience of seduction. But I am unable to present as yet a complete description of the etiology of the compulsion neurosis. I only believe that the final determination as to whether a hysteria or compulsion neurosis should originate on the basis of infantile traumas depends on the temporal relation of the development of the libido. The essence of the compulsion neurosis may be expressed in the following simple formula: Obsessions are always transformed _reproaches_ returning from consciousness which always refer to a pleasurably accomplished sexual action of childhood. In order to elucidate this sentence it will be necessary to describe the typical course of compulsion neurosis. In a first period—period of childish immorality—the events containing the seeds of the later neurosis take place. In the earliest childhood there appear at first the experiences of sexual seduction which later makes the repression possible, and this is followed by the actions of sexual aggressions against the other sex which later manifest themselves as actions of reproach.