The differences which ensue in these two destinies in spite of the common experiences undergone, arise because in one girl the Ego has sustained a development absent in the other. To the caretaker’s daughter sexual activity seemed as natural and harmless in later years as in childhood. The gentleman’s daughter had been “well-brought-up” and had adopted the standards of her education. Thus stimulated, her Ego had formed ideals of womanly purity and absence of desire that were incompatible with sexual acts; her intellectual training had caused her to depreciate the feminine rôle for which she is intended. This higher moral and intellectual development in her Ego has brought her into conflict with the claims of her sexuality. I will explore one more aspect of the development of the Libido to-day, both because it leads out upon certain wide prospects, and also because it is well-suited to justify the sharp, and not immediately obvious, line of demarcation we are wont to draw between Ego-instincts and sexual instincts. In considering the two developments undergone by the Ego and by the Libido we must emphasize an aspect which hitherto has received little attention. Both of them are at bottom inheritances, abbreviated repetitions of the evolution undergone by the whole human race through long-drawn-out periods and from prehistoric ages. In the development of the Libido this phylogenetic origin is readily apparent, I should suppose. Think how in one class of animals the genital apparatus is in closest relation with the mouth, in another it is indistinguishable from the excretory mechanism, in another it is part of the organs of motility; you will find a delightful description of these facts in W. Bölsche’s valuable book. One sees in animals all the various perversions, ingrained, so to speak, in the form taken by their sexual organizations. Now the phylogenetic aspect is to some extent obscured in man by the circumstance that what is fundamentally inherited is nevertheless individually acquired anew, probably because the same conditions that originally induced its acquisition still prevail and exert their influence upon each individual. I would say, where they originally created a new response they now stimulate a predisposition. Apart from this, it is unquestionable that the course of the prescribed development in each individual can be disturbed and altered by current impressions from without. But the power which has enforced this development upon mankind, and still to-day maintains its pressure in the same course, is known to us; it is, again, the privation exacted by reality; or, if we give it its great real name, it is _Necessity_, the struggle for life, _’ANATKH_. Necessity has been a severe task-mistress, and she has taught us a great deal. Neurotics are those of her children upon whom this severity has had evil effects, but that risk is inevitable in any education. Incidentally, this view of the struggle for