Now you will probably have heard that the term “sexual” has suffered an unwarrantable expansion of meaning at the hands of psycho-analysis, in order that its assertions regarding the sexual origin of the neuroses and the sexual significance of the symptoms may be maintained. You can now judge for yourselves whether this amplification is justified or not. We have extended the meaning of the concept “sexuality” only so far as to include the sexual life of perverted persons and also of children; that is to say, we have restored to it its true breadth of meaning. What is called sexuality outside psycho-analysis applies only to the restricted sexual life that is subordinated to the reproductive function and is called normal. TWENTY-FIRST LECTURE DEVELOPMENT OF THE LIBIDO AND SEXUAL ORGANIZATIONS It is my impression that I have not succeeded in bringing home to you with complete conviction the importance of the perversions for our conception of sexuality. I wish therefore, as far as I am able, to review and improve upon what I have already said on this subject. Now I do not wish you to think that it was the perversions alone that required us to make the alteration in the meaning of the term sexuality which has aroused such vehement opposition. The study of infantile sexuality has contributed even more to it, and the unanimity between the two was decisive. But, however unmistakable they may be in the later years of childhood, the manifestations of infantile sexuality in its earliest forms do seem to fade away indefinably. Those who do not wish to pay attention to evolution and to the connections brought out by analysis will dispute the sexual nature of them, and will ascribe in consequence some other, undifferentiated character to them. You must not forget that as yet we have no generally acknowledged criterion for the sexual nature of a phenomenon, unless it is some connection with the reproductive function—a definition which we have had to reject as too narrow. The biological criteria, such as the periodicities of twenty-three and twenty-eight days, suggested by W. Fliess, are exceedingly debatable; the peculiar chemical features which we may perhaps assume for sexual processes are yet to be discovered. The sexual perversions in adults, on the other hand, are something definite and unambiguous. As their generally accepted description implies, they are unquestionably of a sexual nature; whether you call them marks of degeneration or anything else, no one has yet been so bold as to rank them anywhere but among the phenomena of sexual life. In view of them alone we are justified in maintaining that sexuality and the reproductive function are not identical, for they one and all abjure the aim of reproduction.