The most striking process of puberty has been selected as its most characteristic; it is the manifest growth of the external genitals which have shown a relative inhibition of growth during the latency period of childhood. Simultaneously the inner genitals develop to such an extent as to be able to furnish sexual products or to receive them for the purpose of forming a new living being. A most complicated apparatus is thus formed which waits to be claimed. This apparatus can be set in motion by stimuli, and observation teaches that the stimuli can affect it in three ways: from the outer world through the familiar erogenous zones; from the inner organic world by ways still to be investigated; and from the psychic life, which merely represents a depository of external impressions and a receptacle of inner excitations. The same result follows in all three cases, namely, a state which can be designated as "sexual excitation" and which manifests itself in psychic and somatic signs. The psychic sign consists in a peculiar feeling of tension of a most urgent character, and among the manifold somatic signs the many changes in the genitals stand first. They have a definite meaning, that of readiness; they constitute a preparation for the sexual act (the erection of the penis and the glandular activity of the vagina). *The Sexual Tension*--The character of the tension of sexual excitation is connected with a problem the solution of which is as difficult as it would be important for the conception of the sexual process. Despite all divergence of opinion regarding it in psychology, I must firmly maintain that a feeling of tension must carry with it the character of displeasure. For me it is conclusive that such a feeling carries with it the impulse to alter the psychic situation, and acts incitingly, which is quite contrary to the nature of perceived pleasure. But if we ascribe the tension of the sexual excitation to the feelings of displeasure we encounter the fact that it is undoubtedly pleasurably perceived. The tension produced by sexual excitation is everywhere accompanied by pleasure; even in the preparatory changes of the genitals there is a distinct feeling of satisfaction. What relation is there between this unpleasant tension and this feeling of pleasure?