With the arrival of puberty, changes set in which are destined to give infantile sexual life its final, normal shape. The sexual instinct has hitherto been predominantly auto-erotic; it now finds a sexual object. Its activity has hitherto been derived from a number of separate instincts and erotogenic zones, which, independently of one another, have pursued a certain sort of pleasure as their sole sexual aim. Now, however, a new sexual aim appears, and all the component instincts combine to attain it, while the erotogenic zones become subordinated to the primacy of the genital zone. 1 Since the new sexual aim assigns very different functions to the two sexes, their sexual development now diverges greatly. That of males is the more straightforward and the more understandable, while that of females actually enters upon a kind of involution. A normal sexual life is only assured by an exact 18convergence of the affectionate current and the sensual current both being directed towards the sexual object and sexual aim. (The former, the affectionate current, comprises what remains over of the infantile efflorescence of sexuality.) 2 It is like the completion of a tunnel which has been driven through a hill from both directions.