This contribution focuses on Freud’s elaboration of the genesis of sadism and masochism in “Instincts and their Vicissitudes” (1915c). We first briefly recap the standard reading of this text by Jean Laplanche which relies on Freud’s concept of “anaclisis”. In our opinion, Laplanche’s reading implicitly presupposes that Freud’s discussion of sadism and masochism questions the sexualisation of an originally non-sexual aggressivity. In contrast, we argue that Freud’s argumentation starts from the question how the aggressivity that is inherent in sexuality relates to sadism and masochism qua perversion. The matrix of obsessional neurosis and the development of the ego discussed in the same context are of crucial importance for the systematic development of Freud’s answer to this last question.