In this paper the author outlines and discusses the origins and the decline of castration and circumcision as a cure for the nervous and psychic disturbances in women and little girls between 1875 and 1905. The author argues that the opposition to this medical practice affected the conception of hysteria, promoting a distinction between sexuality and the genital organs, and the emergence of an enlarged notion of sexuality, during the period from Freud's medical education to the publication of the Three Essays on the Theory of Sexuality. The hypothesis is put forward that Freud came directly in contact with the genital theory of the neurosis at the time of his training on the nervous disturbances in children with the paediatrician, Adolf Baginsky, in Berlin, in March 1886. It is hypothesized that this experience provoked in Freud an abhorrence of circumcision ‘as a cure or punishment for masturbation’, prompting an inner confrontation which resulted in a radical reorganization of the way of thinking about sexuality. It is also suggested that this contributed to Freud developing a capacity to stay with contradictions, something which would become a central quality of the psychoanalytic attitude.