During the late 1890s Freud , who never abandoned his belief in the sexual cause of neuroses , began to emphasize fantasies built around the Oedipus complex as the primary cause of hysteria and other neurotic symptoms . During the late 1890s Freud , who never abandoned his belief in the sexual etiology of neuroses , began to emphasize fantasies built around the Oedipus complex as the primary cause of hysteria and other neurotic symptoms .