In psychoanalysis, a key aspect of female psychology, originating in a girl's discovery of the anatomic differences between the sexes, causing her to feel deprived, and later, during the Oedipal phase, to develop a desire for a penis, manifested symbolically as a desire to have a child or to possess a penis in sexual intercourse. Sigmund Freud (1856–1939) introduced the concept in 1914 in connection with the castration complex in girls in his article ‘On Narcissism: An Introduction’ (Standard Edition, XIV, pp. 73–102, at p. 92) and developed it further in an article in 1917 ‘On the Transformations of Instinct, as Exemplified in Anal Erotism’ (Standard Edition, XVII, pp. 127–33). The concept was rejected by the German-born US psychoanalyst Karen Horney (1885–1952) and the Welsh psychoanalyst Ernest Jones (1879–1958), among others, and was given less prominence by the British-based Austrian psychoanalyst Melanie Klein (1882–1960). See also phallic stage.