The libido theory is one of the major areas of interest in psychoanalysis. Freud's insights in this field have been widely applied and used by psychoanalysts, adult and child psychiatrists, psychologists, educationalists, experts on child development and social workers. They have thrown light on the normal and abnormal aspects of sexual development from childhood to adulthood and on the role played by sexual development in neurotic disturbances. Further they have made possible an understanding of the complex field of sexual perversions. Originally published in 1969, in this volume the reader will find twenty-four basic psychoanalytic concepts concerning the libido theory including oral erotism, anal erotism, phallic erotism, genital erotism, the Oedipus complex of the girl, the Oedipus complex of the boy, autoerotism, narcissism, masochism, sadism and bisexuality. As in the other volumes in this series, the historical development of each concept and references to Freud's works are clearly given so that students and scholars can pursue any aspect of special interest.