Sigmund Freud introduced the concepts of identification and the ego ideal in Group Psychology and the Analysis of the Ego. Group Psychology was Freud's second contribution on group phenomena, coming as it did after Totem and Taboo, all-powerful father served in 1921 as a concrete foundation for the elaboration of the ego ideal, as yet merged with the superego. In accordance with the duality of its title, Freud's essay can be read as a contribution to group psychology or as an attempt to restructure the concept of the ego. Sandor Ferenczi appears to be more interested in the developments in individual psychopathology furnished by Freud's propositions than in their application to social phenomena. After the World War II, Bion used group psychotherapy to rehabilitate veterans and former prisoners of war and facilitate their return to civilian life. Andre Ruffiot illustrated the specific setting of psychoanalytic family psychotherapy by showing how to transpose the rules of individual treatment to it.