[Georg Groddeck--father of psychosomatic medicine].

Life and work of Georg Groddeck (1866-1934), a nearly forgotten pioneer of psychosomatic medicine, are presented. Special emphasis is laid on the term "Es" and its impacts on putting forward psychoanalytic theories as well as the relationship to Sigmund Freud. The influence of Groddeck on the development of psychoanalysis and his friendship with Sándor Ferenczi are rendered prominent. Finally, the value of Groddeck's ideas for the future of psychosomatic medicine is discussed.