Sándor Ferenczi (1873 - 1933), Hungarian neurologist and psychoanalyst as well as Sigmund Freud's closest confidant and friend, became one of the most productive and creative psychoanalysts. He anticipated many ideas of the object relations theory and psychotraumatology that were developed decades later in his writings. The present four-volume work is a compilation of various publications by the author and demonstrates the versatility and independence of his scientific contributions. Reprint of the original edition from 1939.