This work is a survey of the developments in psychoanalytical knowledge made through the efforts of Melanie Klein. The basic structure of the book is based primarily upon four papers originally read before the British Psychoanalytical Society in 1943 with the object of enabling members to clarify their views in regard to Klein's work. To these papers have been added a chapter by Reviere based upon a lecture given in Vienna in 1936; this she states she added with some misgivings and finds its general formulations not in character with the rest of the book.