The author of these two volumes, Jean-Michel Petot, is described as having a triple degree in philosophy, psychology, and psychoanalysis and is the chief assistant in clinical psychology at the University of Paris X-Nanterre. The volumes were written in 1979 and 1982, in French, but they were not translated into English until 1990 and 1991.

Petot believes that these volumes are the first comprehensive study of Klein's work, particularly of the formation of her thinking. His work is described as an “illuminating historical epistemology.” He explores “the inner-links and coherence of the material so as to bring out, at every stage in its scientific evolution, the unity of her clinical project, the coherence of her theoretical methods, and the suitability for their purpose of the therapeutic tools she in time perfected” (Vol. I, p. viii). He attempts to answer his question, “What are the constants of her clinical, theoretical and technical approach?”

Petot attempts in the first volume to demonstrate how Klein's theories evolved from her clinical experience, how she kept some theories, developed others, and abandoned some in favor of better ideas. He also links these developments both with Klein's personal history and with the history of psychoanalysis.