In this foundational work of psychoanalysis, which is almost akin to a textbook, the focus is on the acquisition and, in a certain sense, the creation of the psychosomatic self and the world through the psyche that ultimately becomes aware of itself. Following in the footsteps of Sigmund Freud, Melanie Klein, and Wilfred R. Bion, and also drawing on the insights of other psychoanalysts, particularly Jean Piaget, the discussions of primitive functions and infantile models, which provide access to regressive processes in clinical work with patients, are condensed into a depiction of the development of a hypothetical infant.