The authors succinctly and clearly outline the theoretical models of the psyche that Sigmund Freud developed, refined, and modified throughout his life to explain the causes of his patients' psychological suffering. They differentiate between the affect-trauma model, the topographical model with its systems of the unconscious, preconscious, and conscious, as well as the structural model with its instances of the ego, id, and superego. Special attention is given to the topographical model, which forms the basis for most later psychoanalytic concepts and has proven to be clinically significant. Furthermore, it is demonstrated that Freud's various models of the psyche are not independent of one another. Rather, there is a development of theory with considerable overlaps of individual concepts.