ABSTRACT
This chapter provides a short and simplified survey of the development of the psycho-analytical theory of the instincts. The first theory made a distinction between sexual and ego instincts and was set up as a result of clinical observation which showed the central importance of mental conflict in the production of neuroses. The motive for taking the second step in the development of the theory of the instincts came from the field of psychiatry. The third step—a step which has for the most part been overlooked in psycho-analytical writings—was that the aggressive trends were ascribed to the ego instincts as being among their essential constituents. The fourth step was due to a growing knowledge of the structure of the mental apparatus as a whole and its division into a "vital" stratum and an organized part, and, more especially, to a study of the unconscious region of the ego, the super-ego.
