2010 reprint of 1927 first English Edition. The Ego and the Id is a foundation document in psychoanalysis first written by Freud in 1923. It is an analytical study of the human psyche outlining his theories of the psychodynamics of the id, ego, and super-ego, which is of fundamental importance in the development of psychoanalytic theory. The study was conducted over years of meticulous research and was first published in English in 1927.