Co-author of A History of Medical Psychology (Norton-1941) Zilboorg presents here for the layman the fundamentals and sources of human behaviour. No easy popularization, this is a serious and relatively uncontroversial exposition of psychiatry which is not intended to make any new contribution in the field but to substantiate its validity, clarify its tenets. In opening, Zilboorg makes the important point that even today the average man is unwilling to recognize mental and illness, and he clears away some of the taints, taboos commonly associated with it. He then re-formulates the basic principles and components -- the unconscious, instincts, ego, etc. He discusses the post-Preudian schools of psychoanalytic thought, relates psychiatry to the social sciences, criminology, religion. A book for a lasting market, intelligent, persuasive.