In this article the author presents a picture of the fundamental aspects of the theory and practice of psychoanalysis, and attempts to bring out the changes in Freud's primary conceptions necessitated by later developments.

The author's study follows two main directions: 1. What psychoanalysis has done for the understanding of human nature and for psychopathology, and what it has contributed to the fields of mental hygiene, education, sociology and anthropology. 2. The influence of psychoanalysis on psychiatry—the decisive increase in modern clinical psychiatric work carried on by practitioners who may accept or reject psychoanalysis, but whose work is in any case really inspired by Freud's approach, who reach the same goal and come to identical conclusions.