In the same way that psychoanalysis makes use of dream-interpretation, it also profits by the study of the numerous little slips and mistakes which people make—symptomatic actions, as they are called. I investigated this subject in a series of papers which were published for the first time in book-form in 1904 under the title of _The Psychopathology of Everyday Life_.[12] In this widely circulated work I have pointed out that these phenomena are not accidental, that they require more than physiological explanations, that they have a meaning and can be interpreted, and that one is justified in inferring from them the presence of restrained or repressed impulses and intentions. But what constitutes the enormous importance of dream-interpretation, as well as of this latter study, is not the assistance they give to the work of analysis but another of their qualities. Previously psychoanalysis had only been concerned with solving pathological phenomena and in order to explain them it had often been driven into making assumptions whose comprehensiveness was out of all proportion to the importance of the actual material under consideration. But when it came to dreams, it was no longer dealing with a pathological symptom, but with a phenomenon of normal mental life which might occur in any healthy person. If dreams turned out to be constructed like symptoms, if their explanation required the same assumptions—the repression of impulses, substitute-formation, compromise-formation, the dividing of the conscious and the unconscious into various psychical systems—then psychoanalysis was no longer a subsidiary science in the field of psycho-pathology, it was rather the foundation for a new and deeper science of the mind which would be equally indispensable for the understanding of the normal. Its postulates and findings could be carried over to other regions of mental happening; a path lay open to it that led far afield, into spheres of universal interest. V I must interrupt my account of the internal growth of psychoanalysis and turn to its external history. What I have so far described of its discoveries has related for the most part to the results of my own work; but I have filled in my account with material from later dates and have not distinguished between my own contributions and those of my pupils and followers.