FREUD AND PSYCHO-ANALYSIS
OPPOSED to behaviourism in somewhat the same way as the hormic psychology (and indeed treated by McDougall as in this respect a potent ally) is another important school-- that of psycho-analysis. Psycho-analysis, however, differs in turn from the hormic psychology (and from all others) in the stress that it lays on the unconscious. A full understanding of human behaviour, this school maintains, is impossible unless we take into account certain mental factors, which can be directly observed neither by introspective nor behaviouristic methods, but which can be inferred from their effects. The general idea of unconscious or subconscious mental states was, as we ourselves have seen, far from being a new one. The notion, in one form or another, had been common in psychology almost from the earliest times. At the dawn of modern philosophy it had been emphasized by Leibnitz, and in the second half of the nineteenth century it had come into prominence in connection with the French studies in psycho-pathology. In its origin, psycho-analysis itself developed from this latter source.
More perhaps than any other school, it is the creation of a single man, Sigmund Freud, of Vienna. Freud, in the eighties, studied with Charcot in Paris, and he and Janet were Charcot's most distinguished pupils. But, whereas Janet may be said to have carried on the French tradition, Freud, soon after leaving Paris, met with another investigator, Breuer (whom we have already mentioned in connection with his theory of the sense