Sigmund Freud is commonly referred to as "the father of psychoanalysis" and his work has been highly influential - popularizing such notions as the unconscious, the Oedipus complex, defense mechanisms, Freudian slips and dream symbolism - while also making a long-lasting impact on fields as diverse as literature, film, Marxist and feminist theories, and psychology. Freud pointed out a constant connection between some part of every dream and some detail of the dreamer's life during the previous waking state. This positively establishes a relation between sleeping states and waking states and disposes of the widely prevalent view that dreams are purely nonsensical phenomena coming from nowhere and leading nowhere. Secondly, Freud, after studying the dreamer's life and modes of thought, after noting down all his mannerisms and the apparently insignificant details of his conduct which reveal his secret thoughts, came to the conclusion that there was in every dream the attempted or successful gratification of some wish, conscious or unconscious. Thirdly, he proved that many of our dream visions are symbolical, which causes us to consider them as absurd and unintelligible; the universality of those symbols, however, makes them very transparent to the trained observer. Fourthly, Freud showed that sexual desires play an enormous part in our unconscious, a part which puritanical hypocrisy has always tried to minimize, if not to ignore entirely. Finally, Freud established a direct connection between dreams and insanity, between the symbolic visions of our sleep and the symbolic actions of the mentally deranged.