Freud is the father of modern psychology and he established the psychoanalytical point of view. No one who is not well grounded in Freudian lore can hope to achieve any work of value in the field of psychoanalysis.

The publishers of the present book deserve credit for presenting to the reading public the gist of Freud's psychology in the master's own words, and in a form which shall neither discourage beginners, nor appear too elementary to those who are more advanced in psychoanalytic study.
Dream psychology is the key to Freud's works and to all modern psychology.

Freud's theories are anything but theoretical.
He was moved by the fact that there always seemed to be a close connection between his patients' dreams and their mental abnormalities, to collect thousands of dreams and to compare them with the case histories in his possession.
He did not start out with a preconceived bias, hoping to find evidence which might support his views. He looked at facts a thousand times "until they began to tell him something." His attitude toward dream study was, in other words, that of a statistician who does not know, and has no means of foreseeing, what conclusions will be forced on him by the information he is gathering, but who is fully prepared to accept those unavoidable conclusions.
This was indeed a novel way in psychology.

Five facts of first magnitude were made obvious to the world by his interpretation of dreams.
First of all, 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.
(Andre Tridon)