The division of the psychical into what is conscious and what is unconscious is the fundamental premise of psycho-analysis; and it alone makes it possible for psycho-analysis to understand the pathological processes in mental life, which are as common as they are important, and to find a place for them in the framework of science.
Sigmund FreudLet us consider the polarity of love and hate.... Now, clinical observation shows not only that love is with unexpected regularityaccompanied by hate (ambivalence), and not only that in human relationships hate is frequently a forerunner of love, but also that in many circumstances hate changes into love and love into hate.
Sigmund FreudIn this way the ego detaches itself from the external world. It is more correct to say: Originally the ego includes everything, later it detaches from itself the external world. The ego-feeling we are aware of now is thus only a shrunken vestige of a far more extensive feeling - a feeling which embraced the universe and expressed an inseparable connection of the ego with the external world.
Sigmund Freud