Reinforcement during the night

...a dream is recognized as a form of expression of impulses which are under the pressure of resistance during the day but which have been able to find reinforcement during the night from deep-lying sources of excitation. The respect paid to dreams in antiquity is, however, based upon correct psychological insight and is the homage paid to the uncontrolled and indestructible forces in the human mind, to the 'daemonic' power which produces the dream-wish and which we find at work in our unconscious.

Chapter VI: The Dream-Work, F. The Unconscious and Consciousness in The Interpretation of Dreams, 1900, Sigmund Freud, James Strachey translation