Structure and Dynamics of the Psyche (Collected Works of C.G. Jung, Volume 8)
As in our waking state, real people and things enter our field of vision, so the dream-images enter like another kind of reality into the field of consciousness of the dream-ego. We do not feel as if we were producing the dreams, it is rather as if the dreams came to us.
They are not subject to our control but obey their own laws.
They are obviously autonomous psychic complexes which form themselves out of their own material.
We do not know the source of their motives, and we therefore say that dreams come from the unconscious.
In saying this, we assume that there are independent psychic complexes which elude our conscious control and come and go according to their own laws. ~Carl Jung, CW 8, Page 580.