The Interpretation of Dreams by Sigmund Freud Chapter 6 Page 44

stimulus as to render it compatible with the continuance of sleep; they interweave this stimulus with the dream in order to rob it of any claims it might make as a warning to the outer world.

But this wish to continue to sleep must also participate in the formation of all other dreams which may disturb the sleeping state from within only. “Now, then, sleep on; why, it's but a dream”; this is in many cases the suggestion of the Forec. to consciousness when the dream goes too far; and this also describes in a general way the attitude of our dominating psychic activity toward dreaming, though the thought remains tacit. I must draw the conclusion that throughout our entire sleeping state we are just as certain that we are dreaming as we are certain that we are sleeping. We are compelled to disregard the objection