In unwittingly setting up waking consciousness as the sole arbiter of all his knowledge, Western man limits that knowledge unnecessarily. And in regarding other forms of consciousness as mere copies or aberrations of waking consciousness, or else denying their existence altogether, he bars himself from the supreme insight and the highest felicity open to him. Unless he brings the dream and the deep sleep states also into his reckoning, he will continue to be deceived by the Unreal and to mistake the shadow for the substance.
-- Notebooks Category 19: The Reign of Relativity > Chapter 3: The States of Consciousness > # 18
-- Perspectives > Chapter 19: The Reign of Relativity > # 12