Unreflective life is often impatient with such enquiries into the relative value of the waking state, for to them its superior reality in contrast with dream is completely beyond all question. They denounce the sleep enquiry as being altogether too flimsy a premise on which to build great conclusions. Yet when we remember that all living creatures from ant to man are plunged into intermittent sleep for substantial portions of their whole lives, how can we hope to grasp the meaning of their existence and the meaning of the universe of which they are parts, without examining the full meaning and proper value of sleep-states? Whatever we learn from a single state alone may always be liable to contradiction by the facts of another state. Therefore unless we coordinate and evaluate the truth of the waking state with the truth of the sleep state we cannot hope to arrive at ultimate truth in its fullness. But when we venture to make such a coordination we shall discover that in sleep there lies the master-key of life and death!
-- Notebooks Category 19: The Reign of Relativity > Chapter 3: The States of Consciousness > # 19
-- Perspectives > Chapter 19: The Reign of Relativity > # 16