Ernest Wood, Practical Yoga: "In this philosophy sleep is not regarded as a total cessation of the mind's activity. There is still an idea there. The mind dwells upon the idea of the absence of everything; so this idea needs a class to itself. It is not considered to be an unconscious state. That is why, it is argued, when we wake in the morning we may say: `I slept well,' meaning not that we now feel refreshed and we therefrom infer that we slept well, but that we remember that we slept well, that we enjoyed the pleasurable idea of absence of anything. We may note here that the mere suppression of ideas--not the system of control propounded in the aphorisms--would be only the concentration of the mind on absence, which would not lead to yoga."
-- Notebooks Category 19: The Reign of Relativity > Chapter 3 : The States of Consciousness > # 131
