When we comprehend that the pure essence of mind is reality, then we can also comprehend the rationale of the higher yoga which would settle attention in pure thought itself rather than in finite thoughts. When this is done the mind becomes vacant, still, and utterly undisturbed. This grand calm of nonduality comes to the philosophic yogi alone and is not to be confused with the lower-mystical experience of emotional ecstasy, clairvoyant vision, and inner voice. For in the latter the ego is present as its enjoyer, whereas in the former it is absent because the philosophic discipline has led to its denial. The lower type of mystic must make a special effort to gain his ecstatic experience, but the higher type finds it arises spontaneously without personal effort at all. The first is in the realm of duality, whilst the second has realized nonduality.
-- Notebooks Category 23: Advanced Contemplation > Chapter 8: The Void As Contemplative Experience > # 130
-- Perspectives > Chapter 23: Advanced Contemplation > # 46