Reason tells us that pure Thought cannot know itself because that would set up a duality which would be false if pure thought is the only real existence. But this is only reason's inability to measure what transcends itself. Although all ordinary experience confirms it, extraordinary experience refutes it.
-- Notebooks Category 28: The Alone > Chapter 2: Our Relation To the Absolute > # 132
-- Perspectives > Chapter 28: The Alone > # 27