A mystic experience is simply something which comes and goes, whereas philosophic insight, once established in a man, cannot possibly leave him. He understands the Truth and cannot lose this understanding any more than an adult can lose his adulthood and become an infant.
-- Notebooks Category 20: What Is Philosophy? > Chapter 4: Its Realization Beyond Ecstasy > # 198
-- Perspectives > Chapter 20: What Is Philosophy? > # 78