He enters into the mastery of philosophy when he not only sees its truth but also feels it fully and loves it deeply. He has attained peace of mind, yes, but he is still a human being, has known suffering and sometimes even tragedy, has blundered and groped his way through a necessary apprenticeship. He has acquired knowledge, yes, but with it a paradoxical sensitivity.
-- Notebooks Category 20: What Is Philosophy? > Chapter 5: The Philosopher > # 129