philosophized only about human life and its moral problems—virtues and vices, wisdom and follies, rights and wrongs. Perhaps that was the reason he knew “Lesson One” so well: Nothing is harder to know than the self. No questions resist certainty and closure more than moral questions because nothing is deeper and closer to us. Try to measure the earth, and you may succeed (as one ancient Greek, Eratosthenes, actually did), and you may think you are wise; but try to measure yourself and your life’s