"In the Nicomachean Ethics, which he is said to have dedicated to his son Nicomachus, Aristotle's guiding question is what is the best thing for a human being? His answer is happiness. 'Happiness,' he wrote, 'is the best, noblest, and most pleasant thing in the world.' But he means not something we feel, not an emotion, but rather an especially good kind of life. Happiness is made up of activities in which we use the best human capacities, both ones...