Book excerpt: This excellent introduction to the essential issues that have preoccupied philosophers throughout the centuries provides fresh and engaging portraits of the greatest thinkers on three perennial questions: What can I know? What may I hope? What ought I to do? The author summarizes the thoughts of Plato and Wittgenstein on the possibility of philosophical knowledge; Kant and Nietzsche on the existence of God; Aristotle and Heidegger on human virtue. The first member of the pair is a builder, the second a destroyer. One explores the promise of a theory, the other the consequences of its ruin. These juxtaposed pairs are not self-contained, however. All six thinkers are engaged in a dialogue with one another on issues that touch our lives directly and profoundly. The author has arranged them in an order that unveils an ever-deepening understanding of the moral, spiritual and intellectual space in which our lives unfold. For anyone wishing to discover, or rediscover, philosophy in its original meaning—"the love of wisdom"—this engaging, clearly written, and accessible volume is an excellent place to start.