"All are lunatics, but he who can analyze his delusions is called a philosopher," quipped Ambrose Bierce, and in this primer on great thinkers and great thoughts, classicist Lesley Levene reveals that the 2500-year pursuit of philosophy has been more about the questions than about the answers. From "The unexamined life is not worth living" (Socrates) to "There is nothing outside of text" (Jacques Derrida), Levene gives us short biographies of key philosophers; -isms and -ologies from atomism to teleology; and the quips, quotes, and conundrums that make for fascinating party talk.