Lloyd Gerson’s latest book issues a challenge to contemporary philosophers to rethink the nature of their vocation, its problems, presuppositions, and ends. Gerson bucks the mainstream to affirm that naturalism in all its varieties, reductive as well as liberal, is a dead-end and that if philosophy is possible at all as a branch of knowledge distinct from the natural sciences, with a subject-matter of its own, then it is possible only as Platonism. The forcefulness and clarity with which he makes his case demand and deserve the attention of a wide philosophical audience.