The writings of Sextus Empiricus, and especially his Pyrrhonism, have played a remarkably influential role in the history of Western philosophy. Their rediscovery and publication in the sixteenth and seventeenth century led directly to the skepticism of Montaigne, Gassendi, Descartes, Bayle, and other major thinkers, and eventually to the preoccupation of modern philosophy with attempts to refute or otherwise combat philosophical skepticism. In recent years, however, it has become apparent that Pyrrhonism-the form of skepticism professed by Sextus-is in several important aspects different from the modern forms to which his writings have given rise. These differences are of particular philosophical interest since they seem to render this ancient form of skepticism immune to many of the standard counter-arguments to skepticism. Accordingly, Mates's book, which includes an analytic introduction, a modern translation, and an in-depth commentary, presents Pyrrhonism not merely as a historical curiosity, but as a philosophical position worthy of serious consideration.