This book translates fourteen essays by Pierre Hadot, born a century ago on the day this review is published (February 21, 2022), that have not previously been published in English; ten have already been collected in Études de philosophie ancienne (2010), and three in the most recent edition of Exercices Spirituels et Philosophie Antique (1993). Most of these essays, of diverse length and explanatory purpose though with remarkably similar tenor, formulate aspects of the thesis most popularly known in English from What is Ancient Philosophy? (2002, BMCR 2002.09.21; French original in 1995). That view is that ancient philosophy overall, from at least Plato till late antiquity, should be understood as a “way of life,” with the various schools of philosophy prescribing overlapping ways of life. In these programs of living, “spiritual exercises” modify one’s desiderative, perceptual, and cognitive responses to the world and oneself, with the aim of increasing one’s happiness. The contrast is with seeing ancient philosophy principally as an endeavor to accumulate and systematize certain fundamental areas of knowledge.