A fresh, irreverent, and wildly original take on why philosophy matters and how it has changed the world. Why have so many philosophers risked their lives for their vocation? Why have reigning authoritarian rulers been so keen to silence them? This book frames the philosophical search for wisdom as part of the human quest for freedom. Matthew Stewart argues that philosophy is not a body of specialized expertise but an activity--like conversation, making music, or starting a revolution--open to everyone and capable of transforming the world. A sweeping new history of philosophy, the book rescues forgotten gems such as Giordano Bruno and Pierre Bayle, challenges our understanding of canonical figures such as Plato and Descartes, and weaves major Eastern and Western traditions into a single global story reaching back to prehistory. Along the way, it offers brisk interpretations of key philosophical subdisciplines such as metaphysics, philosophy of mind, epistemology, ethics, and political philosophy. Lively and accessible, it will be of interest to both novices and seasoned readers in philosophy.