This book is an annotated translation of one of the great Tibetan classics of Mahayana Buddhist thought, mKhas grub rje's sTong thun chen mo. The text is a detailed critical exposition of the theory and practice of emptiness as expounded in the three major schools of Mahayana Buddhist philosophy: the Yogacara, Svatantrika, and Prasangika. Used as a supplement to the scholastic debating manuals in some of the greatest monasteries of Tibet, the sTong thun chen mo is a veritable encyclopedia of Mahayana Buddhist philosophy, dealing with such topics as hermeneutics, the theory of non-duality, the linguistic interpretation of emptiness, the typology of ignorance, logic, the nature of time, and the perception of matter across world spheres. This book is an indispensable source for understanding the Tibetan dGe lugs pa school's synthesis of the Middle Way (Madhyamaka) and Epistemological (Pramanika) traditions of Indian Buddhism. In addition, it is an unprecedented source for the philosophical polemics of fifteenth century Tibet.