The complementary systems of Nyaya and Vaisesika constitute one of the oldest and most important traditions within Indian philosophy. This volume offers a systematic and detailed exposition of the two schools from their beginning to the time of Gangesa (A.D. 150-1350). An extensive interpretive essay introduces summaries of most of the known works written within the tradition. The result is both an excellent introduction for students and an indispensable guide to the thought and literature of early Nyaya-Vaisesika. Originally published in 1978. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.