The Ksanabhangasiddhi is a masterpiece of skillful reasoning by the eleventh-century Indian Buddhist philosopher Ratnakirti. This renowned scholar was a professor at the great Buddhist University of Vikrama??la, and was a master of practically all the classical philosophical schools which preceded him. The present work is informed by centuries of debate between Buddhist advocates of momentariness and arch-rival Nyaya philosophers who believed that both selves and things endure. This book is a first-time translation of Ratnakirti's proof based on positive correlations, and includes a commentary explaining each step of his reasoning.