Zen is not a religion of God. Nor a religion of faith. It is a religion of emptiness, a religion of absolute nothingness. However, it is not nihilistic but dynamically positive. For Zen is based on self-awakening, awakening to the self. In this book, the author tries to clarify the true meaning of Buddhist emptiness in comparison with the Aristotelian notion of substance and the Whiteheadean notion of process. He also emphasizes that Buddhism completely defies and overcomes dualism. Yet the Buddhist philosophy of religion is not monistic, but rather nondualistic. What is the meaning of 'nondualism'? This book examines this issue from a variety of comparative philosophical perspectives.