Volume 1, The Physical World, explores the nature of our material world—from the macroscopic to the microscopic. It begins with an overview of the many frameworks, such as the so-called five aggregates, that Buddhist thinkers have used to examine the nature and scope of reality. Topics include sources of knowledge, the scope of reason, the nature and constituents of the material world, theories of the atom, the nature of time, the formation of the universe, and the evolution of life, including a detailed explanation of the early Buddhist theories on fetal development. The volume even contains a brief presentation on early theories about the structure and function of the brain and the role of microorganisms inside the human body. The book weaves together passages from the works of great Buddhist thinkers like Asanga, Vasubandhu, Nagarjuna, Dignaga, and Dharmakirti. Each of the major topics is introduced by Thupten Jinpa, the Dalai Lama’s principal English-language translator and founder of the Institute of Tibetan Classics.