Tantrism is often represented as somehow disconnected from mainstream Buddhist traditions, sometimes even considered non-Buddhistic, often called "decadent" or worse. Cleary's commentary is exceptional in the clarity with which he documents the spiritual connection of Tantric Buddhism with Theravada and Mahayana Buddhism. Partic-ularly noteworthy is his demonstration of the parallels between original Tantric Buddhism in Bengal and the original Zen Buddhism of China. The treatment of sensuality in the Tantric context, often a subject of distortion and controversy, is noteworthy for its exceptional subtlety and dignity. Symbolic, psychological, and physical aspects of the Tantric teachings are illuminated on a continuum coinciding with the spiritual development of Buddhism.
Cleary's introduction also includes little-known information about the history of world Buddhism and the spiritual continuity of the succession of the main phases of its development. He gives a panoramic view of the network of Buddhism linking Bengal, Indonesia, India, Afghanistan, Tibet, China, and Japan, and illustrates the concrete historical transcendence of pan-Buddhism over political and cultural borders. This global vision is particularly important today for the effective integration of traditional values into modern consciousness.