This book is an adventure into the unexplored territory of French esoteric philosophies and their relation to music. Occultism and esotericism flourished in nineteenth-century France as they did nowhere else. Many philosophers sought the key to the universe, some claimed to have found it, and, in the unitive vision that resulted, music invariably played an important part. These modern Pythagoreans all believed in the Harmony of the Spheres and in the powerful effects of music on the human soul and body.

Faced with the challenge of the rationalist Enlightenment, then with that of modern scientism, they adapted their occultism to the prevailing style.

A widely published musicologist and authority on esotericism, Godwin is able to give a clear and concise context for these philosophers' often surprising beliefs, and he demonstrates how this "speculative music" influenced composers such as Satie and Debussy, who were familiar with occultism. His long study of music and the Western esoteric tradition makes him uniquely qualified to unravel the strange story of these forgotten sages.