This precious book stands next to Blavatsky’s *The Secret Doctrine* (1888) as one of the most important spiritual books of recent centuries. First published in 1931, at a time when charlatans and fortune-seekers were rapidly expanding their efforts to mislead humanity through mischievous spiritual teachings, this mysterious book by an “anonymous” author opened the doors for sincere seekers to real spirituality. He explains how proper management of our psychological and physical energies brings us into harmony with the divine. His message is at once scientific and mystical, intuitive and concrete, and completely in harmony with the scriptures of every religion. Although the author “M” could not state explicitly what was destined to be fully revealed beginning in 1950 by Samael Aun Weor, when illuminated by the light of the ancient Gnostic teachings, the wisdom of this book can truly be understood and valued. It provides a deep yet easy to understand explanation of how our bodies and minds relate to nature and to the superior levels of existence, and what we must do if we long to escape the suffering in our lives. This book is great for readers of all levels: inviting to the beginner, clarifying for the reader familiar with the teachings, and deeply insightful for the experienced aspirant.—Glorian