Ancient Mystic Rites by C.W. Leadbeater is a Theosophical study linking modern Freemasonry to ancient mystery schools in Egypt, Greece, and medieval Europe. It explores the esoteric, occult, and spiritual origins of ceremonial rituals, blending clairvoyant investigation with the history of initiatory societies. The book is often considered a classic text for those interested in the spiritual or esoteric interpretation of Freemasonry rather than its historical or operative origins.