This book, the substance of the doctrine of the most enlightened, most liberal, most truly catholic of the later Christian transcendentalists of the last decades of the 18th century, provides a clear introduction to the theosophical system of Louis Claude de Saint-Martin. He was popularly known as the "Unknown Philosopher" because none of his writings were published under his name during his lifetime. His fame is based on being a true mystic, on his literary abilities to express this true mysticism, and on his passionate search for higher wisdom. Saint-Martin's belief that "the most important problem of all human thinking is to understand man as a free personality, whose very foundation is himself," has an important and significant place in the history of modern man's struggle toward freedom.