This book examines how mysticism can be distinguished from religion in general, and how its main types can be known. The author explores the biblical roots of Christian mysticism in the Gospel of John and in the Christ-mysticism which pervades Paul's letters. The author also interprets some of the great Christian devotional and mystical writers. These include the early and medieval mystics (St. Augustine, St. Bernard, and St. Francis), the Spanish mystics (Ignatius of Loyola, Teresa, and John of the Cross), the emergence of Protestant piety (Martin Luther, John Calvin, Jacob Boehme, Lancelot Andrewes, George Fox, William Law, and the Wesleys), and twentieth century mystics (Frank Laubach, Kagawa, Teilhard de Chardin, and Dag Hammarskjo?ld). The author also surveys more contemporary neo-mysticism, including the pseudo mysticism of the occult, the drug culture, Vedanta and Yoga, Zen Buddhism, celebration, the Jesus movement, and speaking in tongues.