In this seminal work, Steiner lays out practical means of attaining metaphysical knowledge and mystical experience. "There slumber in every human being faculties by means of which he can acquire for himself a knowledge of higher worlds. Mystics, Gnostics, Theosophists — all speak of a world of soul and spirit which for them is just as real as the world we see with our physical eyes and touch with our physical hands. At every moment the listener may say to himself: that, of which they speak, I too can learn, if I develop within myself certain powers which today still slumber within me. There remains only one question — how to set to work to develop such faculties."