Rudolf Steiner 
How to Know Higher Worlds 

There are in every one of us faculties by which we can develop for ourselves 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. You may say: that, of which they speak, I too can learn, if I develop within myself certain powers which lie within me. There remains only one question — how to set to work to develop such faculties. That is what this book is about.