This book covers in detail all the important topics of spiritual life. They concern not only Christian mysticism, but also the esoteric traditions of other religions, the development of modern natural science and the achievements of transpersonal psychology. The book describes in detail the psychological aspects of the inner path, its deep structures and stages, the technique of contemplation, dealing with feelings, the transformation of the shadow and the meaning of depression into process of transformation. Messages from people who began their inner, contemplative path together with Father Willigs testify to the transformative power of mystical knowledge and point to the change that can open up in every person.