Rudolf Steiner shows, by means of mystical knowledge, how the source of Christianity prepared its own ground in the mysteries of pre-Christian times. In this pre-Christian mysticism, we find the soil in which Christianity grew, as a seed of independent nature. Steiner makes it possible to understand Christianity as an independent being, while traced from pre-Christian mysticism. This book is intended to show that Christianity presupposes the earlier mysticism, just as a seed must have its soil. It is intended to emphasise the peculiar character of the essence of Christianity, through the knowledge of its evolution.