This explains, also, why the information in this book concerning the present and the future is given in the merest outline as compared with the more detailed descriptions of the evolution of the world and of humanity in the past. What is said here is not intended to appeal to the love of sensation in the smallest degree; not even to awaken it. We shall only state where the answer can be found to vital questions which naturally present themselves to one who holds a certain definite attitude of mind. Just as the great cosmic evolution can be portrayed in the successive states, from the Saturn to the Vulcan period, so also is this possible for shorter periods of time; for example, for those of the evolution of the earth. Since that mighty upheaval which terminated the ancient Atlantean life, successive periods of human evolution have followed one another which have been called in this work the ancient Indian, the ancient Persian, the Egypto-Chaldean, and the Greco-Roman. The fifth period is that in which humanity finds itself to-day,—it is the present time. This period gradually took its rise in the eleventh, twelfth, and thirteen centuries A.D., after a period of preparation commencing in the fourth and fifth centuries. The Greco-Roman period preceding it began about the eighth century B.C. When one-third of this period had elapsed, the Christ-event took place. During the transition from the Egypto-Chaldean to the Greco-Roman period, the attitude of the human mind and, indeed, all human faculties, underwent a change. In the first of these two periods what we now know as logical thinking, as a mere intellectual concept of the world, was still wanting. The knowledge which a man now acquires through his intelligence, he then gained in a manner suited to that time,—directly through an inner, in a certain sense, clairvoyant cognition. He perceived the things around him, and while perceiving them there arose within his soul the percept, the image that was needed. Whenever knowledge is gained in this way, not only pictures of the physical sense-world come to light, but from the depths of consciousness a certain knowledge of facts and beings arises which are not of the physical world. This was a remnant of the ancient dim clairvoyance, once the common property of the whole of humanity.