Anyhow, the phenomena of clairvoyance, studied from every aspect by present-day savants and doctors, throw an altogether new light on the _rôle_ of divination in antiquity and on a host of apparently supernatural phenomena, with which the annals of every nation and people are filled. Of course, a distinction must be made between legend and history, hallucination and real vision. Still, the experimental psychology of our times teaches us not to reject, in a body, facts which fall within human possibility, but rather to investigate them from the point of view of well-ascertained laws. If clairvoyance is a faculty of the soul, we may no longer simply consign prophets, oracles, and sybils to the domain of superstition. Divination has really been known and practised in temples of old, with fixed principles and a social and religious end in view. The comparative study of religions and esoteric traditions shows that these principles were the same everywhere, although their application may have varied infinitely. What has discredited the art of divination is that its corruption has given rise to the worst abuses, and that its glorious manifestations are possible only in beings of exceptional purity. Divination, as practised at Delphi, was founded on the principles we have just set forth, the inner organization of the temple corresponded thereto. As in the great temples of Egypt, it consisted of an art and a science. The art consisted in penetrating the far-away past and future by clairvoyance or prophetic ecstasy; the science, in calculating the future in accordance with the laws of universal evolution. Art and science checked one another. All I will say of this science, called genethlialogy by the ancients, and of which the astrology of the middle ages is only an imperfectly understood fragment, is that it took for granted the esoteric encyclopedia as applied to the future of peoples and individuals. Though very useful in showing the direction things were taking, it was always of very doubtful application. Only the very loftiest minds knew how to use it. Pythagoras had thoroughly mastered it in Egypt, but in Greece it was practised with a less thorough or clear understanding. On the other hand, clairvoyance and prophecy had made considerable progress.