Even in civilised communities it is extraordinary with what facility suggestive sense-delusions can be produced in waking persons. At least ninety out of every hundred individuals can be persuaded thus to deceive themselves. The extreme contagiousness of such delusions, common enough in civilised conditions, is greatly increased in the savage state. In their lives the phenomena of auto-suggestion are strikingly frequent. Among the African Zulus any adult can cast himself or herself into the hypnotic state, and by this obtain what they consider second sight,—“the power to see where lost objects are, and how absent friends are occupied.” When asked to explain this state of mind, they can only say that it is one “in which a man is awake, but sees things which he would not see, if he were not in this state”[44]; which reminds us of the remarkable doctrine of the Sanscrit Upanishads—“There is no limit to the knowing of the Self that knows.”[45] Among many Australian tribes, among the Kamschatkans, and among the Yahgans of Tierra del Fuego, as well as many other peoples, the mysterious power of the shamans or medicine men is shared by all adults in a greater or less degree.[46] These are at the bottom of the scale. One degree higher, and we find the priesthood a separate class, usually of both sexes, but chosen by natural selection from those members of the community who by temperament or cultivation possess in the highest degree this tendency to mystical power. This is generally indicated by the clearness and character of the dreams and visions which appear at the time he or she enters adult life. These are considered to be direct inspirations from the spirit world, either from the souls of the dead, or the powers other than those which control the destiny of man. These inspired seers represent the priesthood of every primitive religion. They cultivate and preserve it, and in them the missionaries of higher faiths have ever found their most resolute foes and successful opponents. The reason is, as I have said, that the shaman has himself been face to face with God, has heard His voice, and felt His presence. His faith therefore is real, and cannot be shaken by any argument. He may indeed, and he generally does, assist his public performances with some trickery, some thaumaturgy; but that this is merely superadded for effect is proved by the general custom that when one such adept is ill or in straits he will solicit the aid of another.[47] Among his associates he is looked upon as set apart from other men by the divinity which chooses him for its agent, or dwells within him. In the Polynesian islands this is forcibly expressed in the terms applied to the native priests, _pia atua_, “god boxes,” receptacles of divinity; and _amama_, “open mouths,” for through them the god speaks, not their own selves.[48]