We can no longer do so, it is agreed, in the case of hypnotic phenomena. I hope to make it seem possible that we should not do so in the matter of the hallucinations provoked by gazing in a smooth deep, usually styled 'crystal-gazing.' Ethnologically, this practice is at least as old as classical times, and is of practically world-wide distribution. I shall prove its existence in Australia, New Zealand, North America, South America, Asia, Africa, Polynesia, and among the Incas, not to speak of the middle and recent European ages. The universal idea is that such visions may be 'clairvoyant.' To take a Polynesian case, 'resembling the Hawaiian _wai harru_.' When anyone has been robbed, the priest, after praying, has a hole dug in the floor of the house, and filled with water. Then he gazes into the water, 'over which the god is supposed to place the spirit of the thief.... The image of the thief was, according to their account, reflected in the water, and being perceived by the priest, he named the individual, or the parties.'[6] Here the statement about the 'spirit' is a mere savage philosophical explanation. But the fact that hallucinatory pictures can really be seen by a fair percentage of educated Europeans, in water, glass balls, and so forth, is now confirmed by frequent experiment, and accepted by opponents, 'non-mystical writers,' like Dr. Parish of Munich.[7] I shall bring evidence to suggest that the visions may correctly reflect, as it were, persons and places absolutely unknown to the gazer, and that they may even reveal details unknown to every one present. Such results among savages, or among the superstitious, would be, and are, explained by the theory of 'spirits.' Modern science has still to find an explanation consistent with recognised laws of nature, but 'spirits' we shall not invoke. In the same way I mean to examine all or most of the 'so-called mystical phenomena of savage life.' I then compare them with the better vouched for modern examples. To return to the question of evidence, I confess that I do not see how the adverse anthropologist, psychologist, or popular agnostic is to evade the following dilemma: To the anthropologist we say, 'The evidence we adduce is your own evidence, that of books of travel in all lands and countries. If _you_ may argue from it, so may we. Some of it is evidence to unusual facts, more of it is evidence to singular beliefs, which we think not necessarily without foundation. As raising a presumption in favour of that opinion, we cite examples in which savage observations of abnormal and once rejected facts, are now admitted by science to have a large residuum of truth, we argue that what is admitted in some cases may come to be admitted in more. No _a priori_ line can here be drawn.'