The peculiarity of savage beliefs is due, not to corrupt and clouded perception, but to the influence of desire and anxiety upon their imagination, unrestrained by self-criticism and reinforced by the popular consensus. The savage’s imagination is excited by the pressing needs of his life in hunting, love, war, agriculture, and therefore by hunger and emulation, hate and grief, fear and suspicion. Imaginations spring up in his mind by analogy with experience; but often by remote or absurd analogies; and there is no logic at hand and not enough common sense to distinguish the wildest imaginative analogies from trustworthy conclusions. The same pressing needs and the same emotional storms often affect a whole tribe, and simultaneously stimulate every one’s imagination; and originating (no doubt) in ancient times and slowly accumulating and condensing, there grows up a mass of public imagination-beliefs, which are inculcated into every individual by tradition and common ceremonies. Such beliefs embodied in stories and formulæ, and associated with rites and customs, have for a long time the strength of custom in governing the behaviour of individuals and in tribal respect; but they prove at last to be weaker than custom, inasmuch as the observances may continue whilst the beliefs are forgotten or replaced by others, as the progress of culture makes it necessary to think of the old rites in a different way. In their flourishing period they extensively influence practical affairs, sometimes helpfully or harmlessly, sometimes injuriously and disastrously. In general, imaginations are prevented by biological necessity from modifying a tribe’s conduct beyond certain limits; but, exceptionally, they result in tribal insanity, tending toward, if not accomplishing, the tribe’s destruction, as in extreme cases of the practice of human sacrifice or of the ordeal by poison.