Primitive man's belief in arbitrary power does not arise out of thin air, as was always supposed, but is grounded in experience. What we have always called his superstition is justified by the grouping of chance occurrences. There is a real measure of probability that unusual events will coincide in time and place. We must not forget that our experience is not fully to be trusted in this regard. Our observation is inadequate because our point of view leads us to overlook these matters.
