Custom has not commonly been regarded as a subject of any great moment. The inner workings of our own brains we feel to be uniquely worthy of investigation. As a matter of fact,it is the other way around. Traditional custom, taken the world over, is a mass of detailed behavior more astonishing than what any one person can ever evolve in individual actions, no matter how aberrant. Yet that is a rather trivial aspect of the matter. The fact of first-rate importance is the predominant role that custom plays in experience and in belief, and the very great varieties it may manifest.