To a certain extent a clear enunciation of the elementary idea gives us the psychological reason for its existence. To exemplify: The fact that the land of shadows is so often placed in the west suggests its localization at the place where the sun and the stars vanish. The mere statement that primitive man considers the animals as gifted with all the qualities of man shows that the analogy between many of the qualities of animals and human qualities has led to the view that all the qualities of animals are human. In other cases the causes are not so self-evident; for example, in the instance of widespread customs of restrictions of marriage which have puzzled many investigators. The difficulty of this problem is proved by the multitude of hypotheses that have been invented to explain it in all its varied phases. The problem of the origin of elementary ideas has, however, been discussed from a psychological point of view; and the elaborate attempt by Wundt to work out a theory of folk-psychology, as well as the studies of psychological sociologists, indicate lines of attack of the problem. To illustrate this point, I may mention the general discussion of the function of association in the beliefs of primitive people, given by Wundt, or the study of suggestion and hypnotism in primitive life, made by Stoll. A more detailed discussion of this method of treatment of the common elementary ideas may be deferred until a later time (see Chapter VIII). ------------------------------------------------------------------------ VII. THE EVOLUTIONARY VIEWPOINT I HAVE pointed out before that some of the older authors, like Gobineau, Klemm, Carus, Nott and Gliddon, assume characteristic mental differences between the races of man; and these have been revived by the growth of modern nationalism, with its exaggerated self-admiration of the Teutonic race, its Pan-slavism, and similar symptoms developing in other parts of the world; but these views are not supported by the results of unbiassed research.