The source of man’s superiority must be sought in an examination of his mental faculties, and yet the inquiry is vitiated at the very commencement, by the assumption that the mind of man differs from that of the animal only in the degree of its activity. I am prepared to admit that the higher mammalia, at least, have the power of reasoning, with all the faculties which are essential to its exercise. But this very fact makes it utterly incomprehensible how the result of human mental activity can be so superior, unless some further principle or faculty than those which the animal mind possesses operates in that of man. What this principle or faculty is, may be shown by reference to certain facts connected with language. Mr. Darwin ascribes the origin of human speech to imitation and modification of natural sounds and man’s own instinctive utterances.[376] That the primitive elements of man’s language were thus obtained is doubtless true. Something else, however, is required to explain the phenomena presented by the languages of uncultured peoples. Such, for instance, cannot have been the origin of certain ideas which are apparently common to the minds of all peoples however savage. It has been said that these peoples, although having names for every particular object, have no words to express a class of objects. This statement must be received with caution. But if absolutely true in the sense intended, it cannot be denied that nearly all primitive languages have words denoting colours, and these by their very nature, as expressive of attributes, are applicable to a series of objects.