The communications between regions--the migrations and conquests, the trading and the borrowing of customs--must be traced and accounted for.

Finally, on the basis of their distribution, which the learner must chart out for himself on blank maps of the world, the chief varieties of the useful arts and appliances of man can be followed from stage to stage of their development.
Of the special studies concerned with man the next in order might seem to be that which deals with the various forms of human society; since, in a sense, social organization must depend directly on material circumstances.

In another and perhaps a deeper sense, however, the prime condition of true sociality is something else, namely, the exclusively human gift of articulate speech.

To what extent, then, must our novice pay attention to the history of language?
Speculation about its far-off origins is now-a-days rather out of fashion.

Moreover, language is no longer supposed to provide, by itself at any rate, and apart from other clues, a key to the endless riddles of racial descent.
What is most needed, then, is rather some elementary instruction concerning the organic connection between language and thought, and concerning their joint development as viewed against the background of the general development of society.