dialect becomes the common tongue of all. Thus the Latin swept away the primitive tongues of a great part of southern and central Europe, and has become mingled with the speech of all civilized nations, in the Old world and the New. But we are not rashly to infer that such things have happened over and over again in the history of the world. We have rather to inquire what influences make possible a career like that of the Latin, what lends the predominant and assimilating force to a single element where many are combined. And, as was pointed out in the fourth lecture, we shall find that only superior culture and the possession of a literature can give to any tongue such great extensibility. The Persians, the Mongols, have at one period and another exercised sway over an empire not less extensive than the Roman, but their languages were never spread far beyond the limits of the peoples to which they properly belonged. The German tribes, too, conquered in succession nearly every kingdom of Europe; but it was only in order to lose themselves and their dialects together, almost undiscoverably, in the communities and languages into which they entered. Nay, even the wide-spread Greek colonies, with the superiority of Greek culture to aid them, were not able to make the Greek the tongue of many nations. There was an organizing and assimilating force in Roman dominion which the world has nowhere else seen equalled. And if the career of the Arabic furnishes something like a parallel to that of the Latin, it is due, not to the sword of Islam, but to the book, and to the doctrine and polity which the book enjoined and the sword imposed. Since, then, such movements must be connected with culture and literature, they cannot but leave their record in written history, and find there their explanation. Nor could there occur in every region or in every period such an inpouring and assimilation of nationalities as is now going on among us; it is only possible under the conditions of civilized life in the nineteenth century, and the historical conditions which have been created here. The wild and uncultivated races of the earth generally are simply maintaining themselves by growth from generation to generation, taking in no immigrants, sending out no emigrants. Culture
