to segregation is paramount; local and clannish feeling prevails, stifling the growth of any wider and nobler sense of national unity and common interests; each little tribe or section is jealous of and dreads the rest; the struggle for existence arrays them in hostility against each other; or, at the best, the means of constant and thorough communication among individuals of the different parts of the country is wanting, along with the feelings which should impel to it. Thus all the diversifying tendencies are left to run their course unchecked; varieties of circumstance and experience, the subtler and more indirect influences of climate and mode of life, the yet more undefinable agencies which have their root in individual and national caprice, gradually accumulate their discordant effects about separate centres, and local varieties of speech arise, which grow into dialects, and these into distinct and, finally, widely dissimilar languages. The rate at which this separation will go on depends, of course, in no small degree, upon the general rate of change of the common speech; as the dialects can only become different by growing apart, a sluggishness of growth will keep them longer together—and that, not by its direct operation alone, but also by giving the weak forces of an imperfect and scanty communication opportunity to work more effectively in counteraction of the others. Thus all the influences which have already been referred to as restricting the variation of a language from generation to generation are, as such, equally effective in checking its variation from portion to portion of a people. But the most important of them also contribute to the same result in another way, by directly strengthening and extending the bonds of community. Culture and enlightenment give a wonderful cohesive force; they render possible a wide political unity, maintenance of the same institutions, government under the same laws; they facilitate community of memories and traditions, and foster national feeling; they create the wants and tastes which lead the people of different regions to mix with and aid one another, and they furnish the means of ready and frequent intercourse: all of which make powerfully for linguistic unity also. A tra-
