770 THE AMERICAN JOURNAL OF SOCIOLOGY
strong foreign authority. It is always despotism which makes up for the differences within a state as well as between nations. There is, however, nothing more frail than the social or intersocial tie of military force. The empire of Alexander did not survive its founder; new political frontiers were formed by its dissolution. But Greek civilization continued nevertheless to embrace regions that were farther extended than those of former Greece.
SECTION VI. THE ROMAN WORLD
Geographically, Latium is the plain between the Tiber and the sea, the Alban Mountains and the foothills of the Apennines. It is the primitive territory, or Ager Romanus, equally distant from the Great Etruscan civilization and the already civilized tribes of southern Italy. Here at a certain period adventurers, at the same time bandits and colonists, settled, who were least adapted to the regular existence of more advanced societies and constituted a real military frontier in contact with other military societies : ^guians, Volscians, Sabines, Samnites, etc. This military frontier existed thus at the Ixmndaries of nations of different origin : toward the north the Etruscans and Ligurians; Italianized Aryans, Greeks, and Phoenicians in the south. This military frontier, with Rome as its center, was destined to become the natural nucleus of a new empire and to impress, according to the social development, its military character upon the economic, moral, and juridic structure of this empire.
Rome, the center of this frontier, is driven in like a hard wedge between the north and the south of Italy, already more plastic, and subdues them gradually. Since 270 B. C. all of Italy is Roman as far as the Rubies and the Arno. Thereupon the frontier is constantly moved forward. Sicily is conquered, Corsica and Sardinia are annexed ; the Gauls are repelled to the other bank of the Po; the Ligurians are exterminated, and their remnants are transported into Samnium. The Roman frontier touches the Alps. This natural frontier is transgressed; for the social forces, in their evolution, ignore and pass over these pre- bended boundaries.
From 143 to 95 the first invasion of the northern valleys of the Alps takes place. In these mountains the rivers have their
