he far-away periphery reacts upon the center to vivify and
rejuvenate it.

[Sidenote: Relation of ethnic to political expansion.]

The laws of the territorial growth of peoples and of states are in
general the same. The main differences between the two lies in the fact
that ethnic expansion, since it depends upon natural increase, is slow,
steady, and among civilized peoples is subject to slight fluctuations;
while the frontiers of a state, after a long period of permanence, can
suddenly be advanced by conquest far beyond the ethnic boundaries,
often, however, only to be as quickly lost again. Therefore the
important law may be laid down, that the more closely the territorial
growth of a state keeps pace with that of its people, and the more
nearly the political area coincides with the ethnic, the greater is the
strength and stability of the state. This is the explanation of the
vigor and permanence of the early English colonies in America. The slow
westward protrusion of their frontier of continuous settlement within
the boundaries of the Allegheny Mountains formed a marked contrast to
the wide sweep of French voyageur camp and lonely trading-station in the
Canadian forests, and even more to the handful of priests and soldiers
who for three centuries kept an unsteady hold upon the Spanish empire in
the Western Hemisphere. The political advance of the United States
across the continent from the Alleghenies to the Mississippi, thence to
the Rocky Mountains, and thence to the Pacific was always preceded by
bands of enterprising settlers, who planted themselves beyond the
frontier and beckoned to the flag to follow. The great empires of
antiquity were enlarged mechanically by conquest and annexation. They
were mosaics, not growths. The cohesive power of a common ethnic bond
was lacking; so was the modern substitute for this to be found in close
economic interdependence maintained by improved methods of
communication. Hence these empires soon broke up again along lines of
old geographic and ethnic cleavage. For Rome, the cementing power of the
Mediterranean and the fairly unified civilization which this enclosed
sea had been evolving since the dawn of Cretan and Phoenician trade,
compensated in part for the lack of common speech and national ideals
throughout the political domain. But the Empire proved in the end to be
merely a mosaic, easily broken.

[Sidenote: Relation of people and state to political boundary.]

The