The second point of difference between the expansion of peoples and of states lies in their respective relation to the political frontier.  This confines the state like a stockade, fixing the territorial limits of its administrative functions; but for the subjects of the state it is an imaginary line, powerless to check the range of their activities, except when a military or tariff war is going on.  The state boundary, if it coincides with a strong natural barrier, may for decades or even centuries succeed in confining a growing people, if these, by intelligent economy, increase the productivity of the soil whose area they are unable to extend.  Yet the time comes even for these when they must break through the barriers and secure more land, either by foreign conquest or colonization.  The classic example of the confinement of a people within its political boundaries is the long isolation of Japan from 1624 to 1854.  The pent-up forces there accumulated, in a population which had doubled itself in the interval and which by hard schooling was made receptive to every improved economic method, manifest themselves in the insistent demand for more land which has permeated all the recent policy of Japan.  But the history of Japan is exceptional.  The rule is that the growing people slowly but continually overflow their political boundary, which then advances to cover the successive flood plains of the national inundation, or yet farther to anticipate the next rise.  This has been the history of Germany in its progress eastward across the Elbe, the Oder, the Vistula and the Niemen.  The dream of a greater empire embraces all the German-speaking people from Switzerland, Tyrol and Steiermark to those outlying groups in the Baltic provinces of Russia and the related offshoot in Holland.[314] [See map page 223.]

Though political boundaries, especially where they coincide with natural barriers, may restrict the territorial growth of a people, on the other hand, political expansion is always a stimulus to racial expansion, because it opens up more land and makes the conditions of life easier for an increasing people, by relieving congestion in the older areas.  More than this, it materially aids while guiding and focusing the out-going streams of population.  Thus it keeps them concentrated for the reinforcement of the nation in the form of colonies, and tends to reduce the political evil of indiscriminate emigration, by which the streams are dissipated and diverted to strengthen other nations.  Witness the active internal colonization practiced by Germany in her Polish territory,[315] by Russia in Siberia, in an effort to make the ethnic boundary hurry after and overtake the political frontier.

[Sidenote:  Expansion of civilization.]