on are important primarily as factors in the
development of actual or possible inhabitants. A land is fully
comprehended only when studied in the light of its influence upon its
people, and a people cannot be understood apart from the field of its
activities. More than this, human activities are fully intelligible only
in relation to the various geographic conditions which have stimulated
them in different parts of the world. The principles of the evolution of
navigation, of agriculture, of trade, as also the theory of population,
can never reach their correct and final statement, unless the data for
the conclusions are drawn from every part of the world, and each fact
interpreted in the light of the local conditions whence it sprang.
Therefore anthropology, sociology and history should be permeated by
geography.

[Sidenote: Political geography and history.]

In history, the question of territory,--by which is meant mere area in
contrast to specific geographic conditions--has constantly come to the
front, because a state obviously involved land and boundaries, and
assumed as its chief function the defence and extension of these.
Therefore political geography developed early as an offshoot of history.
Political science has often formulated its principles without regard to
the geographic conditions of states, but as a matter of fact, the most
fruitful political policies of nations have almost invariably had a
geographic core. Witness the colonial policy of Holland, England, France
and Portugal, the free-trade policy of England, the militantism of
Germany, the whole complex question of European balance of power and the
Bosporus, and the Monroe Doctrine of the United States. Dividing lines
between political parties tend to follow approximately geographic lines
of cleavage; and these make themselves apparent at recurring intervals
of national upheaval, perhaps with, centuries between, like a submarine
volcanic rift. In England the southeastern plain and the northwestern
uplands have been repeatedly arrayed against each other, from the Roman
conquest which embraced the lowlands up to about the 500-foot contour
line,[79] through the War of the Roses and the Civil War,[80] to the
struggle for the repeal of the Corn Laws and the great Reform Bill of
1832.[81] Though the boundary lines have been only roughly the same and
each district has contained opponents of the dominant local party,
nevertheless the geographic core has been