The build of the land-masses influences fundamentally the movements and hence the development of the races who inhabit them.  A simple continental structure gives to those movements a few simple features and a wide monotonous distribution which checks differentiation.  A manifold, complex build, varied in relief and ragged in contour, breaks up the moving streams of peoples, turns each branch into a different channel, lends it a distinctive character through isolation, finally brings it up in a cul de sac formed by a peninsula or mountain-rimmed basin, where further movement is checked and the process of local individualization begins.  Therefore great simplicity of continental build may result in historical poverty, as in the flat quadrangle of European Russia, the level plateau of Africa, and the smooth Atlantic slope of North America, with its neatly trimmed outline.  Complexity, abounding in contrasted environments, tends to produce a varied wealth of historical development.  Africa lies on the surface of the ocean, a huge torso of a continent, headless, memberless, inert.  Here is no diversity of outward form, no contrast of zonal location, no fructifying variety of geographic conditions.  Humanity has forgotten to grow in its stationary soil.  Only where the Suez Isthmus formed an umbilical cord uniting ancient Egypt to the mother continent of Asia was Africa vitalized by the pulse of another life.  European influences penetrated little beyond the northern coast.

Asia, on the other hand, radiating great peninsulas, festooned with islands, supporting the vast corrugations of its highlands and lowlands, its snow-capped mountains and steaming valleys, stretching from the Equator through all the zones to the ice-blocked shores of the Arctic, knowing drought and deluge, tundra waste and teeming jungle, has offered the manifold environment and segregated areas for individualized civilizations, which have produced such far-reaching historical results.  The same fact is true of Europe, and that in an intensified degree.  Here a complex development of mountains and highlands built on diverse axes, peninsulas which comprise 27 per cent. and Islands which comprise nearly 8 per cent. of the total area,[772] vast thalassic inlets cleaving the continent to the core, have provided an abundance of those naturally defined regions which serve as cradles of civilization and, reacting upon the continent as a whole, endow it with lasting historical significance.[773] Even Strabo saw this.  He begins his description of the inhabited world with Europe, because, as he says, it has such a “polymorphous formation” and is the region most favorable to the mental and social ennoblement of man.[774]

[Sidenote:  Structure of North and South America.]