Note 226 — Chapter IV · —The Movements Of Peoples In Their Geographical Significance

Historical development advances by means of differentiation and assimilation. A change of environment stimulates variation. Primitive culture is loath to change; its inertia is deep-seated. Only a sharp prod will start it moving or accelerate its speed; such a prod is found in new geographic conditions or new social contacts. Divergence in a segregated spot may be overdone. Progress crawls among a people too long isolated, though incipient civilization thrives for a time in seclusion. But in general, accessibility, exposure to some measure of ethnic amalgamation and social contact is essential to sustained progress.226 As the world has become more closely populated and means of communication have improved, geographical segregation is increasingly rare. The earth has lost its "corners." All parts are being drawn into the circle of intercourse. Therefore differentiation, the first effect of the historical movement, abates; the second effect, assimilation, takes the lead.