Dorous Fi Al Tareekh | Will Durant

Civilizations are buried under the sand only because there is not enough rain, as happened in Central Asia, or they are submerged in forests if there is too much rain, as happened in Central America. If the temperature rises twenty degrees, our prosperous region will relapse into a state of primitiveness and idleness. In a subtropical climate, a nation of half a million people could breed like ants, but its atmosphere of laziness might make it subject to frequent occupation by warriors from other, more stimulating environments. Generations may be able to establish control over the land, but in the end it is destined to turn into fossils beneath its surface.