Civilizations die from suicide, not by murder. - Arnold J. Toynbee

Civilizations, I believe, come to birth and proceed to grow by successfully responding to successive challenges. They break down and go to pieces if and when a challenge confronts them which they fail to meet.

If we take the antiquity of Man to be something like 300,000 years, then the antiquity of civilizations, so far from being coeval with human history, will be found to cover less than 2 percent of its present span: less than 6,000 years out of 300,000 . On this time-scale , the lives of our twenty-one civilizations-distributed over not more than three generations of societies and concentrated within less than one-fiftieth part of the lifetime of Mankind- must be regarded, on a philosophic view, as contemporary with one another.

A city that outdistances man's walking powers is a trap for man.