History says that lead piping was the reason for the decline of the Grecian Empire. And with that analogy, the textbooks of past times produce a reason to explain the fall of each empire.
Today's World is starting to mutate, at least from a social standpoint. Whether that's bad or good, time will tell.
My question to you all, is what will become of future empires? I quess the U.S. and China are the two powerhouses now, but resources are scattered across our planet, especially in the Yukon Territory of Canada and obviously in Africa.