I am particularly interested in Rome, and most curiously, England. Also, is there a common, causal thread through the failure of all of the Great Empires in time? Middle Kingdom China, Assyria, Babylon, Egypt, Spartica Greece, Persia, Rome, Napoleonic France, England....America. Why do Empires burn out, wilt and fall? If you had to pick one, specific, greatest cause, what would it be? I claim that Empire is an unsustainable 'condition.' To be an Empire, a nation-state has to project power, thwart enemies, conquer and rule for its own necessities. An Empire has to cull, harvest, tax and impose its will and project its authority, whether by force or culture. Anything less, and the decay has already begun. An Empire is no longer an Empire the moment it loses forward momentum in its quest for growth of wealth and power. An Empire is, ipso facto, a predetermined period of time, whether 3,000 years, or 100.
I subscribe to the viral theory. The human race, by virtue if being the dominant, if not most "successful" species, behaves like a virus-overbreeding, destroying resources, until it collapses and starts again, in a different, or at least slightly different form. Empires, are simply the collective organism of the concept. A handful you mention, actually went broke from never ending warfare, simply overreaching-when the ability to SUSTAINABLY exploit conquered resources wasnt there. More importantly , there own land, of course. Most empires, may well have not just overreached militarily, but.......praying for rain isnt going to necessarily prevent a calamitous drought, any more than it could prevent new crop diseases, epidemics, or stop some white people you mistook for gods conquering your lands. In short, Empires are a non sustainable contagion, like the human race itself.