Consider the Roman Empire, so vast and “eternal.” At least it would have seemed eternal to a Roman citizen living in it. At its height it stretched from Scotland to North Africa, from the Atlantic Ocean to Iraq. Imagine yourself as a Roman citizen living in the year 200 A.D. You would have considered the Roman Empire (your empire) to be something that would last forever. It had already lasted 600 years, and in fact it would continue on in one form or another for another 1200 years. It was all you had ever known. You would not be able to conceive of a day when the empire no longer existed. It was the world’s first superpower. It was militarily dominant. It exported its art, culture, and values to most of the known world. No one could remember the last time they ever lost a war. They even survived some incredibly bad emperors. I am talking: Nero, Domitian, Caligula, etc. These guys should not even have been allowed to run a tavern, let alone an empire. Yet even with these incompe...