The history of the rise and fall of powerful nations offers a lesson that Americans today must not ignore: Great powers are rarely brought down by outside adversaries; they destroy themselves from within. Very often, they do it by falling victim to economic imbalances and the decay of once-vibrant governing institutions that prove unable to adapt to changing circumstances. 

The pattern has repeated itself with remarkable regularity. In examples as disparate as the demise of the Roman Empire, the decline of imperial Spain, the fall of the Ottoman Empire, and Britain's loss of global power, we find a common story: As political institutions fail to keep up with economic changes, elites respond by concentrating political power, increasing public spending, and eventually taking on an unbearable burden of debt that brings down the entire system. If America's global economic power comes to an end in our lifetime, it will surely result from a loss of fiscal balance that forces the nation down this well-worn path. The subtle signals we have already received — a minor credit warning from Moody's, acrimonious political fights over the debt ceiling — confirm that trouble is coming.

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