" O.K., Lerner: His argument was that countries that (a) rely on fiat money they control and (b) don’t borrow in someone else’s currency don’t face any debt constraints, because they can always print money to service their debt. What they face, instead, is an inflation constraint: too much fiscal stimulus will cause an overheating economy. So their budget policies should be entirely focused on getting the level of aggregate demand right: the budget deficit should be big enough to produce full employment, but not so big as to produce inflationary overheating. "

― Paul Krugman , Arguing with Zombies: Economics, Politics, and the Fight for a Better Future