Of course, shedding the debt burden would be a happy development for our country, but it would nevertheless pose a big dilemma for the Fed. Our primary lever of monetary policy was buying and selling treasury securities-Uncle Sam's IOU's. But as the debt was paid down, those securities would grow scarce, leaving the Fed in need of a new set of assets to effect monetary policy.

Chapter Ten, "Downturn", p. 214. - The Age of Turbulence (2008)