CENTRAL bankers ordinarily strive to be boring. But these are not ordinary times. On December 16th the Federal Reserve unveiled a three-part assault on America’s slump that lit up the news wires like a pyrotechnic display. The Fed’s policy panel, the Federal Open Market Committee (FOMC), announced that it had cut its target for the federal funds rate to between zero and 0.25%, the lowest on record; it indicated it would stay there “for some time”; and having used up its conventional monetary firepower, it promised an unconventional strategy, such as the buying of mortgage-related securities and, possibly, Treasuries to lower long-term borrowing costs.