But, while at that stage of the crisis no one could have complained about Bernanke's actions, his vocabulary would probably have annoyed Friedman, who waged a war of words against most other economists (and not a few non-economists), with an insistence that what mattered was "money", not "credit". He repudiated the claim that bank-lending was important to expenditure by pointing out that a money balance could be spent many times, whereas a loan financed a purchase only once. 

In early 2009, Bernanke wanted market participants to know that his objective was not to raise the quantity of money. When commentators referred to the Fed's asset purchases as quantitative easing, Bernanke tried to correct them by saying that they should instead be described as credit easing. The emphasis on credit had its roots in Bernanke's academic work, where he had devised a "credit channel" approach to monetary economics. In this approach, little or no attention is paid to the quantity of money and outright sneers are directed at so-called "broadly-defined measures of money". Broadly-defined money includes all or nearly all bank deposits, with M2 as a leading example.

As 2009 has gone by, it has become increasingly clear that Bernanke is not interested in the quantity of money on any definition. To the extent that he relates practice and theory, his focus is on the credit variables of which he was so fond in his academic work. The nearest contemporary analogue to the quantity of money in Monetary History is actually the very broad measure, M3. The Fed stopped publishing M3 numbers in 2006. But since then, independent analysts at the research firm, Shadow Government Statistics, have put together a private M3 series. 

The latest M3 numbers are a horror story. In late 2008 and early 2009, this measure of money continued to grow, but since June M3 has started to fall. The rate of decline has not been as extreme as in the Great Depression (typically about one per cent a month), but it has been at about half of one per cent a month. Has Bernanke broken his promise to Friedman? Will recession and deflation persist in the world's largest economy? This year will be interesting for the American economy and the commentators who debate its ever-changing fortunes.