The crisis and recession have led to very low interest rates, it is true, but these events have also destroyed jobs, hamstrung economic growth and led to sharp declines in the values of many homes and businesses.

Inflation is certainly low and stable and, measured in unemployment and labour-market slack, the economy has made a lot of progress. The pace of growth is disappointingly slow, mostly because productivity growth has been very slow, which is not really something amenable to monetary policy. It comes from changes in technology, changes in worker skills and a variety of other things, but not monetary policy, in particular.

Monetary policy is not a panacea.

The best approach here, if at all possible, is to use supervisory and regulatory methods to restrain undue risk-taking and to make sure the system is resilient in case an asset-price bubble bursts in the future.

A collapse in U.S. stock prices certainly would cause a lot of white knuckles on Wall Street. But what effect would it have on the broader U.S. economy? If Wall Street crashes, does Main Street follow? Not necessarily.

In the future, my communications with the public and with the markets will be entirely through regular and formal channels.

September and October of 2008 was the worst financial crisis in global history, including the Great Depression.