Brad DeLong blogged Paul Krugman’s intro to the General Theory…

Stripped down, the conclusions of The General Theory might be expressed as four bullet points:

Economies can and often do suffer from an overall lack of demand, which leads to involuntary unemployment

The economy’s automatic tendency to correct shortfalls in demand, if it exists at all, operates slowly and painfully

Government policies to increase demand, by contrast, can reduce unemployment quickly

Sometimes increasing the money supply won’t be enough to persuade the private sector to spend more, and government spending must step into the breach

To a modern practitioner of economic policy, none of this – except, possibly, the last point – sounds startling or even especially controversial. But these ideas weren’t just radical when Keynes proposed them; they were very nearly unthinkable. And the great achievement of The General Theory was precisely to make them thinkable….