He might be the grandfather of activist government, but Keynes also said, in effect, that you should never think you have it covered, that you've abolished boom and bust.

BBC: Masters of money: John Maynard Keynes

This, in effect, is the argument that Hayek made against Keynes in the late 1920s and 1930s: he said the Fed caused the crash, by keeping interest rates too low and encouraging a lot of "malinvestment" - investment in projects or assets which were not economically worthwhile.

BBC: Masters of Money: Friedrich Hayek