"Keynes himself was very much interested in monetary policy. He was a specialist all his life in the theory of money and interest rates. But this approach fell out of fashion and people concentrated on fiscal policy. Then, when monetary policy came back into fashion, people concentrated on the money supply and other monetary aggregates, such as M1 and M2, rather than interest rates, but that was not the way to go about it. Fortunately, I think interest rate policy is more effective now."