Keynes was a great economist. In every discipline, progress comes from people who make hypotheses, most of which turn out to be wrong, but all of which ultimately point to the right answer. Now Keynes, in 'The General Theory of Employment, Interest and Money,' set forth a hypothesis which was a beautiful one, and it really altered the shape of economics. But it turned out that it was a wrong hypothesis. That doesn't mean that he wasn't a great man!