"Keynes was aware of the differences that exist between the social and natural sciences. He was a man of great intellect but of a rather limited knowledge of economic theory. When I had the opportunity of discussing economists with him, I was taken aback when many surprising gaps in his knowledge appeared. He had not read Ricardo's work carefully, for instance. The theory guiding monetary and financial policy in many countries over the last thirty years is based on Keynesian ideas, and it is based on the assertion that there is a simple positive correlation between total employment and the size of aggregate demand for goods and services. This has led to the false belief that we can permanently assure full employment by maintaining the total money expenditure at an appropriate level. This Keynesian doctrine has caused great harm and is responsible, to a great extent, for the problems the international economy has experienced in the seventies."