ABSTRACT
‘What do we know about Macroeconomics that Fisher and Wicksell did not?’ asked Oliver Blanchard in the year 2000 in an overview article published in the QJE. I am so bold as to ask a quite opposite question: What did Keynes know that modern macroeconomic theory does not? To discuss this, the first question to clarify is: what is modern macroeconomic theory? In a second step I try to identify what Keynes has contributed to macroeconomics, and the last issue is to compare his contributions to the received wisdom of modern macroeconomic theory.
