10  The Role of Expectations in Monetary Policy: Evolution of Theories and the Bank of Japan's Experience Speech at the University of Oxford  June 8, 2017  Haruhiko Kuroda Governor of the Bank of Japan  Chart 1  Monetary Policy Discussions by Economists in the UK in the First Half of the 20th Century (1) John Maynard Keynes (1883-1946)  Liquidity trap “…after the rate of interest has fallen to a certain level, liquidity-preference may become virtually absolute in the sense that almost everyone prefers cash to holding a debt which yields so low a rate of interest.
In this event the monetary authority would have lost effective control over the rate of interest. But whilst this limiting case might become practically important in future, I know of no example of it hitherto.