The cat is out of the bag. Now that Robert Zoellick, the president of the World Bank and a former senior official of the US Treasury, in Monday's Financial Times called for the G20 to move towards a "cooperative monetary system" and consider including in it a role for gold "as an international reference point of market expectations", perhaps we can have a reasoned debate rather than the mud-slinging that has usually been the response of mainstream economists to any suggestion of a renewed role