Monetary union in Europe was not a pathway to more efficient markets but, at least in part, a dirigiste attempt to rein them in. The untidiness of Europe’s old foreign-exchange markets must have outraged Brussels’s central planners, but their fluctuations acted as invaluable warning signals to investors and lenders of trouble to come and, in the shape of a currency crisis or two, gave miscreant governments a powerful incentive to take away the punch bowl before it was too late.