No man, wrote the poet John Donne, is an island. No central bank can ever be, either. The European Central Bank has for too long interpreted its price stability mandate in a way that disavows any interest in or responsibility for the wider economic well-being of the eurozone. This must change.

The ECB is not the main cause of Europe's economic malaise. Its effectiveness is constrained by inflexible labour markets, weak public finances and underdeveloped retail financial markets. But it is part of the problem.