One can often hear echoes of the stern old German Bundesbank in European Central Bank pronouncements. Jean-Claude Trichet, interviewed on Monday in the Financial Times, showed prudent resolve in standing up for the fiscal rules that support the monetary authority that he oversees. The French ECB president, however, also hinted helpfully that there was space for a German stimulus package.

The eurozone is a unique political achievement. Monetary union brought 11, now 15, sovereign countries, with as many different political cultures, into one currency area without creating a central fiscal policy authority. Policy co-ordination relies on debt rules set out in the stability and growth pact.