It has become something of a mantra among European leaders that we can be sure they will save the euro because they have to save the European Union. You can see where they are coming from. European integration would struggle to survive the demise of its flagship project.

The assertion, however, misses something rather important about the causality. The reason the single currency is in such terrible trouble is that governments across Europe have failed to persuade electorates that the EU itself is worth saving.

I have given up counting the erudite commentaries I have read about the future of monetary union – or the absence of one. Some say the crisis could be resolved at a stroke by the issue of eurozone bonds. Timothy Geithner, the US Treasury secretary, has come up with a wheeze that would allow governments to leverage their financial firepower.