Martin Wolf quotes Marco Annunziata (hat tip: Felix Salmon):

European orthodoxy is that the crisis is, at root, fiscal. Marco Annunziata of UniCredit summarises it in a recent note: “In hindsight, it seems obvious that the flaw in the eurozone’s institutional setup is both extremely serious and extremely simple: first, a currency union cannot work without sufficient fiscal convergence or integration; second, the eurozone has been unable to create incentives for fiscal discipline.”

It didn’t really need hindsight to see this. And it shouldn’t require hindsight to see that fiscal integration will eventually be unacceptable to nations that are suffering. The political integration that all this other integration implies, however, will mean that these nations will have no outlet for their frustrations. It’s not hard to imagine serious violence in Europe, with “No taxation without representation” as the battle cry, as a result, if not of this crisis, of some future one. The problem is, it might not happen this decade, or next. When it does happen, everybody will think European integration has been a success, and be just as surprised as they are today about the woes of the euro.