The point here is that everybody agrees that the eurozone's economic institutions are, to say the least, suboptimal. Nobel laureate Chris Pissarides has written that the region "is clearly not satisfying" the conditions needed to make the single currency a success. And even European Commission President Jean-Claude Juncker has said that "our economic and monetary union remains incomplete".
Most economists agree that, if the currency is to succeed, it needs some mix of: closer banking union, with perhaps a eurozone-wide deposit insurance scheme; closer co-ordination of fiscal policy; better risk-sharing across member states; and some debt restructuring.
And yet despite the obvious inadequacies of its economic architecture, the eurozone economy is doing well, at least for now. There are at least three reasons for this:
■ Pent-up demand. Retail sales volumes were lower in 2015 than they were in 2007. This eight-year decline in spending means that a lot of consumer goods have become clapped out and need replacing. There's a reason why we speak of economic 'cycles'; it's because weakness eventually begets recovery - and rising replacement demand is one mechanism here.
■ An end to fiscal austerity. The OECD expects cyclically-adjusted government borrowing to increase slightly this year, having fallen by 4.6 per cent of GDP between 2010 and 2015. Demand is recovering for the same reason that a man takes deep breaths when you take your boot off his windpipe.
■ Less unhealthy banks. Bank lending to both firms and households is now growing, albeit slowly.
Of course, one quarter's growth might be just a statistical blip. Nevertheless, it is a reminder of a hugely comforting fact about developed economies - that their normal state is one of expansion, even in the face of inadequate policies.
If that sounds cheerful, there are two big caveats here. One is that the euro area is still afflicted by the same long-term troubles that are holding back growth in the UK and US: stagnant labour productivity and a reluctance of firms to invest, perhaps for more than merely cyclical reasons.
Secondly, there's a risk that better economic times will reduce politicians' incentives to take the difficult measures to fix the eurozone's institutions. The region might end up like the man with the permanently leaky roof: on sunny days he doesn't need to fix it and on rainy days he can't get on the roof to do so.
