When differences of opinion have a positive effect. The mechanism of reciprocal concessions at the most recent European Council gave rise to a balance of commitments: no member state was able to secure what it held as a priority without in exchange having to concede something considered vital by its neighbour. The result is an overall, well-balanced step forward by the eurozone, even going beyond the expectations expressed the day before. I am talking of the eurozone and not of the EU as a...