Three years ago, the euro risked exploding under pressure from the markets. After considerable tensions, Europe’s political leaders pulled together to avoid a crisis. The European Central Bank found the measures they took convincing enough to justify offering support of its own.

Today, amid quiet markets, it may be governments that are undermining the euro. The French president, the German chancellor and the Italian prime minister have not refrained from mutual recriminations.

Even when couched in diplomatic terms, these reveal differences of policy and, more deeply, of national cultures. Such differences need to be handled responsibly, not exploited between one summit and the next. That will only benefit the populists. If the EU is to remain a harmonious community, two things must happen: the rules must be complied with, we must have more growth. We will either achieve both or neither.