So why did this customarily prudent chancellor do it? Because she is a German, and to be German is to carry a special responsibility for those terrorized in their homeland and forced into flight. Because she once lived in a country, East Germany, that shot people who tried to cross its border. Because a united Europe ushered Germany from its darkest hour to prosperity, and she is not about to let the European Union pitch into mayhem on her watch — as it would with more than a million ragged refugees adrift. And, yes, because she has a heart.

Merkel did the right thing. The question now is how she handles the consequences. Management involves setting limits. After taking in more than one million refugees last year, Germany cannot take in that number again in 2016. As Germany’s president, Joachim Gauck, said recently: “A limitation strategy may even be both morally and politically necessary in order to preserve the state’s ability to function.” He added, “If democrats refuse to talk about limits, they leave the field open to populists and xenophobes.”

But setting limits is not a just a German issue. It’s a Syrian issue. It’s a Turkish issue. It’s a Russian issue. It’s an American issue. It’s a European issue. Merkel needs Europe to have a functioning external border if it is to remain borderless within the 20-plus-nation Schengen zone. Otherwise national borders will go up. The European Union will unmake itself. “No European border, no Schengen!” Thomas Kleine-Brockhoff, Gauck’s chief adviser, told me.