This worsening climate inevitably affects the tone of debate about the future of the euro zone. According to a new poll, 82% of Germans doubt that Greece will carry through the reforms it has promised, and 52% want it to exit from the single currency. In a sign of her concern, Mrs Merkel has invited Mr Tsipras to Berlin on March 23rd. It will take all her vaunted skill to save Europe from an unintended disaster.