THE French cockerel and the German eagle have strutted together for so long that few took much notice of this week’s 50th anniversary of the Elysée treaty that sealed their partnership in 1963. The pairing has known memorable times: think of de Gaulle and Adenauer, Giscard d’Estaing and Schmidt, or Mitterrand and Kohl holding hands at the site of Verdun.Now Angela Merkel and François Hollande must tend the near-sacred relationship, a pillar of peace in Europe and of wider co-operation in the European Union. On January 22nd they went through the pomp of celebration in Berlin with joint cabinet meetings, speeches to assembled German and French parliamentarians and an encounter with young people from both sides of the Rhine. Yet for all the words of undying friendship there was something tired and loveless about it all. French opposition leaders talk of relations being marked by “indifference” and even becoming an “empty shell”.Perhaps this is because Mrs Merkel and Mr Hollande come from rival political families. Perhaps they don’t yet know each other well (though in public they use the familiar tu and du forms,…