The scene at Bratislava Castle last week was a familiar one: European leaders gathered for another summit in a typically idyllic setting, where the natural beauty of their surroundings belied the deep imperfections of the union they were struggling to salvage. But now, in the wake of Britain's vote to leave the Continental bloc, delusion steeped in the ideals of an "ever-closer" union is wearing thin, and the realists in the room seem to be gradually gaining ground....