There is a famous painting of the young Napoleon crossing the St Bernard Pass on his way to the Italian campaign which rocketed him to fame. Louis David's canvas shows him on a rearing horse, and everything about the painting is motion; the horse rears, its mouth open and eyes wide, its mane is wind-whipped, the sky is stormy and the General's cloak is a lavish swirl of gale-driven colour. Yet in the centre of that frenzied paint is Napoleon's calm face. He looks sullen and unsmiling, but above all, calm. That was what he demanded of the painter, and David delivered a picture of a man at home amidst chaos.