The choicest of the seven paintings by Rubens are the two large landscapes he painted for his own enjoyment c.1618-19: Winter: The Interior of a Barn and Summer: Peasants Going to Market. Summer is a shimmering pastoral with plump peasants and equally hearty animals processing through rolling, un-Flemish countryside. While it symbolises God's bounty, it also shows a sense of optimism brought by the end of the Eighty Years War. Winter is a bravura performance: as snow falls outside, a farmer contentedly surveys his family, his workers and his livestock safely gathered within. In this one scene, lit by the light from a small fire, Rubens shows his mastery of landscape and weather, flesh and fur, pose and anecdote.

It shows too that he was a true son of the Flemish tradition, at the head of which was Pieter Bruegel the Elder. It was Bruegel's delight in peasants "engaging in various drolleries" that transmitted itself down the Flemish painterly line. There is nothing droll about his Massacre of the Innocents, 1565-67, though. In a snow-covered Low Countries village (no hint of the Holy Land here) soldiers dressed in the garb of the hated Spanish are running amok, knocking down doors and, deaf to the pleas of the inhabitants, slaughtering birds and animals.

At first it makes no sense until you look harder and discern that beneath the plumage of a swan a pair of childish legs is sticking out and that all the other animals are painted over the ghostly figures of children too. The Emperor Rudolph II, the same man painted by Arcimboldo, ordered the children covered over and the scene changed from a biblical massacre to one of plunder. He may have smiled at seeing himself as a pile of vegetables but not at such a stark image of the slaughter his fellow Habsburgs had unleashed.