TOWARDS the end of the nineteenth century, the connoisseur Alfred Bredius went to Poland. After a difficult journey, Bredius later wrote, he arrived at the castle of a certain Count Tarnowski. He knew, the minute he entered, that he had found what he was looking for: ''There it hangs! Just one look at it, a few seconds' study of the technique, were enough to convince me instantly that here in this remote fastness one of Rembrandt's greatest masterpieces had been hanging for nigh on a century!'' The rest, as they say, is his-tory.
Count Tarnowski was persuaded to part with The Polish Rider, which hangs today in the Frick Collection in New York: never loaned abroad, it has become a powerful symbol of the erosion of the great Euro-pean art collections by American money. But in fact, by the time Bredius discovered it, the painting was already a symbol of the destruction of what had once promised to be a great Polish national art collection - not by the Americans, but by the Russians and Prussians, who had carved up the country between them a century earlier and seen to the dispersal of most of the royal possessions. Sold from the royal art collection into private ownership, The Polish Rider represented in miniature (as Bredius noted) the failure of the grand cultural ambitions once harboured by the court of Poland.
The Frick Collection is not the only museum in the world to have benefited from the failure of those am-bitions, a fact demonstrated by a small but exceptional exhibition which opened last week in Dulwich: ''Treasures of a Polish King''. The king in question is Stanislaus III Augustus, the last monarch of Poland, former royal owner of The Polish Rider and, also, the unwitting founder of the Dulwich Picture Gallery...
