Captaining the artworld force is Ernst Beyeler, the Swiss collector and dealer in 20th-century classics.
To encourage others to follow his example, he has donated one of his paintings - Andy Warhol's version of Munch's The Scream, a silkscreen on canvas valued at about pounds 135,000.
News of the sale comes just weeks after Munch's The Scream was recovered after it was stolen from the National Gallery in Oslo.
However, Mr Beyeler said that was pure coincidence. As a devoted supporter of both Greenpeace and the Worldwide Fund for Nature, he has planned the donation for some time. He said: 'It is very expressive. As a cry, it connects very well. It is also a cry for Greenpeace.'
Sotheby's yesterday sold a pair of rare vases, elongated to a height of 3 feet, for pounds 287,500. The estimate for the William & Mary Delft 'flower pyramids' was just pounds 50,000 to pounds 70,000. They were bought by an anonymous telephone bidder.
Each of the blue and white vases has 24 spouts for the innovative flower arranger. Among few such vases to have survived is a set at Hampton Court Palace.