WHEN works by Zhang Daqian are auctioned in Hong Kong this week observers will use the prices to help judge the health of the art market.
When the market is strong, paintings by the mainland-born, cosmopolitan artist - who died in 1983 aged 84 - break records.
And when the market is weak . . . Christie's and Sotheby's hope they will not find out this week how to end that sentence.
Several pieces are on sale. Sotheby's is selling some important ink and colour works by Zhang this afternoon at 2pm, including one spectacular splashed ink Boat In A River and Raining In Spring Mountain which show the artist's skilled wildness with the brush.
But tomorrow morning Christie's will offer a small collection of works by this controversial man - he was a big spender, excellent host, world traveller, gardener, father of many - with an interesting curiosity value.
They are owned by Heidi Wang, who, in California in the 1960s, was perhaps the only person Zhang taught to cook. 'If he really wanted to teach you something it had to be very formal,' said Mrs Wang, who is selling 11 pieces - 10 by Zhang and one by the late Qing prince Pu Ru.
'At the beginning of each class I had to kneel down and touch my head to the ground in a kowtow. He liked that,' said Mrs Wang, widow of Wang Ren, a physicist who had been a family friend of Zhang's.