"The essence of watercolour, say aficionados, is a highly personal, immediate relationship between the artist and his subject, whether it is a still life, landscape, or the human figure. Watercolours can be done quickly, on site, and mistakes cannot be corrected -- the work must be changed to incorporate them.

"The watercolourist takes risks, reacts like a fighter-pilot to changes in front of him, and races against time, light and the weather. The greatest of all, J.M.W. Turner, had himself lashed to a ship's mast to record a storm first-hand."

[Such was his dismay at having to sell his paintings that Turner would often fall into a funk for several days after a sale. "This week," he often declared, "I've lost one of my children."]