Dej View

The five characters are clustered together on screen in a silent tableau. It could be a photographic still. But watch for a few momentsin ultraslow motion, one of them blinks and the fingers of two characters entwine. There's no script, no context, just a set of faces ranging from anger to ecstasy. The Quintet of the Astonished is mesmerizing, a study of emotional extremes by American video artist Bill Viola. It is utterly modern, yet its inspiration is Bosch's Christ Mockeda picture painted 500 years ago. "I don't believe in originality in art," Viola explains. "We're always borrowing."

So Viola was delighted when London's National Gallery asked him to do just that. For its latest exhibition, "Encounters: New Art from Old" (until Sept. 17), the gallery invited 24 of the world's leading artistsincluding Jasper Johns, David Hockney and Antoni Tpiesto choose a painting from the collection and respond with a work of their own. The result is a mixed-media bag, from photography to sculpture to abstract art, derived from paintings that span six centuries. Guest curator Richard Morphet wanted 24 distinctive new works "which stand up in their own right but which have a very intimate connection with the source work which inspired them."

That connection seems tenuous at times. For Euan Uglow the curve of his nude's arm supposedly reflects that of Monet's bridge in The Water-Lily Pond (1899), while Johns asks viewers to make a conceptual leap from Manet's fragmented Execution of Maximilian (1867-68) to his own solid grey painting with a piece of string suspended across it. Motivated by Turner's Sun rising through Vapor, sculptor Louise Bourgeois has created Cell XV (For Turner), a kind of caged conical fountain surrounded by mirrors and jam jars containing blue liquidwhat she calls a metaphor for "the unbroken thread of time." Maybe that's the nature of artistic inspirationit doesn't have to make sense to anyone else.

But other works are more obvious. The painting by realist Lucian Freud, completed over many months at night in the National Gallery, is almost a direct copy of Chardin's Young Schoolmistress (circa 1735-36). And even Jeff Wall's oddly moving transparency of a dejected Blackpool donkey seems a reasonable reply to Stubbs' majestic stallion, Whistlejacket (1627-30).

Hockney chose Ingres' 1811 portrait of Jacques Marquet, but he sought to emulate the master's technique rather than content. Using an optical device to position the facial features, he drew 12 National Gallery guards, each in a single sitting, after meeting them briefly a day or so beforejust as he believed Ingres had done. The portraits Hockney has produced are arresting, precisely because of their ordinariness.

"All great art comes out of great art," says National Gallery director Neil MacGregor. Or as Viola puts it: "Creativity is infectious." "Encounters" has its limitationsnamely, only three women artists and no one under the age of 48but it still offers a fascinating insight into the artistic mind. It also demonstrates that continuous exchange: great contemporary artists may draw from an awesome inheritance, but they also add to itleaving inspirational legacies of their own.