Here's a thought. An artist comes up with an idea, but it doesn't involve making anything. It is just that pure thing, an idea. What he needs is publicity, if the concept is to work. And faith in the general public that they will engage seriously with his idea.
That is the challenge of sculptor Antony Gormley. It's his task to fill the fourth plinth in Trafalgar Square for one hundred days. And his idea is to invite people from all over the UK to apply for a one hour slot to do whatever they want on the plinth, as long as it's not illegal.
He has 2,400 hours to fill, because the plinth will have someone on it 24 hours a day, seven days a week.
The selections will be made randomly, although allocated hours will be given to areas according to their population in an effort to make this a national work.
It is a hugely ambitious idea which focusses on Gormley's long-standing interest in the body as a metaphor. He hopes that in the context of Trafalgar Square, with it military, valedictory and male monuments, he will be facilitating a living monument, which will allow us to reflect on the individual in contemporary society.
Gormley told me he will apply for an hour on the plinth. When I asked him what he would do, he said he might sing, he might take some clay and clingfilm up there and make a sculpture - he didn't really know.
It pleased me that he didn't know - the art will be in the unknown, and as he said, it will take great courage to get up there in the first place. Doing nothing but that may be a profound experience.
The work has got big money behind it, which will pay for the four cameras on the plinth, recording everyone's hour. People's experiences will be logged and archived and kept for anthropological purposes.
All this presumes that individuals will be transformed by the experience, and those watching will be too. I suspect that a fair few will be applying because they want their Andy Warhol moment of fame.
Public art has come a long way from plonking a Henry Moore on a grass verge, but along the way, side issues have surely become absurd. In the case of the plinth, hours have been devoted to health and safety, which must be soul-destroying for an artist interested in ideas. A net will be constructed around the plinth which will be manned 24 hours a day.
It is potentially a thrilling idea, and could elicit some profound results, or could be relegated to the visual arts equivalent of The X Factor meets David Blane.
What do you think about Antony Gormley's plan to hand over the fourth plinth to the people?