Yet one of his toughest challenges will be to readjust to living in the real world. When he emerges from his plastic prison after 44 days - if he can survive this marathon fast - David will not have spoken with, or even touched, another human being for more than six weeks. Suddenly he will be surrounded by the full blaze of media attention. Every celebrity in Europe will want to be photographed with him.

And of course there will be the reunion with his girlfriend Manon von Gerkan, who has been sending him silent messages of love.

I predict he will take many months to recover, for the worst days of his fast lie ahead of him still. But somewhere in the future, he will be aiming to pull off an even more spectacular performance.
And I suspect that, as he reclines in his box and watches the people and boats flitting about below, he has already begun to make plans.