Where physics meets with dream of high life

In his preface to the Lyrical Ballads , Wordsworth writes of men "who speak of what they do not understand...who will converse with us gravely about a taste for Poetry... as if it were a thing as indifferent as a taste for Rope-Dancing or a taste for Sherry". Reading Philippe Petit's To Reach the Clouds you would rather think rope-dancing was high art and poetry an aspiring imitation.

Susan Sontag has written of the artist as a "freelance explorer of spiritual dangers" and of art as "the dearly purchased outcome of an immense spiritual risk". On Wednesday, August 7 1974, as Manhattan bankers swarmed below, Petit walked across a steel cable stretched between the tops of the north and south towers of New York's World Trade Center. If Sontag is right, Petit embodied the process of art, and the role of the artist. He performed it. Petit's rope-dancing is a metaphor for art-making, as well as an art itself.

In everyday speech, we associate walking the tightrope with living dangerously - "living on the edge", "treading a fine line". Petit's story is about this, of course, but his actual feat was more surgical operation than adventure. Hidden away behind his charisma, behind the picaresque, undetected night flights to the top of the twin towers, his high-wire walking was above all a procedure. There was as much physics and meteorology in it as there was dream.

What shocks, beyond the immense grandiloquence of his basic idea, beyond even the courage of his conviction, is the clean, clinical professionalism with which he carried it out.

Auden wrote of a poem: "Here is a verbal contraption, how does it work?"

Petit's poem was made from cable so heavy it took two men to lift, cavaletti wires, wind gauges, spare blocks of wood and a bow and arrow.

But what did his performance achieve? When he strung his wire between the twin towers, Petit invented the space between them. He drew a cheese cutter across a void, and made the void real. He made negative space concrete, positive. He showed a million New Yorkers something they had never seen before - a third pillar between the first two, made of air. The towers were the great symbol of New York, and Petit changed that symbol's shape. Jean Genet, another writer/rope-dancer, talks of rope dancing thus: "A peculiar experiment: to dream, to concretise that dream so that it would turn into a dream once more in the minds of others."

To Reach the Clouds should be required first-year reading for all creative writing classes. And perhaps Petit should act as a key consultant to Daniel Liebeskind's WTC reconstruction project - for Petit has promised another walk, to complete the symbol again.

Turi Munthe is a writer and editor.