As I was going up the stairs, I met some art that wasn't there. It wasn't there again today ... and will continue not to be there until the end of February. "Why take up space when it's not necessary?" shrugs artist Lawrence Weiner, as I scan Canary Wharf in search of his latest installation, Towards Motion.
One of the granddaddies of conceptual art, New Yorker Lawrence Weiner has been designing non-existent sculptures for over 30 years. What's more, for every one of those years, the world's most prestigious art institutions have continued to commission him to do it, from Dokumenta and the Whitney to the new Guggenheim in Bilbao.
Closer inspection of the escalators in between the Docklands Light Railway and the Canary Wharf Tower does in fact reveal the scantiest wee suggestion of an artwork. There, against the glass-sided up- and down-escalator panels, thinly traced out in blue-edged transparent type, are the words "One for the money ... Two for the show ... Three to get ready ... And four to go ( )".
For the most part, the office-workers glide between floors oblivious of Weiner's work, but every once in a while, there's a glimmer of a double- take, as an unduly perceptive punter notices the slight modification to his or her habitual surroundings. "What goes in the brackets, then?" asks a maintenance man. "You," Weiner replies triumphant - "that's where you place yourself." Maintenance man wanders off perplexed.
Filling in the gaps yourself is what Weiner's work is all about. The phrases he chooses to display are all deliberately indeterminate but vaguely suggestive. One "what" for the money? Two "what" for the show? Each viewer will read the phrases differently - depending whether they are on their way to or from work; or perhaps, on how much they like their jobs and how tasty the "to go" option is. Perhaps it's even sending out a subliminal message for people to hand in their notice?
"Being with this for two months will give the people here the opportunity to relate this into their lives," Weiner whispers conspiratorially into his gingery whiskers. "If it takes, it will give them something to help understand their relation to the world," he adds. "And that is all that art is supposed to be about."
Working out what "art is supposed to be about" is Weiner's favourite occupation. Aesthetics don't come into it. "You make art because you're dissatisfied with the configuration of the world as it's presented," he insists.
Weiner's earliest works, back in 1960, tried to alter the configuration of the world rather literally, using truckloads of explosives to blast huge craters in fields across California. He soon gave up on the macho pyrotechnics, however, deciding to change the world by more discreet means.
He formulated a theory, which he has stuck to ever since, that building his sculptures was a mere optional extra. ("1. The artist may construct the work. 2. The work may be fabricated. 3. The work need not be built.")
Instead of laying physical things down on a gallery floor, Weiner would now just paint a no-nonsense phrase on a gallery wall, such as "many coloured objects placed side by side to form a row of many coloured objects".
"I feel it can transcend cultures," he explains, "because, no matter what materials I choose - even the simplest many-coloured objects - they are going to take on a different cultural metaphor in each different place. I would prefer that a work of mine is not exotic. In Japan they would think of other configurations of many-coloured objects. It's reinvented by each person who comes to it."
"Why give them your metaphor?" Weiner asks, in low wide vowels. "Why not give them the phenomena of the materials together and let them find the metaphor that they need - or don't need - because all art cannot be for everybody."
The phrase "smashed to pieces in the still of the night" would have set off different resonances, he points out, when he painted it on the side of a bunker in Vienna, than it would have done if it had been laid out in pebbles on a South Sea beach. One environment might, after all, be punctuated by the sound of breaking bottles, the other by the sound of falling coconuts.
"It intrigues me that a sound in the day is so different from a sound in the night, when it's supposed to be the same material," he says. "At 2 o'clock in the morning, hearing the same three tons of steel falling goes from being an annoyance to a complete catastrophe."
Weiner got used to the sound of lumps of steel crashing around during his pre-art career as a dockworker. The son of second-generation working- class Russian immigrants from the South Bronx, he started working on the docks at the age of 12, got involved as a union organiser, and then perfected the art of watching his back. "A baling hook in the back was the approved way of getting rid of lefty pinko faggots," he remembers matter-of-factly.
At the same time, young Weiner was studying, discovering Camus and Sartre at the Public Library, and noticing that the Museum of Modern Art provided "a better quality of girl to flirt with". Aged 16, he started dropping by the Cedar Bar to listen to the conversations of the artists who hung out there. "As a young person, I was terribly impressed by the abstract expressionists," Weiner recalls. "They were extremely open - Kline specifically, Rothko, Newman, as well as poets like Kenneth Patchen and Gregory Corso."
Involvement in Civil Rights protests in the South led to several stints in jail, then plans to become a teacher got diverted by art, for which Weiner still feels slightly guilty.
So why a sculptor? Why not a poet, I ask? An eyebrow is raised in horror, as Weiner reaches with long, angular fingers for another treacly Mexican Delicados cigarette.
"Poetry says the reality of the person presenting it is of a different reality to the person reading it," he asserts. "It's a belief that there's an inspiration, and I do think art is just an observation with the acquired skills of presentation. The materials I use are all accessible to all people. Poetry is about a feeling - feelings are not accessible to all people."
Although Weiner regularly shows his text-sculptures in galleries, he is happier creating public works. Already for 1998, he is working on a massive piece to be set around Paris's main ring-road, the Peripherique; and a new commission for the docks in Hull (as part of Arts Transpennine 98). "Art is something looking for its place in the world. When it ceases to look for its place and it finds its place, that work of art becomes art history," says Weiner.
"I have a liking for extremes," he admits. "The only places I'm really happy are places where there's no anecdote."
Then, as if by magic, Weiner suddenly forgets his grand mission to explain the purpose of art and gets anecdotal.
"I used to ride icebergs," he muses, rearranging the silver bracelets around his tattooed wrist. Come again? "You go to the north of Scandinavia, and literally, for the price of the gas or whatever, you get a helicopter to drop you off by the cable. Then you'd make a deal with some fishermen - and hope you understood them and they understood you - and a day or two later they'd pick you up. It worked fine."
Oh, no! Has he given too much away?
"I don't want people, when they look at a work of mine, to know terribly much about me," he growls mellifluously. "They don't have to. I want them to know terribly much about themselves."
`Towards Motion': at The Rotunda, Cabot Place East, Canary Wharf, London E14 to 28 Feb. `Lawrence Weiner', a new book about the artist, will be published by Phaidon in March