Dialogue: It cost a mint, but at last we've joined the greatness club

One point eight million dollars. I'm as excited as you are. When I heard that the Museum of New Zealand had paid that sum for A Painting for Uncle Frank, by Colin McCahon, my heart stretched up and crowed like a rooster. New Zealand art has come of age. The barrier is shattered and the future unlimited.

Any sum under a million dollars is merely money. It is sense in cents, the stuff that buys bread and milk and houses, the stuff that we work for and cling to and count. But on the far side of a million the rules evaporate.

There it is like Einstein's vision of space, where the dimensions turn back on themselves and defy all mundane reasoning. A million dollars is where great art starts. It is the big boys' club and New Zealand art has made it at last. It is time to puff out our chests.

At the same time we must retain a sense of scale. In New Zealand one point eight million is huge, but internationally it's kitty-litter. Why, New York holds paintings which are great to the tune of two hundred million bucks.

When I get to curate one of the mighty museums of the world - my eye is fixed, if I am to be honest, on the Louvre - I shall install a meter next to each of the more celebrated paintings. The meter will tell the likely sale price at auction. Patrons will be able to watch the Mona Lisa grow older and more valuable there as they stand and gawp. And the people will come running, for they love nothing more than concentrated money.

They love to see it compressed into a single canvas, the smaller and the less impressive the better.

The ideal is a dowdy renaissance miniature valued in the millions. The crowds flock. They peer and tut with wonder and they pretend to make a grab for it to see how the security people react and then they giggle at their own stupendous parody of naughtiness.

Of course the moment I heard the news of the McCahon canvas I sent myself to Wellington as fast as a plane could carry me. And when I beheld Te Papa's Stalinist brutality blotting the waterfront as starkly as the day it was built, I felt a warmth infuse me. Inside I found that old familiar theme-park feel - the crowds of trippers, the shops and restaurants, the kiosks staffed by people in shirts that start migraines, and, above all, that lovely sense of having to travel with difficulty to find any exhibits. In its few brief years of existence, Te Papa has become the cultural staff on which I lean.

But last weekend I had no time for leaning. I had come to see one point eight million dollars of canvas. And when I found it I was not of course alone. Money is a magnet. The crowd had gathered. To either side hung other paintings - a fabulous Bill Hammond, a dreadful Seraphine Pick, a nice 19th-century mock-up of picturesque natives - but no one paid them any attention. The mob was tuned to the dollar.

And oh the reverence that tinged their conversation. "Is that it?" asked a woman in scarlet. Her man nodded. "Mmmmm," said the woman. And that mmmmm said it all. For A Painting for Uncle Frank belongs to the puzzling school of modern art. It is black. On the left of the canvas the artist has drawn a stylised Mt Egmont in white paint. It is mere snow-topped outline. On the right a hill. Beneath both is biblical text, handwritten in white paint, crude, apparently clumsy, hasty and even flawed by an error of spelling.

None of the patrons stayed long. They moved on in search of interactivity.

But that didn't matter a jot. They had sought out the canvas, been confused by it, disappointed by it, but at the same time touched by wonder. For here hangs the glory that is art. Here hangs mystery. The people cannot understand how it can be worth so much money. And however much they may gasp with derision, they are delighted by their own incomprehension.

A Painting for Uncle Frank offers something rare in our secular world, a glimpse of something beyond our ken, as baffling as a godhead, wondrously expensive and apparently useless. Had the painting been worth nothing the public would have done no more than glance at it.

What matters is not whether the painting is worth the money, but that someone believes that it is. When the price is vast, the aura grows. New Zealand art has joined the greatness club. It is a time to rejoice.