Apocalyptic wallpaper: that was the brilliant phrase coined by the New York critic Harold Rosenberg, and it has stuck to Jackson Pollock's paintings ever since. It sums up the Pollock dilemma. Are these dense fields of looping drips and spatters profoundly meaningful - or profoundly meaningless? Whichever way they take you, there's no escaping the fact that, 50 years after his death, Pollock is still enormous.
No. 5, 1948 is one of his classics. It was made at the height of Pollock's powers. A year later Life magazine was asking: "Is he America's greatest living artist?" He was only in his late thirties. But it wasn't long before the claims got even bigger. Not just America's greatest, but the world's.
Of course, the hand of history was partly pulling the strings. Here was the United States: just won the war, richest nation, top of the free world, supremely confident. It needed something equivalent on the cultural front - something new and dynamic and ruggedly individualistic. Circumstances meant that the next big thing in American art was likely to get very big indeed.
Pollock's work fitted the bill perfectly. Its temperament was free, raw, expansive, commanding. It had wild pioneer spirit. But also it was - really was - highly original. The novelty of the paintings he made in a barn at the back of his Long Island home was partly in how they looked, partly in how they were done. The composition was "all over". There was no image, of course, and no governing design or obvious focal points. Pollock abandoned handiwork, too. Dripping his paint from sticks and old brushes, he substituted gravity for touch.
The relationship between painter and painting was changed. The canvas was laid on the floor. It became an arena for action. What developed on the surface wasn't so much a picture as a record of spontaneously choreographed body movement, energy, reflex. When someone asked why he didn't work from nature, he replied simply: "I am nature."
But he was myth too. "Jack the Dripper" was the archetypal boho rude-boy, famous for pissing in his patron's fireplaces. He was a violent brawling drunk, who would quite likely have drunk himself into oblivion if he hadn't died, aged 44, at the wheel of his car. But that premature death, that sudden crash, only made the myth stronger, more romantic, more desperate, more tragic. Along with Albert Camus and Marilyn Monroe, Pollock became one of the first great celebrity casualties.
Hard to see past a fame like that, and when a record sale price is added, even harder. But paintings are still just visible. And their power is that, for all their status and influence, when you're in front of them they refuse to settle into being works of art.
Pollock was right: he was nature. His achievement was to make human artefacts that have the fascination of convulsive natural phenomena, like geezers, like nebulae: blank wonders, endlessly interpretable.