ART / 'I love all images and hate all symbols': Painting for Patrick Heron is a formal business, and he likes to dress formally for it. But his palette is more shell-suit than pinstripe, his landscapes more acid house than Glyndebourne

There are certain exhibitions whose sheer quality makes a critic's heart sink. The Manchester City Gallery's Antoni Tapies show, earlier this year, was a case in point. There are theories about the man, but the important truth is that, when he smears a little grimy pigment over the underside of a bed, or on a stretch of lino ripped from his studio floor, the result is great painting. But, even while you marvel, a nasty thought nags away: some poor deluded art student is going to be inspired by this and, years from now, is still going to be wondering why the results looks so horribly like the contents of a skip. Patrick Heron's exhibition, at the Camden Arts Centre, may have a similarly catastrophic effect. There's no explaining him, either.

Which may be why, though an exceptionally gifted writer, he is so reluctant to put pen to paper. 'The whole thing is to do with intent and feeling. I have to use words if I talk to you - that's the trap. If you are at all verbally articulate about what you have been doing, people assume there always was a coherent reason.' And Heron is deeply suspicious of art which grows out of, as opposed to towards, a logical position: 'I love all images and hate all symbols. The autonomy of paintings is complete. What establishes the quality of paintings of all periods is in the realm of the abstract.'

That could hardly be a more unfashionable position. The avant-garde is, nowadays, supposed to deal not with the sensuality of vision but with the social construction of perception. Heron is a survivor of the school of modernist painting which grows from Matisse - who, he says happily, 'we haven't yet begun to understand. We know all about Cubism - but we have no rational understanding of his composition.' There is barely a sufficient vocabulary to chart visual explorations of the delicacy Heron routinely undertakes - the best attempts are probably Heron's own (even the titles of two of his most celebrated lectures, The Shape of Colour, and The Colour of Colour, suggest something of the difficulties involved).

Since there is no intelligent language available to describe the work, it is easy to conclude that it is, simply, unintelligent. But the visual acuity and agility of Heron's painting is astonishing. Of all British painters now working, Heron is probably the only one graced with the visual equivalent of perfect pitch.

Heron's approach could be described as purely formalist; he eschews the paint- slapping antics of the expressionists. Painting is about paint, not painters; it's a formal business, for which he dresses formally. 'I like to paint in my best clothes; there's a photo of Matisse in his studio in his suit, complete with spats'.

He also has firm, and formal, views about diptychs: the physical break between two canvases, violating the integrity of the pictorial space which he sees as the heart and soul of easel painting, embarrasses him. Shaped canvases are even worse. They not only disrupt our sense of space within the painting, but corrupt the relationship between the canvas and the (rectangular) gallery, of which he is acutely conscious. 'The architectural setting,' he says, 'is the equivalent of the acoustic for music.'

But there is nothing remotely dry about his art. He describes his latest works as 'garden paintings', and they are, as always, saturated with unconscious references to the St Ives landscape, and, in particular, his moorland garden - it took him, he says, nearly 20 years to identify one form, which recurred in several paintings, as deriving from a favourite, lichen-covered boulder.

Critics enjoy being rude about the supposed complacency of landscape art. But these safe-sounding 'garden paintings' come as a shock: the colours are a million miles away from the grey and silver dreams of Gertrude Jekyll. To my eye, the palette (mauves and lemons, violets and pinks) is more shell-suit than sea- shell. They ought to clash quite horribly. But they don't.

'I think they're totally harmonious, but they're new harmonies,' says Heron. 'As Eliot says, 'Only the really new can be truly traditional.' The truth of the matter is that the most deadly thing is to repeat what you or anyone has done.

'As a painter, you're always pushing, but you never push into chaos. What looks chaotic at first resolves into harmony in your eyes. It took me years to see the shapes of my paintings in the rocks, in the landscape - but the fact of the matter is that you don't see these shapes until you've seen them in paintings. The landscape is infinitely diverse: people think Constable painted the East Anglian landscape 'as it is'; in fact we're projecting into the landscape the paint we've seen in Constable.'

There is a well-established syndrome of Late Paintings: the work of an artist, with name and career made, revelling in a new freedom from the pressures of technical convention and good taste. It's a tradition these canvases flirt with irresistibly. There is something frankly mischievous about the artist's impossible colour combinations and cranky, web- like compositions. The draughtsmanship is peculiar, too. Despite Heron's life-long devotion to Matisse (he made a pilgrimage to visit the artist in 1949, but was turned away at the door by the artist's companion), there is nothing here of Matisse's buoyant clarity. One predominantly green canvas is dominated by two areas marked out, in outline, in the rough form of a yellow and black triangle and a bold, red, boulderish circle.

'When I'd finished, I took a red tube and drew a circle, and it didn't come off, it skidded - so I went round again,' he explains. That openness to intuition is the mark of an artist assured of his mastery of the medium.

'Often you're thinking about something else and you find you've made this rhubarb green mixture and taken it for a walk across the canvas. You think 'Oh Christ, what have I done' - and then you see that it works. I've often wondered if I can analyse it, that moment of decision: I can't, of course. Sometimes I feel a little bit like Joyce. All he demanded of his readers was that they should devote the rest of their lives to reading his books. I'm just as arrogant.'

'Big Paintings' can be seen at: Camden Arts Centre, London NW3 (071-435 2643) until Nov 13; Bodilly Galleries, Cambridge (0223 566555) until Oct 15

(Photograph omitted)