The genius of Crazy Vinnie

After seeing a rare show of Van Gogh's drawings, Robert Hughes has one question: how could an artist who became so great start out so badly?
Vincent van Gogh self-portrait
From earnest duffer to visionary: one of Vincent van Gogh's self-portrait drawings. Photograph: Metropolitan Museum of Art /AP

Did ever an artist have a less promising start than Vincent van Gogh? People love to imagine that if only they had had the chance to see Vincent's early work, they would have recognised his talent, coddled it, saved him from neglect and his famous suicide. His genius would have been - well, just obvious.

But if one thing seems apparent from the big show of Van Gogh's drawings that opened last week at New York's Metropolitan Museum of Art, it's that anyone could have been forgiven for looking at his early work and passing it by. Perhaps no artist who got as good as Vincent has ever started out so bad. Not just bad, but worthy bad, which is (if anything) worse. Even today, you'd hardly want one as a present, unless it was from someone you didn't want to offend. Those dogged, I-share-your-suffering images of ground-down peasant women and Dutch cloggies grouped around the sacramental potato, done in glum, awkward homage to Jean-François Millet and English social-consciousness painters such as Luke Fildes, all testify that sincerity, on its own, is not an artistic virtue. Gazing at early Van Gogh, at that murky stuff from the mid-1880s, you thirst for some signs of style - and there are none, or none that count.

And yet the amazing fact - and it has never ceased to be amazing, which is one of the components of the Van Gogh myth - is that this earnest duffer pupated into one of the great visionaries of western art, and did so across a working life of hardly more than 10 years. Most of its greatest achievements were compressed into four years, between 1886, when he first caught sight of the paintings of Georges Seurat in Paris, and 1890, when he shot himself to death in a cornfield at Auvers sur Oise, just north of Paris.

It is difficult to get anywhere near Van Gogh today. There are obstructions. The main one used to be his reputation as Crazy Vinnie the Ear-Slasher. People used to think that the heavily modelled surface of his paintings, their fierce contrasts of colour, and their coiling, violently rhythmical drawing, were in themselves indices of neurosis, perhaps of outright insanity. But gradually it became clear that Van Gogh didn't paint, indeed couldn't work, when in the grip of the bouts of depression that intermittently assailed him: that he had to have his lucidity, and that without it his work would have been as banal as any Sunday painter's. In one of his great letters to his brother Theo, the only person who believed in him, he wrote about this. "I am not strictly speaking mad, for my mind is absolutely normal in the intervals ... but during the attacks it is terrible - and then I lose consciousness of everything. But that spurs me on to work and to seriousness, as a miner who is always in danger makes haste in what he does."

Decades after his death, when the crude stereotype of the "mad artist" receded, it was replaced by something even more toxic: the artist as an incontinent Midas, who could not touch anything without making it ludicrously valuable and hence, as art, virtually meaningless. After the market insanities of the 1980s and 1990s, will anyone be able to look at Van Gogh's sunflowers, his irises or his portrait of his therapist, Dr Gachet, without seeing the price first and the picture second? It is a form of radioactivity that never decays.

And yet Van Gogh cannot be avoided by serious art lovers, especially since he is so adored by frivolous or casual ones. He is an absolutely central figure in the story of modern art, and the debt its protagonists owe him - chiefly Matisse, the Fauves and the German expressionists - is enormous and fundamental. There are some artists about whom the last word never seems to be said. Van Gogh is one.

The Met has held two great previous Van Gogh shows in (relatively) recent memory. The first, centred on the work he did in Arles during the 15 months he spent there in 1888-89, consisted entirely of paintings. It was held in 1984. The second, similarly curated by the art historian Ronald Pickvance, covered his hardly longer sojourns in St-Rémy and Auvers, and went on view in 1986. So the "recent memory" is not all that recent - 20 years. But haven't we seen enough of the enormous cliche that Vincent van Gogh, through no fault of his own, has become? Actually, no. Neither of the great retrospectives was able to pay full, or even much, attention to Van Gogh's drawings.

Van Gogh was an untiringly prolific draughtsman: more than a thousand drawings by him have survived, over half his output as an artist. His unpromising early years opened out into a brilliant graphic maturity - and then closed, with a gunshot, when he was 37. It was his habit to think of drawings - some of them, anyway - not as mere preliminaries to painting, but as final works of art in their own right. This is complicated by the fact that while many of his best drawings were spontaneously done in front of the motif (landscape, park, mountain, courtyard of the asylum), others, no less beautiful, were second versions and copies made of earlier drawings so that he could show his painter friends (Gauguin, Emile Bernard or the obscure Australian expatriate John Russell) what he had been up to.

For Van Gogh, drawing had numerous ends. It follows that there can be no full account of his genius (not too strong a word, relentlessly used though it is) that does not give full weight to his drawings. And the Met's show, curated by the art historians Colta Ives and Susan Stein, is the first proper retrospective of them that has ever been held in the US. Some of its 113 items are familiar, but many of them are decidedly not, and they touch the eye with the bloom of newness. They will not be seen together again any time soon, for the simple reason that works on paper (as museums now know only too well) are so vulnerable. Black ink goes brown, papers bleach or darken, colour values change for ever under the action of light. This is not quite the nightmare it is in certain other areas - nobody today, for instance, can have any idea what cubist collages with newsprint once looked like, because the cheap paper has gone irreversibly from white to yellow, even to tobacco-brown - but the curator who does not err on the side of caution when dealing with Van Gogh is still a fool.

Van Gogh submitted himself with abandon to the influence of Japanese art. This went beyond the bounds of what he and his colleagues like Gauguin called "cloisonnism", the inlaying of distinct patches of colour, like enamel, with unambiguous bounding lines. He seems to have been fascinated by one of the most marvellous properties of Japanese sumi-e painting, the direct application of brushed forms to rice paper or silk so that the white ground itself supplies the light in the image, not so much negative shape or absence as a positive whiteness burning through the black or dark grey shapes. The white of the paper became the blazing heat of Provence. Sometimes, peering into these drawings, you almost feel it like radiation on your face.

Van Gogh's preferred drawing tool was the reed pen. This was simply a piece of dried reed-stem, hollow and shaped to a chisel point. Not very many artists liked to use it. The only Dutch artist who preferred the reed to a quill or metal nib was Rembrandt, and this must have borne its own significance for Van Gogh. The reed was not flexible, like other pens. Nor did it hold a lot of ink, so it would not produce long, sinuous lines. The style it favoured was short, blunt, angular and (in a limited way) calligraphic. In some drawings you can see Van Gogh brilliantly exploiting the limitations of the reed. He draws a tuft of grass, for instance, as five or six springing, more or less parallel strokes. The first one is heavy with ink. The next, less so. By the fourth or fifth, the reed is almost empty and the ink strokes faint. This creates the impression of a round tussock, rendered not as flat pattern, but turned towards the light. Then he dips his reed in the ink bottle, recharges it and begins again, on a different clump of grass. The marks are abstract and yet not: they have a tremendous graphic sufficiency, tiny though they are.

The reed pen also favoured shortish parallel marks, curving exuberantly. Hence the sense of flow in some of the drawings: the wreathing and twining of substance. In a way, some are reminiscent of Leonardo's water studies, except that you know (or at least think) that you are on solid ground.

It was common for artists, when using pen and ink without resort to wash, to render areas of darkness and shadow by means of cross-hatching. Van Gogh very seldom did this. His drawings are accumulations of shorthand forms, squiggles and dots, dashes and hooks, whose density provides surface with its fluctuation of light; but they have almost no chiaroscuro as such. What you see is a tapestry of microforms, sometimes linear - such as the water patterns on the beach or the internal coilings of the cypress trees - and sometimes dotted. Perhaps he got the idea for the dots from Seurat, but they amount to a kind of notation that is entirely Van Gogh's own.

This use of tiny shapes, linked in their almost riotous accumulation but each distinct from its neighbour, is the basis of some of his most powerful and exquisite drawings, such as Garden with Sunflowers, 1888. Now and then the effect is as fecund and near-dissolute as an unusually good Jackson Pollock. Wild Vegetation, 1889, can only be "oriented" as a landscape by a glimpse of hills behind the tangle of bushes, but it is hardly descriptive at all: what the drawing is about is less the character of leaves, vines and blossoms than the primordial character of making marks. Katsushika Hokusai, one of Van Gogh's Japanese gods, called himself "the old man crazy about drawing". So might van Gogh have done, but he didn't have the chance to get old.

· Vincent van Gogh: The Drawings is at the Metropolitan Museum, New York, until December 31. Details: 001 212 535 7710.