Stream of consciousness

"Seurat and the Bathers" is an elaborate version of those National Gallery exhibitions in which a familiar masterpiece from the national collection is re-examined with the aid of drawings, studies, related pictures and reports from the conservation department. Such exhibitions go under the title "Making and Meaning", and hitherto have been without an entrance charge. The show dedicated to Georges Seurat's Bathers at Asnieres costs pounds 6 (concessions pounds 4) and the fee strikes me as a little steep. We normally see Seurat's marvellous picture for free; and although there are some fine things in the supporting material, the general tone of the exhibition is rather dry. You can't fully get the point of the display without the catalogue, priced at pounds 14.95. Many visitors will feel that they have been lured into an academic exercise - and at some personal cost.

This said, the National Gallery could not have chosen a better academic than Richard Thomson to explain Seurat's picture. He makes a speciality of such things, and was responsible for the exhibition "Landscape in France" at the Edinburgh Festival a couple of years ago, in which the work of famous impressionist artists was hung alongside canvases by painters whose names are now forgotten. The aim was to demonstrate that there was much common ground between the avant-garde and the representatives of official salon painting. This attitude is much in favour among today's art historians. It's often accompanied by analyses of social class, the changing nature of French rural and suburban life and the nuances of the political atmosphere in the late 19th century. The National Gallery is wise not to be tendentious about such matters. On the other hand, it's obvious that some pictures in this display are exhibited to demonstrate a historical rather than an aesthetic point.

The painting itself is so familiar that one didn't think a reappraisal could be possible. Its virtues are permanently in the mind's eye of all who relish pictorial art. Bathers at Asnieres is simultaneously serene, mysterious and comfortingly banal. The large size of the canvas immediately announces a grandeur of intention on the artist's part. The ordinary people on the river bank are grand too, however modest their place in life, and the three central figures, descending in steps from the left to the right, have a classical look, reminding us of Renaissance art. The light in the picture is lovely. So is the impression of distance and warmth. All these things we already knew. And yet, revisiting the painting in the context the National Gallery has devised, something else appears. The painting looks vulnerable, as though its separate excellencies might fall apart. As all the world is saying at the moment, it is an astonishing feat for an artist who was in his mid-twenties. The feat is none the less fragile, and the more one considers the painting, the more it looks to be the work of a youth.

Seurat calculated his ambitions as some young men plot their ways of getting a first-class degree. Having decided around 1883 that he was going to paint a masterpiece, he began a campaign of studies with only that end in mind. Seurat's numerous small pictures almost always tend toward a future big picture. He didn't paint them from the casual, intimate love of painting which distinguishes true masters of the intimate and spontaneous sketch. It is salutary to look at the little painting by Corot, the River Scene with a Bridge of 1854, included in this show because he was a (rather distant) influence on Seurat, and also because he depicted unremarkable places somewhere between city and country. This unassuming Corot is not a masterpiece, but only a master could have painted it. With Seurat, it's the other way round. He was never at ease, and this is the more paradoxical because Bathers at Asnieres is so obviously about people who are relaxed.

Seurat is indisputably a pioneer of modern art. But he might have become a more accomplished painter had he not lived in an age in which theory and experiment forced his pace. He died young, and it's hard to guess what he might have become in mature years. Anyway, the contrast between innovation and traditional art in the 1880s caused him many difficulties. His drawings in rich, dark conte crayon on thick paper are universally admired. It is not often said how conservative they are, so dependent on modelled light and shade. Seurat couldn't draw with a pen. A fine point would not have allowed him his luscious chiaroscuro. At the same time, it's evident from the drawings that he could not construct pictorial space. They are always better when he produced a silhouette, however much that silhouette is muffled in spatial indecision.

It's the same with the paintings. The most helpless conte drawing corresponds to the least convincing passage in the painting, the litter of hats and clothes on the bank between the main figures. It's similar with the reclining man in the foreground, or rather two foregrounds, for he awkwardly sprawls across different planes of the picture. Seurat wins our total appreciation when his figures are painted flat, as though one silhouette had been placed a couple of feet behind or in front of the other. This is what happens with the three major figures in Bathers at Asnieres, and the drawings for these separate people in the painting are just as beautiful as the people appear in coloured pigment. Personally I prefer the drawings.

A final section of this instructive, uncritical show presents some studies for Seurat's next major picture, A Sunday on the Grande-Jatte. It is clear that his new little oil sketches were a confident advance on the National Gallery pictures, though painted only a couple of years later. Seurat was an incomplete artist who was learning fast. And then death cut him off. The exhibition includes notable paintings by Van Gogh, Bernard, Signac and Monet. Curiously, the catalogue nowhere includes a reproduction of Bathers at Asnieres itself. No doubt the National Gallery reasons that all possess a postcard of the picture, for the postcard is its best-seller in the gallery shop and has been for many years.

National Gallery, Trafalgar Square, WC2 (0171 839 3321), to Sep 28.