EXHIBITIONS / Third man at deep square: An exceptional week in the galleries begins with Juan Gris: not the most celebrated of Cubists, but the most colourful

THREE YEARS ago there was a monumental exhibition in New York called Picasso and Braque: Pioneering Cubism. To go by the catalogue and other accounts it was an essential, unrepeatable, unmissable show. Unfortunately, like many people in this country, I did miss it. Now, with The Cubisms of Juan Gris at the Whitechapel, we have some compensation.

Gris is generally reckoned the third man of Cubism. He was a close friend of his fellow Spaniard-in-Paris, Picasso, and though not himself a pioneer - he picked up on the movement in 1911, about two years after it got going - he was a great developer of it. While Picasso and Braque were working hand in hand and were sometimes almost indistinguishable, he shaped his own course, and continued to develop it until his death, aged 40, in 1927.

It is never easy to say precisely what Cubism was about. It was subjected almost immediately to a good deal of theorising from critics, poets and the artists themselves - Gris included. There was the belief that it offered not only a revolutionary way of representing the world, but also access to some kind of new reality - a view of objects as they really were, perhaps in a scientific, or perhaps in a metaphysical sense.

Gris himself has been seen as somehow an especially 'logical' painter. But it is important to remember that Cubism's 'discoveries' were always confined within works of art. It wasn't a way of seeing that could be adopted by the general viewer beyond the edges of canvas or paper - in the way that Impressionism was. When Oscar Wilde wrote, 'Where, if not from the Impressionists, do we get those wonderful brown fogs that come creeping down our streets . . ?' his reversal of life and art was partly in earnest.

Impressionism had altered vision, or at least raised people's consciousness of certain things. Cubism has altered the way almost everyone has drawn or painted in the remainder of this century; but it hasn't changed the way anyone has looked at the contents of a table top.

The old idiot's-guide description of Cubism, that it was about abandoning the single viewpoint and recording objects from a multitude of angles, still has some virtue. It describes something of what the pictures look like. What it doesn't say is how all the shards are to be put together, the business of transition. In some of the earliest pictures here, Gris adopts rather a literal-minded method. He draws a bold black-line grid, making the picture into a network of separate little frames, and through each of them he takes a different shot at the subject. These are bright, twinkling images, like stained-glass windows.

Gris' achievement was to let daylight and colour in on the Cubist operation. At that time Picasso and Braque were working in muddy browns and greys, and the problem of transition could be solved by allowing the pieces to be swallowed back into the general miasma. Gris brings things into the open, but runs into the difficulty that a simple grid is not a very interesting solution.

He moves on though. And what is especially seductive about the pictures of 1913-16 - they are almost all still-lives - is the graceful work of blending with which Gris covers the traces of his discontinuous images. The guitars, bottle and crockery are splintered and dislocated. A variety of idioms are used - solid form, outline, silhouette. Pieces of collage are introduced. Yet the pictures always appear coherent.

Abrupt cut-offs are modified with fade-outs, overlaps, intersections. One shape is lost in another and then picked up again on the other side. The whole ensemble is sustained with a geometrical architecture that sometimes coincides with the form of a thing, and sometimes takes off on a life of its own before leading into something else. The impression is of superimposed planes of transparency and opacity, moments of perfect clarity connected by visual feints and sleights-of-hand.

The pleasures of Gris' Cubism are, in a way, simple pleasures. There is pleasure in neatness and simplification, in the way the forms of known things are squared or rounded off, and fitted or slotted together in an economy of design. And there is the pleasure of unravelling complexity, a version of the commonplace picture puzzle: 'There are 10 animals hiding in this woodland scene, can you find them?'

For the thing is, you never quite accept the 'new realities' of Cubism as completely proven. You want always to be working it out, putting it together or taking it apart, trying to make a more familiar sense of it, even while the attempt is always losing its way. A resistance between painting and viewer is what makes the viewing interesting.

Gris' pictures are generally thought to have gone off in his later years. I think this happens rather earlier than that, around 1918, because it's then that the patterning starts to override any loyalty to things out there.

The sense of resistance is lost - and with it that peculiar and immediate beauty which Gris offers, the feeling of intricate, ghostly thinginess which is prior to any perception of identifiable things - not quite a new reality, but an intimation of what it might be like to have been until now unconscious of the object- world and only just waking up to it.

'The Cubisms of Juan Gris' is at the Whitechapel Gallery, London E1 (071- 377 0107), to 29 Nov.

(Photograph omitted)