EXHIBITIONS / The shape of shapes to come: The Tate's mix of Picasso's paintings and sculpture is a curatorial triumph

THE TATE's compelling Picasso exhibition allows mortal art-lovers the opportunity to consider the private ruminations of a genius who could not bear the thought of his own death. When Picasso died in 1973 he left no will and no instructions about the immense collection of his own work that he had been building up for half a century and more. Eventually this hoard was sorted out and cataloguing begun. Some works were given to the artist's dependants, but the bulk of the collection went to the French state in lieu of death duties This is why we have the Picasso Museum in Paris, the major lender to the present show.

In effect, Picasso studies began afresh as the implications of the hidden treasures made us reassess his art as a whole. In the last 15 years there have been big exhibitions in Paris, New York and London, and in each of them there has been more to wonder at. New knowledge of the sculpture has been especially significant, for Picasso was particularly protective of his three-dimensional work. 'Picasso: Sculptor / Painter' at the Tate now attempts an overview of his life as a sculptor. It has the premise that he was as much an innovator in sculpture as in painting. That's probably true, and the show is a moving - though puzzling - account of one of the great upheavals in modern art.

The display is a triumph for the exhibition's curators, Elizabeth Cowling and John Golding. Of course, their account is not complete: it could never be. The emphases of the exhibition will be disputed. Personally I would like to have found more Cubist constructions and fewer of the very late pieces in folded cardboard. Important works that have recently appeared on the art market have eluded the selectors. On the other hand their scholarship and diplomacy have brought extraordinarily rare loans to the Tate (the exhibition's only venue). Here are sculptures we have previously known only in contemporary photographs. There are unfamiliar paintings too, for Cowling and Golding have been diligent in seeking out canvases that complement Picasso's sculpture. So this is also a painting exhibition, and the balance of works in different media is perfectly judged.

Initially, though, the paintings look much more important. Picasso had been a fluent artist with pigment and canvas for years before he made his first sculpture. Indeed one is puzzled to know why he did not seriously take up sculpture until 1906, when he had been painting with ease and conviction for a decade. I explain the omission by looking at the other sculpture of the era. It was still dominated by Rodin, an artist of little interest to Picasso. And sculptural innovation had turned into the decorative projects of Art Nouveau. Picasso saw plenty of such art, both in Barcelona and Paris, but again he was not moved to emulate its forms.

The 1906 busts of his mistress, Fernande Olivier, are of much interest but hardly compare with the new maturity of Picasso's painting in that year. Seated Nude with Crossed Legs, as is well known, is a landmark on Picasso's route towards 'primitivism'. The serenity of this picture, however, is that of a master classicist. Picasso's primitivist sculpture lacks mastery. The oak Figure of 1907-8 is contemporary with the epochal Demoiselles d'Avignon. But while the painting bursts with ideas, the sculpture is constricted.

Picasso's sculptural genius was liberated by the Synthetic Cubism that followed the invention of collage in 1912. Previously, sculpture had either been carved (reduced from a block) or modelled (built up and adjusted from supplies of malleable material). Cubism's discovery was that sculpture could be made simply by putting things together, whether they were pieces of wood, sheared metal, found objects or indeed practically anything. This principle was to stay with Picasso all his life. The exhibition now shows the immediate advantages for Picasso's art.

First, his assemblage allowed sculpture to take on still life, a genre that had not previously existed in three-dimensional art. Picasso has a claim to being the greatest of all still-life artists, and with Cubist sculpture and painting he added many more emotions to his Spanish inheritance of grave examination of pitchers and fruit. The very early constructed Guitar of 1912-13 is still Iberian in this way, solemn as a monk. But then the Guitarist with Sheet Music from the following year and the superb Still Life of 1914 are quite different: witty, iconoclastic, casual and terribly clever.

They differ in still more ways from previous sculpture. Picasso's pieces are painted and include materials such as cloth. They don't aspire towards the timeless realm of dignified statuary but, like Cubist paintings with their newspaper collage, exist in the present tense, vulnerable to what the next day might bring. Throwaway art of this

type has a special preciousness. The sculptures seem to wink at you, but the moment of their grace is fragile.

The drawback was that constructed Cubist sculpture was not able to expand into grandeur. It does not reach the deep aesthetic level of Picasso's contemporary painting. Glass of Absinthe (1914), delightful though it is, suggests that the jokiness of such sculpture could not last for ever. The large Violin of 1915 - which, like so many other constructions, is made to be hung on a wall - announces that the future of Picasso's sculpture would, paradoxically, be in a return to two- dimensional art. Indeed Violin prefigures certain rather grand paintings and had no significant sculptural progeny.

The exhibition now presents paintings, drawings and prints which have the inklings of sculpture, depicted and not actual. Here are bony seaside monuments, Surrealist furniture, putative towers, women bathers like Greek goddesses, floppy and limbless humanoid figures. It was the powerful presence of the Surrealist movement on the Paris art scene that made Picasso think of such bizarre or grotesque objects. But he did not make the objects that he dreamt up. Their notional life on paper was enough. Real existence in palpable sculptural materials would have brought Picasso into a world of absurdity. He was wise to have felt Surrealism and not succumb to it.

He was also astute in getting Julio Gonzalez to work for him. A longstanding but never intimate Catalan friend, Gonzalez was suited to his role as an inspiring assistant and reinvigorated Picasso's sculpture by showing him that constructed sculpture might be welded. His first task was to fabricate things that Picasso had drawn as possible monuments to Apollinaire. The resulting sculptures are not quite satisfactory. The thin steel rods, famous for 'drawing in air', in fact draw too much. Their lines cancel each other out. One wants the sculpture to be more substantial. And so it became, at least in one piece: Woman in a Garden (1931-32), made with Gonzalez's help, is Picasso's sculptural masterpiece, a symphony of welded lines and shapes, blocky or sinuous, forthright or suggestive, that - alas - was treated by Picasso as a one-off, when he should have further explored its marvellous potential.

In the middle years of the exhibition's span the tone becomes darker. It looks as though Picasso repeatedly turned to sculpture to summarise his thoughts on death. At least a dozen sculptures are concerned with the end of life and their presence fills the galleries with baleful and funereal messages.

Death's Head (1941) is a disturbing work. In the first place it is a sculpture of a skull. But not quite of a skull, for the head is not bony. It might therefore be a skull in decomposition. However, Picasso would not have wished to simulate rotting flesh. So it's as though he had found a skull and vainly attempted to give it living form by building it up with clay. The bronze cast also gives the skull a helmet-like appearance. It makes one think that the sculpture had been excavated from some field of battle, either of the First World War or some more ancient conflict.

Death's Head was made during the German occupation and Picasso and his helpers ran risks to have it cast. No doubt Picasso's art in the early 1940s was affected by life under Nazi rule. His thoughts of death also took the form of tributes to departed comrades. Bull's Head (1942) is that celebrated

work made simply from a bicycle saddle and handlebar. Picasso characteristically used 'found objects' to amuse. The mood of this sculpture is almost ruthless. In my opinion it represents a skull rather than a head and is a tribute to Gonzalez, who died in Paris in 1942, the year this sculpture was made.

More mysterious themes of death and survival are to be found in Woman with a Vase of 1933. This enormous sculpture, previously hardly known, is the revelation of the show. I have never seen anything like it, within Picasso's art or elsewhere. Yet of course it has links with his characteristic themes. A huge, lumbering figure, both imposing and precariously balanced, with swollen breasts, belly and rump, holds out a vase in one hand. Half of her other arm is missing, giving the impression that the sculpture has been recovered from an archaeological site. You would say that the first inspiration of the piece is neolithic. A more immediate stimulus would have come from Picasso's new mistress, Marie-Therese Walter. The sculpture relates to contemporary paintings in which the young girl is shown as drowning, or being rescued from a watery death, which prefigure certain motifs in Guernica. With the present sculpture do we see Marie-Therese? Maybe, but this figure has emerged from the sea: its features are strangely seal-like.

What kind of vase do we find in Woman with a Vase? I am not convinced that it is a vase at all, but rather a container for a candle or sacred flame. We see the motif again in the figure holding a light on the right-hand side of Guernica. This sea-monster has another connection with the mural painting. Picasso chose the sculpture to be exhibited with Guernica in the Spanish Pavilion at the International Exhibition in Paris in 1937, the occasion when his protest against Franco was first made public. The painting and the sculpture must have made unlikely companions. No doubt, however, that the sculpture expresses something deep in Picasso's psyche - just as Guernica does, for its true subject is Picasso himself, his buried fears and fantasies, all rehearsed many times before the Basque bombing.

The bronze cast of Woman with a Vase now at the Tate belongs to the Prado. The one other cast was erected over Picasso's grave. The catalogue says that the original plaster was destroyed immediately after the artist's death 'presumably in obedience to Picasso's wishes'. But Picasso would not have made such a request, and I learn from sources close to his family that the plaster was destroyed by Jacqueline and Paulo Picasso. Perhaps Picasso's widow and the son of his first wife did not wish to be reminded that his love for a shopgirl had stirred his most profound and magisterial art. So it was, however.

No less than with his painting, Picasso's sculpture takes us to the centre of his imaginative world and takes nothing for granted, least of all peace and civic progress. Man with a Lamb, erected in Picasso's adopted town of Vallauris, is not humane in spirit. It is obviously about a pagan sacrifice. It's interesting that Picasso's sculptural art, obviously unsuitable for the mairie, is not much better suited to the museum. However challenging his paintings were, they still preserved the conventions of painting. But the sculptures are quite without convention. After the war there was a private occasion when Picasso tried some of his paintings in the Louvre, to see how they stood up to various Old Masters. One cannot imagine the same exercise with his sculptures. They are so wayward and difficult, and they still belong essentially to a domestic setting.

His materials were ordinary, gathered from the home. Yet the sculptures subverted the proper order of family and property, just as their creator himself did. There are many negligent aspects of Picasso's sculptures. Generally he is indifferent to their surfaces. A less imperious and hasty artist might have lingered over finish and texture. Picasso never did this. His hands were made to form and transform, not to model and caress. So we find meaningless textures made by, for instance, corrugated paper pressed into the clay. Picasso's suaver and perhaps more satisfying pieces often come when he has used an instrument other than his hand to complete them - to wit, a brush. His touch is rather happy and luxurious when painting on metal (perhaps he should have done so more often) and this helps the comparative lightness of many later works.

However, I cannot escape the feeling that a beautiful and limpid sculpture like Woman with Outstretched Arms of 1961 is in some way posthumous. The exhibition reopens the question of the value of Picasso's later art. I feel that nothing he ever made is without deep interest and that all his art in any medium has a touch of the immortal. None the less he could not maintain the supremely searching quality of his work in his last decades. I date this decline from the time he gave up still life, notably absent from his late painting. As for the late sculpture - it does have an Arcadian air, as Cowling and Golding argue. But the Arcady was just the garden of his Provencal chateau, cut off from the world at large. Here the restless old man spent essentially lonely years, fearing the end more than ever and unable to do anything about it.

Tate Gallery, 071-887 8000, to 8 May.

(Photograph omitted)