Henri Matisse was born in 1869. The year he died, 1954, the first hydrogen bomb exploded at Bikini Atoll. Not only did he live on, literally, from one world into another; he lived through some of the most traumatic political events in recorded history, the worst wars, the greatest slaughters, the most demented rivalries of ideology, without, it seems, turning a hair. Matisse never made a didactic painting or signed a manifesto, and there is scarcely one reference to a political event - let alone an expression of political opinion - to be found anywhere in his writings. Perhaps Matisse did suffer from fear and loathing like the rest of us, but there is no trace of them in his work. His studio was a world within the world: a place of equilibrium that, for sixty continuous years, produced images of comfort, refuge, and balanced satisfaction. Nowhere in Matisse's work does one feel a trace of the alienation and conflict which modernism, the mirror of our century, has so often reflected. His paintings are the equivalent to that ideal place, scaled away from the assaults and erosions of history, that Baudelaire imagined in his poem L'Invitation al Voyage:

Furniture gleaming with the sheen of years would grace our bedroom; the rarest flowers, mingling their odours with vague whiffs of amber, the painted ceilings, the fathomless mirrors, the splendour of the East ... all of that would speak, in secret, to our souls, in its gentle language. There, everything is order and beauty, luxury, calm and pleasure.

"In its thoughtfulness, steady development, benign lucidity, and wide range of historical sources, Matisse's work utterly refutes the notion that the great discoveries of modernism were made by violently rejecting the past. His work was grounded in tradition - and in a much less restless and ironic approach to it than Picasso's. As a young man, having been a student of Odilon Redon's, he had closely studied the work of Monet and Cézanne; a small Cézanne Bathers, which he bought in 1899, became his talisman. Then around 1904 he got interested in the coloured dots of Seurat's Divisionism. Seurat was long dead by then, but Matisse became friends with his closest follower, Paul Signac. Signac's paintings of Saint-Tropez bay were an important influence on Matisse's work. So, perhaps, was the painting that Signac regarded as his masterpiece and exhibited at the Salon des Indépendants in 1895, In the Time of Harmony, a big allegorical composition setting forth his anarchist beliefs. The painting shows a Utopian Arcadia of relaxation and farming by the sea, and it may have fused with the traditional fête champétre in Matisse's mind to produce his own awkward but important demonstration piece, Luxe, Calme et Volupte, 1904-5. In it, Matisse's literary interest in Baudelaire merged with his Arcadian fantasies, perhaps under the promptings of Signac's table-talk about the future Golden Age. One sees a picnic by the sea at Saint-Tropez, with a lateen-rigged boat and a cluster of bulbous, spotty nudes. It is not, to put it mildly, a very stirring piece of luxe, but it was Matisse's first attempt to make an image of the Mediterranean as a state of mind.

"In 1905 Matisse went south again, to work with André Derain in the little coastal town of Collioure. At this point, his colour broke free. Just how free it became can be seen in The Open Window, Collioure, 1905. It is the first of the views through a window that would recur as a favourite Matissean motif. All the colour has undergone an equal distortion and keying up. The terracotta of flowerpots and the rusty red of masts and furled sails become a blazing Indian red: the reflections of the boats, turning at anchor through the razzle of light on the water, are pink; the green of the left wall, reflected in the open glazed door on the right, is heightened beyond expectation and picked up in the sky's tints. And the brushwork has a eupeptic, take-it-or-leave-it quality that must have seemed to deny craft even more than the comparatively settled way that Derain, his companion, was painting.

"The new Matisses, seen in the autumn of 1905, were very shocking indeed. Even their handful of defenders were uncertain about them, while their detractors thought them barbaric. Particularly offensive was his use of this discordant colour in the familiar form of the salon portrait - even though the "victim" was his wife, posing in her best Edwardian hat.

"There was some truth, if a very limited truth, to the cries of barbarism. Time and again, Matisse set down an image of a pre-civilized world, Eden before the Fall, inhabited by men and women with no history, languid as plants or energetic as animals. Then, as now, this image held great appeal for the over-civilized, and one such man was Matisse's biggest patron, the Moscow industrialist Sergey Shchukin, who at regular intervals would descend on Paris and clean his studio out. The relationship between Shchukin and Matisse, like the visits of Diaghilev and the Ballet Russe to France, was one of the components of a Paris-Moscow axis that would be destroyed forever by the Revolution. Shchukin commissioned Matisse to paint two murals for the grand staircase of his house in Moscow, the Trubetskoy Palace. Their themes were "Dance" and "Music".

"Even when seen in a neutral museum setting, seventy years later, the primitive look of these huge paintings is still unsettling. On the staircase of the Trubetskoy Palace, they must have looked excessively foreign. Besides, to imagine their impact, one must remember the social structure that went with the word "Music" in late tsarist Russia. Music pervaded the culture at every level, but in Moscow and St. Petersburg it was the social art par excellence. Against this atmosphere of social ritual, glittering and adulatory, Matisse set his image of music at its origins - enacted not by virtuosi with managers and diamond studs but by five naked cavemen, pre-historical, almost presocial. A reed flute, a crude fiddle, the slap of hand on skin: it is a long way from the world of first nights, sables, and droshkies. Yet Matisse's editing is extraordinarily powerful; in allotting each of the elements, earth, sky, and body, its own local colour and nothing more, he gives the scene a riveting presence. Within that simplicity, boundless energy is discovered. The Dance is one of the few wholly convincing images of physical ecstasy made in the twentieth century. Matisse is said to have got the idea for it in Collioure in 1905, watching some fishermen and peasants on the beach in a circular dance called a sardana. But the sardana is a stately measure, and The Dance is more intense. That circle of stamping, twisting maenads takes you back down the line, to the red-figure vases of Mediterranean antiquity and, beyond them, to the caves. It tries to represent motions as ancient as dance itself.

"The other side of this coin was an intense interest in civilized craft. Matisse loved pattern, and pattern within pattern: not only the suave and decorative forms of his own compositions but also the reproduction of tapestries, embroideries, silks, striped awnings, curlicues, mottles, dots, and spots, the bright clutter of over-furnished rooms, within the painting. In particular he loved Islamic art, and saw a big show of it in Munich on his way back from Moscow in 1911. Islamic pattern offers the illusion of a completely full world, where everything from far to near is pressed with equal urgency against the eye. Matisse admired that, and wanted to transpose it into terms of pure colour. One of the results was The Red Studio, 1911.

"On one hand, he wants to bring you into this painting: to make you fall into it, like walking through the looking-glass. Thus the box of crayons is put, like a bait, Just under your hand, as it was under his. But it is not a real space, and because it is all soaked in flat, subtly modulated red, a red beyond ordinary experience, dyeing the whole room, it describes itself aggressively as fiction. It is all inlaid pattern, full of possible "windows," but these openings are more flat surfaces. They are Matisse's own pictures. Everything else is a work of art or craft as well: the furniture, the dresser, the clock and the sculptures, which are also recognizably Matisses. The only hint of nature in all this is the trained houseplant, which obediently emulates the curve of the wicker chair on the right and the nude's body on the left. The Red Studio is a poem about how painting refers to itself: how art nourishes itself from other art and how, with enough conviction, art can form its own republic of pleasure, a parenthesis within the real world - a paradise.

"This belief in the utter self-sufficiency of painting is why Matisse could ignore the Four Horsemen of the Apocalypse. When the war broke out in 1914, he was forty-five - too old to fight, too wise to imagine that his art could interpose itself between history and its victims, and too certain of his alms as an artist to change them. Through the war years, stimulated by a trip to North Africa, his art grew in amplitude and became more abstract, as in The Moroccans, 1916. In 1917 he moved, more or less permanently, to the South of France. "In order to paint my pictures," he remarked, "I need to remain for several days in the same state of mind, and I do not find this in any atmosphere but that of the Côte d'Azur." He found a vast apartment in a white Edwardian wedding cake above Nice, the Hótel Regina. This was the Great Indoors, whose elements appear in painting after painting: the wrought-iron balcony, the strip of blue Mediterranean sky, the palm, the shutters. Matisse once said that he wanted his art to have the effect of a good armchair on a tired businessman. In the 1960s, when we all believed art could still change the world, this seemed a limited aim, but in fact one can only admire Matisse's common sense. He, at least, was under no illusions about his audience. He knew that an educated bourgeoisie was the only audience advanced art could claim, and history has shown him right..."