Modern art was born ugly. "It was Matisse who took the first step into the undiscovered land of the ugly," an American critic wrote, describing the 1910 Salon des Indépendents in Paris. "The drawing was crude past all belief, the color was as atrocious as the subject. Had a new era of art begun?" Even Henri Matisse himself was sometimes shocked by his creations. According to his biographer Hilary Spurling, "His own paintings filled him with perturbation. At some point in 1901 or 1902 he slashed one of them with a palette knife."

If Henri Matisse was regarded as the father of modern art at the dawn of the 20th century, Pablo Picasso was sleeping with the same muse. When Picasso finished his form shattering masterpiece Les Demoiselles d'Avignon in 1907, portraying five prostitutes with primal masklike faces, their nudity more geometric than erotic, even his early dealer Ambroise Vollard blurted out, "It's the work of a madman." Matisse and Picasso didn't like each other's paintings at first, but they seemed to sense at once the power each had to challenge and stimulate the other. For the rest of their lives each would keep a keen eye on the other's new work, provoking each other to paint the same subjects, sometimes even with the same title. There are many ways to describe their relationship. It could be called a rivalry, a dialogue, a chess game - Matisse himself once compared it to a boxing match. But it also became the abiding friendship of two titans who, daring to paint the ugly, transformed our sense of beauty in art.

You have got to be able to picture side by side everything Matisse and I were doing at that time. No one has ever looked at Matisse's painting more carefully than I; and no one has looked at mine more carefully than he. ”
-Pablo Picasso

Wassily Kandinsky, whose book On the Spiritual in Art, published in 1912, constitutes the fundamental theory of abstract art and contrasted the two artists: "Matisse: colour, Picasso: form. Two great tendencies, one great goal". The relationship of Matisse and Picasso reflects on the whole history of modern art. Seeing Matisse and Picasso through each other's eyes allows the us to look at modern art in a fresh way, with the same sense of discovery that electrified the artists and their friends, and shocked their critics, nearly a century ago.

Picasso once said, "If I were not making the paintings I make, I would paint like Matisse," and Matisse said much the same about Picasso. One begins to see, when their paintings are set side by side, that their choices depended as much on their personalities, their temperaments and emotions, as on their skills and styles as painters. They were both figurative, and both abstract.

Matisse, who often painted goldfish, was later described by a fellow student in Paris art classes of 1900 as seeing like a goldfish "who takes intense delight in the rainbow colors and forms visible through the distorting globe of his glass bowl, and who, if he could paint, would depict them without worrying about what they actually represent." Picasso, on the other hand, insisted that he was painting directly from nature. "I always aim at the resemblance," he told his friend the photographer Brassaï. In each case, the quotes are misleading yet true, because both artists were full of inconsistencies, and always ready to change what they - or other artists - had done before.

The two painters were well versed in the art of the past, and both were seeking ways to escape its influence when they met circa 1906. The meeting was arranged by the American avant-garde writer and expatriate Gertrude Stein, who, with her brother Leo, had daringly begun collecting Matisse's new paintings when almost everyone else in Paris was laughing at them. As a writer, Stein was rearranging English syntax into new forms that seemed an outrage to all good sense. No wonder she loved Matisse's defiantly crude figures and wild colors, affronting the canons of beauty and sensibility.

When the Steins first visited Picasso's studio, they purchased 800 francs' (roughly $3,000 today) worth of paintings - a huge sum for a painter who had burned his own drawings to keep warm in 1902 and was not much better off when the Steins showed up in 1905. Although Matisse's and Picasso's works were exhibited together in a small gallery in 1902, they had apparently not met. The Steins took Matisse to Picasso's studio and invited both painters to their weekly salons. There the two artists could see each other's paintings on the walls, among the Cézannes.

At the time Matisse and Picasso met, they seemed to have little in common. They were as different, said Matisse, as the North and South Poles. Matisse was born in a northern district of French Flanders in 1869, into a family and region steeped in the weaving of brightly colored textiles. He had gone to Paris to study law, later taking up painting on the sly, attending art classes before and after a day's work as a law clerk. He was 22 years old when he determined to become an artist, ready to copy the old masters in the Louvre and keener still to capture Parisian life on paper and canvas.

Picasso was born 12 years later, in 1881, in the Spanish town of Málaga. His father was a painter, and the baby's first word was said to be "pencil." A child prodigy, he soaked up his father's lessons. As biographer Patrick O'Brian writes, when Picasso's father could teach him no more, he "handed his brushes over to the boy." In 1900 Picasso was nearly 19 and ready for Paris. By then he could draw like Francisco Goya and El Greco, but there were furies in him that demanded something else. "Academic training in beauty is a sham," he once said. "We have been deceived, but so well deceived that we can scarcely get back even a shadow of the truth."

Matisse had nearly a decade of radical painting under his belt in 1906, while Picasso was just emerging from his blue and rose reveries, and about to explode into Cubism. Matisse was the leader of the "fauves," or "wild beasts," as they were known, for their use of "brutal" colors. "All they give us in the way of sunlight," a critic carped of Matisse's paintings in 1906, "is trouble with the retina." Matisse's companion in creating fauve landscapes, André Derain, later recalled their sense of artistic violence. "Colors became sticks of dynamite," he said. "They were primed to discharge light." Matisse, more gently, said that he was finding out "how to make my colors sing."

One of the paintings Picasso saw in 1906 was Matisse's extraordinary synthesis of his fauve experiments - Le Bonheur de vivre, or The Joy of Life. It is an idyllic scene of reclining nudes, embracing lovers and carefree dancers. The colors are flat, the figures sketched in, some drawn as sensuously as Ingres' nudes, others as boldly as Cézanne's bathers. Nothing like it had ever been painted, even by Matisse. Picasso understood this at once and took it as a challenge.

First shown at the Salon des Indépendents in 1906, La Joie de Vivre seemed incomprehensible. It was greeted, recalled Matisse's first dealer Berthe Weill, with "an uproar of jeers, angry babble and screaming laughter. . . . " Yet in this painting Matisse had achieved a new kind of serenity, a harmony of unexpected elements, that he would draw on throughout his career. Picasso might well have had this canvas in mind when he said, years later,

In the end, everything depends on one's self, on a fire in the belly with a thousand rays. Nothing else counts. That is why, for example, Matisse is Matisse. . . . He's got the sun in his gut. ”
-Pablo Picasso

And in a sense, Picasso became Picasso because he would not let Matisse outshine him. Soon after seeing Le Bonheur de vivre, he set to work on his most ambitious and startling painting, Les Demoiselles d'Avignon. He repainted it over and over, using primitive masks and postcards of African women for models, drawing on Cézanne and Gauguin as guides, summoning all his will to undo the past and invent the future. It began as a tableau with a sailor surrounded by five prostitutes, all surprised by a student holding a skull entering stage right. It ended with just the women, their stares directed straight out at the viewer. As Picasso worked, he simplified, reducing the faces to crude masks, the bodies to fragmented fetishes, imbuing the canvas with a power both primitive and unimaginably new. None of this came easily or quickly.

As Picasso was struggling with his Demoiselles, he was jolted again by Matisse, who exhibited his shocking Blue Nude in 1907. Matisse had also used a postcard (of a nude figure) as the model, and was looking hard at Cézanne and Gauguin. With this new painting Matisse was stepping on Picasso's toes before Picasso could even put his foot down. The Steins grabbed up the Blue Nude, with its misshapen (some critics said "reptilian") figure reclining against a decorative background of palms. At the Steins, Picasso saw a young visitor from New York, writer Walter Pach, staring at the work. Pach later gave this account: " 'Does that interest you?' asked Picasso. 'In a way, yes . . . it interests me like a blow between the eyes. I don't understand what he is thinking.' 'Neither do I,' said Picasso. 'If he wants to make a woman, let him make a woman. If he wants to make a design, let him make a design. This is between the two.' "

It's a comment that reflects Picasso's own struggle at that moment. Years later he would tell the French writer André Malraux of something else that shaped his Demoiselles. Matisse had shown him an African statue he'd bought. Then Picasso went to the dingy ethnographic museum in Paris, the Trocadero, with its collection of primitive artifacts. It smelled like a flea market, but it opened his eyes to the magic of masks and fetishes. "If you give spirits a shape, you break free from them," he said. Suddenly, "I grasped why I was a painter. All alone in that museum, surrounded by masks, Red Indian dolls, dummies covered with dust. The Demoiselles' must have come that day . . . because it was my first exorcizing picture." When he finished painting it, Picasso had indeed changed everything. British art historian John Golding, writes: "If Le Bonheur de vivre is one of the landmarks in the history of art, the Les Demoiselles . . . changed its very course. It remains the most significant single twentieth-century painting." But in 1907, nobody knew that, not even Picasso. Matisse was horrified, along with the others who came to see it in Picasso's studio. The painter Georges Braque almost choked, Vollard recoiled, Leo Stein laughed and Picasso, frustrated and hurt, eventually took the canvas off its stretcher and put it aside without exhibiting it.

Matisse wasted little time in painting an unflinching response - his 1908 Bathers with a Turtle. It's a painting that truly set the two painters apart, even as they drew on the same sources. Paul Cezanne was everywhere in Picasso's painting, especially in its geometric fragmentations. But another aspect of Cézanne was evident in Matisse's new work, an awkward, almost childlike drawing style. As commented by one art historian: "Picasso is taking Cézanne's elements - the cone, cylinder and sphere - into Cubism. Matisse is taking Cézanne's interest in the wholeness and the clarity of figures. They're taking almost opposite interpretations of what they see in Cézanne: Picasso is understanding it as decomposition, and Matisse is understanding it as composition."

Cézanne was not their only source of inspiration. Both Picasso and Matisse had viewed a collection of Paul Gauguin woodcuts in 1906, and his South Seas primitivism showed up in woodcuts they both made soon after. Both Matisse and Picasso were looking at anything that would help them break with the past. Picasso was completely fascinated by photography, and Matisse said he used photographs to get over his academic way of drawing. They used images from erotic cinema meant for voyeurs, not painters. The question of line, of composition, was secondary, although the distortion, the perversion of line, was very important to them. It was a game with form, with figuration.

In the autumn of 1907, Matisse and Picasso had agreed to swap paintings. As Gertrude Stein tells it, each painter selected what he considered the worst example of the other's new work, as if to reassure themselves. Picasso picked a portrait of Matisse's daughter Marguerite, and Matisse chose a still life, Pitcher, Bowl and Lemon. It was said that Picasso hung the Matisse in a room where his friends threw fake darts at it.

And Picasso's painting held a joke for Matisse as well. A short time before the exchange, Matisse had been attacked in the press for a still life of his own. "Lemons are not flat, Monsieur Matisse," a critic had written. Picasso's lemon was even flatter than Matisse's. Moreover, Picasso's still life, made at the same time as the Demoiselles, is a clear leap into Cubism. "It's a very important exchange," said by one art critic, "a beautiful exchange. It's like an emblem, showing each other that they understand each other's program. It's like the first key to understanding them." It's as if they were saying to each other: "Here's how to be modern."

Neither was convinced. When Picasso's friend Braque sent a group of his own new paintings to the Salon d'Automne in 1908, Matisse was one of the jurors. "They're made of little cubes!" he protested as he voted to reject them. A critic heard this and baptized "Cubism" in the press. At the same time, though, Matisse took his most important collector,a Russian textile czar named Shchukin, to see the Demoiselles in Picasso's studio. Shchukin, whose Moscow home already boasted walls of Claude Monets, Pierre-Auguste Renoir's, van Goghs, Gauguins and Cézannes along with his Matisses, was at first shocked, but soon began buying Picassos too. It was an act of great generosity on Matisse's part.

Picasso plunged into Cubism with both feet, collaborating in the beginning with Braque. Matisse's response can best be seen in one of his most beautiful paintings, Portrait of Madame Matisse made in 1913, in which her face appears masklike. Picasso was sick that summer and Matisse visited him often. In Picasso's studio, he saw a white African mask hanging near the portrait of Marguerite he had given Picasso. Of Madame Matisse's portrait, the poet Guillaume Apollinaire said Matisse had reinvented voluptuousness in painting. Abstract as it is, with its masklike face and flattened sense of space, the serene portrait contrasts strikingly, despite certain similarities in format and subject, with Picasso's Portrait of a Young Girl, done the following year. In this painting, Picasso's Cubist approach undermines the serenity of the pose. But even in opposition, as in these two portraits, the dialogue between the two artists was clear.

Sometimes, however, it was more subtle. One painter might look far into the other's past, taking up where he had long ago left off. There are many examples of such cross-pollination, but one of the most striking is Picasso's monumental The Three Dancers. It was done in 1925 when he was working on the sets for the great Diaghilev's Ballets Russes. Matisse had done the sets and costumes for a Diaghilev ballet a few years before, which irked Picasso when he heard about it. "Matisse!" he snapped. "What is a Matisse? A balcony with a big red flowerpot falling all over it!"

But when Picasso set to work on The Three Dancers, he was likely looking over his shoulder at a painting Matisse had made in 1912, Nasturtiums with 'Dance'II. The visual analogies are obvious: they both distort the classic theme of the Three Graces, that trio of Greek goddesses who dispense charm and beauty. Picasso's painting, however, was utterly savage, while Matisse's retained some sense of grace. At the time, Picasso's marriage to Olga, an ex-ballerina, was failing, and he'd just gotten news of an old friend's death. The Three Dancers, like the Demoiselles, was a kind of exorcism.

By the 1920s, the two painters had drifted apart. Matisse was ensconced in a hotel in Nice painting luxurious odalisques and drawing portraits of women in plumed hats. "The sun-drenched fauve," wrote filmmaker and poet Jean Cocteau of Matisse, "has become a Bonnard kitten." In contrast, Picasso was drawing Minotaurs and Satyrs and painting stony neoclassical figures. But even then they kept an eye on each other.

In the late 1920s Picasso fell in love with Marie-Therese Walter, a young woman almost Grecian in her grace. To paint her, Picasso found himself borrowing the more flowing lines, rounded figures and vivid colors of Matisse. For his part, Matisse continued to distill the luminosity of Nice in his paintings. "A little while ago I took a nap under an olive tree," he had written in 1918 to a friend, "and the color harmonies I saw were so touching. It's like a paradise you have no right to analyze, but you are a painter, for God's sake! Nice is so beautiful! Alight so soft and tender, despite its brilliance."

Bathed in that light, Matisse was more or less abandoning the god Cézanne. In earlier years he had taken courage by telling himself, "If Cézanne is right, I am right." But talking to a visitor in 1920, he took a painting by Gustave Courbet from his wall and said, "This is what I call painting! Whereas this [he pointed to a Cézanne] . . . has less of an effect on me." And Picasso, drawing on Matisse and even Renoir as he painted his new paramour, was mellowing as well. There were moments when Picasso's portraits and Matisse's seemed painted with the same brush, if not the same hand.

Though Picasso stayed in Paris and Matisse remained in the south during World War II, their respect and friendship deepened. Picasso looked after Matisse's paintings, stored in a bank vault. Matisse, in ill health, defended Picasso against his critics. "This poor man," Matisse wrote to his son Pierre, "is paying a hard price for his uniqueness. He is living in Paris quietly, has no wish to sell, asks for nothing."

Yet both men were far too prickly to keep their peace. At the war's end in 1945, a major show of their work was held at the Victoria and AlbertMuseum in London. As he prepared for this exhibition, Matisse wrote in a notebook: "Tomorrow, Sunday, at 4 o'clock, visit from Picasso. As I'm expecting to see him tomorrow, my mind is at work. I'm doing this propaganda show in London with him. I can imagine the room with my pictures on one side, and his on the other. It's as if I were going to cohabit with an epileptic."

As Matisse's health sank in his 80s, his art soared. His long struggle to purify form, to make figures beautiful by making them simpler, to show essence and erase detail, led him back to the child's art of paper cutouts. Some of these were huge, others small enough for him to manage from bed. When a Dominican priest invited him in 1947 to design a chapel in the town of Vence, he prepared some of the images for the stained-glass windows and wall decorations by cutting out paper. Picasso, too, took up a pair of shears. He made a series of sculptures that look like paper cutouts, though they are of sheet metal. And his paintings seemed to take on a Matissean simplicity of form, even a decorative exuberance.

In retrospect, one should have seen this coming. Some of their earlier paintings, like Matisse's portrait of Marguerite, had a paper cutout look. And Picasso's collaborations with Braque involved cutting and pasting paper in Cubist collages. There were even earlier hints. Matisse always drew on the weaving traditions of his birthplace, using textile patterns to subvert perspective. Picasso had learned the same trick from his father, who used cut-out paper to construct his own paintings. It's an old, formal means for academic painters to build a painting. Cut-and-pasted paper was a way for a painter to conceptualize his work. Picasso and then Matisse took this from a low level, a hidden technique, and put it out front, on the surface, in the art itself. And that is a major part of modern art."

The 19th-century painter Eugene Delacroix, who inspired Matisse's odalisques and, after Matisse died, Picasso's, once wrote of his own struggle to be modern. The problem, as he saw it, was how to keep the freshness of a first sketch when making a final, finished painting. That's what putting hidden tricks up front was all about. It's why Matisse and Picasso chose to draw crudely when each could draw like Ingres, why Matisse liked his paintings to look unfinished and Picasso was bent on tearing everything apart. They took different approaches, but between them they made art modern.

"Only one person has the right to criticize me," said Matisse. "It's Picasso." After Matisse died in 1954, Picasso was alone, but not quite. "When Matisse died, he left me his odalisques as a legacy," he proclaimed, and proceeded to dissect them in a series of his own paintings. Picasso died in 1973, believing to the end, as he said, "All things considered, there is only Matisse."