"Kahlo was born in Mexico City in 1907, the third daughter of Guillermo and Matilda Kahlo. Her father was a photographer of Hungarian Jewish descent, who had been born in Germany; her mother was Spanish and Native American. Her life was to be a long series of physical traumas, and the first of these came early. At the age of six she was stricken with polio, which left her with a limp. In childhood, she was nevertheless a fearless tomboy, and this made Frida her father's favourite. He had advanced ideas about her education, and in 1922 she entered the Preparatoria (National Preparatory School), the most prestigious educational institution in Mexico, which had only just begun to admit girls. She was one of only thirty-five girls out of two thousand students.

"It was there that she met her husband-to-be, Diego Rivera, who had recently returned home from France, and who had been commissioned to paint a mural there. Kahlo was attracted to him, and not knowing quite how to deal with the emotions she felt, expressed them by teasing him, playing practical jokes, and by trying to excite the jealousy of the painter's wife, Lupe Marin.

"In 1925, Kahlo suffered the serious accident which was to set the pattern for much of the rest of her life. She was travelling in a bus which collided with a tramcar, and suffered serious injuries to her right leg and pelvis. The accident made it impossible for her to have children, though it was to be many years before she accepted this. It also meant that she faced a life-long battle against pain. In 1926, during her convalescence, she painted her first self-portrait, the beginning of a long series in which she charted the events of her life and her emotional reactions to them.

"She met Rivera again in 1928, through her friendship with the photographer and revolutionary Tina Modotti. Rivera's marriage had just disintegrated, and the two found that they had much in common, not least from a political point of view, since both were now communist militants. They married in August 1929. Kahlo was later to say: 'I suffered two grave accidents in my life. One in which a streetcar knocked me down... The other accident is Diego.'

"The political climate in Mexico was deteriorating for those with left-wing sympathies, thanks to the reactionary Calles government, and the mural-painting programme initiated by the great Minister of Education Jose Vasconcelos had ground to a halt. But Rivera's artistic reputation was expanding rapidly in the United States. In 1930, the couple left for San Francisco; then, after a brief return to Mexico, they went to New York in 1931 for the Rivera retrospective organized by the Museum of Modern Art. Kahlo, at this stage, was regarded chiefly as a charming appendage to a famous husband, but the situation was soon to change. In 1932 Rivera was commissioned to paint a major series of murals for the Detroit Museum, and here Kahlo suffered a miscarriage. While recovering, she painted Miscarriage in Detroit, the first of her truly penetrating self-portraits. The style she evolved was entirely unlike that of her husband, being based on Mexican folk art and in particular on the small votive pictures known as retablos, which the pious dedicated in Mexican churches. Rivera's reaction to his wife's work was, however, both perceptive and generous:

Frida began work on a series of masterpieces which had no precedent in the history of art - paintings which exalted the feminine quality of truth, reality, cruelty and suffering. Never before had a woman put such agonized poetry on canvas as Frida did at this time in Detroit.

"The enterprise was finally rescued by Marcel Duchamp, and the show opened about six weeks late. It was not a financial success, but the reviews were good, and the Louvre bought a picture for the Jeu de Paume. Kahlo also won praise from Kandinsky and Picasso. She had, however, conceived a violent dislike for what she called 'this bunch of coocoo lunatic sons of bitches of surrealists.' She did not renounce Surrealism immediately. in January 1940, for example, she was a participant (with Rivera) in the International Exhibition of Surrealism held in Mexico City. Later, she was to be vehement in her denials that she had ever been a true Surrealist. 'They thought I was a Surrealist,' she said, 'but I wasn't. I never painted dreams. I painted my own reality.'

"Early in 1940, for motives which are still somewhat mysterious, Kahlo and Rivera divorced, though they continued to make public appearances together. In May, after the first attempt on Trotsky's life, led by the painter Siqueiros, Rivera thought it prudent to leave for San Francisco. After the second, and successful attempt, Kahlo, who had been a friend of Trotsky's assassin, was questioned by the police. She decided to leave Mexico for a while, and in September she joined her ex-husband. Less than two months later, while they were still in the United States, they remarried. One reason seems to have been Rivera's recognition that Kahlo's health would inexorably deteriorate, and that she needed someone to look after her.

"Her health, never at any time robust, grew visibly worse from about 1944 onwards, and Kahlo underwent the first many operations on her spine and her crippled foot. Authorities on her life and work have questioned whether all these operations were really necessary, or whether they were in fact a way of holding Rivera's attention in the face of his numerous affairs with other women. In Kahlo's case, her physical and psychological sufferings were always linked. in early 1950, her physical state reached a crisis, and she had to go into hospital in Mexico City, where she remained for a year.

"During the period after her remarriage, her artistic reputation continued to grow, though at first more rapidly in the United States than in Mexico itself. she was included in prestigious group shows in the Museum of Modern Art, the Boston Institute of Contemporary Arts and the Philadelphia Museum of Art. In 1946, however, she received a Mexican government fellowship, and in the same year an official prize on the occasion of the Annual National Exhibition. She also took up teaching at the new experimental art school 'La Esmeralda', and, despite her unconventional methods, proved an inspiration to her students. After her return home from hospital, Kahlo became an increasingly fervent and impassioned Communist. Rivera had been expelled from the Party, which was reluctant to receive him back, both because of his links with the Mexican government of the day, and because of his association with Trotsky. Kahlo boasted: 'I was a member of the Party before I met Diego and I think I am a better Communist than he is or ever will be.'

"While the 1940s had seen her produce some of her finest work, her paintings now became more clumsy and chaotic, thanks to the joint effects of pain, drugs and drink. Despite this, in 1954 she was offered her first solo show in Mexico itself - which was to be the only such show held in her own lifetime. It took place at the fashionable Galeria de Arte Contemporaneo in the Zona Rosa of Mexico City. At first it seemed that Kahlo would be too ill to attend, but she sent her richly decorated fourposter bed ahead of her, arrived by ambulance, and was carried into the gallery on a stretcher. The private view was a triumphal occasion.