Beware of all art not created by the possessed, say I. And the Mexican painter Frida Kahlo (1907-1954) was nothing if not possessed. She was by temperament a religious painter, even though her religion often took the form of grotesque narcissism. The martyrdoms she depicted were her own, and, as a card-carrying Communist, she was by definition an atheist.

Still, no twentieth-century artist was more consumed by a sacred, self-appointed mission than Frida Kahlo, a furibunda, as Virgil said of the Cumaean Sibyl, one "inspired with mad divination." She is the saint and recording angel of suffering, disease and death, depictor of gruesome episodes, champion of la raza, the people; of women; of the freakish; of the sexually ambiguous; and of animals.

Frida Kahlo was born in 1907 in Coyoacán, the blue house in a suburb of Mexico City where she would die forty-seven years later. Her father, Guillermo Kahlo, was a Hungarian-Jewish portrait photographer who had immigrated to Mexico, her mother, Matilde Calderón, an illiterate, religion-obsessed Mexican. It is the fusion of European and indigenous sensibilities that creates the oscillating elements of Kahlo's personality and makes her paintings so mesmerizing. Painter and subject, victim and heroine, urbane primitive and realistic hagiographer of her own androgynous stations of the cross.

Her life was a series of physical and emotional calamities through which she transformed herself. As a child she had polio, but out of this illness emerged her most fantastic creation, the imaginary Frida, the strong, robust, beautiful, heroic Other.

In explaining the origin of her doppelganger self-portrait, The Two Fridas, Kahlo wrote:

At seventeen she was seriously injured in a horrific accident when a trolley collided with the bus in which she was riding. In the collision a metal pole entered her hip and came out through her vagina, her spinal column was broken in three places, her ribs were crushed, her foot and leg broken. With her macabre sense of humor she announced that she had lost her virginity to the accident. A bizarre detail of the crash suggests the combination of the grotesque and the exotic that is characteristic of her paintings: Her body was found in the wreck covered in both blood and gold dust (which a passenger had been carrying in a paper bag).

Bored and isolated during her long recovery, she began to paint, using her father's paintbox and brushes. Although she had no formal art training, her early paintings—done either in a primitive cubism or (like the glamorous self-portrait she made for her boyfriend) in the style of Modigliani—are far from amateur. Perhaps she learned from her father, an amateur painter himself.

This being the age of the heroic mural painters in Mexico, Diego Rivera, José Clemente Oroxco and David Alfaro Siqueiros were all toiling at their epic paintings on the walls of post offices and ministries of agriculture. Emboldened by the response her paintings received, Frida went to show them to Rivera. Although they were the ultimate odd couple—he was childish, gregarious, huge and hugely fat; she frail, neurasthenic and morbid—they fell in love at once, and in August of 1928 they were married. The marriage, said Frida's parents, was that of an elephant and a dove.

They remained passionately fond of each other until Kahlo's death in 1954, but Rivera's chronic womanizing made the marriage an ongoing torment for Kahlo. An unlikely Don Juan—Kahlo described him as a cross between the Buddha and a frog—he had numerous affairs, including flings with the movie stars Paulette Goddard and María Félix. Although Frida had many liaisons herself with both women and men (the exiled Leon Trotsky, the sculptor Isamu Noguchi), she was devoted to Rivera and deeply wounded by his unfaithfulness.

After her marriage Kahlo began to paint decorative, heroic portraits of Mexican-Indian women in Rivera's stirring, populist manner. In 1932, while Rivera was working on a mural in Detroit, Frida had a miscarriage. Her despair at the loss of "little Dagueito," however, also precipitated her most creative period.

Rivera, seeing her inconsolable desperation, suggested she try painting on a piece of sheet metal in the manner of a Mexican retablo. A retablo is a votive painting made to commemorate a miracle, showing the tragedy—a disease, an accident—and the saint who helped avert or overcome the tragedy. A banner or a panel below the painting would explain the story.

The magic power of the retablo comes from its refusal to distinguish between fact and fantasy. In the retablo, belief subsumes reality within its cosmic eye. And it was the retablo's supernatural capacity to link inner and outer, sacred and profane that Frida took as her model. Like a retablo or an icon, Kahlo's paintings (with a couple of exceptions) conform to the small, intimate scale of folk art, most of her pictures measuring eleven inches by fifteen inches or fifteen by twenty.

The painting recording her miscarriage, Henry Ford Hospital, in which a nude Kahlo on a hospital bed is connected by an umbilical ribbon to six strange objects (three of them suspended in the air), might at first resemble a painting by Magritte or Max Ernst, in which incongruous objects are juxtaposed for an unsettling effect. But although she was embraced by the surrealists, Kahlo's surrealism is (mostly) unintentional (though she was far from being a naive painter and well aware of European movements).

Where a surrealist painting depends on absurdity, Kahlo's paintings, like medieval Annunciations, bristle with meanings. Not a single object is put in her paintings that does not bear some, often many, symbolic purposes: the prayerful floating fetus, the anthropomorphic pelvic skeleton, the hemorrhaging uterine orchid, the giant snail (indicating the painful slowness of the operation), the pink translucent anatomy torso (objectification of female mysteries), the sinister machine (clinical coldness).

In the early '30s, Kahlo began her series of autobiographical self-portraits in earnest by making a painting to represent every year of her life, beginning with My Birth (1932). When she says the painting represents "how I imagined I was born," she means it with hair-raising literalness. In this horrific nativity we see a room with grey walls and a wooden floor bare of all furniture except a wooden bed. On the white sheets of the bed is a scene so graphic and startling it might be an early Francis Bacon: A woman, with legs spread, is giving birth to a baby. No detail is spared: the folds of the mother's vagina, her pubic hair, the contorted head and closed eyes of the newborn emerging from the womb, the blood-soaked bed. What makes this picture particularly gruesome is that the mother's head is entirely covered by a sheet.

On one level the newborn is clearly meant to be Kahlo herself, as is indicated by the joined eyebrows. But Frida also thought of the baby as the child she had recently miscarried. We learn that the mother's face is covered because Kahlo's mother died just as Frida was completing this painting.

As with all Kahlo's paintings, interpretations multiply. The painter herself saw it as representing "the one who gave birth to herself... who wrote the most beautiful poem of her life."  But the painting above the bed of the Mater Dolorosa, who knows of the crucifixion to come, suggests a more universal reading. The grief-stricken Virgin Mary with two daggers sticking in her throat underscores the spiritual agony of the event and symbolizes the suffering of women, death fertilizing birth, and other cosmic themes that obsessed Kahlo. The fusion of the sacred and the grotesque, the symbolic and surreal, the Freudian and the folkloric—this is the essence of Kahlo's disturbing style.

My Birth, like all Kahlo's work, is painted in the meticulously detailed style of folk art, in which every floorboard, every filigree of lace is depicted. Everything in the room is centered, symmetrical, frontal, iconic. Kahlo was not a primitive, she moved in cosmopolitan circles, her diaries are decorated with sophisticated, modernist sketches, but she chose the stilted poses of portrait photography and painstaking detail of naive paintings to lend her art an ingenuous authenticity.

Her subtle overlapping of disparate styles of representation is what gives the faces in her paintings their hypnotic quality: the immobility of the sitter in formal nineteenth-century photographs, the earnestness of primitive portraits, the stunned gaze of the psychologically damaged in clinical records and the hieratic pose of the religious icon.

Kahlo's most memorable paintings are her self-portraits. The odd thing about them is that, unlike those of Rembrandt or Picasso, which show a wide and inventive range in their introspection, the face that peers out at us in Kahlo's self-portraits—interrogating, pleading, asserting—is virtually the same in all her paintings. But we hardly notice this, because the face itself is so amazing—the eyebrows touching like the wings of a tiny bird, the faint "Zapata" mustache, the sensual lips and dark, wary eyes. Like the Mona Lisa, her haunted features become a sort of palimpsest into which infinite meanings can be read.

Multiple interpretations arise as this enigmatic head is placed against allegorical backgrounds of claustral, menacing vegetation, stormy clouds or empty rooms. In Itzcuintli Dog and I (in which Frida sits on a chair smoking a joint with an absurdly small dog at her feet) or Self-Portrait with Monkeys, for instance, her baleful gaze, immobility and melancholy are made more poignant by the presence of the restless energy of the cats, dogs, parrots, pet deer and spider monkeys that surround her, animals being Mayan symbols of sex and freedom. Immobile and wearing exotic costumes, she has the aspect of a wounded, vengeful goddess surrounded by her familiars.

In the fantastic Little Deer of 1946, she fuses utterly with the stricken stag. A wounded miniature deer with Frida's face is set against the theatrical set of a decaying wood with the sea in the distance. Kahlo's backgrounds, with their shallow, two-dimensional space, reminiscent of a photographer's painted backdrop, lend a ritual quality to the events in her paintings that intensifies their actions. Like some feral St. Sebastian, nine arrows penetrate the deer's bleeding flank, the nine wounds, like the nine tines of its horns, representing Rivera's most grievous infidelities—the last straw being his affair with her younger sister, Cristina.

Her divorce from Rivera in 1939 inspired some of her most ferocious paintings, including the hysteric allegory The Wounded Table, her self-portraits from 1940 with necklaces of thorns and a dead hummingbird and The Suicide of Dorothy Hale, commissioned by Clare Booth Luce. Luce was so horrified by the result that she had portions of the picture painted out.

The most alarming of all is her Self-Portrait with Cropped Hair, in which a sullen and murderous Kahlo in a man's black suit sits in a yellow chair (reminiscent of the one in van Gogh's room), her head shorn and a pair of scissors in her hand. The floor is strewn with locks of her hair that, like her venomous thoughts, have turned into a sea of thrashing snakes intent on doing her vindictive bidding.

Kahlo's teenage sweetheart, Alejandro Gomez Arias, once said, "The personality of this woman was so contrary and multiple that you could say there were many Fridas. Maybe none the one she wanted to be." In her most fantastic self-portrait, The Two Fridas, all the imaginary doublings and painful ambivalences of her life are written with unnerving precision. Against the backdrop of a turbulent El Greco sky, her divided selves sit for a formal phantasmagoric portrait.

On the right is the Frida beloved of Diego, dressed in native costume; on the left is the rejected Frida, stiffly enclosed in a white wedding dress. Both women's hearts have been removed, but the bridal Frida's heart has been ripped apart and in her hand she holds a pair of scissors that have just snipped the vein that connects her to Rivera. Blood drips on her lap. This split in Kahlo's attitude to herself may explain why we accept what might otherwise appear to be morbid self-indulgence.

On May 20, 1940, Trotsky was gunned down by one of Stalin's agents. Under suspicion of murder, Rivera fled to San Francisco, where Kahlo joined him. They were remarried on December eighth, Rivera's birthday. But his carnal habits did not change. As late as 1949, he again considered divorce, so that he could marry the Mexican movie star (and Kahlo's close friend) María Félix.

By the mid-'40s, Kahlo's health declined, and she went through a series of horrendous operations. A metal rod was inserted in her spine, and for almost a year she was forced to wear a steel corset. Her leg was amputated. Some of her paintings from this period—The Broken Column, Without Hope and The Tree of Hope—are so graphic that they are excruciating to look at, but her spirits were apparently high.

"With my new bone," she told a friend in a drug-induced euphoria, "I feel like shooting my way out of the hospital and starting my own revolution."

She began painting a series of hallucinatory still lifes, in which fruits and vegetables become writhing, sexualized and vaguely menacing presences. In Roots, a vine intended as a symbol of fertility—but still monstrous—grows out of her chest, forming giant mutant leaves.

Her colors became more saturated and took on idiosyncratic, emblematic meanings. "REDDISH PURPLE," she noted in her diary, represented "old blood of prickly pear; YELLOW: madness, sickness; COBALT BLUE: electricity, purity, love; LEAFY-GREEN: leaves, sadness, science. The whole of Germany is in this color. DARK GREEN: the color of bad news and business."

On July 2, 1954, she got out of her hospital bed and demonstrated in her wheelchair against the CIA-engineered takeover of Guatemala, shouting, "Get out, gringo murderers!" Eleven days later she died, reportedly of a pulmonary embolism (those close to her suspected she had taken her own life). The final entry in her diary showed a hovering black angel with the words: "I hope the exit is final and joyful—and I hope never to come back. Frida."

Had you found that magic door again that, as a child of six, you had painted with your breath on the window pane? Did you disappear into your imaginary world through the eye of the letter "O" that, like a blank face, waited for you at the end of your name?