Five years ago at Indigo, Cholet's folk-arts gallery in Philadelphia's Old City, a customer squinted at a religious amulet from India.

"Shiva or Frida?" the shopper asked, unsure whether it represented the Hindu deity of transformation or the Mexican artist, transformer of pain.

"Frida. She's gone global," Cholet heard herself say.

One can honor the centenary of Frida Kahlo (1907-54) in many ways. Buy one of the ubiquitous trinkets adorned with the artist's unibrowed face. See one of the seven biopics, perhaps the Oscar-winning Frida (2002) starring Salma Hayek. Light a votive candle. But for both acolytes and agnostics, a pilgrimage to the retrospective at the Philadelphia Museum of Art that opens Wednesday is essential.

That Frida - known by one name, like Athena, Garbo and Beyoncé - is one of the most popular and widely recognized 20th-century artists is "a mixed blessing," Victor Zamudio-Taylor writes in the exhibition catalog.

Matron saint of Mexican women, undocumented workers and unwed mothers, Mother Courage of feminists, multiculturalists and the disabled, Frida is holy to many.

If the museum retrospective accomplishes anything, says Hayden Herrera, the artist's biographer and cocurator of the show (with Elizabeth Carpenter of Minneapolis' Walker Art Center), it will rescue Frida's art from Fridamania. Says Herrera, "I hope this show will make her known less as a saint and more as an artist."

There are many faces of Frida, almost as many as the two dozen self-portraits in the show, which in all comprises 45 paintings and 100 photographs.

In a 1926 study she wears European clothes, a cryptic expression, and the elongated features of a Modigliani subject. In 1929 - the year she married legendary muralist Diego Rivera, twice her 21 years and three times her 100 pounds - she depicts herself stone-faced, in a Mexican peasant blouse and pre-Columbian necklace. ("She has an important place as a figure who preserved and advertised Mexican folkloric culture," says Julia Zagar, owner of Philadelphia's Eyes Gallery.)

By 1932, in the unnerving My Birth, which Zamudio-Taylor reckons as the first time in Western art history this theme had been explicitly treated, she paints her own parturition: A mature, unibrowed head - recognizably Frida, but also recognizably the Aztec goddess Tlazolteotl - emerges from the womb, while above the birthing bed an image of the Mater Dolorosa witnesses the delivery.

Does it influence how we look at this painting if we know that this stunning canvas of and about self-creation is in the collection of another self-created phenom, Madonna?

Regardless, in these early works Frida seeds her enduring legacy: the wedding of European modernism and Mexican folk art.

It came naturally to the daughter of a German-born photographer, believed to be an atheist Jew, and an observant Hispano-Indian Catholic.

In intimate, deeply personal work that was the antithesis of her husband's epic, public projects, Frida synthesized modern and traditional, irreverence and piety, the personal and the universal. She was both a creator and self-creator.

"Frida unified Europeanized Mexico with pre-Columbian Mexico in the way Guadalupe, 'the brown Virgin' and Mexico's patron saint, unified European Christianity with indigenous beliefs in Mexico," observes Judy Baca, muralist, UCLA professor, and one in the legion of artists for whom Frida has been a lodestar.

Creating a visual language that spoke to the humblest of her own countrymen and to artists such as Pablo Picasso made Frida a cultural heroine in her lifetime. Posthumously, she became an international art star when first Latino artists in the 1960s and then feminist artists in the 1970s rediscovered her. But those achievements do not a saint make.

In 1925, Frida - whose leg had been withered by polio in childhood - was planning to study medicine. Instead, she became a medical case study.

Returning from school, she was on a bus that collided with a trolley. On impact, the trolley's handrail skewered her spinal column - "the way a sword pierces a bull," she later recalled - before exiting her vagina. Her spine and pelvis were shattered; doctors initially held out little hope that she would even survive. During her foreshortened life - she died at 47 - she endured numerous surgeries and miscarriages.

Encased in plaster casts during her convalescence, she began to paint in bed, with brushes and an easel that were gifts from her photographer father. (The tender brushwork may be the product of having helped her father carefully retouch photos.)

Her family installed a mirror in the canopy of her four-poster and she found a handy subject: herself. In self-portraits anchored by a frontal gaze that engages as it unnerves, her recurring motif is pain - physical, psychological and romantic pain - transformed into death-defying strength.

In The Broken Column, a superb 1944 self-portrait, she represents her fissured body with a crumbling Ionic column for a spine, carpenter's nails imperfectly holding together a broken body. There are tears on her face, but her features are stoic and the body language impervious. She is not her pain. She is about its exorcism, the face supremely composed in a decomposing body.

Does knowing the pain she transcended influence how we read her paintings?

"We'll never know how her physical constraints influenced how she painted," reflects Anne d'Harnoncourt, Art Museum director.

Trussed in a cast or an orthopedic corset, Frida could not handle large-scale canvases, which limited the size of her work. Says d'Harnoncourt, "Her best-known work is the scale of notebook paper."

An exception is The Two Fridas (1939), 4 feet square, one of the two large-scale canvases she produced. It was painted on the eve of her divorce from the philandering Rivera, whom she would remarry a year later.

In this image of her own duality, she honors both her European and her Mexican heritage. The Frida on the left, the unloved one, wears a Victorian dress open at the bosom, and literally nurses a broken heart bleeding on her white frock. The Frida on the right, in Mexican folk dress, is wholeheartedly strong, sustaining her grieving double.

Does it influence how we read this painting if we know that Frida was likewise a sexual adventurer, one whose lovers included sculptor Isamu Noguchi, Communist Leon Trotsky, and many women?

"Frida was a politically and socially engaged artist," says Norma Broude, professor at American University. "When cultists frame her as a victim, that legacy gets swept under the rug."

"What I find fascinating is how Frida appropriates religious artistic forms, but does not use them for religious purposes," says Janet Kaplan, art history professor at Moore College of Art and Design.

Frida's use of the ex-voto - folk paintings giving thanks to saints for intercession - invites religious interpretations, as does imagery like the bleeding heart in The Two Fridas.

But rather than use such form and content to express the spiritual and sacred, Frida communicates the personal and profane, in that potent and impertinent gaze. For an artist whose apparent subject was herself, there is no self-consciousness.

There is acceptance.

Does it influence how we consider her legacy if we know that her last diary entry read, "I hope the exit is joyful; and I hope never to come back"?

At the Museum of Art, Frida is intensely present in self-portraits that engage, reproach, seduce and transcend. Even Herrera, who wants to refocus attention on her art rather than on her eventful life and fervent cultists, has to admit, "Her paintings give you strength."

Likewise Frida's gaze. Despite her wish, she keeps coming back, each time bigger than ever.

A local artist creates larger-than-life Frida puppets at http://go.philly.com/frida