Legend has it that Madonna once said she would not be friends with anyone who didn't like her prized Frida Kahlo painting, My Birth. The painting -- reproduced below -- depicts Kahlo's head poking out of a vagina, presumably her mother's. Madge's former husband Guy Ritchie was reportedly creeped out by the painting and by Madge's insistence on hanging it on their bedroom wall. This purportedly helped along the dissolution of their otherwise perfect union.

Madonna has loaned paintings from her extensive Frida Kahlo collection to other galleries, but My Birth is not among the collection now showing at the AGO. The Kahlo paintings that are in the show are extraordinarily gut-wrenching and beautiful, though whether they are powerful enough to drive away pretentious English auteurs remains to be seen.

By this point Kahlo's paintings have become part of the wallpaper of our visual existence. The unibrow, the mustache, the monkeys -- most of us are familiar with the iconography. But, as with all great art, the objects themselves are luminous and, though much smaller than expected, have an emotional impact that transcends reproductions.

But what about the pesky "& Diego" in the exhibition's title? In the 1930s Diego Rivera was one of the world's most famous painters, both as an artist and as a celebrity. Kahlo was his 20-years-younger wife. A 1929 photograph of the couple included in the exhibition is titled Diego Rivera and his Bride. As time passed and feminism, queer theory and Madonna took hold, Kahlo's fame overtook Rivera's, and she is now more familiar to a mainstream audience. Part of this exhibition's purpose appears to be an attempt to restore the patriarchal balance and reassert Rivera's mastery. Tough luck. Though Rivera's huge murals and beautiful paintings are certainly wonderful, Kahlo's tiny canvases pack a punch that Rivera just can't compete with. How much of that has to do with Kahlo's back story and the film of her life is debatable, but Kahlo's paintings demand attention while Rivera's are just admirable. Portraits of Natasha Gelman, painted in 1943, hang side by side in one gallery. Rivera paints her as a beautiful woman with a come-hither look, but she is an object. Kahlo has Gelman swathed in furs, her face haunted and mysterious. No contest.

Rivera was a professional painter, and seeing his style evolve -- even through an unfortunate flirtation with cubism -- is fascinating. But once his metier was found, that was it. Kahlo's cris de coeur -- even with her unfortunate penchant for clumsy surrealism -- grab at your heart, the anguish visible in every meticulous brush stroke. Their love affair was purportedly tumultuous, but Kahlo's last paintings are filled with a palpable longing, and Rivera died, supposedly of grief, shortly after she did. As the documentation of a love story between artists and egos, Frida & Diego is delicious and heart-breaking.

The photographs accompanying the paintings not only illustrate the relationship and history of the artists, but also provide a clue to Madge's identification. In every self-portrait -- and most of Kahlo's paintings are self-portraits -- the face is depicted in the same position; Kahlo appears very aware of her most flattering angle. In the photographs, while still stunningly beautiful in her androgyny and in control of the image presented, Kahlo is at the mercy of the photographer. I'm sure Madge wishes she could control her posthumous future as effectively.

Frida & Diego: Passion, Politics and Painting runs Sat, Oct 20-Sun, Jan 20 at the Art Gallery of Ontario, 317 Dundas St W. ago.net