Kara Walker's subject is history, a dark past full of cruelty, both real and imagined. It is the fearful and ecstatic dream life of slavery -- historical catastrophe for African people.

Although her work is cut-paper collage, it is a spiritual ancestor of history painting, once the highest genre of post-Renaissance academic art, a painting and sculpture that spoke to moral and civic values using the materials of history, religion and myth. But hers is a surrealist history painting of the wounds of race in the American psyche, a fearless exploration of its psycho-sexual imaginary.

In imagining how life was lived and dreamed by a people generation after generation through the total disaster of enslavement and oppression, she has given us a grisly parade of fornicators and cannibals with protruberant bones and broken ecstatic bodies.

Walker works rich formal territory for a figurative artist -- she uses highly charged stereotyped imagery, combined with pictorial formats from the 19th-century popular press. It is territory probably only an African American artist can work. For instance, the white artist Conrad Vogel, born in the South, has worked similar themes for years. But he has been condemned to allegory -- the principal referents of his bacchanalian silhouetted figural ensembles are medieval, literally the demons of the past.

Walker follows on from Robert Colescott's career of grand cartoonish history painting. (Both might be seen as latter-day inheritors of the freaky cartoonish art of 19th-century painter John Quidor, and for Colescott early van Gogh.) Walker's work amounts to the hardcore version of Colescott's bluesy tales of color, war and lust, authorized into further formal reaches by Fred Wilson's project Mining the Museum.

Walker builds her art of historical depiction proceeding from the cheapest pre-photographic means of portraiture, the twopenny silhouette cut on the spot of a subject in profile. She enlists the ancient stock graphic format of march and processional (e.g., Triumph of Bacchus) which she perturbs with flying and hanging figures, as in 19th-century circus posters and the higgledy-piggledy "raucous house" pictures of Bill Traylor.

In this show she has plunged deeper into the resources of vernacular imagery, scooping up formats from the printed ephemera called "paper" in the collectibles trade, things like scrapbooks and greeting cards, and the handmade friendship tokens Victorians so esteemed.

At the same time she has launched her works into depth, placing her signature black paper silhouette cutouts onto the wall positioned in relation to a projected image. This comes from the simplest of means, the overhead projector familiar from grammar school, the snorkel-shaped lens throwing up swirled shards of brilliant color.

In the most startling instance of the tiny made large, a black and white picture of a flat-bottomed riverboat steamer is projected to become a vast indeterminate Piranesian space on the wall peopled with cutouts large and small, some tiny and distant within the smoky environs.

What is the utility of this art? One may ask as well what is the use of suffering? Humankind shares its evil nature as well as its fine aspirations, and in an art that drives fearlessly into this psychically terrifying and exhilarating terrain there is help for descendants of both oppressed and oppressor.

Kara Walker's work is imbued with mad love. And, by being made into pornographic cartoons, we find the seamier aspects of American visual culture partly redeemed.