The Piano Lesson, which opens tonight at the Arden Theatre, is the play set in the 1930s, about a family whose past is rooted in slavery. It is, in fact, a debate between a brother and sister about a beautifully carved piano depicting their ancestors' violent history.

The play begins with Boy Willie arriving at the home of his sister, Berniece, in Pittsburgh's Hill District, where Wilson grew up and where he set most of his plays.

Boy Willie wants to sell the piano so he can buy and farm the Mississippi land on which their ancestors worked as slaves. (Wilson frequently expressed his belief that the migration of agrarian African Americans to the industrialized, urbanized North was a fundamental error. "I think if we had stayed in the South, we would have been a stronger people," he said.)

Berniece, on the other hand, is determined to keep the heirloom; she believes "money can't buy what that piano cost."

Their struggle over the value of the past is the central conflict of the play, punctuated by the repeated offstage appearances of the ghost of Sutter, the plantation owner who bought and sold their ancestors.

Walter Dallas, who directs the Arden's production, says of The Piano Lesson, "It's a play about people who have relationships with the dead. Boy Willie's style of mourning is to build the American Dream on the foundation of land."

Dallas identifies with that yearning - his own ancestors were sharecroppers in Georgia. "My grandmother had a two-room shack on a farm. We sold it in the late 1980s," he says with mild regret.

The Piano Lesson's issue is the issue of every Wilson play: In his words, "If you don't connect with the past, you don't know who you are in the present."

In the course of the play we learn that two of Boy Willie's and Berniece's ancestors were traded for the piano, that another carved the images into it, and that a fourth was killed trying to retrieve it. Berniece, Dallas says, knows that "the piano needs to exist: We can't undo [history] but we can't forget" it either.

But the piano is not only a symbol and a shrine, it's also a musical instrument, and music is always central to Wilson plays, making them theatrical in a way most family dramas are not. People not only eat in Wilson kitchens, they sing in them, too.

The piano in this production is on loan from Baltimore's Center Stage theater company, for which it was designed in 2001 by Donald Eastman and built by Jennifer Stearns, an intern at the time and now props master. It's a player piano that comes equipped, literally, with an inner glow.

Its placement creates a staging problem: For its dramatic carvings to be completely visible, anyone playing it must face away from the audience - something no actor wants to do, particularly in a big scene.

But the piano is the show's real star, and also is the agent of the exorcism of Sutter's ghost in the climactic scene.

First the preacher, Avery, tries to get rid of the ghost with conventional prayer, and fails. Then Boy Willie, whom Dallas calls the "folk hero," physically battles it - "he fights the devil at the crossroads," Dallas says - and fails.

It isn't until Berniece, at the piano, calls on their ancestors through song that the ghost is driven out, by a powerful musical invocation described in Wilson's stage directions as "a rustle of wind blowing across two continents."

Wilson, talking about his experience while writing The Piano Lesson, said that he somehow knew from the beginning that the play would involve an elaborately carved piano but that he didn't know what the carvings would be or what they would mean. Then, well into writing the script, he saw a poster for a show of African carvings, and things fell into place.

(He went on to recount that when he wrote, early in the play, the line of dialogue "Sutter fell in the well," he paused over this previously unmentioned character and wondered, "Who's Sutter?" Such are the mysterious workings of the creative process.)

In the handsome 10-volume boxed set of Wilson's "Century Cycle" recently published by Theatre Communications Group, Toni Morrison wrote the new introduction to The Piano Lesson. Her essay concludes: "The struggle between memory and foresight, regret and promise operates within a world of terror. In that context, the battles are truly mighty; the victories as rough as they are noble."

The Arden Theatre Company, celebrating its 20th-anniversary season, tonight takes up August Wilson's challenge to stage those battles, those victories.

Theater

The Piano Lesson

7 tonight through April 6 at the Arden Theatre, 40 N. Second St. Tickets: $27-$45. Information: 215-922-112 or www.

ardentheatre.

org