Two different


feelings hit me during

House, Divided

, the often-smart play by Larry Loebell that opened Wednesday with a first-rate cast, in a world-premiere production by InterAct Theatre Company. It is, remarkably, one of the rare pieces of theater to deal with the conflict between Israel and the Palestinians.

My first reaction came after Act I, which forcefully mirrors the conflict by focusing on a 33-year estrangement of two brothers in a Philadelphia Jewish family and the growing friendship between their two sons. Loebell, a Philadelphia playwright, establishes the family conflict - and in doing so, the Mideast conflict - with impressive clarity.

"Oy!" I said to myself: Not even

Sixteen Wounded

, a fine play about a Jewish baker and his Palestinian apprentice that somehow failed on Broadway in 2004, spelled out the political, social and religious conflicts so efficiently. It was the "oy!" you utter when you're caught by surprise, and impressed.

After Act 2, I had a different take. Loebell adds layers of complications and revelations to his plot, presumably to further plumb the conflict - particularly the way it involves Jews who look at Mideast issues from differing perspectives. Describing the plot surprises would reveal too much of the play, but they spurred my second "Oy!," one of sad disbelief. Instead of clarifying the issues with his twists, Loebell muddies them.

Even so, the fully engaging

House, Divided

is an important play: It handles delicate arguments and forcefully presents all sides - and does so using only Jewish characters: older brother Louis (David Howey), who moved decades ago with his widowed father to Israel, where he's a proud tour guide; the younger brother Doug (Paul Meshejian), whose passion for social justice bloomed into a job in Philadelphia with Amnesty International; Louis' son (Davy Raphaely), an Israeli soldier; and Doug's son (Dan Hodge), who writes computer war games for a living.

Robert T. DaPonte and Noah Herman play younger versions of Lou and Doug, who move in and out of scenes on Dirk Durossett's clever set to chart the roots of their estrangement. Every cast member is convincing, offering an articulate character study. Raphaely's role as the soldier is toughest, in part because he's saddled with much of the second-act complications. But he establishes a point of view quickly, making it easier for the audience to consider a change in plot that's hard to buy.

In an evocative piece of staging, InterAct's producing artistic director, Seth Rozin, has the young Lou and Doug walk quietly into scenes when the older versions of themselves, reunited by a family crisis, attempt awkwardly to communicate. That's a tip of the hat to a basic value in Judaism: Pivotal concepts evolve when each generation hands them to the next.

Ultimately, the play succeeds in posing the question: What are we, on whatever side of the conflict, handing down?

House, Divided

Presented by InterAct Theatre Company at the Adrienne, 2030 Sansom St., through June 22. Tickets: $23-$27.

Information: 215-568-8079