Wendy Wasserstein's thought-provoking and amusingly drawn Third, in a first-class production by the Philadelphia Theatre Company that opened Wednesday, offers us a woman we can identify with in every way . . . until she begins talking. Wasserstein has drawn Jamison in the extreme - a professor with an unflagging feminist agenda, whose latest book is Girls Will Be Boys: The Demasculinization of Tropes in Western Literature. She teaches a class called "Uncorseting Elizabethan Drama," in which King Lear, for instance, is interpreted in the most unorthodox fashion - if fashion were even a tolerable idea to Professor Jamison.

What's fascinating about the character - nailed in all her self-righteousness by talented Lizbeth MacKay - isn't the unrealistic whole of her personality: the arrogance of her confidence, or the insufferable way she's turned herself into a living political screed, or her constant parade of pretensions. ("When I was writing my thesis at Harvard . . ." or "How can you have a problem with Rena? She's a Guggenheim scholar!") What makes the professor real is the little pieces of her character. We all know people who have bits of Laurie Jamison and, more to the frightening point, we probably carry a few of them around ourselves.

When she tries teaching a student named Woodson Bull 3d (a finely crafted performance by Will Fowler), the professor can't help but hate him. He's from the Midwest, he's a college wrestler, he wants to be a sports agent - how can he possibly understand the way male-dominated cultures have misinterpreted King Lear for centuries? He is, in fact, "practically a walking red state," says Jamison, her ultimate dismissal.

Lymphoma ended Wendy Wasserstein's life and brilliant playwright career (a Tony and Pulitzer for The Heidi Chronicles, and much other respected work) in 2006. Third, her last play, produced by Lincoln Center just before her death, examines how life forces us to reconsider our judgments and, sometimes, the values we live by. It's not flawless - Third ends a little too easily, before enough tough discussion in the final scene to make it all seem natural. Still, the play's anything from farfetched.

Mary B. Robinson's rhythmic production, on James D. Noone's simple, effective set of Ivy League brickwork and moldings, even employs the stagehands as college kids who literally keep the play moving. The supporting cast members Melanye Finister as the colleague with cancer, Jennifer Blood as the forlorn daughter at Swarthmore, and Ben Hammer as the dad afflicted by Alzheimer's are first-rate, all doing honor in the way they make Wasserstein live on.