Productions like the Source Theatre Company's "The Good Woman of Szechuan" put a critic in a quandary.

Bertolt Brecht's drama is one of the landmarks of 20th-century theater, part parable, part lecture, and part epic adventure. Cast in the deceptively simple terms of a Chinese fable, it confronts an age-old riddle: Why does wretchedness persist in the world? Are the gods incapable of eradicating it? Is mankind itself flawed? Or is goodness simply too weak a virtue to stand on its own two feet?

Brecht's heroine is a generous-hearted prostitute named Shen Te, whose giving nature leaves her open to exploitation by the greedy populace of Szechuan. To survive in the world, Shen Te is forced to invent and periodically impersonate a ruthless cousin, Shui Ta. If the cousin saves the prostitute from ruin, the prostitute invariably tempers the oppressiveness of the cousin. One cannot exist without the other.

Brecht is tossing a bold, elemental paradox in our laps. His text (three hours long at the Source) demands an equally bold staging and the kind of acting that has the forcefulness of caricature, without caricature's chilliness. Unfortunately, it gets neither in this production and therein lies the critical dilemma.

On one hand, it is surely preferable for Source to spend its time and energy, not to mention the man-hours represented by a cast of more than 20, on Brecht's philosophical and artistic challenges. Young actors can only learn so much (or so little) from "Barefoot in the Park," and if you're serious about this business of theater, as Source is, you aim high.

On the other hand, if you decide to tackle Brecht, Shakespeare, Euripides or any of those playwrights who occupy the theatrical peaks, you run the clear danger of perishing on the slopes, long before you've reached the top. This, I fear, is what is happening at Source, where the evening's ambition far outstrips the hard realities on stage.

The production strikes its most forceful note with an original score composed by Ed Rejuney and played on the piano with matching vigor by Michelle Scanlon. As a rule, the cast sings Brecht's accusatory lyrics with a bite and directness that is missing in the spoken performances. The direction by Sabina Lozovsky, drawing on improvisational techinques and theater games, degenerates more often than not into self-indulgent sloppiness. Jewels Crowe, as a wealthy landlady, is the only performer who strikes me as consistently credible, although Megan Morgan, in the tricky double role of Shen Te and Shui Ta, is persuasive enough at least as the latter half of the equation. Otherwise, the performances seem marked by an almost palpable eagerness to do a good job, which, alas, is not quite the same thing as doing a good job.

THE GOOD WOMAN OF SZECHUAN, By Bertolt Brecht; music by Ed Rejuney; directed by Sabina Lozovsky; musical director, Michelle Scanlon; choreography, Lea Hart. With Megan Morgan, Robert Fass, Elizabeth Pratt, Jewels Crowe, Peter Galitzin, Susan Cassidy, Michael Heintzman, Stephen Kelley. At the Source Theatre, Wednesday through Sunday until Nov. 21.