David Mamet at the New School in New York last year.(Andrew H. Walker/Getty Images)

A book jacket photo dated 1977, from around the time playwright David Mamet first began to hit it big, shows him holding a cigarette and glasses gingerly in one hand. His other hand slides into the front pocket of his tight jeans; he wears a leather bomber jacket with the collar rakishly turned up, and a black turtleneck. Eyes sad and dark, skin smooth and white, he appears as the child of two figures he became obsessed with: the Tough Jew and the Scholar. You can imagine that even then Mamet might have been dreaming up the title of his most recent polemic, The Secret Knowledge: On the Dismantling of American Culture.

Critics on the left and right have given the book, an attack on big government and other staples of liberal thought published this month and now on the New York Times best-seller list, too much weight. It’s surprising to see a book by a playwright generate so much heated debate. But it was not surprising to see how the pundits focus primarily on being either for or against Mamet’s book. The book itself is yet to be understood in the context in which it was written, namely as a stellar, if strange, incomplete piece of theater, a rehearsal for some future play.

Read literally, as a political polemic—the way most critics, including Christopher Hitchens, writing in theNew York Times Book Review, approached the book—The Secret Knowledge leaves a lot to be desired. From his first foray into conservative politics, a 2008 essay in the Village Voice titled “Why I Am No Longer a Brain-Dead Liberal,” Mamet’s opinion writing has seemed half-baked. (In 2006, Nextbook Press published Mamet’s The Wicked Son, an attack on Israel-hating, tradition-denying liberal American Jews.) The writer whose characters famously do not say what they mean is ill at ease playing the writer saying what he means.

This is not to say that Mamet is disingenuous, or that he’s playing with his ideological conversion only to convert again at some point in the future. But read The Secret Knowledge as a yet-to-be-written play, and it will make more sense.

Perhaps this sounds far-fetched, but ever since he appeared, in 1975, at Chicago’s Goodman Theatre holding a play in his hand and announcing that he would put $5,000 in escrow while the director Gregory Mosher decided whether to produce it (the play was American Buffalo), Mamet has gravitated toward flamboyant monologues and ballsy turns. This knack is most evident, of course, in his famous plays—think of the “always be closing” speech from Glengarry Glen Ross—but it is more than an affectation. Watching Mamet’s career as an artist, you get the sense that what he wants to do now, his major artistic quest, is to transfer some of that manic energy from the stage and into real life.

Mamet expressed something like this sentiment in the introduction to his 1985 collection of monologues and short plays, Goldberg Street. “Tradition has it,” Mamet wrote, “that Shakespeare finished King Lear and handed it to Richard Burbage saying: ‘You son-of-a-gun, I’ve finally written one you can’t perform.’ ”

In the two decades since, it seems, Mamet has spent some time trying to turn from plays to polemics and turn his polemics into plays. He might have half succeeded with The Secret Knowledge.

Mamet’s best work paints a portrait of a dense world, rich with the idioms of noir and the grit of 1970s Chicago streets. It’s a world of con men and femmes-fatales who end up sticking their stilettos in your face, a world in which the good guys always get knifed in the back. Mamet made the grievance of the everyday person both mean-spirited and Aeschylean, both self-deluded and avuncular; such sleights of hand seem directly descended from Nathaniel West or cadged from hieroglyphs on the walls of some mid-century tomb shared by Hemingway and Patricia Highsmith.

The Secret Knowledge contains these themes, but abstracted. Instead of describing them from the inside, it prescribes cures and extols points of view. It fits with the rest of the Mamet canon in that it’s about jive, about how Americans try to cheat each other and steal each other’s essentials, be it real estate leads or American Buffalos or ideological validation or big ideas.

It’s easy to imagine that the man who for so long tried to stick a needle into America’s veins got tired. Or that the theater no longer seemed like enough. Mamet is hardly the only Jewish writer who migrated from trying to tell stories about life to screaming about its injustices from on high. The Secret Knowledge seems most interesting as an iteration of Mamet’s evolving interest in mysteries, rites, and ciphers. In his early plays, like American Buffalo and A Life in the Theatre, he used parentheses to indicate that his characters were moving to “a more introspective regard.” Maybe that’s where he’s headed now.