Mason & Dixon.

I've never been any good at keeping secrets. So: Thomas Pynchon's Mason & Dixon is not only the most stunning novel I've read in the last twenty years, but one of the most stunning novels I've read, comma, period. At this point I think we can safely argue that the radiant center of American fiction is inhabited by only three characters, Melville, Faulkner, and Pynchon, and I'm not too sure about Melville, and I left out the unapproachable Henry James only because he didn't really want to be American. So am I telling you that if you don't read Mason & Dixon your life will be, by that measure, impoverished? You bet. But of course most of you won't - or at least you won't finish it. It's long, by which I mean long; it's involuted, convoluted, self-referential - it's Thomas Pynchon - and it has, as all of Pynchon's novels, virtually no plot. It is, simply, magnificent.

I've been haunted by Pynchon for thirty-four years. In 1963, my Notre Dame classmate Mike McClintock - now a distinguished professor of literature at the University of Montana - loaned me a copy of V - Pynchon's first novel - suggesting that I might enjoy it.

Well, "enjoy" was not precisely the word. I was at first amused, then fascinated, and then I fell into the book, and, to tell you the truth, I'm not sure I ever got back. This man, I thought then and am sure now, possessed or was possessed by the right and real voice of his, which also happened to be my, moment - and yours, too, like it or not. The voice is irreverent - Pynchon loves jokes, the dumber the better, erudite, ranging from physics to Kabbalah and back again - and breathtakingly eloquent, nearly ever sentence, as in Faulkner, a tiny masterpiece.

It is also profoundly, maybe despairingly, religious; we'll get to that.

Mason & Dixon is Pynchon's fifth novel, after V, The Crying of Lot 49, Gravity's Rainbow, and Vineland. And it continues a pattern in his work first noticed, I think, by my brilliant student Parker Douglas: one large, sprawling novel embracing as much Euro-American history as possible, then one shorter and jokier novel set in California, jokiest state of them all, then another large, sprawling novel und so weiter.

Well, Mason & Dixon, right on schedule after Vineland, is large and sprawling - or better (Pynchon imposes these paradoxes upon you), focused and sprawling.

This much is fact. Between 1763 and 1767, Charles Mason, a British astronomer, and Jeremiah Dixon, a British surveyor, were commissioned by the Crown to determine the exact boundary between Pennsylvania and Maryland. A more tediously quotidian task could probably not be invented - except that the Mason-Dixon Line became the demarcation of America's very own Gulag Archipelago, the line between our free and our slave states, still the symbol of our national failure to live up to our promise to ourselves.

But Pynchon can't deal with one theme without dealing with all the related themes, and all themes are, finally, related: This was also Faulkner's curse and blessing.

What I mean is, this isn't a novel about slavery - though it is a novel about slavery - and it isn't a novel about America - though it is a novel about America - and it isn't even a novel about the limits of reason, thought it's surely that, too.

At last - and this is why I believe Pynchon is the only living and maybe the only American novelist who deserves to be called "great" - it is a novel full of nostalgia for the departure of God.

"I was back in America once more, finding, despite all, that I could not stay away from it, this object of hope that Miracles might yet occur, that God might yet return to human affairs, that all the wistful Fictions necessary to the childhood of a species might yet come true,...a third Testament...."

That is said by the Reverend Wicks Cherrycoke (yeah, yeah - Pynchon likes making up dopey names). Cherrycoke is the main storyteller of Mason & Dixon, reminiscing years later about accompanying them on their survey, after they're both dead. But other narrators, some identified and some not, weave intricately in and out of his tale, in this, the greatest eighteenth-century novel of the twentieth century.

Everett Zimmerman, in his recent book, The Boundaries of Fiction (Cornell University Press), argues persuasively that the novel as a form exists, ab origine, in the creative tension between history and myth, the urge to describe the world as it is and the urge to imagine the world as we desire it. We need novels, that is, because they articulate our condition as cosmic amphibians, living in the ineluctable pressure of the real and in the hope of a final, human meaning - forever speaking, as Karl Rahner writes, into the endless desert of God's silence.

Now all Pynchon's books are set on this boundary: His Central Plot is that an investigator finds him/herself embroiled in a wide-ranging conspiracy - a plot which has no name - which may be directed either toward the final dehumanization of the human race or toward a moment of dark/radiant transcendence.

But never before have the terms been stated as uncompromisingly as here. Bear of little brain that I am, I was halfway through the book before I got the sublime point of Pynchon's choice of subject. Mason and Dixon - a melancholy, vaguely spiritualist astronomer and a jovially carnal surveyor; a disciple of the stars and a disciple of the earth - what are they doing? They are using the stars and the earth to draw an imaginary line that will determine the course of American history, and therefore - at least for Pynchon - the fate of hope, in our world, altogether.

Their journey into America, which occupies the great bulk of the novel, is a journey into hallucination - nothing new for our lad Tom - but hallucination whose point is simply that all our national agonies and glories lie implicit in the conditions of our founding, a Republic of Reason administered by Born-Again Christians. If this is a great eighteenth-century novel, it's an even greater twentieth-century one, a perfect distillation the of the ironies of faith and despair that define the America of the soul.

I don't have space to tell you about Mason and Dixon smoking dope with George Washington and his black-Jewish-slave-standup-comic Gershom; or about Ben Franklin, or Samuel Johnson, or the cameo performance by an unnamed Thomas Jefferson; or the performing electric eel Felipe; or Fang the talking dog or the robot Duck who wants to learn about sex; or the squint-eyed, large-forearmed, pipe-smoking sailor who translates God's eyeh asher eyeh into "I am that which I am." You'll have to find them yourselves. Pynchon is as metaphysically serious as Rahner, and also - I think - as funny as George Carlin. If a new character is introduced on every other page of this book, a new joke - and a good one - is told on every page. His laughter, like Lord Byron's, is the laughter of a kind of cosmic sanity, humanizing us even as we guffaw.

This is the book of a lifetime, and God bless him for it.

Frank McConnell, Commonweal's media critic, teaches English literature at the University of California, Santa Barbara.