[For many years the chief film critic of The New York Times, Canby is also a novelist, playwright, and theater critic. In the following excerpt, he favorably reviews Arcadia.]

There's no doubt about it. Arcadia is Tom Stoppard's richest, most ravishing comedy to date, a play of wit, intellect, language, brio and, new for him, emotion. It's like a dream of levitation: you're instantaneously aloft, soaring, banking, doing loop-the-loops and then, when you think you're about to plummet to earth, swooping to a gentle touchdown of not easily described sweetness and sorrow.

That's the play.

Trevor Nunn's Lincoln Center Theater production, which opened last night in the Beaumont, is a reasonable American facsimile of those he staged in London, first at the Royal National in 1993, then at the Haymarket in the West End transfer last year. The Beaumont production looks gorgeous and is true to the letter and spirit of the Stoppard words, but it should be better.

Arcadia demands something more than a reasonable facsimile if American audiences are to be consistently beguiled by this most ambitious of English comedies. It's a complicated piece, played in two time frames (1809 and the present) by two sets of characters. They share the same great country house, Sidley Park, and occasionally the same stage props, including a tortoise that's named Plautus in 1809 and Lightning today.

Mr. Stoppard's theatrical conceits are exhilarating; his interests are diverse but interlocking, always riveting and sometimes brazenly deep-dish, which is part of the fun. Among his concerns here: first love, Newtonian physics, hustling pedants, landscape gardening, sexual infidelity, class, the mathematics of deterministic chaos, manners and the absolute end of the universe when, one character observes, "We're all going to wind up at room temperature."

Mr. Stoppard pushes the audience to the edge of delicious bewilderment, then he suddenly pulls back to make all as clear as need be. The playwright is a daredevil pilot who's steady at the controls.

At the center of Arcadia is a mystery that is the consuming passion of a contemporary literary don, Bernard Nightingale (Victor Garber): did Lord Byron, while visiting Lord and Lady Croom at Sidley Park in 1809, fight a duel in which he killed a grossly untalented poet, Ezra Chater, over the honor of Chater's wife? And was that the reason for Byron's hasty, heretofore unexplained departure from England for the Continent?

Bernard is hungry for acceptance in academe, and even hungrier for the celebrity that comes with publication and the inevitable talk-show appearances. He's a loose cannon, a dangerously quick-minded, noisily self-centered man who doesn't care whom he insults or makes passes at. Chief among his victims: Hannah Jarvis (Blair Brown), a best-selling author and landscape historian; Valentine Coverly (Robert Sean Leonard), an Oxford student of scientific mind, and his sister Chloë (Haviland Morris), two children of the present Lord and Lady Croom.

In the course of his research, Bernard becomes convinced he has made "the most sensational literary discovery of this century." He has, of course, got it all wrong. Arcadia crosscuts between the present-day shenanigans at Sidley Park and the events that took place there nearly 200 years earlier. These involve poor Ezra Chater (Paul Giamatti), though only in a helplessly funny subsidiary role. Byron himself remains off-stage.

The more important players in the 1809 mystery are Septimus Hodge (Billy Crudup), a randy young man and parttime literary critic who is the tutor of 13-year-old Thomasina Coverly (Jennifer Dundas); Lady Croom (Lisa Banes), Thomasina's mother, who has never put off a man who had the good taste to presume on her virtue, and a celebrated landscape architect, Richard Noakes (Peter Maloney). Noakes is transforming Sidley Park's grounds from their comparatively natural look to a picturesque style that Hannah Jarvis in 1995 calls "the Gothic novel as landscape."

Hannah, too, becomes intent on solving a mystery: the identity of the hermit whom the earlier Crooms installed in their picturesque hermitage, built by Noakes as he was making mountains on land that had always been flat, and constructing ruins where no castle had ever existed.

The principal Stoppard characters are often driven, not always self-aware, very intelligent and furiously articulate, which is not to say they mean everything that comes out of their mouths. Bernard's vitriol is both hilarious and mean. Of scientists, he says to Valentine: "I'd push the whole lot of you over a cliff myself. Except the one in the wheelchair; I think I'd lose the sympathy vote."

The play's most affecting characters are Thomasina and Septimus, who affectionately regards his pupil as the child she is.

Thomasina, who doesn't yet know what "carnal embrace" means, doodles away in her notebook, apparently to stumble onto today's new, nonlinear mathematics. She has the gift, sometimes possessed by the young, to conceive abstract concepts beyond the comprehension of those whose minds have been made soggy with received wisdom. She is also in love with Septimus, which has melancholy consequences.

As Bernard continues his investigations, it's clear to the audience, if not to him, that both Thomasina and Septimus are part of the mystery whose solution he so thoroughly muddles.

At the beginning of Arcadia, the two time frames are presented in separate, usually alternating scenes. As the play progresses, the times begin to merge, at first when the present-day characters are seen in 1809 costumes for a fancy dress ball. Further along, the characters from each section occupy the stage at the same time.

As Thomasina, Septimus and Lady Croom, and Bernard, Hannah and Valentine play around and through one another, they create the contrapuntal effect of a piece of music. It's tricky but hugely effective. The two stories come together in a way to give dramatic dimension to some of the more esoteric notions that have been bandied about earlier.