Irving Berlin was right, of course. There is no business like show business, no people like show people, and nothing quite so tempestuously entertaining as a rocky pre-Broadway tryout in Boston.

Actually, Berlin didn't say that about Boston tryouts. Moss Hart did in "Light Up the Sky," which observes, not without a touch of sweet malice, a clutch of theater folk just before -- and just after -- their disastrous opening night performance out of town.

The 1948 comedy, which opened Wednesday night at Arena Stage, is still sidesplittingly funny. Actors, I suspect, like nothing better than playing actors, unless it's producers, directors and playwrights. This cast, under the shrewd and loving direction of James C. Nicola, certainly takes to the play like ham to rye.

Things may have changed drastically since the days when Boston was a crucible for the commercial theater. The fabled road is now but a footpath and you could probably scour all the hotels in Boston without locating a single jittery author sweating out an opening. What hasn't changed and never will is the theatrical temperament -- giddy, volatile, self-centered and altogether captivating. In what other profession is having two faces considered an asset, not a moral liability?

"Light Up the Sky" begins hours before the curtain rises on "The Time Is Now," a high-minded allegory that apparently takes place in the ruins of Radio City and calls for its leading lady, the celebrated Irene Livingston, to remain mute for the entire first act. No one quite knows what the play means, but that's a clear indication, or so the company members think, that they have a galloping hit on their hands.

As they gather in Irene's hotel suite to toast impending success, the sense of artistic camaraderie in the air is almost as thick as the pink and aqua carpets on the floor. Irene (Tana Hicken) can't bless everyone enough. The director (Richard Bauer) keeps bursting into tears, although he has a proclivity for crying even "at card tricks." The big bluff producer (Mark Hammer, looking startlingly like Don Rickles) is flush with anticipation of the artistic laurels he will soon be able to hang alongside his Old Masters.

Straight out of the Midwest, the young playwright (John Leonard) wonders what could be nobler than this world of generous souls. A convention of piranhas, maybe. "Nothing can hurt this one," notes Irene's mother (Francine Beers), in a characteristically crusty aside. "Just the curtain going up will be enough."

The next time we see them all, the curtain has not only gone up, it's come down with a thud. "The Time Is Now" has met with outright derision. Characters who couldn't wait to peck one another on the cheek are now raring to sink their claws in one another's throats. The producer is threatening to close the show, Irene is developing a severe case of laryngitis, the director is still crying -- but for a whole new set of reasons -- and the bewildered playwright is packing his bags for home.

You could have predicted it. The surprise -- especially for anyone who caught the leaden revival of the play at Ford's Theatre a decade or so ago -- is how fresh these creatures are in the right hands, how sharp their dialogue and how lethal their quips. "If you want to get even with a producer," goes one, "you talk him into doing an Ibsen revival."

It was said, when the play first opened, that Hart had based his characters on such celebrities as Gertrude Lawrence, Guthrie McClintic, Billy Rose and Eleanor Holm. That may have added spice to the original production. But these egomaniacs, for whom the sun rises around 8 p.m. and sets sometime after midnight, have no trouble standing (and posing) on their own. An obsession remains an obsession -- wherever and whenever plays are produced.

The ratio of splendid comic performances per square inch is about as high as it gets at Arena. Hicken's leading lady alternately drips with magnanimity and venom; depending on her mood, "Dahling" can be an intimate caress or a foul insult. I'm not sure how the actress does it -- is it the way she pitches her head or slants her eyes? -- but you'll swear that Irene Livingston has had a face lift or two.

Bauer's ability to negotiate lickety-split transitions has rarely been put to better use. As the moody director, he can be awash in sentimentality and still notice through his tears that the theater marquee has not been turned on -- whereupon he explodes with the sort of indignation most people reserve for mass murderers. Hammer comes on crass and corpulent as the producer, eager for artistic credentials to match his wealth. It's a fine, blustery performance, in no small part because Hammer recognizes the man's underlying insecurities.

As the producer's wife, a famous skater who tends to dress for life as if it were the finale in her ice show, Brigid Cleary continues to hone her considerable ability to play bimbos appealingly. And Beers, as the star's mother, views the heated proceedings with the resignation of one who may have witnessed a lifetime of histrionics but still can't keep herself from shooting off a sobering rejoinder. Her bluntness, cutting through the general fog of self-preoccupation, is hilarious.

This is the sort of carefully prepared, minutely etched production in which a starchy Tom Hewitt wins a big laugh merely by singing a few bars from "Oklahoma!"; Walt MacPherson scores as a plainclothes policeman, although he isn't on stage for more than a minute; and even that old standby, the whoopee cushion, registers as a new gag.

If you love the theater, I don't see how you can keep from loving "Light Up the Sky." Arena's spanking revival does just what the producer in it claims he wants to do: It "pushes a Roman candle in the tired face of show business." Light Up the Sky, by Moss Hart. Directed by James C. Nicola; set, Andrew Jackness; costumes, Marjorie Slaiman; lighting, Nancy Schertler. With Richard Bauer, Brigid Cleary, Ralph Cosham, Francine Beers, John Leonard, Mark Hammer, Tana Hicken, Tom Hewitt, Terrence Currier, Cary Anne Spear. At Arena Stage, through Jan. 17.