THE MIRROR HAS TWO FACES ***

Surprise Number Two for me is that for once I enjoyed watching a movie with a large audience. I normally go to earliest possible shows on the least trafficky days. No odious smells, no sticky goo on the floor, no crinkling cellophane and loud chomping, no running commentaries, no laughter at the wrong places. For "The Mirror, " however, the theater though packed was odorless, noiseless and the audience laughed unboisterously at the right times.

The film is most enjoyable, well paced and without dull moments. Its improbabilities or exaggerations vanish behind the qualities of script, acting and Miss Streisand's direction, her third after "Yentl" and "The Prince of Tides. "

It starts as Jeff Bridges' picture, then is shared by him and Streisand before the focus moves on her --an interesting progression. A mathematician at Columbia University, Greg is addressed as Professor Larkin. He should really be called Professor Dullski or, if he taught literature, Professor Yawnesco. He knows and loves his stuff, even has a new book out, but he bores his students to perdition. I have never seen such a somnolescent or indifferent group outside some Hollywood high school pictures.

Bachelor Gregory is also a basket case in his private life. At 46 (I give him the age of Bridges), he still gets terribly distracted by sex -- and sex is everywhere, from a gorgeous redhead in his classroom's front row to television where insects mate in educational programs and so many products are sold through sex. (I waited in vain for the sound track to come up with that vigorous old song "Everybody's Doing It. ")

Larkin is influencable with a vengeance. At a book-signing gathering, he opens his address with some flat academic humor. A beauty (model Elle MacPherson) walks in, sits down, silently but blatantly provokes him a la Sharon Stone with her sex appeal. Gregory's talk becomes gibberish. Very funny.

We learn that she is his latest ex-paramour and that he is unhappy with the fact that all his relations with women fail because they revolve around sex. His conclusion is that he ought to be looking for a kindred soul and mind, minus the sex.

Like the famous revue "No Sex Please, We're British, " the mathematician's new slogan could be "No Sex Please, I'm Gregory. " He places an ad ad in which he seeks only companionship and specifies "Must have a Ph. D. and be over thirty-five. Physical appearance not important. "

The other thread of the plot deaks with two sisters, Claire (Rogers, "the pretty one") and Rose (Streisand, "the smart one") . Claire spots the ad and sneakily mails Greg the picture of Rose. She looks just right to Greg.

Rose, by coincidence (well, it's only a movie) is also a Columbia professor, of literature. As she readies herself in an awful dress for Claire's wedding. Always a bridesmaid and never a bride, brainy, lively, witty but without lasting relationships with men, she is a perfect match for Gregory.

They and their minds meet, hit it off, develop an odd, platonic rapport . They eventually marry, but always under the no sex strictures imposed by Gregory and accepted by Rose, reluctantly as we shall see soon enough, when Rose wants romance and what comes naturally. This leads to complications and a transformation. . .

The acting, broad but not too, with a huge assist from direction and script keeps hitting the bull's eye. Jeff Bridges, never a looker, has been a major, versatile talent. Think of "Bad Company, "" Fat City, ""Thunderbolt and Lightfoot, "" Hearts of The West, "" Starman, " " Nadine, "" Tucker, "" The Fabulous Baker Boys, "" Fearless. " Streisand's great one-woman band abilities are a given. Here, in odd ways, she may remind you at times of the still-moving "The Way We Were. "

Mimi Rogers, who possesses the most interesting crooked mouth in pictures, and her new husband Pierce Brosnan (of whom she gets quickly tired), are pallid, superficial characters. This makes a contrast with the personalities of the Gregory-Rose duo, lets Bridges and especially Streisand bask in the spotlight. They deserve it.

Lauren Bacall plays the mother of the two women with a combination of chic, fading glamour, sure-of-herself presence and egotism, and motherly limitations, notably her non-understanding of Rose. This incomprehensio comes to an end in a long-delayed, moving scene that flirts dangerously with maudliness but survives it. Mother and daughter stop snipping and sniping. They open their hearts as Rose comes out squarely with her complexes about her appearance. Here Streisand seems to be exorcising her own demons.

With her refrain "I raised two daughters, buried a husband, " Bacall is a Jewish mother, but one pushed neither into a cartoon or a caricature. Overall, Jewishness in the film is not insisted upon. Sometimes it comes through gently in details, like Rose's "Talk to me already. "

Gags are in good supply and nicely timed, like Rose's showing Greg how to capture his students' interest. There also humorous rather than outright comic parts, such as Rose's astounding of Greg with her comprehension of math. Better yet, the audience is rewarded with an even larger number of subtle bits of business. Examples: the early sequence about Claire's wedding is used for character portrayals and spares us the actual ceremony; the talkative meanderings of Rose and Gregory in which the discussions are amusing, novel and attention-grabbing but always cut before they become cumbersome; the first semi-kiss of the couple and Rose's wary reaction -- she pats Greg's back. There is much more along those lines, with excellent details.

Some weak areas do exist in the film, most of them papered over. When Gregory drops in on Rose's huge, lively class, she is in the process of charming and too manipulating her students with a discussion of love and sex which rings phony. She gets far too personal in her "confessions, " uses medieval courtly love (adoration of the lady but no sex) in sketchy ways, knows the name of every student in that crowded amphitheater (!!!). The well over 50 prof fishes for the sympathy of students in their 20s with hip language. About complete love she exclaims: "When it does last, it feels fucking great!" The young scholars applaud.

She also tells them that when you fall in love you hear Puccini. At film's end Rose and Gregory, previously separated, are reunited in a sequence out of old screwball comedies. We hear Puccini 's "Nessun' dorma" but then, with the filmmakers clearly worried about this cultural-musical reference becoming lost on most audiences, the finale and end credits switch over to the couple's endless gyrations in the street and the old cliche of a pop song pops up. Otherwise, the movie is truly fresh. Whether or not it is read closely as a throwback to romantic comedies, as a part-feminist tract or whatever, it holds many pleasures for any mature audience.