The Washington Opera Society presentation of a shared production of Mozart's ''Cosi fan tutte'' is important not just as a musical event but as an example of how best to cope with the ever-increasing problems of mounting opera in these modern times.
Musically, the production boasted Daniel Barenboim's operatic conducting debut in the United States, as well as Julia Varady's Fiordiligi - one of the finest Mozart performances it has been my privilege to witness.
Jean-Pierre Ponnelle's sets and production highlighted the darker side of this much-misunderstood opera.
One felt, at the final curtain, that ''Cosi'' had been wrestled with. And this is more than can usually be said for the opera, in this country at least.
The production is just the sort that should be seen all over the world - Ponnelle at his finest - and the idea of an entire package traveling with conductor and cast is a good one.
This ''Cosi'' was offered as a partnership between the Washington Opera Society and the Orchestre de Paris. Co-production is a concept that too often works better on paper than in the theater. In New York alone, countless evenings of opera have fallen apart because a set designed for another house does not work at the Met or at the City Opera.
Nevertheless, the Ponnelle ''Cosi'' represented something different. The production was first put on in June at the Theatre des Champs-Elysees with the same cast heard in Washington, except for the tenor. The production fitted neatly onto the Kennedy Center Opera House stage. The Washington Opera Society Orchestra was in the pit. But in effect, it was an intact ensemble forged in Paris and brought over five months later.
Yes, there were problems, but first and foremost there was Ponnelle's handsome production, one that focused on the serious side of ''Cosi'' rather than resorting to the sort of slapstick that directors usually think audiences will enjoy.
In truth, the story is a dark one: Two young soldiers try to trick their ladies into being unfaithful, all for a silly bet. No one wins in the end; the apparently cheery finale masks a terribly sad irony. For once, a director gets that point across - no cheap comedy, no sunny happy ending, no swap of partners as the final curtain is coming down.
Ponnelle's physical production is fairly lean, depending on a gorgeous gray-tinted backdrop of the Bay of Naples, expert lighting (superbly executed by John McLain), lavish-looking yet simple sets, and magnificent costumes. The mood is always magically sustained, the contrast between introspective moments and public display deftly communicated, the singers allowed at all times to be the strict, clear focus of the action.
This production also boasted an exceptional Fiordiligi in Miss Varady. The voice suits the role impressively, from a lustrous, gleaming top to rich, potent bottom. But more than that, she is a consummate actress and a splendid musician. Her gesture of frustrated shame at discovering the trick played on her at opera's end was devastating. When she graced the stage, this ''Cosi'' truly reflected an exalted international-house standard of operatic performance.
And Carlos Feller, the Don Alfonso, made a forceful impression in a role that must dominate the action. Ponnelle makes Alfonso the clear deus ex machina - commanding lights, sets, even music - and Feller put strength into every gesture , even if the voice revealed a few rough edges.
From there on down, standards slipped to a regional domestic level. And ironically, the rest of the cast was American, all young singers of increasing reputation. Yet throughout, they offered a mere competency that proved all the more colorless when Miss Varady was on stage.
Janet Perry, Herbert von Karajan's newest discovery, offered an enchanting presence as Despina. But her thin, hollow soubrette soprano voice soon became monochromatic. Katherine Ciesinski's Dorabella was not especially well sung - her voice loses quality in the upper reaches. And her heavy-handed approach to the character did not give any sense that she is Fiordiligi's sister.
Stephen Dickson's Guglielmo proved one-dimensional, physically suitable, but vocally overparted. The same could be said for David Kuebler's Ferrando. Mr. Kuebler, at least, managed his ''Un aura amorosa'' sweetly. Both singers, however, ran out of voice shortly into the second act.
In the pit, Mr. Barenboim tried to give a darker color to this ''Cosi,'' replacing the Neapolitan sunshine with a gloom right out of ''Don Giovanni.'' Some of the most beautiful pages - such as the sublime trio ''Soave sia il vento'' - passed by without effect. Yet other moments took on an unexpectedly interesting beauty and interpretive depth. At times, the orchestra seemed to wander out of synchronization while the conductor was focusing on the singers, and vice versa.
One emerged with the distinct impression that Barenboim is not a natural for the opera pit. He does not anticipate problems so as to forestall them and keep a performance in perfect coordination and balance.
Next year, the opera offered in this three-year project, underwritten by the American Express Foundation, will be Mozart's ''Le Nozze di Figaro,'' followed by ''Don Giovanni,'' all conducted by Mr. Barenboim and staged by Mr. Ponnelle. The consistency of vision is but one of the unusual aspects this project will offer Washingtonians and anyone interested in challenging but not eccentrically staged performances of these three masterpieces of the operatic literature.
The Washington Opera Society season runs through Jan. 22 with productions of Offenbach's ''La Belle Helene,'' Handel's ''Semele,'' Donizetti's ''L'Elisir d'Amore,'' a Menotti double bill of ''The Medium'' and ''The Telephone,'' and Rossini's ''La Cenerentola.''