Urban centers were much more malodorous in the 18th century than they are today, but they were also considerably less noisy, a concept brought home quite forcefully on Saturday evening at Zankel Hall as violinist Mark Steinberg and pianist Mitsuko Uchida had to compete for our attention with the R train just on the other side of the wall. Pursuing our passion for listening to such delicate gems as the Mozart sonatas for violin and piano may be decidedly eccentric in the ambient noise of the constantly connected, short attention-span society that we have, for better or worse, so recently created, but if we are intent on doing so, we could do much worse than this pair of superbly integrated musicians.

Ms. Uchida assumes the mentor role in this fruitful relationship. As co-director of the Marlboro Festival, she has developed a strong interest in young performers, shepherding an ongoing series at the Metropolitan Museum. Mr. Steinberg, first violinist of the Brentano String Quartet, looked to her often during this recital for tempo and stylistic encouragement, the former of which she gives with a nod of her head, the latter with maneuvers of her extremely expressive face.

Ms. Uchida has just the right touch for these lighter-than-air works. Her ability to enunciate every note of a trill in perfectly equal measure is enviable. She escapes the keys rapidly, leaving the impression that they have been not struck but rather gently caressed. It may be somewhat academic to speak of Mozart’s music as having been spawned in neatly demarcated frames of time, but this music is definitely of the middle creative years and relies heavily on the lightest of interpretations.

Mr. Steinberg intones this music as if he had never been a combatant in the periodicity wars. He has a vital sense of vibrato but employs it sparingly, achieving a compromise that would be acceptable to all but the most fundamentalist on both sides of the authenticity debate. Together they polished five small-carat diamonds.

The K. 303 in C Major, for example, was treated lovingly. The main theme of the Adagio is unusually expansive for Mozart. It sounds much more like the mature Haydn – think of that most famous of Andante cantabile quartet melodies. Mr. Steinberg played it with healthy dynamics and admirable restraint. Ms. Uchida complimented him with nimble, ephemeral landings, the pollinations of a butterfly leading deftly into the Molto allegro. Three of tonight’s five sonatas concluded with minuets, two of which end inconsequentially. In order for this courtly politesse to have any relevance to our own day, it must be communicated with the optimum of charm and grace. On this evening, it was.

Glenn Gould, in a moment of superb iconoclasm, said that Mozart did not die too early, but rather too late. He was referring specifically to the flawless construction of these types of imitations of a Deist creator, unencumbered by the depths of emotions of contemporary life that Mozart would soon express most intensely. For such cleanly designed music, a well-crafted performance.

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It is rare to see and hear a fortepiano at a modern recital, but very rare to have two of these beautiful instruments on the same small stage. It is rare to hear music for two pianos, while pieces written for four hands at one piano are even less frequently performed, but to hear both combinations on the same program is almost unprecedented. To have all of these conditions at one event is positively unique.

Those of us who have been attending the soirees of Robert Levin at Weill Recital Hall all season have been treated to educative music-making at its best. Mr. Levin, in addition to being an expert keyboardist, is also a very fine teacher, and Thursday evening he brought his own teacher, forte pianist Malcolm Bilson, for an 18th-century show-and-tell. The program was all Mozart and all written for this one almost-forgotten ancestor of the modern piano, but the evening was notable for its variety of compositions.

The pair began with a fragment designed for two fortepianos, one of whose parts was never fully written out. Titled Larghetto and Allegro, Mozart fashioned the work so that one of his more talented students could perform at the first keyboard, for which every note is written, while he himself would be the second artist, performing only from sketches and using his superlative improvisatory skill. Mr. Levin has attempted to flesh out the bottom accompaniment in a new version. Mr. Levin is extremely skilled as a communicator, even pointing out after the fact where Wolfgang ends and he begins, stating, “here is the exact moment when you should begin to be disappointed.” We, however, were not.

Next came the four-hand sonata K. 497, composed while the master was putting the finishing touches on “The Marriage of Figaro.” Messrs. Levin and Bilson together made an unbeatable team, although the naked nature of the instrument, with no pedal mechanisms for subterfuge, exposed each and every wrong note. In the talking portion, Mr. Bilson, at least as profound as his protege but perhaps not as polished a speaker, pointed out the built-in mistunings of many Mozartean passages, a phenomenon simply lost at the contemporary Steinway. In a very elemental way, many in the audience were hearing the music of Amadeus for the very first time.

The performance of this sonata was extremely revelatory, but also a very good, collegial realization. In a shocking bit of derring-do, the pianists switched places between movements, Mr. Levin giving the “thumbs-up” sign when he was able to move into the higher, melodic part. The Andante was full of warm gemutlichkeit, the Allegro charming and just a tad nostalgic. The piece also takes the opportunity to show off all five octaves of the old instrument, eloquently expressing the comfortable, nesting concept that the further one ranges from home – middle C – the more discordant life becomes. Listening to this type of re-creation (both instruments were indeed recent replicas) explains eloquently without words the natural human need to return to the tonic.

Perhaps the most interesting experiment was the combining of two familiar pieces into an unfamiliar whole. Most fans have heard either the Fantasia in C Minor, K. 475 or the Sonata in C Minor, K. 457 or, certainly for devotees, both. When, however, have you heard the two “complete” works joined as one?

Apparently Mozart thought of them as part of the same totality, designing the fantasy as an improvisatory prelude to the sonata for performance. This is an almost totally lost art in 21st-century presentation of the classics: In Mozart’s day (or Liszt’s for that matter), it was standard procedure to perform transitional pieces to make the journey from one key to another or one mood to another more natural to the ear of the listener. Certain works are meant to be played in tandem. Today’s stand-alone recital practice eliminates one of the most important elements in the composer-performer’s art.

For me, the best performance of the evening was Mr. Levin’s intense and emotionally disturbing reading of the Fantasia (Mr. Bilson then performed the Sonata immediately).This traversal explored deeply the angst of the troubled composer, expressing the desperateness of the human condition as only Mozart – only Mozart – could. The accompanying sonata offers little consolation. Luckily the program ended with an upbeat, two-piano essay in D Major, K. 448, which brought us back to a sense of balance enabling us all to go on with our lives.

In the anniversary year of 2006 there will be many concerts of Mozart, and separating the wheat from the chaff may require expert intuition and a great deal of dumb luck. At least Mr. Levin’s fine series has been renewed for another season. He will provide an island of substance in what could easily degenerate into a sea of fluff.