I was listening to Yo-Yo Ma playing Tchaikovsky's ''Rococo Variations'' with the Mostly Mozart Festival Orchestra, Gerard Schwarz conducting, recently. I marveled anew at the soloist's prodigious technical gifts and his unique communicative powers.
In Mr. Ma's program biography, Isaac Stern calls him ''one of the greatest instrumental talents alive.'' Strong praise, fully deserved. At 28, he is already in the forefront among cellists, and indeed, as Mr. Stern so accurately avers, one of the finest solo instrumentalists before the public today.
What is it specifically that sets Yo-Yo Ma apart? It is not just his unique sound, or his exceptional technique, his ability to phrase imaginatively, his uncanny ear for shading and nuance, or even his ever-alert ear so keenly attuned to the orchestra around him. Rather, it is as if his cello were plugged directly into his heart.
This much heart, so eloquently controlled, is rare in any age. But these days , heart in the arts - the sense of an artist committing himself wholly to the performance and demanding that an audience commit with him - is rapidly vanishing from the music scene. It is one of the most alarming, and ultimately damaging, trends I can think of. For without heart - the essence of communication - the entire purpose of music is rendered null and void.
By heart, I do not mean an unbridled outpouring of sentimentality and bathos. Heart - some would call it soul - is something one must tame and nurture. The expression of heart in the right way is something an artist must contemplate and develop. He or she must deduce what each line of music is meant to express and how to make that line communicate just the right shading of feeling. It is a constantly demanding process that involves serious introspection and a certain amount of self-exposure - and a lifelong dedication to the refining of it.
This is a risky undertaking for the artist: This commitment of feeling, no matter how deftly controlled, is a challenge to any artist's resources. The artist needs time to restore his or her soul, gain new insights, and explore new vistas.
Nowadays, successful careers are a financial treasure trove involving the performers, their managers, and the recording companies. Because these highly acclaimed artists are in such demand, they find themselves with unmanageable schedules crammed with dates. Too often they cannot sustain the artistic energy needed for a 150- or 200-performance-a-year schedule for any length of time.
After a while, that cherished communicative edge drops out of their musicmaking so that the artists do not have to become totally immersed in the performance. They find a way to keep a musical distance - to remove heart altogether, or perhaps merely give the appearance of heart. Such gestures are ultimately transparent and bankrupt, cheating both audience and performer.
I was never more struck by all this than during the two concerts Claudio Abbado led with the London Symphony Orchestra (LSO) here this spring. A conductor who used to be so passionate, so exciting, had slowly metamorphosed into something altogether different - cerebral, calculated, chilly.
This overall approach works well for a certain slice of 20th-century music, but it does not lend itself satisfactorily to the bulk of the standard symphonic literature. Where once Abbado sought the expressive mood, he now seeks clarity of balance. Where once he captured the grand sweep of drama and let a full musical climax carry shattering conviction, he now seeks to contain that sense of the exultant. Where once he reveled in the programmatic, he seems to now be trying to demonstrate - even in something as specific as Berlioz's ''Symphonie fantastique'' - that the composer had nothing more than absolute music in his mind.
True, the Berlioz as heard in Carnegie Hall ended up being a superbly virtuosic account from the LSO's standpoint. Mr. Abbado gets his orchestra to play handsomely, but it tends to sound like any other orchestra - and that's a far cry from the days when Andre Previn used to bring the LSO to these shores and show off a rich, distinctive orchestral ensemble.
I can only venture to guess that the severe demands on Mr. Abbado's time - in London, with the Chicago Symphony, with La Scala Opera and other opera companies , with recordings and so forth - have forced him to find a way to give less of himself so as to survive this schedule. There is always the expectation that this is a phase that will pass quickly and that he will emerge in sure control of both the objective and the heartfelt. Perhaps some sort of synthesis of those two qualities will foster new insights into the music at hand.
I very much doubt that Yo-Yo Ma will fall into the same trap. His roots are chamber music, and that particular art form demands the sort of exploration, attentive ear, and time for rumination that will keep Mr. Ma in one artistic piece. He is acutely sensitive to what is going on around him musically in a performance - and he responds to it. He appears not to have the star-soloist complex that mars so many promising artists early on.
Mr. Ma is hardly the only artist I admire for his heartfelt commitment to music, but as one of the very finest performers on the music scene today - so fine one feels it a privilege to be in his presence - he is the best example of what makes great musicmaking great.
Mr. Ma's incandescent performance of the Tchaikovsky ''Rococo Variations'' was the high point of one of the best Mostly Mozart concerts I have heard in many a summer. Credit music adviser Gerard Schwarz for taking a reliable orchestra and molding its musicians into something really worth listening to. They play with a fresh commitment, great enthusiasm, and a sense of purpose they so often lacked in earlier years. They always were a fine bunch, needing only someone who could inspire them and make them feel their own importance.
Horracio Guttierrez offered a robustly emotive, oddly unassimilated account of the D minor Piano Concerto, (No. 20, K. 466). Mr. Schwarz concluded the program with Mozart's ''Prague'' Symphony (No. 38, K. 504) in a spirited, attentive performance that kept a nice balance between authentic performance style - the orchestra now sits as it did through the end of the 19th century, with the first violins in the their usual place, the seconds across from them on the conductor's right - and the exigencies of performance in a 2,800-seat concert hall. The entire evening augured well for the festival, which runs nightly (except Sunday) through Aug. 27 in Avery Fisher Hall.