In a conversation several years ago, Rudolf Serkin described pianist Leon Fleisher as "a great artist." One heard just how great last night in his performance with the National Symphony of Ravel's Concerto for the Left Hand -- by turns glowingly tender and awesomely thundering.

Both emotionally and physically, it was a performance of breathtaking power. One can discern on his numerous recordings the power of Fleisher's musical mind. But one has to hear him live to fully experience the force he can let loose from a keyboard -- the range of sonority, the precision of the attacks, the unfailing attention to the music's overview as well as detail.

The problem that has troubled Fleisher's right hand in recent years is a terrible loss to him, but it is an even greater loss to music in general.

The Ravel, though, was just a part of one of the National Symphony's most distinguished programs of the year (to be repeated three times).

Mstislav Rostropovich conducted the lengthy, almost Mahler-like 10th Symphony of his mentor, Dmitri Shostakovich -- quite memorably. The 10th is this writer's favorite among the dark and brooding symphonies. It is the most beautifully sustained -- grim like some of the others, but with a nobility, a true tragedy that in some of the others is sometimes obscured by the composer's rage. Its broad, melancholy opening movement, in particular, caught this spirit. It is so fine, and so long, that one would almost be satisfied for the work to end right there.

Rostropovich was in grand form. The slow, elusive pulse of the first movement was superbly sustained. Balances were outstanding. Solo winds especially were lovely. The performance had the surging impregnability that one remembers from the magnificent old Mitropoulos recording.