Last night the National Symphony played the first of this week's three concerts previewing works that it will play on its two-week tour of the Midwest and Canada that starts Monday. The program was imaginatively balanced, pitting the sinewy warmth of the Beethoven Fourth against the playful brass splendor of Lully's little "Fanfares pour le carrousel de Monseigneur de 1686." The evening then ended in the sonic eruptions of Debussy's "La Mer."

The Beethoven was the gem. It's hard to remember a symphony that music director Mstislav Rostropovich had so completely in the palms of his hands -- even a Shostakovich symphony.

The key to a marvelous Fourth is to let it sing. There is the question, though, of how to let it sing. Rostropovich had the answers. One is balance. As Beethoven's lyric melodies shift back and forth between the strings and the winds, it is important that everything be heard. The countermelodies, the inner voices and the textures are often almost as important as the main line.

Rostropovich clarified all this with impressive skill. He seemed to really know this work -- and not at all just in the sense of knowing the notes.

For instance, some cello lines in the first movement that are almost never heard were crystal clear. And he brought out an inner figure for the low winds in the finale that is almost never heard. Those are just a few of the examples.

The performance, though, was hardly just an accumulation of bewitching details. Rostropovich took his time with the music, phrasing warmly, and exercised great care with dynamics, to keep the Fourth from getting too far on the grand scale -- a common failing of many conductors.

The Fourth will be repeated in Saturday's preview.

"La Mer" was a windy sea -- the ocean winds pushing things along at a fast clip. And there were some unusual crosswinds in the central movement ("Play of the Waves") where Rostropovich used some unexpected little shifts of tempo. There were many inner voices that sometimes get submerged in more luxuriant versions.

The Lully was spirited. The overture to "La scala di seta" had the right tempos, but would benefit in the solos from wit that was more pointed.

The evening was dedicated to the memory of Eugene Ormandy.