For Rostropovich, Ma played the first movement of Antonin Dvorak's cello concerto. The composition is a staple in the relatively scant cello repertoire, and as such is probably as familiar to Rostropovich as the Lord's Prayer is to the Pope. Rostropovich, naturally, has thought a great deal about the work, and his suggestions to Ma about performing it, reflected the more than 20 years he has been performing the concerto.

In one particular passage, the portly Rostropovich advised Ma not to give everything he had, for doing so would detract from the importance of the climax. "You have to guard your temperament a little bit," he said to Ma. "If you fall in love with a girl and tell her everything in five minutes that you can tell her...this is not the culmination of all things."

When he plays the cello Rostropovich adopts the same manner he uses to captivate a master class audience--animated gesture and colorful language. But with the instrument before him he is more at home, more self-assured, more convincing. "You must be like a conductor when you play," Rostropovich insisted as Ma played in the master class. "You must not be only you." From watching the Russian rehearse with the Dvorak concerto with Boston Symphony a week ago, it was clear that he has taken his own advice to heart.

When Rostropovich is not playing the solo part, he often conducts with his bow; when he is playing, he conducts with his head and his body gestures. Rostropovich and Seiji Ozawa seem almost to dance together, even when they lose eye contact. If Rostropovich has a comment to make to the orchestra--and he knows every instrument's part--he demonstrates what it should sound like on his cello. Rostropovich is a thorough musician, and when he plays or rehearses with an orchestra, he takes charge.

With only a one-shot rehearsal before a concert, as was the case last Wednesday, there is not time for fuss, and the atmosphere is usually very businesslike. Though obviously still still angry over the Logan-Colonnade affair, Rostropovich loosed the atmosphere with his antics. At one point in the concerto's slow movement, the oboe and the solo cello join in a singing contrapuntal duet. The oboist was playing too loudly for Rostropovich's taste, and so he stopped playing, turned around, and, shaking his index finger, abruptly accused and convicted the offender. "Are you the cause of this?" Rostropovich mockingly sneered. The wind players laughed, and Rostropovich grinned like a satisfied child.

It is business, though, when Rostropovich performs, and in solo recitals, as in concerti, his own concentration never falters. He describes the almost supernatural power which an artist should have over his audience, leading it into a trance-like state. "When I play a lot of concerts," he says, "I know in which places I allow the audience to turn their pages. The public can't hear it, they have to overhear it. When the public listens badly and doesn't pay attention, you have to do something. Your fantasies, your heart must be in it."