Is the artistry of performance negotiable? History suggests that it is, to some extent at any rate.

There's a line that connects Paganinl to Joachim to Heifetz, and continues on through present-day fiddle virtuosos. Fingerings, bowings, tempos get transmitted from generation to generation, along with something far more elusive and important, that fugitive intuition that translates dead notes on a page into living, compelling music.

This is true of other performance arts as well - dance, for instance. The insights of one era are handed down to the next through personal contacts, from master to disciple, in a tradition as old as human wisdom.

One of the most valuable means of effecting the transfer - unique to the performing arts, perhaps - is the so-called "master class." The term has many connotations. One is that it is a session or series of sessions led by a "master" - that is, a performer who has reached a level of technical and interpretive authority beyond serious challenge. Another is that instruction is offered simultaneously to a group, rather than to a single pupil, as in a private lesson. Still another is that the master class itself should serve as an ideal model of the educational process, a blueprint for the kind of instructional dialogue by which artistic knowledge can be formulated and conveyed.

This past week, the celebrated Guarneri String Quartet offered several master classes for string players and chamber music ensembles at Tawes Recital Hall at the University of Maryland. The two-hour session I attended was a reminder that teaching a master class is an art in itself.

The "pupils" or participants at a master class (the Guarneri session included professional musicians as well as students) are generally very advanced in their training. The purpose of a master class is not to unravel the bedrock technical problems that are better dealt with in individual instruction, but to hone an already polished performance to greater degree of live performance.

Even so, the master class ambiance is like a special kind of fishbowl, calculated to put the participants in an ultimate state of jitters. The listeners aren't just interested laymen, primed for enjoyment, but artists and colleagues of competitive stature, their ears cocked for every last slip or lapse of judgment.

It takes a lot of courage, therefore, to stand the gaff. By the same token, the "master," to successfully communicate anything other than intimidation, must be aware of the class vulnerabilities and compensate for them.

Arnold Steinhardt, first violinist of the Guarneri Quartet, and David Soyer, the group's cellist, approached the task with a splendid mixture of sympathetic concern and critical rigor. After each of the five participating artists or ensembles had finished his performance, the first comments from the "masters" were invariably words of praise, appreciation for the disciples' strong points and accomplishments. "Bravo!" exclaimed Steinhardt to a young man who'd just completed the big fugue from Bach's G. Minor Violin Suite. "That was very, very well played."

The critical commentary, when it came, carried the implication of making something good even better. "I noticed that often you played the notes without vibrato, and that tends to give the sound a bit of a steely edge. Particularly in those big, four-note chord passages. It's easy to get into the habit of not vibrating here, because it's so hard, hard on the hand to keep the vibration going while trying to span the chords accurately. But you see, you must be like one of those fakirs who walk on nails - and feel no pain!"

Once in a while there was a direct acknowledgment of the high-wire tension the master class atmosphere induces. When Soyer broke in repeatedly on a string quartet going through a Haydn opus, he injected at one point, "I'm sorry to be interrupting again - it must seem like we're persecuting you." The half-joking statement prompted a cathartic laugh all around, and broke the web of nerves one could feel gathering.

When a master class is going well, improvement seems almost instantaneous, and it is often brought on by the minutest of suggested changes - a mere hair's breadth of a pause, an all but inaudible shift in dynamic level. The key to such progress frequently lies in a brief demonstration from the "master" - a practical example, like a picture, is often worth a thousand words. But there are a variety of other tactics that work equally well, and sometimes it's better for the learner to come to his own insight without being shown how directly. And inspired metaphor, a bit of ludicrous exaggeration of a fault, or a dash of theatrics will often accomplish the same end.

"You should try not to make any waves," Soyer told a group assaying Beethoven's "Archduke" Trio. "This opening theme needs to be very serene - like a large mass moving very slowly. Nothing angular should intrude on its smoothness."

"I think you've got to fight," Steinhardt told the cellist in the same group later. "Be very nasty, but make sure you assert yourself, or you won't be heard. The cello part is very important here, it's not just filler, but it lies in a rotten register half the time. I would take more bow here, if you can't get any more sound by pressure alone - or if your colleagues don't play any softer."

"It's wrong to assume that going faster here makes the music more exciting," Steinhardt remarked to another group laying a Beethoven quartet."Sometimes you lose the excitement that way. It's like a rubber band - if you pull it too far, it loses its tensile quality."

Somehow, a wonderful sense of generational continuity pervades the whole process. The participants know that the "masters" achieved their mastery by going through the same painstaking - and occasionally mortifying - procedures, at the hands of those they themselves regarded as masters. And the current crop of disciples will soon be passing on what they've acquired to a younger brood of musical aspirants. It's like the ancestral chain of witch doctors, bestowing from dynasty to dynasty the sacred mysteries of the ancients.

The master class is a rite of initiation, and in some ways, as much of a marvel of human ingenuity in itself as the arts it helps preserve.