Scholars of sonata form will pardon my paraphrase of Fontenelle's eighteenth-century query, "Sonata, what do you want of me?," reformulated here for present-day performers: "Urtext, what do you want of me?"

We live in an age that values the urtext, and that is a good thing. While I cannot speak for other instrumentalistsoboists, trumpeters, guitarists, and all those that make up the study of performance at the college levelI know that pianists are very concerned with the editions from which they learn or teach masterworks. Gone are the days when piano teachers assign a Beethoven sonata without discussion of the recommended edition(s).

Never mind, for a moment, that the precise function and format of an urtext edition differ from publisher to publisher. Some editions include extensive annotation and information on sources; others offer virtually no added commentarylet alone that two urtext editions of the same piece are likely to differ, sometimes substantially. Reading of texts to determine a composer's intentions, to make interpretative decisions, and to express what is written and connoted isn't for the faint of heart or for those who fear exploring murky areas.

Yet I perceive, at least among piano teachers, a certain overvaluing of the urtext, as if "textual fidelity" were an absolute and tampering with the text were a sacrilege. In my view, the urtext is nothing more than a fertile bed from which all kinds of textual manipulations and free fantasy can sprout. Imagination and the id must be at the heart of any truly compelling performance (bolstered, to be sure, by left- brained activity, such as comparing texts and studying style). This includes the possibility of changing notes, if the situation warrants, or actually improvising.

Long before the National Association of Schools of Music decided that our music students needed to have some exposure to the practice of improvising music, most musicians of every culture have improvised. In the Western canon, it is worth recalling that many great composers were also great improvisers, including J. S. Bach, Mozart, Beethoven, Chopin, and Liszt.

Every now and then, a student shows me a critique from some well-meaning judge who noted in the student's performance an omission of a "standard ornament" in a Bach invention. Alas, we live in an age of literalism! Far more perverse, in my estimation, is to perform Bach's inventions (and suites and toccatas) always with the same ornamentation. Assuming Bach had time to perform his works more than once, it is conceivable that he would have changed them at every performance. Evidence thereof exists in the 1723 variant of his C Major Invention, where Bach replaced triplets with sixteenth notes.

Or what about Mozart, who sometimes barely had time to write down the notes before a first performanceparticularly of the piano concertos, expecting to fill in at the moment certain Eingang and Durchgang passages, not to mention complete cadenzas?

Even Beethoven, who made his mark in Vienna first as an improviser, was a notable "adder of notes" to his own compositions, as Czerny relates in his "Anecdotes and Notes About Beethoven." This makes Czerny's later admonition highly ironic that "the player must by no means allow himself to alter the composition, nor to make any addition or abbreviation." Perhaps Czerny was still smarting from that 1816 letter he received from Beethoven, chiding the young Czerny for having changed Beethoven's written score. Surely Beethoven wasn't pooh-poohing the whole idea of tampering with the text, only Czerny's unimaginative brutish efforts.

And Chopin's notorious habit of allowing varying versions of his works to be published probably reflects his own improvisatorial disposition. He was forever changing his mind about fioritura flourishes. I see no reason not to experiment with my own versions of, say, the various repeated episodes of Chopin's B Major Nocturne, Op. 9, No. 3. If Chopin experimented with his own works, why shouldn't I?

"Ah, but that would require erudition, taste, and a knowledge of keyboard harmony," you may retort collectively. Hmm. Fancy that! Imagine seeing that dominant chord in third inversion in bar 34 of Bach's E Major Sinfonia and knowing that you can add, among many other possibilities, a descending and ascending scale in the soprano voice, a little lead-in, connecting to bar 35. What a triumph of stylistic and theoretical awareness: a celebration of imagination!

There are several philosophical subtexts to these suggestions: for one, that the "work of art," at least in the realm of musical composition, is not the score but the performed piece, perhaps differing at times from the printed page. Notice too that this argument gives hierarchical primacy to the performer over the composer, or at least equal partnership, in making the music come to life. In this regard, I imagine that the relationship of composer to performer is much more akin to the relationship of playwright to director-actor. Every actor who has ever performed a role knows that absolute "textual fidelity" is a myth, that phrases and words can be changed to make a more powerful presentation. To the question "How has Tennessee Williams survived all those permutations of his original script?" must be answered: "Only with those vital actors and their 'permutations' who take risks and bring the play to life with spontaneity and conviction!"

A work of art isn't some immutable Platonic ideal. The music isn't on the page. It is in the air, filtered through the performer's imagination. Don't tell me not to enter the compositional world of Scarlatti, Ravel, and even present-day composer Lowell Liebermannall of whom wrote music of improvisational character. I once asked composer Kenneth Frazelle if he minded if I (or other pianists) were to change his score. He replied, "If it makes the piece better"a challenging answer to be sure. But why shouldn't performers know as much about the pieces they play as the composers who wrote them? That immersion, including the freedom to change notes, redefines our relation to the urtext, even as it injects the interpreter's art with a new vitality.