Copyright 2000 New York Times

ON Oct. 22, 1894, a skeleton was uncovered here in the cemetery of St. John Church. No stone or sign marked the grave site, but the excavators, guided by archival documents to look for an oaken coffin and by an oral tradition to seek a spot six paces from the south door of the church, believed they had found the earthly remains of Johann Sebastian Bach, laid to rest on July 30, 1750.

The bones were examined by a team of medical experts from Leipzig, nearby Halle, and Vienna, declared authentic and studied for abnormalities. (There were none.) Then, in a moment of inspiration, the director of the group, the eminent Leipzig anatomist Wilhelm His, summoned the local sculptor Carl Ludwig Seffner to reconstruct Bach's countenance from the skull. The Seffner Bach Bust served in turn as the basis for Seffner's well-known 1908 statue of Bach, which stands alongside St. Thomas Church here. The New Bach Monument, as it is known (having succeeded a smaller memorial of 1843, sponsored by Mendelssohn), has become an object of veneration by Bach pilgrims the world over.

The quest to capture the ''real'' Bach started well before His (pronounced hiss) and Seffner, and it continues to the present. Indeed, at the recent Leipzig International Bach Conference, which brought together experts from around the world as part of Bach Year 2000, the city's commemoration of the 250th anniversary of the composer's death, Bach's personality was pondered anew in light of material discovered of late in Kiev, Ukraine. The finds verify that our image of Bach is still changing and shows few signs of taking definitive form. What is it that makes the composer so elusive? What drove His to flesh out Bach's bones?

There is an authentic portrait of Bach from his own time: a modest painting of 1746 by the local artist Elias Gottlob Haussmann, which hangs here in the Old Town Hall. It is this portrait, or Haussmann's 1748 copy of it (now in the William H. Scheide Collection in Princeton, N.J.), that graces the covers of countless modern publications on Bach and his music.

For His and his diggers of 1894, however, the Haussmann picture was insufficient. It shows Bach the dutiful cantor, professional composer and upright middle-class citizen, but no more than that. There is nothing to suggest the writer of the ''St. Matthew Passion,'' the B minor Mass, ''The Art of Fugue'' and other transcendent masterpieces. So His and his team took the discovery of Bach's bones as an opportunity to mold the composer's visage afresh, to bring Bach the man into greater harmony with Bach the creative artist. If in the end Seffner's towering, conquering figure of Bach seems closer to Otto von Bismarck than to the cantor of St. Thomas, it is only because of the tendency of every age to recreate Bach in its own image.

This began with the first biography, Johann Nikolaus Forkel's ''On Johann Sebastian Bach's Life, Genius and Works,'' of 1802. To Forkel, Bach was a Teutonic hero whose keyboard works represented a national treasure similar to the piano sonatas of Beethoven. Philipp Spitta, writing in the midst of the Protestant church-music revival of the 1870's, presented a different image. In his monumental ''Johann Sebastian Bach,'' he drew a vivid portrait of the St. Thomas cantor as the Fifth Evangelist, proselytizing for the Lutheran faith through his church cantatas and Passions.

Spitta's view held sway until the 1950's, when a redating of the church cantatas revealed that Bach had written most of his sacred works during the first six years of his Leipzig tenure and then, for the next 21 years, turned to different endeavors. To Friedrich Blume and others writing in the ''God is dead'' era of the 1960's, this could mean just one thing: Bach was a secular composer who moved away from the church to compose the harpsichord concertos, the ''Goldberg'' Variations and other worldly masterpieces. And now, in a new and important biography, the noted authority Christoph Wolff presents Bach as a ''learned musician,'' a composer-intellect whose systematic mastery of musical genres and continual search for perfection seem not so distant from the methodical technological breakthroughs of today.

Why does Bach lend himself to so many different interpretations? The reason is straightforward: while his music is brilliantly detailed, his biographical facts remain painfully sketchy. The most important stations of his life are clear: from court and church documents we know his positions and salaries and have official reports and petitions. Here and there a brief newspaper account or secondary report of local and regional concerts survives.

But about his personality, character and artistic credo, we remain largely in the dark, for we have only a handful of personal letters showing his inner thoughts. Even the datings and the purposes of major compositions are sometimes unclear.

Take the B minor Mass: scholars now believe that it was written in the last years of Bach's life and acknowledge that it is a Roman Catholic, not Lutheran, work. (Bach's son Carl Philipp Emanuel called it the Great Catholic Mass.) But what was its purpose? To fulfill a commission? To be used at a special service in Dresden? To provide private diversion? To serve as classic example for posterity? We simply do not know.

Bach himself contributed to the biographical quandary. With immense amounts of music to write, 10 children to rear (10 others died in infancy) and more than 80 students to teach, he seems to have been too busy to record the details of his life. He certainly had opportunities. Johann Mattheson, the prolific music theorist from Hamburg, asked Bach three times for information for the Foundation of an Honor Gate, a biographical dictionary of the most prominent musicians of the era. When the volume appeared in 1741, it included entries for Badenhaupt, Bertuch and Bleyer but not Bach.

''With his many activities, he hardly had time for the most necessary correspondence and accordingly would not indulge in lengthy written exchanges,'' Carl Philipp Emanuel later said of his father. ''Since he never wrote down anything about his life, the gaps are unavoidable.''

And gaps there are: for instance, Bach's departure from Weimar. Bach worked for Duke Wilhelm Ernst and his co-regent, Ernst August, at the Weimar court from 1708 to 1717, and ''the pleasure His Grace took in his playing fired him with the desire to try every possible artistry in his treatment of the organ,'' the obituary of 1750 says. ''Here, too, he wrote most of his organ works.''

Bach was esteemed and well paid. Yet strife between the dukes ultimately compelled him to seek employment elsewhere. When he found a position in Cothen, his petition for leave from Weimar was denied, and he was jailed for refusing to give up his request. After a month, when it became clear that he was adamant, he was released.

Spitta viewed the incarceration as a time of reverie, a quiet moment when Bach could work without interruption on the chorale preludes of the ''Orgelbuchlein'' (a collection now known to have been compiled several years earlier). Only lately have scholars come to realize that Bach's stand was not only obstinate but also deeply courageous. Recently recovered records show that another Weimar court musician was imprisoned and given 100 lashes when he sought dismissal. When he later fled, he was declared an outlaw and hanged in effigy.

Or consider the matter of Bach's deathbed scene. For Mozart, we have the very detailed account of Sophie Haibel, a sister of Mozart's wife, Constanze, which concludes: ''A long search was made for Dr. Closset, who was found at the theater but who had to wait for the end of the play. He came and ordered cold compresses to be placed on Mozart's burning head, which, however, affected him to such an extent that he became unconscious and remained so until he died. His last movement was an attempt to express with his mouth the drum passages in the Requiem. That I can still hear.''

For Bach, we have a similar description. It appeared in the foreword to the first edition of ''The Art of Fugue,'' from 1751, a year after the composer's death, and was probably written by Carl Philipp Emanuel: ''The late author of this work was prevented by his eye disease and by his death . . . from bringing the last fugue . . . to conclusion. Accordingly, we wish to compensate the friends of his muse by including the four-part church chorale added at the end, which the deceased in his blindness dictated on the spur of the moment to a friend.'' We have a manuscript copy of the chorale in question, ''Vor Deinen Thron Tret Ich Hiermit'' (''Before Thy Throne I Kneel Herewith''), and it is in an unknown hand, presumably that of Bach's friend.

So ''Vor Deinen Thron'' is Bach's ''Requiem.'' Or is it? In another manuscript, containing the last contrapunctus of ''The Art of Fugue,'' Carl Philipp Emanuel wrote: ''While working on this fugue . . . the author died.'' In yet another manuscript, of the sonatas for violin and harpsichord, another Bach son, Johann Christoph Friedrich, noted that his father ''wrote these trios just before his end.''

Modern handwriting experts believe that the last portion of the B minor Mass dates from this final period. And at the Leipzig conference, Mr. Wolff presented persuasive evidence from the material recently discovered in Kiev that toward the end, Bach might have been working on an arrangement, perhaps for his own funeral, of the motet ''Lieber Herr Gott, Wecke Uns Auf'' (''Dear Lord God, Awaken Us'') by his forebear Johann Christoph Bach. So what is Bach's last testament? The chorale prelude? The fugue? The violin sonatas? The B minor Mass? The funeral motet arrangement? Here, too, we remain uncertain.

There was understandable excitement at the conference over a second Kiev find, this one by Peter Wollny of the Bach Archive. Mr. Wollny discovered a series of contrapuntal exercises written by Bach and his eldest son, Wilhelm Friedemann. Appearing in the empty space at the end of an instrumental trio by Friedemann, the exercises date from around 1738, when Friedemann was the organist at St. Sophia Church in Dresden.

They appear to be a musical after-dinner conversation between father and son, in which the two exchange ideas about invertible and modal counterpoint and canons. Friedemann writes a two-part canon, Sebastian makes suggestions for improvements and so forth. Later, they move to inversion, stretto and other advanced techniques with the give-and-take of two professional musicians discussing tools of the trade.

Although scholars have long known the materials Bach used for teaching -- his own pieces, mostly, and a contemporary continuo manual by Friedrich Erhardt Niedt -- they have lacked evidence of the precise nature of his pedagogical approach. The new-found sketches suggest that Bach employed a type of Socratic questioning and dialogue. Mr. Wolff may thus be on the right track in portraying him as a learned musician.

Why is it so necessary to know Bach the man? Isn't his music enough? One suspects that it is the consummate nature of the works that drives us to understand their maker. As the pianist Andras Schiff's recent cycle of the keyboard suites at Lincoln Center reminded us, when Bach set out to write dance music -- or instrumental concertos, or chorale cantatas, or preludes and fugues -- he did so in an intense, exhaustive way, summarizing all that had gone before and carrying the endeavor to a new level of perfection.

''Everything must be possible,'' Bach said, according to his pupil Johann Philipp Kirnberger, who added that his teacher would not hear of anything's being ''not feasible.'' Standing at the beginning of a new millennium, 250 years after Bach's death, we still want to know how this can-do composer did it. Like His and his archaeological team, we want a fuller picture of Bach. But that remains a work in progress.