A note sounds. Then it sounds again. But everything has changed. Not only is the note colored by a different resonance the second time around, but featureless time has been marked with the beginnings of a grid. The one note at the start defined only a before and an after. The second discloses a pulse. In accordance with this pulse, a third sound appears, but up a step, encouraging the accompaniment—which has not drawn attention to itself so far—to move conversely down.

We have reached only the beginning of the second measure of the Goldberg Variations and already a process is at work, a process that will be partly completed at the end of this measure but whose every completion will imply continuation. This first two-measure phrase will summon another, and so on, until there is a whole thirty-two-measure dance, which will be only the beginning of a chain of such pieces, again thirty-two in number.

One wants to know where all this comes from, this symmetry in action, this intimately designed time, this serene logic dependent not only on deep musical science but also on wild shifts of speed, character, and allusion and, from the performer, on dazzling feats of virtuosity and stamina. Hence the number of esoteric clues to Johann Sebastian Bach's music that have been offered, having to do with numerology, astronomy, the kabbalah, motific cross-referencing, or whatever. Hence, too, the enduring fascination with the person who wrote down these extraordinary notes.

As Martin Geck remarks in one of two new comprehensive books on the composer, the documentary record is meager. One possible approach is to draw these scant traces into a sweeping narrative; this Christoph Wolff has done for the present age in his masterly Johann Sebastian Bach: The Learned Musician (2000). The new books, by Geck and Peter Williams, work differently. Geck, in a slightly strange maneuver, approaches the biography by way of the biographers, so that, before we have learned much about Bach, we have been introduced to Johann Nikolaus Forkel, who corresponded with Bach's sons and published the first life of the composer in 1802. The Bach story is then duly told, if with some curiosities. For example, Geck has the composer's second wedding taking place in the palace church at Cöthen, the small town whose prince was then Bach's employer, whereas Wolff and Williams agree it happened at home. Geck also unsettles his readers by switching back and forth between past-tense narration and the historical present, a stylistic device that perhaps works better in the original German. The life, though, is not Geck's main concern; he gets it all done in fewer than 240 pages so that he can spend almost twice that many surveying the music.

Williams proceeds through the life and music together, in an original and highly productive manner. What he presents is effectively a commentary on the obituary written jointly by Bach's second surviving son, Carl Philipp Emanuel, and a musician of the same generation, Johann Friedrich Agricola, who had studied with the great man alongside C. P. E. Sagely reflecting that "evidence is seldom straightforward," Williams presses the obituary not only for what it tells but also for why it does so and what it ignores or withholds.

The basic facts are not at issue. Bach was born in 1685 into a prodigiously musical family. Nearly all his male relations—father, father's father, uncles, brothers, cousins—were professional musicians, most of them in the ancestral territory of Thuringia, in central Germany. Orphaned at nine, Johann Sebastian moved in with his eldest brother but from the age of fifteen was pretty much on his own, and at eighteen, after receiving schooling in return for singing in a church choir, he set out on his career. He spent most of his early manhood as court organist at Weimar, then moved to Cöthen for a few years before gaining one of the most prestigious posts a church musician could hope for in Germany, that of cantor, or musical director, at St. Thomas's in Leipzig. There he stayed, from 1723, when he was thirty-eight, to his death in 1750.

But have these facts, repeated through a quarter of a millennium, become no more than a husk over the experience they report? Bach's music, as Geck puts it, "comes from far away." Williams, on almost every page, indicates quite how far, and in doing so brings us startlingly close to the composer and his work.

There is so much we do not know—even about an incident to which the Bach-Agricola obituary gives more space than any other, that of the composer's routing of one of his French contemporaries, Louis Marchand, with whom he had been invited to engage in a contest of keyboard skills but who fled the scene. Geck barely mentions this victory by forfeit, but Williams finds it full of potential, pointing out, for instance, that it affords a useful allegory (for the obituary's purposes) of Bach's absorption and surmounting of French keyboard music, as represented by Couperin, as well as by Marchand. As Williams also observes, the story must have come—since C. P. E. Bach was three at the time and Agricola not yet born—from Bach himself, in which case any embroidery of the details "reveals a great deal."

This is not the only occasion when Williams has us ponder how much the obituary reflects the store of family conversation in the busy Bach home, or how much our view of the composer depends on the nature of the surviving documents. It is only because so many of these moments have to do with business affairs that the composer comes across as preoccupied with his financial rights and professional prerogatives—though one might add that zeal over detail is something that a post-Romantic age, believing in consonance between life and work, would want to find in the author of such intricately made music.

Similar is the desire for some creative reaction from Bach to such blows as the sudden death of his first wife, Maria Barbara, when they were both in their midthirties and the parents of four young children—hence, for many writers, the exceptional vehemence of the Chaconne in D Minor for solo violin and the Chromatic Fantasy and Fugue in the same key. Neither Williams nor Geck takes this line, though Geck, whose writing is generally more lyrical, does call the Chromatic Fantasy "the first instrumental work consciously to attempt the portrayal of an emotional state—grief—from a first-person perspective."

So it may be, but only if we take the feeling and the subjectivity as coming after the fact, placed in the music by the responses of others—such as Beethoven, two of whose late sonatas Geck aptly cites in this instance. Shown within a world that includes not only Beethoven but also Schumann, Wagner, even Picasso, Bach shines through the pages of Geck's monograph as the sort of commanding artist we can understand. The preludial introductions to the great biographers of the past eventually come into place, for Geck gives us a Bach who has been accommodated into our culture, by later artists and by the scholars to whom the author makes frequent reference. And this familiar, familiarized Bach is honored by a book that acclaims, warmly and appreciatively, such relatively unfamiliar works as Cantata no. 127 ("Herr Jesu Christ, wahr' Mensch und Gott") and the G minor viola da gamba sonata, besides the revealing attention it gives the Passions and the Goldberg Variations.

Williams, too, is enlightening about a huge range of works—and enlightening about modern valuations that, for instance, place the Christmas Oratorio (which he evidently esteems highly) below the Passions, because we are "more affected . . . by the moving and touching than by the exciting and exhilarating." Nor is he afraid to identify the odd artistic failure by Bach—a judgment for which Williams is qualified not only by his erudition (formerly a professor at Edinburgh, Cardiff, and Duke, he is one of the most eminent Bach scholars of our time) but also by his experience as a keyboard performer. But his bridges to the music are made across the abyss of the vast uncertainty and ignorance that separate us from the past, which only means that they have to be so much the stronger. Bach here is not a familiar figure at all, and the world he comes from—the world not of Beethoven and Picasso but of Telemann, Corelli, and many others in his immediate musical context—is strange.

In what may be the most disturbing passage in either book, Williams considers whether Bach's duties in Leipzig might not have included, as occasion required, supervising the St. Thomas choirboys as they sang songs of death for those condemned to be hanged or beheaded in public. If so, the words "Ach! Golgotha" in the St. Matthew Passion could have "aroused more than a vicarious, expressive horror at the place of an execution long ago."

More generally, and hardly less challengingly, Williams asks us to contemplate a Bach who found nothing in his world that might conflict with a devout trust in, respect for, and devotion to the God of the New Testament. Having grown up, in organists' households, with a sense of music as divine worship, he could hardly separate the musical from the sacred. Williams underlines the composer's participation in coffeehouse concerts and even regrets Bach never had the opportunity to fulfill the potential for comic opera revealed in some of the secular cantatas (a regret he goes so far as to imagine Bach also feeling). But we may well be sharing Bach's view, both Williams and Geck suggest, if we interpret The Art of Fugue, the Goldberg Variations, and much of the other solo instrumental music as no less religious than the Passions.

How, though, does Bach's music achieve, or at least point to, transcendence? One mark is the claim it makes of permanence. Geck and Williams both remind us that much of the music was repeatedly in transition: One cantata might be revised three times; another, written for the birthday of the Electress of Saxony, would furnish material for the Christmas Oratorio. Such variants allow us to participate in Bach's "march through the institutions" (Geck) or to witness the "sustained endeavour" that Williams finds deeply characteristic of him. They also alert us, as both authors note, to the conditions of performance in the churches of Weimar and Leipzig, how a work might need to be adapted for the personnel available. Williams typically keeps us aware of how much we do not know about the size of Bach's choir and whether the congregation joined in the chorale movements of the church cantatas and Passions; he also makes the striking point that cantatas at St. Thomas's were sung from a back gallery and so reached their audience—as they do modern listeners to a recording—in the form of invisible music. Still, beyond these circumstances of the time, Bach seems to have had his eye on eternity, above all when drawing up such compendious and unprecedented works as The Well-Tempered Clavier, the Goldberg Variations, The Art of Fugue, and the Mass in B Minor.

Surely, his ear was pointed in the same direction as the eye. In entering the cloudy area of musical expression, Williams is cautious. He remarks how one of the abiding features of Bach's work is "the sensuality of his music at moments of marked piety" and gives as an example the rich harmony of the alto aria "Ach, schläfrige Seele, wie?" from Cantata no. 115. As he also comments, the music here does not seem to be expressing the words. The anonymous text admonishes the slumbering soul to wake up, lest punishment carry it into "the sleep of eternal death." But Bach's setting—in E minor, prefiguring the aria "Erbarme dich" in the St. Matthew Passion, lulling the listener with a siciliano rhythm—makes this endless rest sound exquisitely delectable.

Williams strives to believe that such beauty is there to seduce the intended audience of believers, so that they would pay attention to the words. But did they hear the beauty, those Leipzigers who had no experience of such expressively intense and long-range effects being achieved with tonal harmony? Perhaps Bach was on his own, or in a relationship of two. As Williams concludes: "One can believe that Bach was at his most devout not when his sacred music moved or delighted his neighbour but when it was so complex that only he and his Maker understood it."

We might feel ill prepared to join such company. On the other hand, we have the advantage over Bach's original audiences of a far closer acquaintance with his musical language—and of guidance such as both these admirable books provide. Transcendence is here, in how, as time proceeds, eternity is always present—how, in that gorgeous aria from Cantata no. 115, the shadow of a fall reappears again and again; how, in the D Minor Chaconne, the keynote is forever being revisited, with whatever feelings of homecoming or hopeless inevitability; and how, in the Goldberg Variations, the opening dance is there again at the end, "as if nothing has happened" (Geck) or as if it had been present all along, beneath and upholding "a world of sound unfamiliar and unrepeatable" (Williams).

A note sounds. Then it sounds again. But everything has changed.

Paul Griffiths is the author of A Concise History of Western Music (Cambridge University
Press, 2006).