From 1 hour, 5 CDs

Releases from living jazz musicians account for less than 3 percent of all CD sales, but the late Miles Davis is still good for business. Several thousand people a week buy reissues of the 1959 album "Kind of Blue," making it the top-selling jazz CD of all time.

In a slow season of jazz CD releases, Columbia/Legacy has managed to come up with yet another way to expand the trumpeter's corpus. "The Complete Jack Johnson Sessions" is the eighth Miles Davis box set released by the reissue arm of Sony music. Producer Bob Belden has managed to expand the one-hour 1971 soundtrack for the boxing biopic "Jack Johnson" to a five-CD set. With a voluminous booklet, obsessive-compulsive recording details, and a variorum of alternate takes, Columbia thinks it can extravagantly multiply a 32-year-old record fivefold and turn a profit.

If the sales figures for their earlier reissues are any indication, it is probably right.

"Jazz is dead," Miles Davis intoned in 1975, "the music of the museum," but in 2003, the trumpeter's museum pieces sell better than ever.

A museum piece was surely the last thing Davis wanted to make when he first entered the studio to record these sessions in 1970. Filling in his rhythm section with the rock drummer Billy Cobham (after Davis couldn't get his first choice, Jimi Hendrix Band of Gypsies drummer Buddy Miles) and the R&B bassist Michael Henderson, a 19-year-old fresh from tours with Aretha Franklin and Stevie Wonder, Davis wanted to drown out his jazz past with cranked-up amps and pulsating grooves.

Gone were the features of his great quintet that had disbanded just two years earlier: Herbie Hancock's impressionistic splashes, Wayne Shorter's harmonic conceits, Ron Carter's peripatetic upright lines, and Tony Williams's intricate polyrhythms were replaced with a younger generation's reverb and backbeat.

Many critics have accused the Davis of this period of making what poet Amiri Baraka called "dollar sign music," but while the steady rhythms and grungy guitars of rock 'n' roll are present, the melodic centers are not. Davis, still playing at the peak of his form, emerges from the sonic swirl with some shockingly raw phrases, brass screeches above the electric din.

But unlike the music of Hendrix and Sly Stone that he wanted to capture, this music had no hooks, no tunes, nothing to sing along with. Half a million hippies could dance in the mud to "Purple Haze." But when the Davis of 1970 plugged in at the Isle of Wight Festival rambling over "Call It Anything," the crowd in the movie of that concert seemed bewildered. Today's audiences for groove music would have embraced such meandering rhythms, but in 1970, they must have seemed less like a generational anthem than an acid flashback. The Davis of "The Complete Jack Johnson Sessions" was using commercial sounds to engage in avant-garde concepts, making music that didn't swing and didn't exactly rock either. Any listener with the patience to listen to all five takes of "Willie Nelson" may be left wondering what a minor third bass line, repetitive common time beat, and stuttering horn lines have to do with the redheaded stranger. The five versions of "Willie Nelson" last almost as long as the entire original "Jack Johnson" album, and no matter how many ways you hear it, the meaning of the song's title will not be any clearer.Fans of electronica and ambient music could claim the Davis of this period as a precursor, but those kinds of music are essentially background music. "Jack Johnson," like Davis's 1958 "Elevator to the Gallows," was, after all, a soundtrack. Although old recordings by Davis are still used by filmmakers -- providing muted carnality for "In the Line of Fire" or rebellious cool for "Pleasantville" -- Davis's most vital music has always belonged in the foreground.And in over five hours of music, Davis did of course create some sounds that belonged on center stage. The first take of "Go Ahead, John" -- some encouragement for the English guitarist John McLaughlin -- is as pure a blues as Davis ever recorded. Before the funky pyrotechnics that emerge in the subsequent four versions, this warm-up shows how Davis could be vulnerable, melodic, nasty, and wry, with impeccable timing and superb instincts.Davis's blues on this take display his masterful economy and -- for a player so often pegged as "cool" -- astonishing warmth. The distortion of McLaughlin's guitar and the thud of Jack DeJohnette's high hat make perfect sense on this track. This take of "Go Ahead, John" shows that Davis could play the electrified blues of his moment and still take it back to Lester Young, Skip James, and, well, the best of Miles Davis.Moments like that "Go Ahead, John" take are rare on the "Complete Jack Johnson" set, but then artists such as Miles Davis are rarer still, and in a moment when most living jazz artists have trouble selling CDs, the posthumous Davis continues to astound. Davis is often quoted as saying that he "changed music five or six times," and even if the fifth or sixth time included a descent into synthesizer-drenched treacle, this document of the third or fourth has its stirring moments.In 1970, Davis was running as fast as he could from jazz. Columbia Records had just dropped Dave Brubeck and Thelonious Monk, and Davis surely saw the writing on the wall. Accompanying a movie about a boxer who was the personification of black pride and pugnacious masculinity, Davis's liner notes for the album tell us to "dig" the irony that Johnson eventually took a dive for "whitey" to make his final fortune. Davis may have been taking a dive for record executives sniffing out the commercial possibilities of rock 'n' roll, but however much he wanted to pronounce the death of jazz, from beyond the grave he is now leading a reissue label -- one that continues to unload Brubeck and Monk from its vaults.Every transformation of Davis is worth the scrutiny of these lavish releases, but they also remind us that Davis did not always follow the path of Jack Johnson's final career move. Miles Davis should be most remembered for the moments when he came up swinging.

David Yaffe is working on "Fascinating Rhythm," a book about jazz and American writing.