A great jazz number doesn't fade out like a mere pop song or rock anthem. A great jazz number has an ending -- often abrupt, sometimes even in a different key, but always an ending that fits what has come before. So it was on Saturday with one of the great careers in the history of this surpassing American art form.

If you've never heard of Keter Betts, who was found dead at 77 in his apartment near Washington, you're not alone. Betts played upright bass, not one of the glamorous solo instruments. But you've heard of some of the people he toured, jammed and recorded with: Dinah Washington. Ella Fitzgerald. Oscar Peterson. Nat Adderley. Stan Getz. Charlie Byrd.

No fade-out: Betts was working at his craft until the very end. He was scheduled to play at the Kennedy Center next month; later this week he was supposed to participate in a jam session with local musicians.

I mark the passing of this man who never achieved the fame he deserved because the story of his life and work is so quintessentially American. Born William Thomas Betts in Port Chester, N.Y., to a single mother -- that's two strikes already, black and poor -- he bootstrapped his way to the top of his profession through talent, persistence and luck. He haunted stage doors until the musicians he idolized would come out to talk and offer advice, maybe even listen to him play. He took advantage of every opportunity and never came to a gig with anything other than his best.

And his life spanned the glory years of jazz, decades when American musicians were combining European melodies and African rhythms to create a new kind of music unlike anything the world had ever heard. It was music of exceptional rigor, grounded in the most advanced theories of composition. Betts played with many of the greats of jazz and was a friend or passing acquaintance of all the rest -- jazz is a small world, steadily getting smaller. It was Betts who became enchanted with Brazilian rhythms during a trip to South America and shared his new enthusiasm with saxophonist Getz and guitarist Byrd. Betts played bass on the two stars' seminal 1962 album "Jazz Samba," which introduced America to the bossa nova.

Best of all, at least for those of us who met him late in his life, Betts had a near-photographic memory. He could sit and spin his wonderful stories for hours on end. He'd be talking about the time he ran into "Diz" at some European festival, "Diz" being Dizzy Gillespie, and he could remember the hotel where he stayed, the venue where he played, what the two men talked about over dinner, what they ate. And, of course, what songs he played that night and who else was on the bandstand.

So many jazz legends had their lives shortened by drugs, like Charlie Parker and Miles Davis, or illness, like John Coltrane. Others sacrificed brain cells and hepatic function to alcohol; once, in the late '70s, I went to see Getz perform in a club in San Francisco, but the show was canceled after he proved to be too drunk to assemble his saxophone. Betts was a counterexample -- stable, happily married, immune to the depredations of the sporting life.

As a result, he reached old age with all his faculties intact. He could still flat-out play -- driving be-bop, soulful ballads, smooth Brazilian samba. He had a lifetime of experience to draw from, and the young musicians who learned from him could have had no better teacher.

Sometimes, after he'd told one of his great stories about Ella or Dinah or the New York jazz scene in the '50s, friends would tell him that he really needed to write it all down -- write down the history of America's great contribution to modern music from the vantage point of an insider, someone up on the bandstand instead of out in the audience. But the fact was that he was more interested in making music than writing about it.

Maybe that's the way it was meant to be. A great jazz number is evanescent; attempts to capture it on vinyl or magnetic tape, or to translate it into bits and bytes, are like putting a bird in a cage. Great jazz is meant to be performed live and appreciated live. When the music is gone, only memory can do it justice.