Lennon Is Sad Image of Our Mortality.

WHAT do we mourn when we mourn John Lennon? He was, after all, only one-fourth of a famous band. The Beatles might have been to rock 'n' roll what Michael Jordan was to the NBA, but excellence alone would not explain the emotional eruption that occurs every Dec. 8 on the anniversary of Lennon's murder.

Fans weep. Disc jockeys go misty. Radio stations play marathons of Lennon songs, always saving his hopeful lullaby "Imagine" for the most poignant moment:

You might say I'm a dreamer

But I'm not the only one

I hope some day you'll join us

And the world will live as one.

Mourners gather in Central Park for a candlelight vigil. They did it again this month on the 20th anniversary of his death. They sang songs. They held their flames. The man himself -- who readily admitted his failures as a father, his tendency toward violence, his years of drug addiction and his doubts about some of his music -- was hardly a saint and would never describe himself as such.

For what are we weeping?

The man, or the myth?

Remember that the Beatles cradled neatly into the timeline of the '60s. They rose to mass popularity in 1964, just after the death of John F. Kennedy, the turning point of that decade. Their most productive musical years paralleled the Vietnam War -- when we embraced messages like "All You Need Is Love." They did drug songs when we did drugs. They experimented with religions and philosophy when we were doing the same. They were prolific in 1966-69, the most volatile cultural years in American history.

And when the '60s ended, so did they.

In 1970, the Beatles broke up.

Now I think that, had Lennon lived, the Beatles would surely have gotten back together for something. As we have seen with the surviving members -- Paul McCartney, George Harrison and Ringo Starr -- they are not above making oodles of money. They lifted a few Lennon tracks and threw their own voices behind his to sell a series of boxed sets a few years ago.

A Beatles anthology book -- by the three survivors -- now tops the bestseller charts. A new release of their greatest hits is a top-selling CD of the Christmas season.

If the Rolling Stones could keep coming back, if Paul Simon could reunite with Art Garfunkel, if the Eagles could put aside bickering for a concert series and an album -- if virtually every important 1960s group eventually got together again -- then why not the Beatles?

Only death halted that.

And in so doing, cemented the Beatles as the only band that had to do what the rest of us did: grow up and leave the '60s behind forever.

If you ask me, that is why Lennon's passing still haunts us the way it does. We mourn his death -- by gunfire, not. by self-indulgence, a la Jimi Hendrix" or Janis Joplin -- but we also mourn our own childhoods.

Contrary to the message sent by our culture, you don't get to be young forever. The Beatles are never coming back. Neither is your first bicycle, your prom, or your college dorm.

When we see pictures of Lennon, they are mostly of his Beatles years (since in the last five years of his life, 1975-1980, he was more of a recluse.) We see his wild and prolific youth; we see his hair switch from bangs to shaggy to shoulder-length to Jesus-like. When was the last time you changed your hairstyle on an annual basis?

Exactly. When you were a kid.

This is what we mourn when we mourn John Lennon. The brevity of youth, and the inevitability of death: his and, without saying it, our own.

Mitch Albom is the author of the bestselling book "Tuesdays With Morrie."