Former Beatle Paul McCartney turned 70 years of age on Monday.

Think about that for a moment. The dominant pop songwriter of our time and the symbol of youthful optimism and exuberance is now SEVENTY years old. Not fifty, not sixty, but seventy.

We can no longer refer to McCartney as an “aging” anything -- he is now instead “aged” (five years beyond the age of typical retirement in the United States).

When the other surviving Beatle, Ringo Starr, turned 70 two summers ago, it didn’t seem all that strange, but McCartney entering the twilight of his life is something else entirely since he has had a far greater influence on global pop culture than the little man with the big nose and rings on every finger.

Of course, McCartney has made absolutely no concessions to his age -- indeed, he is still performing (witness his recent appearance at Queen Elizabeth’s Jubilee celebration), he wears his hair unnaturally long and artificially dark brown, and he tries to stay “hip” by remaining constantly in the media and speaking like someone one-third his age.

Rock 'n' roll musicians, by definition, cannot (and should not) age. The Who’s famous declaration “hope I die before I get old” has become a dreadful cliché, but it points out the rank hypocrisy of pop musicians who simply refuse to age gracefully and relinquish their youth.

Jimi Hendrix, Elvis Presley, Jim Morrison, Buddy Holly and John Lennon, among many others, died in the true spirit of rock 'n' roll (that is, they perished young, thereby remaining forever young in our minds and guaranteeing themselves as everlasting legends).

If one is an immortal, one should not live ordinary, mortal lives.

But Paul McCartney? Well, he was never really a “rocker,” despite his many assertions to the contrary. He was always a well-behaved boy with bourgeois aspirations who simply wanted a comfortable lifestyle (which he got by the time he was 22).

McCartney is and has always been obsessed with material success: hits, charts, album sales and, of course, money (he is, after all, a billionaire now and even a knight of the British realm).

Since the Beatles broke up in1970 (more than half of McCartney’s life ago), McCartney's image has taken on a bizarre trajectory: His brilliant work as a Beatle will last forever and has gained even more of a shine in the four decades since, but his work as a solo artist (with Wings and various other iterations) have tarnished his history and wrecked what was once a sterling reputation.

There are few artists living today who simultaneously elicit such profound admiration and grievous condemnation in equal measure as McCartney.

Yet, I still treasure McCartney and the millions of hours of enjoyment his music (pre-1977) has given me.

But perhaps the more sobering thought is that, within 10 or so years (maybe sooner), there will be no Beatles left on Earth. That thought alone makes the future an even darker and scarier place.