brent johnson digs up another lost treasure, this week from recent 70th birthday boy Paul McCartney …

Many years ago, a young man named Paul McCartney sang wistfully about spending a lazy life of “doing the garden” and “digging the weeds” when he turned 64.

Well, that hasn’t happened.

Critics like to mock rock stars who shun retirement and continue to step on stage well into their golden years. But you can’t mock Paul McCartney. He turned 70 last week, yet doesn’t seem as haggard as senior-citizen rockers like Billy Joel or Elton John. He may be the only musician over 60 who still seems energized and crisp in concert.

And where others his age seem to have lost the allure of their songwriting — or stopped composing music altogether — Sir Paul has flourished in the studio over the last decade or so. His last four albums are better than anything he’d done since the mid-1970s. You’d think he’d have run out endlessly clever chord progressions and catchy melodies by now.

Every once in a while, he also comes up with a neat piece of experimentation. Like ‘Mr. Bellamy,’ the standout track on his last album of original music, 2007′s Memory Almost Full — released just before he actually did turn 64. The song almost sounds like Paul McCartney fronting Radiohead: It’s a mash of mock-classical piano, scary voices and lilting woodwinds.

It’s no surprise, though, that McCartney manages to be durable years well into his AARP years. John Lennon may be everyone’s favorite Beatle — he was the smart one, the leader, the one with the weightier songs. But McCartney was my favorite because even when his songs were lightweight, they were always vivid, original and insanely memorable. He puts a good tune above everything else. And that’s what truly makes music timeless.