The unsurprising un-retirement of Michael Phelps – who’ll compete April 24-26 at the Arena Grand Prix in Mesa, Ariz. – has set off a spate of he-was-too-young-and-too-passionate-about-swimming-to-retire-anyway columns.

“If Roger Federer can play on quite respectably at age 32, why can’t Phelps head to a fifth Olympics at age 31 and try to add a medal or two (or more) to his uniquely large collection of 22, including 18 gold?” Christopher Clarey wrote in his “Why Not?” column.

Surely, Ryan Lochte – Phelps’ great friend and rival – isn’t throwing in the towel, even though he’ll be 32 in 2016. But why not compete? Why not do what you love as long as you want to do it? (That’s what Daniel Reiner-Kahn, one of the swimmers at the heart of my new novel “Water Music,” thinks when his father wonders what he’s going to be doing with the rest of his life. As far as Daniel is concerned, he has a career. He swims.)

I suspect , however, that the columnists are not just talking about Phelps or Federer. Athletes have always been poignant metaphors for ourselves.