Glass sparked the minimalist revolution – then pronounced it dead. But he’s still propelled by the manic energy of those early works.

A couple of summers ago I was sitting in a hot Brooklyn backyard among musicians from MATA, a festival for young composers that Philip Glass helped set up in the ’90s. As cold drinks were gratefully drained I found myself chatting to a cheery man who introduced himself as Glass’s tour manager. At one point he drew from his back pocket a crumpled sheet of paper that on close inspection yielded a long list of cities and dates.

“This,” he declared, “is Phil’s schedule. Right now he ought to be in a cab in Kuala Lumpur heading towards the concert hall. In a few hours’ time he’ll be on a plane to Tokyo. He hits London the following morning then flies on to LA. He plays here in New York next week.”

This has been the way of life for Glass for as long as anyone can remember. At an age when many have long retired and hit the golf courses of Florida, he’s on the go as much as ever. Even with the bulge of birthday events...