India, April 12 -- A few days ago, in the crisp Nordic air of springtime Helsinki, Ian Anderson, the 77-year-old pied piper of prog rock, took the stage with his band, Jethro Tull.

He walked onto stage on a weeknight, dressed like an old codger, beaming like a benign grandad. Was he too old to rock and roll?

In an instant, all that changed. He was as sprightly as ever, flute in hand, one leg occasionally cocked in that iconic stance, weaving spells over an audience that spanned generations but also one with its fair share of grey hair. (Oh, there were many of us oldies at the Kulttuuritalo auditorium that evening.)

The Helsinki gig was part of Tull's ongoing Seven Decades tour, the name reflecting the band's remarkable longevity and ca...