Composer, conductor, author, pianist, lecturer — was there anything Leonard Bernstein couldn’t do?

On 17 May 1969 Leonard Bernstein ended his 12-year run as musical director of the New York Philharmonic with a performance of Mahler’s Third. The next night he went to see Jimi Hendrix play Madison Square Gardens. And there you have him. Was Bernstein a fragile romantic or a firebrand rocker? Was he the spiritual visionary who gave us Chichester Psalms or the tin-pan-alley tunesmith behind West Side Story?

Bernstein went to his grave claiming it was possible to be all these things and more — insisting that you could be a political activist and a concert pianist, a conductor of the challengingly atonal and a writer of the melodically unforgettable. Not everyone was convinced. There were, and are, critics who believe that Bernstein’s facility and fecundity was mere dilettantism. Allen Shawn’s suave new biography hopes to give them pause.

Bernstein was a child prodigy, talking before he was 18 months old, picking out tunes on an aunt’s piano from the moment it fetched up in his parents’ Boston home. A few months later he was outplaying his first tutor, and within a couple of years had mastered Gershwin’s Rhapsody in Blue (a struggle for the average Grade 8 student). He was composing at 12, and by the time he got to Harvard, his party piece was flattening the dominants in Mozart sonatas to make them sound ‘like Grieg’. Little wonder a musician as variously gifted as Richard Rodgers once asked Bernstein whether there was ‘anything you don’t do better than anyone else?’

Well, his score for Zeffirelli’s biopic of St Francis, Brother Son, Sister Moon was rejected — mercifully, you might think, when you learn that Bernstein subsequently transformed much of what he’d written for the movie into his Mass.