To illustrate both the power of music and its weak correlation with objective phenomena, the adagio of the 7th symphony will always, for me, summon a weird and awesome spectacle: the colossal stone head of an angry, snarling god floating above post-apocalyptic Ireland through fog toward me, whom it will devour…because I first heard it, arranged for organ and two male altos, in 1974 on the soundtrack to John Boorman’s film Zardoz. No other association has usurped it.