“Rock music, to adopt Nietzsche’s famous distinction, is perceived as alluringly Dionysian – a surrender to instinct and emotion, an invitation to the orgiastic. Classical music, on the other hand, has become purely Apollonian: it represents restraint, structure, order and discipline.” But, writes Rupert Christiansen, the way to incite the passions about classical music isn’t to hip it up. Rather, play to the strengths…