had​ a piano teacher who used to talk about the most familiar musical cadence – in which a piece returns, after wandering and variation, to its original key, the tonic – as ‘going home’. It seemed so easy when music did it: who wouldn’t want to swat away those black accidentals and come back to sunny C major? These satisfying resolutions are sometimes called ‘perfect cadences’; there is a lovely subspecies called the ‘English cadence’, used often by composers like Tallis and Byrd, in which, just before the expected resolution, a dissonance sharpens its blade and seems about to wreck things – and is then persuaded home, as it should be.