Opera redeems the dead theatre of the past: who would remember the world-conquering Victorien Sardou if it weren’t for Tosca, the plays of Victor Hugo but for Rigoletto? And Oscar Wilde’s Salomé too: an 1891 piece of self-conscious decadence detailing (with absolute neutrality) incest, murder and necrophilia in the Herod family, presenting moral sickness as aesthetic spectacle; it was satisfactorily notorious and banned in many places, but is surely unperformable now. Richard Strauss rescues it …