Philip Glass has long since passed from the realm of controversial minimalist into compositional elder statesman, but that doesn’t mean that his music is any less polarizing than it ever was. Rupert Christiansen’s response to being forced to sit through a Glass opera this week: “There are times in the opera house when the tedium reaches such a peak that I am hit by a vertiginous urge to leap out of my seat, strip off my clothes and run on to the stage screaming like a banshee.”