At first impression, Philip Glass might seem to embody all that is intimidating about opera at its most culturally exclusive: shows five hours long (without intermission); obscure, coded symbolism; and plots that are difficult or elusive, if present at all. But for anyone willing to brave shows like Satyagraha, his music is immediately recognisable and redeeming. That’s because Glass has so influentially permeated cultural common – his sound has reached from ground-shaking film scores like Inception, to the finely tuned world of soporific-yet-focussed study music. Listening to any opera by Glass, even for the first time, always feels like re-listening to some extent. That’s also because the composer’s stylistic trademark, minimalism, is all about repetition: music that builds and falls in waves, where the slightest change can have a profoundly moving effect on the audience.