There are repetitions aplenty here, naturally. But by the time Glass sat down to record these piano pieces, he’d already begun to stray beyond the hardcore tenets of minimalism that he had helped develop in the '70s. His experience with operatic writing is clear throughout: The gorgeously lyrical “Wichita Sutra Vortex” (whose namesake is an Allen Ginsberg poem) became a staple of the contemporary repertoire shortly after this album was issued. There are more metrically precise readings of “Metamorphosis” available, but the composer’s own slightly ramshackle technique has a charm that will never be topped.