Music With Changing Parts is one of the seminal works in Philip Glass' career, and a defining point for the genre known as minimalism. Recorded in 1971, five years before he would break through to the public consciousness with Einstein on the Beach (which, arguably, was the moment his music ceased to be minimalist in the strict sense of the term), it represents the genre in a very pure form. Over its hour-long course, it both maintains a steady-state of sameness while percolating with all manner of variations. In retrospect, it's easy to see the affinities to the contemporaneous work of Terry Riley (A Rainbow in Curved Air and In C) and Steve Reich (Drumming), though all would soon branch apart. Here, the electric keyboards provide a pulsating substructure over which the winds, violin, and voice cast long, sighing lines forming the essential tension between dreaminess and rigor. There's also a palpable sense of excitement in the performance, the musicians very aware that they're on to something new and wonderful. This is an aspect of Glass' work which would diminish over time as his compositions became increasingly rote and academic. Listeners who only know his music from the period after he had attained a degree of pop stardom should certainly hear his more vital, formative compositions including this one and Music in Similar Motion.
AllMusic Review by Brian Olewnick