Founding work of minimalism, Music with Changing Parts is a piece with free instrumentation. The musicians choose which part to play among the 8 staves of the score. At each indicated cue, the musicians can change part, which produces an abrupt change of instrumentation. While the music is based on a melodic material limited to a few notes that are repeated in patterns that expand or contract, the changes in orchestration refresh the listening  experience by producing sonic contrasts.  These techniques at work in Music with Changing Parts , written in 1970, will lead Philip Glass to renew his language and move from the monochromatic works that precede it to more dramatic works such as music in 12 parts and especially the opera Einstein on the Beach.

When Philip Glass began rehearsing the piece, he was surprised to hear long notes when everything was written in eighth notes. After making sure that none of the musicians were playing held notes, he realized that the fact that the same notes were played by all the instruments in the ensemble produced, through a psycho-acoustic effect, a harmonic substrate of resonant frequencies. He then decided to add to the score the possibility of playing long notes to reinforce this effect.

For this recording, we chose to record first the eighth notes, then the long notes in re-recording. This utopian version, with each musician playing short and long notes at the same time (!), illustrates the minimalist aesthetic that plays with our perception and allows us to reconcile opposites and cultivate the apparent paradox of a music that moves forward without Moving and changes constantly while remaining the same.