[1] This work cycle was originally scored for ten instruments, played by five musicians: three electric organs, two flutes, four saxophones (two soprano, one alto, one tenor) and one female voice.
The music develops slowly, and there are long periods during which a casual listener would not notice any change.
The pieces are therefore challenging to the listener, but they have still enjoyed a significant level of popularity and are often cited as a major work of the second half of the 20th century.
Andrew Porter for The New Yorker magazine (1978) wrote of the transitions from one track to the next: A new sound and a new chord suddenly break in, with an effect as if one wall of a room has suddenly disappeared, to reveal a completely new view.Interestingly, Glass makes use of a 12-tone row in Part 12 of this work.
On Monday 1 May 2017, the work was performed at the Barbican Hall in London, England, UK, by a group of musicians assembled and led by keyboard player James McVinnie, the first time the work had been performed live other than by the Philip Glass Ensemble.