On the new album MODERN MUSIC by Brad Mehldau and Kevin Hays which was produced by Patrick Zimmerli, I was asked to identify the piece of music which had been arranged by Zimmerli and I immediately recognized the piece as Glass' piano étude No.5 played in a slightly different key. 

In fact, I was surprised to find out that the piece which Zimmerli arranged was the introduction to the fourth movement of the Fifth Glass string quartet. 

Zimmerli uses only that introduction and then either he or the performers add flourishes on top of the Glass chords. 

Here is the Glass piano étude:

Etude No.5

Here is the Glass String Quartet No.5 (intro)

String Quartet No.5 - Movement IV

Here is the two piano Zimmerli arrangement of the intro the fourth movement of String Quartet No.5

(listen to a sample at iTunes)

It's a cool piece - but in both Glass pieces there's development - in the fifth piano étude there's a slow and intentional variation in structure which characterizes most of the piano etudes; and in the string quartet, the whole fourth movement functions as a preamble to the wild square dance of the fifth movement finale.  Ultimately, the Fifth String Quartet is a 25 minute work meant to be played as if it were one movement. 

Whereas the new arrangement for pianos seems to hang its hat on the atmosphere of the chords, and there's nothing wrong with that! This type attraction to "mood" is what permits Glass' music to function in film.  I could go on and on about this but generally I'm very pleased that these three artists latched on to this bit o'Glass.