An event which snuck up on the world, from the Perth Festival website:

"Experience the fascinating evolution of Glass’ compositions, and
playing style, on stage in this world premiere of all 20 Etudes – the
final three commissioned by Perth Festival.  This is a landmark musical occasion."

Glass composed his original six piano etudes for Dennis Russell Davies 50th birthday in the mid-1990s.  They served a dual purpose: in the late 1980s/early 1990s Glass had found that more and more he had been invited to perform as a solo pianist.  For years this meant that he needed piano repertoire.  Until the composition of the etudes, the piano music he was playing and continued to play were his own transcriptions of other music (Mad Rush-originally for organ; Metamorphosis I-V originally for the ensemble used in the film The Thin Blue Line).

During the recent Q2 Festival on Philip Glass' music, they aired an old interview from the early 1990s in which Glass was discussing this.  Interestingly, at that point as he was composing those first etudes he was calling them "preludes."  The first set of ten pieces were filled out and completed through other commissions:  one etude was once called "Now So Long After That Time."

For anyone who has seen Glass in concert, he would always say from the stage that he'd be playing from the first book of ten etudes, the second set, of which six had been completed, would also be a second set of ten.  I had read recently that Glass intended to premiere one new etude on December 2 at the de Menil Collection in Texas.  I have also long suspected that "A Musical Portrait of Chuck Close" is in fact one of the piano études in part or in whole.  On the other hand, the only new piece of piano music by Glass, Dreaming Awake, is its own piece.

So this concert in Perth is interesting.  Do we assume that the whole second set of ten etudes will be performed?  Do we assume that those six etudes which Glass said had been completed were completed over a decade ago?  I had heard at some point that the second set would be six longer pieces (8-10 minute range) rather than 10 pieces in the 4-6 minute range.  So we will see.