At the Institute for Advanced Study in Princeton, in a public conversation with me and Jon Magnussen, Philip said: “Every music has its own style of performance, and every new music has to have a new style of performance, otherwise it's not new.”

In Princeton, we talked about how musicians are coming along today who play music that seemed almost impossible when it was new. Sometimes performers do exactly what the writer of a piece had in mind. Sometimes though, performers do something quite different — unintentionally, or willfully.
I  think Philip’s piano pieces lead to what can be called “molecular” piano playing. In some pieces, my desire to maintain an unbroken sound fabric of repeating note-patterns challenges the resources of some pianos — pianos that would seem of the highest quality in music by Beethoven! Glass’s hypnotic, slow shifts call for an instrument that produces no accidental lumps. There can be no notes prone to stick out, no unmatched voicing of the hammer felts, no unequal regulation of the action mechanism. And the greatest tonal equality must sometimes be attained at the softest dynamic levels — something not required in most traditional classical repertory.

Glass’s piano music has taught me how to play the instrument better, and listen with more subtlety. The loud, fast repetitions of Mad Rush yield more left-hand finger acuity. Long passages of moderately slow unchanging two-note ostinato allow for the heightened perception of rhythm in time. Micro-inflections can have large musical impact.

Philip has described his realization that theatrical work by Samuel Beckett is actually completed by each audience member at each performance. Roland Barthes declared the omnipotent “author” dead, in the 1960s. The kind of participatory involvement Philip (and Barthes) advocate for the audience applies to performers too. No matter what the performer’s intentions, or the composer’s wishes, each new reading (and each different instrument) adds to, reveals more of, and even alters, the complete identity — the complete range and possibility — of the music being played and heard.

Philip has written: “Art objects — be they paintings, string quartets, or plays — don’t exist or function by themselves as abstract entities. They function and become meaningful only when there are people present.”