One of its subjects is the beauty of mathematics, which it conveys in a manner which reminded me of Tom Stoppard's "Arcadia" (one of the very best plays I've ever seen) in the way it let the magic of the stage enact mathematical processes, lending each a new vibrancy and beauty. And beauty is truth here. Says an actor early in "A Disappearing Number":
ANINDA: (In an Indian accent.) I'm Aninda, that is Al and this is Ruth. (Pause. His accent changes.) Actually, that's a lie. I'm an actor playing Aninda, he's an actor playing Al and she's an actress playing Ruth. But the mathematics is real.
Complicite, A Disappearing Number (London: Oberon, 2008), 23
The play's other subject might be stated thus: is our reality any greater, in relation to mathematics, than that of actors on a stage? In the sense in which mathematics is reality, truth, beauty, are we real at all? Perhaps the way to true reality is to feel the force of the question.
It gets - dare I say it - pretty religious, the religion of the Upanishads. (If we do Religion & Theater again, maybe we can include this!)