Hungarian composer György Ligeti’s Poème Symphonique for 100 Metronomes calls for fivescore clacking timepieces to be set up across the stage, wound fully, and set to different speeds. Once they’re all going, the performers leave, the audience enters, and everyone watches them run down.

This takes 20 minutes. “It is up to the conductor to decide the duration of the pause, before he leads the players back on to the stage to receive the thanks due from the public.”