From Alex Ross, The Rest Is Noise:
[John] Cage’s definitive refutation of Beethoven came in the form of an epic, almost daylong performance of Erik Satie’s piano piece Vexations. The original score is only a page long and would normally take just a minute or two to play, but at the top appears this instruction: “In order to play this motif 840 times, one would have to prepare oneself in advance, and in the utmost silence, through serious immobilities.” Cage took this sentence at face value, and, on September 9 and 10, 1963, at the Pocket Theatre in New York, he presented Vexations complete. A team of twelve pianists played from 6:00 p.m. until 12:40 p.m. the following day. The New York Times responded by sending a gang of eight critics to cover the event, one of whom ended up performing. In the audience for part of the time was Andy Warhol, who remembered the experience when he made an eight-hour film of the Empire State Building the following year.
Cage was the fifth pianist to perform; John Cale was the fourth.