Legend has it that 45 years ago a stoned Terry Riley sat on a San Francisco city bus and in a cloud burst of avant genius composed the groundbreaking minimalist piece "In C," a loose conjoining of quick melodies over a steady glass ping to be played by any number of people and instruments over any period of time. To celebrate the piece's anniversary, David Harrington of Kronos Quartet, a longtime collaborator of Riley, organized a huge collection of friends and family to play "In C" at Carnegie Hall. We were lucky enough to sneak into the rehearsal, almost opening the door on a very focused Philip Glass on keys. We spoke to a few of the players—who included everyone from a choir of New York City children to blistering vocal legend Joan La Barbara to beloved children's musician Dan Zanes to Terry's son Gyan—and caught some of Riley directing the piece's very loose structure. We also went back to Carnegie the next night to see the performance, which lasted near two hours. Riley's standing ovation lasted about a year.