The centennial of John Cage (his actual birthday falls on September 5) has generated an unprecedented wealth of international concerts and recordings of the composer’s music in 2012, and this Thursday through Saturday Northwestern University is adding to the slush pile with the John Cage Festival, a two-day symposium and handful of concerts, including the So Percussion performance on Saturday that I wrote about in this week’s Reader. The school’s library has an ongoing exhibition called “Sound & Silence: John Cage Composing Himself,” consisting of Cage’s correspondence, scores, and audiovisual commentary from some of his former colleagues at Northwestern; the NU library possesses one of the most important collections of Cage’s work in the world. The show opened on September 5 and runs through December 21.