Cage was an American avant-garde composer and writer. In the 1930s, he began writing all-percussion pieces and proclaimed the use of noise as the next musical horizon. In 1938, he introduced the “prepared piano,” an instrument whose sound is radically modified by various objects placed on the strings. He developed the idea of indeterminacy, music that is not strictly controlled. The notorious 4’33”, probably his most famous piece, consists of 4 minutes and 33 seconds of what? Discuss