John Cage (1912-1992) was one of the most prolific composers of the 20th century and one of the leading figures of the postwar avant-garde. After studying with Arnold Schoenberg and Adolph Weiss in the 1930s, he moved on to his own compositions, heavily influenced by the work of Edgar Varèse. By his twenties he was a leading exponent of the musique concrète movement that combined electronics with traditional sounds and eventually led to the development of the synthesizer. His "utilized sounds" included doors slamming, water pouring, and radio static, and he is credited with the invention of the prepared piano technique, wherein the piano has everyday objects lodged inside the instrument in order to produce unusual sounds when played. He studied Zen Buddhism in the Far East during the 1950s and used the principles of the I Ching (Book Of Changes) to develop his own brand of experimental music. Far and away his most famous piece of music is "4'33"", which consists of complete silence (barring natural environmental sounds). The performer, usually a pianist, is expected to show the audience which of the piece’s four movements he is "performing" by the use of his fingers, as if a composer. Cage encouraged performers to add their own artistic input to the composition. He remained one of the biggest influences on many of the electronic and industrial exponents of the 1970s and 1980s, from the Grateful Dead to the Pet Shop Boys. The influence of his compositions, writings, and personality has been felt by a wide range of composers around the world. He had a greater impact on music in the 20th century than any other American composer.