He was commissioned by a great many of the most important performing organizations throughout the world, and maintained a very active schedule. It would be extremely difficult to calculate, let alone critically evaluate, the stimulating effect and ramifications that Cage's work has had on 20th century music and art, for it is clear that the musical developments of our time cannot be understood without taking into account his music and ideas. His invention of the prepared piano and his work with percussion instruments led him to imagine and explore many unique and fascinating ways of structuring the temporal dimension of music.

He is universally recognized as the initiator and leading figure in the field of indeterminate composition by means of chance operations. Arnold Schoenberg said of Cage that he was an "inventor – of genius".