Beginning around 1950, and throughout the passing years, he departed from the pragmatism of precise musical notation and circumscribed ways of performance. His principal contribution to the history of music is his systematic establishment of the principle of indeterminacy: by adapting Zen Buddhist practices to composition and performance, Cage succeeded in bringing both authentic spiritual ideas and a liberating attitude of play to the enterprise of Western art. His aesthetic of chance produced a unique body of what might be called "once-only" works, any two performances of which can never be quite the same. In an effort to reduce the subjective element in composition, he developed methods of selecting the components of his pieces by chance, early on through the tossing of coins or dice and later through the use of random number generators on the computer, and especially IC(1984)