In the first documentary on the DVD, John Cage : The Works for Piano 7, Margaret Leng Tan gives an in depth explaination of Cage's prepared piano technique. Tan was the first woman to graduate from the Julliard School with a doctorate in music. She worked with John Cage for the last eleven years of his life and today is hailed as the leading exponent of Cage’s music. The prepared piano technique involves inserting certain items between the strings on a piano in order to achieve unique sounds. Items such as pencil erasers and weather stripping can be used to mute a string or achieve a muffled sound, while screws and washers will produce certain percussive sounds. The sounds of Cage's prepared piano have been compared to that of a gamelan--an Indonesian ensemble of percussion tools. Margaret Leng Tan explains that the prepared piano technique originated from Cage's struggle to produce a wide array of sounds during a concert, but with a limited amount of space on the stage. In the documentary, Margaret Leng Tan spends the majority of the time demonstrating how one prepares a piano, noting Cage's meticulous instructions for how to do so. It takes almost the entire lenght of the film before the audience actually gets to hear the piano, but the final pay off is worth it. Cage succeeded; the piano preparations produce exquisite results.