Philip Glass is by now surely up there in the Telemann class among the most prolific composers in history. There must be an explanation, preferably a non-defamatory one, for how his technique has enabled him to produce such an enormous quantity of music. A glance at my iPod shows that Varese’s collected works are over in 150 minutes: Berg, Ravel and Debussy each managed to produce between ten and 15 hours of music at most.