Good discussion on this article. I went to a Vampire Weekend concert last night and they used the 45 minute encore to play covers that were requested by the audience. They got through about 10 songs (a verse or two and chorus), everything from Talking Heads, to Creed, Sublime, Beastie Boys, and Prince and Bob Dylan (the concert was in Minneapolis, so they probably rehearsed the last two). So basically the band knew/memorized the tune for hundreds/thousands of songs from the past couple decades and the singer knew/memorized the words. So I think that this example supports the authors premise that creativity comes from some form of memorization.