All creative work is derivative (video +)
Check out this really cool video by Nina Paley, setting forth the exact same thought that I expressed at TedXNewStreet in London last year (slides / post, video) in my talk on The Future of Copyright and IPR: in a networked society, all (...well, I said, almost all) creative work is derivative in some way or on another.
From Youtube: "Our second "Minute Meme," illustrating how all creative work builds on what came before. Photographed and animated by Nina Paley. Music by Todd Michaelsen ("Sita's String Theory," a Bonus Track on the soon-to-be-released Sita Sings the Blues soundtrack CD!). Photographed at the Metropolitan Museum of Art, New York City. More information. High-res and Ogg versions...."