On the surface it's about the democratisation of poetry, which at the time was the preferred form of popular entertainment. But more profoundly it's about politics and society, and the ideal of a meritocratic system where greatness naturally rises to the top while banal entries are summarily dismissed...
http://www.theguardian.com/stage/2014/jul/30/rap-canterbury-tales-what-chaucer-and-eminem-have-in-common
