This piece of youtubery illustrates the fascinating properties of Johann Sebastian Bach‘s Crab Canon (or, more precisely, the first of ten canons in The Musical Offering) where he takes a complicated theme and then proceeds to play it backwards, forwards, and both in unison.
This little piece is well known to anyone who has read Gödel, Escher, Bach: An eternal golden braid, which should be required literature on, well, any course, really. As my old boss Erling Iversen used to say, there are two kinds of IT people: Those who had read Hofstadter’s Gödel, Escher, Bach and those who should. Consider yourself tapped.
(Hat tip to Joho).