Doug Hofstadter of GEB fame wrote an interesting book on this called Le Ton Beau de Marot (http://en.wikipedia.org/wiki/Le_Ton_Beau_de_Marot) where he argued that 100% translation was pretty much impossible, and machine translation in particular. In that book he translated one poem from French to English thirty-six times, each time capturing some nuance of the original, but showing that no single translation could possibly capture everything.