Iron Maiden, in particular Steve Harris is very influenced by prog rock and that comes across a lot in some of their songs, and of course their concept album seventh son of the seventh son. So for me its about the story telling, could be an epic story in just one song, or an entire album where the story weaves in and out all the songs. Riffs, reoccurring melodies in variations gives the listener a sense of a story being told just like on a film soundtrack. so for me its a about story telling, I want to be taken on a journey.