Every story has a perspective. A Narrator, or a point of view from which the story itself is told. According to Lucas in an interview some time ago, the 'Narrator' for the entire Star Wars saga, is none other than...
R2D2.
He's the only character that is there from the beginning of every episode. Even C3P0 is in the process of being built in EP1.
According to Lucas, the entire story is being related by the Droid sometime after it all happens.
I thought it was an interesting perspective.