In <em>Frankenstein</em>, by Mary Shelly, <em>why did the author decided to have the character Walton and his letters to his sister frame the novel when he has no real role in the plot itself?</em>
(An answer to this would be that his presence give Victor a reason to be telling the story-as in he is given a meaning to the story and the way that Victor decides to tell it as a cautionary tale)