Robert Walton’s letters are a crucial literary device in understanding Shelley's purpose

The structure of the book is arranged: we know that the unnamed stranger will be the general narrator, and Walton, substituting for all readers, will be the audience to whom he speaks. Shelley is setting up a number of themes in this clever kind of introduction. Walton's intense desire for discovery and the unknown, to the point that he would risk his life at sea, molds him along the lines of the epic hero type. Diction such as "glorious" and "magnificent" is used to describe his mission.