Mary Shelley’s use of letters in the beginning of Frankenstein serves several purposes:

1. Setting the Stage: The epistolary format, using letters written by Robert Walton to his sister, provides a framing device for the main narrative. It allows Shelley to introduce the themes of exploration, ambition, and the pursuit of knowledge that will be central to the story.
2. Building Suspense: The letters create a sense of mystery and anticipation, as Walton recounts his encounters with Victor Frankenstein and his chilling tale. This builds suspense and draws the reader into the story.
3. Providing Context: The letters offer valuable context, such as Walton’s background and motivations for his expedition. This helps the reader understand the setting and the characters involved.
4. Framing the Narrative: The epistolary format allows Shelley to control the flow of information and the perspective from which the story is told. By framing the narrative through Walton’s letters, she can manipulate the reader’s understanding and interpretation of events.
5. Mirroring the Theme of Isolation: The letters themselves can be seen as a metaphor for the isolation and alienation experienced by both Victor Frankenstein and the creature. Both characters are isolated from society and struggle to connect with others.

In essence, Mary Shelley’s use of letters in Frankenstein serves to enhance the narrative, build suspense, provide context, and explore themes of isolation and the pursuit of knowledge.