metanarrative

E L Doctorow said that whatever a writer says about their own novel, is just part of the fiction and not to be trusted.

This applies in an interesting way to Mary Shelley's introduction to the 1831 edition of Frankenstein because, firstly, there are reasons to doubt the veracity of the story that Mary tells, but also, it's the perfect story told with all the verve and wit of the novelist that Mary Shelley is. 

Like Wuthering Heights, Frankenstein's structure is one of nested narratives - a story within a story within a story - and in a way, Mary Shelley's introduction is like the perfect packaging - a perfect outer narrative for the novel/ a perfect introduction/ a great story. 

She needed to answer the question that was frequently put to her - “How I, then a young girl, came to think of, and to dilate upon, so very hideous an idea?” - with a story, and that's what she provided.