What are the motifs in Northanger Abbey by Jane Austen?

The novel is a concise coming-of-age story featuring Catherine Morland as the protagonist or, as the novel terms her, the heroine. At the novel's opening she is seventeen years old and recently emerged as a beautiful young woman from a somewhat unpromising youth spent as a tomboy. She is utterly naïve about nearly everything, and especially uninformed about social propriety. She has never been in love and has apparently never been outside of Fullerton.