Here is a summary of the Wikipedia article about Ian Watt's The Rise of the Novel:

Ian Watt's The Rise of the Novel, published in 1957, is a seminal work in literary criticism exploring how the novel emerged as a distinct literary form in the 18th century. Watt argued that this new genre, characterized by "formal realism," arose from five fundamental societal shifts, including a preference for realistic fiction, growing individualism, an influential middle class, and a significant increase in female readership. He identified Daniel Defoe, Samuel Richardson, and Henry Fielding as the pioneers whose works embodied this new genre and reflected the changing society of their time.

The book became highly influential, shaping discussions about the novel's origins for over four decades and solidifying its place as a key study of literary realism. While foundational, Watt's contribution is also seen as codifying existing scholarly ideas about the novel's connection to societal changes and the importance of realism, rather than presenting entirely new discoveries.