The first and last sentences show postmodern self-reflexivity.
In the first sentence, the author describes the setting and names the characters and after that, he directly addresses the reader and tells him how other writers used to enhance the illusion of reality by using proper names.
In the last sentence the author reflects on how these devices used by realist writers were in fact artificial.
In these sentences, Barth addresses the reader and gives his opinion on certain literary devices used by other writers. It is a piece of metfiction, reflecting on its own fictional character and techniques.
