How does Barth employ metafiction to examine ordinary life?

Certainly the story is about Ambrose. But, the story's central project is the exploration of the process of writing and the compensations of imagination. The story's constant metafictional play highlights the fact that the process of writing and the exploration of imagination is akin to the life of the contemplative mind. Like a great writer, Ambrose is too sensitive to live as happily in the funhouse of life as his happy-go-lucky brother Peter can. It is easier to live life without thinking too deeply; but, if one must contemplate rather than act, and it seems that Ambrose must, then the imagination will be a vital compensation. To explain how one might share and use that imagination as a writer, Barth employs metafiction both as a lesson on the frustrations of writing and reading and as a warning about the limitations of a (writer's) life. The story suggests that Peter will be happier and more sexually fulfilled, but Ambrose will become the next Proust.