In a 1939 essay titled When Fiction Lives in Fiction, Argentine writer Jorge Luis Borges considers At Swim-Two-Birds, a 1939 novel by Irish writer Brian O'Nolan, writing under the pseudonym Flann O’Brien…

I have enumerated many verbal labyrinths, but none so complex as the recent book by Flann O'Brien, At Swim-Two-Birds. A student in Dublin writes a novel about the proprietor of a Dublin public house, who writes a novel about the habitués of his pub (among them, the student), who in their turn write novels in which proprietor and student figure along with other writers about other novelists. The book consists of the extremely diverse manuscripts of these real or imagined persons, copiously annotated by the student. At Swim-Two-Birds is not only a labyrinth; it is a discussion of the many ways to conceive of the Irish novel and a repertory of exercises in prose and verse which illustrate or parody all the styles of Ireland. The magisterial influence of Joyce (also an architect of labyrinths, also a literary Proteus) is undeniable, but not disproportionate in this manifold book. Arthur Schopenhauer wrote that dreaming and wakefulness are the pages of a single book, and that to read them in order is to live, and to leaf through them at random, is to dream. Paintings within paintings and books that branch into other books help us sense this oneness.