These two stories catalog the works of two fictional authors; together and apart, they constitute substantial literary commentary on the nature of identity and like conceptual manifestations across time. The former author is renowned for seeking to write all of Don Quixote from his own experiences; the latter wrote works about labyrinths and possible futures.
An overview of Menard's collected works suggest his preoccupation with studying and crafting a linguistic method that accesses ideas required for the craft of writing, as opposed to common conventions and concepts (89). He sought to achieve this by translating the works of others, intentionally taking up opinions which were not his own, and by intensely studying logic. He is most known, however, for his attempt to recreate Cervantes' Don Quixote.
Menard only succeeded in writing the ninth and thirty-eighth chapters of Part I of the book, a well as a portion of the twenty-second chapter (90). What made his work remarkable was his method behind it: he did not want to simply write an updated version of the book, nor did he want to study the life of Cervantes in order to write it as him - a process that he did not consider challenging or interesting enough (91). He instead sought to write the book verbatim organically by drawing on his own experiences.
Borges lauds Menard for his effort on the grounds that what came naturally to Cervantes based on his life experiences is absolutely inspired coming from a man such as Menard, centuries later. This praise is hilariously presented to the reader by Borges analyzing a section of Cervantes' work and being completely uninspired, then analyzing literally the same words - but written by Menard - and praising its inspiration and brilliance. The review closes with a motivating quote by Menard in the vein of Plato, expressing a belief that all people will one day be capable of thinking all ideas (95). Borges suggests that the anachronistic craft which Menard has pioneered could be an ingenious way to revitalize old literature: that is, to take a famous piece of literature and imagine that was written by someone else.
In A Survey of the Works of Herbert Quain, Borges reviews the major works of modest experimental author Herbert Quain. His labyrinthine fiction, according to Borges, was underappreciated in its time. His first work, the mystery novel The God of the Labyrinth, was notable for its false ending: the readers thought the mystery had been properly explained until the sentence in the last paragraph, "Everyone believed that the chess players had met accidentally," which prompted readers to review the story and arrive at an ending that the characters never discovered (108).
April March, another of Quain's novels, was similarly labyrinthine, exploring different possible timelines: the first chapter is an event common to all timelines, and chapters beyond that explore different timelines of events that could have lead to that point - three events preceding the common first event, and three even earlier events linked to each of those three events (109). In this way, the novel is actually nine very different novels that end up in the same place.
The final surveyed work, Statements, reflect Quain's belief that everyone is a writer or potential writer, and that readers no longer truly exist (111). The eight stories are designed so as to prefigure a good plot, but are then frustrated by the writer. They compel the reader to think they have outsmarted the writer, yet all the while the frustration is of the writer's design. Borges boasts that he was able to extract his story The Circular Ruins from one of these stories (The Rose of Yesterday), thereby unwittingly making Quain's point.
Menard's story, which Borges recognizes as an absurd (but justifiably absurd) endeavor from the start, serves as a bold challenge to what constitutes the ownership or originality of an idea (90). Suppose that two people, years apart, wrote the same verbatim story: would they truly be the same story, given that they were generated from different experiences? Perhaps not to the author; yet it would do the reader well to remember that even given one author, a story is experienced differently by different readers. This perspective is almost certainly more relevant to the reader - though perhaps not more philosophically relevant - than the writer's inspiration.
One could argue, of course, that such a notion has no practical application because two writers being inspired to write literally the same story is virtually impossible. Borges himself suggests this by mentioning how many failed drafts it took before Menard managed to write even the small fraction of the Quixote which composed his final work. However, true though this may be, one should consider the case of Isaac Newton and Gottfried Wilhelm Leibniz supposedly independently discovering calculus in the seventeenth century. It is the scale of Quixote which makes it so implausible; ideas can arise separately quite easily, and thus the question of ownership can become sticky quite easily.
Borges' piece on Quain is salient because it largely reflects his own work, particularly in regards to labyrinth motifs. Quain's April March, with its branching timelines, reflects the book by Ts'ui Pen in The Garden of Forking Paths. The notion of treating books as puzzles as much as stories is also a very Borgesian idea, for even his practice of reviewing meta-fiction challenges the reader to engage the fiction in a more advanced way than usual.
It is worth noting that Quain's Statements contains eight stories, and Borges' The Garden of Forking Paths collection also contains eight stories. This, combined with Borges' quip about drawing The Circular Ruins from a Quain story, suggest that Borges' entire collection may be derivative of Quain's. This implication hearkens back to the questions of idea ownership and identity treated in the review of Menard.