In this story, Borges reviews The Approach to Al-Mu'tasim, a book by fictional author Mir Bahadur Ali. In so doing, he address themes of identity, goodness, and divinity. In the end, the philosophical question at play in this piece is to what extent an absolute good can manifest itself in a single entity.
Borges begins by succinctly summarizing what critics have said about the book with much more pedantry: that the story has elements of a detective novel and mystical undertones (82). He then describes the different iterations through which the book has gone: the original was published in Bombay in late 1932, after which Ali released a second, illustrated version called The Conversation with the Man Called Al-Mu'tasim: A Game with Shifting Mirrors (82). This second version was reprinted in London in 1934, the time at which Borges writes review. Borges reviews this version, and supposes that the original is a much better novel, though he has not read that version (82).
Borges then briefly summarizes the plot of the story, which follows the journey of an unnamed law student from Bombay. He has renounced his parent's Islamic faith, but then finds himself in a street riot between Muslims and Hindus on the tenth night of the moon of Murrham (83). He ends up believing that he has killed a Hindu, and then flees, hiding in a tower inhabited by a depraved man. Afterwords, remembering someone whom the depraved man spoke of despising, he assumes that such a person would be of good moral character, and he goes on a search to find that person.
The overall structure of the novel, then, proceeds by the protagonist searching by a matter of degrees for people with ever more moral goodness to their character. The title, The Approach to Al-Mu'tasim, refers to the idealized person of perfect goodness, about whom the protagonist hears while on his quest, and whom he nears by finding people who have known Al-Mu'tasim more and more closely and have increasingly better moral characters. The book ends with the protagonist being called into a room by Al-Mu'tasim.
Borges' main critique is the surplus of religious overtones, which he guesses were emphasized in the second version and less present in the first version. He sees Ali as making Al-Mu'tasim more of a symbol in the version he read, as opposed to an actual person with unique character traits. He sees this change as rendering the novel more allegorical in nature: the story is about an approach of the soul to God, rather than a journey to the pinnacle of humanity (85).
Borges also notes that the allegory presented - the notion of Al-Mu'tasim as a singular God who embodies the similarities of humankind - is not particularly interesting (85). Borges is more interested in the concept of all people, regardless of their level of sublime goodness, necessarily seeking someone of greater or equal goodness across time, either into infinity or cyclically. He supports this better idea by the etymology of the name "Al-Mu'tasim" - "He who goes in quest of aid" (86).
Borges closes by comparing the novel to other similar stories. Of particular note is the story of The Conference of the Birds, as told by the Persian poet Attar. In the story, a feather from Simurgh, king of birds, drops into the center of China. The birds decide to find him, and, after an arduous journey, thirty birds arrive at the mountain where Simurgh lives, only to find that all of them are Simurgh. Notable is the fact that Simurgh's name means "thirty birds."
One important theme Borges underscores here is the difference between messianic goodness and human goodness. The less interesting version of the story which Borges describes is that of a messiah: one whose goodness is divine, but who, consequently, is more of a symbol than a person. The notion of a messiah as a singularity also runs in opposition to the capacity for goodness to revolve infinitely along with the infinite nature of time, portraying apex goodness as something which can only exist at one point, as opposed to a goal towards which all journey.
This contrast is brought out well by the comparison between Ali's story and Attar's story. In Attar's story, the apex of goodness is accessible to all thirty of the birds, and is revealed to live inside all of them. They see Simurgh in the end because Simurgh is all of them. Ali's story, on the other hand, cannot show the reader Al-Mu'tasim because Ali has pigeonholed goodness in a single literal entity - and no single human could manifest messianic goodness in a way satisfactory to both human and symbolic.
Consider Christ as a proof of this last point. Traditionally, Christ is mainly an allegorical figure, serving as a symbol of divinity and its associated properties. When authors seek to reimagine Christ as a more human figure (see, for example, The Last Temptation of Christ by Nikos Kazantzakis]), readers are often unsettled or uncomfortable because Christ lacks the divine austerity afforded by a pure symbol of apex goodness. Thus, the notion of true moral goodness as exclusive to the very few, messianic humans, leaves one unsatisfied as to the ultimate human capacity for good.
In contrast, Attar's story is successful and inspiring because supreme goodness is found to rest within all thirty birds that reach Simurgh's home, with the pilgrimage acting as a proof of worth. What's more, the fact that the story began with a feather of Simurgh landing on earth suggests that it is a cyclical tale, which means this supreme goodness is timeless. In this way, ultimate goodness is divine in its infinity, as opposed to being divine by definition in its godliness.
Another paradigm to consider is one similar to Hermann Hesse's Demian. While not the manifestation of perfect moral goodness, the title character is the example of a human who is also a symbol. The paradigm functions adequately because the protagonist of the novel, at its close, finds that he has internalized Demian as a component of his identity. In this way, a symbol is also humanized in a way that allows for more nuance than either of the paradigms we have hitherto considered.