Although the book in its entirety is highly recommended for fans of Lem, I would like to present some comments extracted from the essay entitled Unitas Oppositorum: The Prose of Jorge Luis Borges.
Lem states: "In each story we can find the same kind of method: Borges transforms a firmly established part of some cultural system by means of the terms of the system itself. In the fields of religious belief, in ontology, in literary theory, the author "continues" what mankind has "only begun to make." Using this tour d'adresse Borges makes comical and absurd those things which we revere because of their current cultural value."
"However, each of these tales has in addition another - wholly serious - hidden meaning. At base, his curious fantasy is, I claim, quite realistic. The author therefore has the courage to deal with the most valuable goals of mankind just as mankind himself does. The only difference is that Borges continues these combinatory operations to their utmost logical conclusions."
"Considered from a formal point of view, the creative method of Borges is very simple. It might be called unitas oppositorum, the unity of mutually exclusive opposites. What allegedly must be kept separate for all time (that which is considered irreconcilable) is joined before our very eyes, and without distorting logic. The structural content of nearly all of Borges's stories is built up by this elegant and precise unity."
"In the beginning he was a librarian, and he has remained one, although the most brilliant manifestation of one. He had to search in libraries for sources of inspiration, and he restricted himself wholly to cultural-mythical sources. They were deep, multifarious, rich sources - for they contain the total reservoir of the mythical thought of mankind.
But in our age they are on the decline, dying off as far as their power to interpret and explain a world undergoing further changes is concerned. In his paradigmatic structures, and even in his greatest achievements, Borges is located near the end of a descending curve which had its culmination centuries ago. Therefore he is forced to play with the sacral, the awe-inspiring, the sublime, and the mysterious from our grandfathers. Only in rare cases does he succeed in continuing this game in a serious way. Only then does he break through the paradigmatically and culturally caused incarceration which is its limitations, and which is quite contrary to the freedom of artistic creation he strives for. He is one of the great men, but at the same time he is an epigone. Perhaps for the last time. He has lit up - given a paradoxical resurrection to - the treasures transmitted to us from the past. But he will not succeed in keeping them alive for any long period of time. Not because he has a second-rate mind, but because, I believe such a resurrection of transitory things is in our time quite impossible. His work, admirable though it may be, is located in its entirety at the opposite pole from the direction of our fate. Even this great master of the logically immaculate paradox cannot "alloy" our world's fate with his own work. He has explicated to us paradises and hells; but in his books Borges knows nothing about them."
"If Schopenhauer had never existed, and if Borges presented to us the ontological doctrine of "The World As Will," we would never accept it as a philosophical system that must be taken seriously; we would take it as an example of a "fantastic philosophy." As soon as nobody assents to it, a philosophy becomes automatically fantastic literature."