An infinite library of every possible book sounds wonderful until you contemplate the realities of it, which Jorge Luis Borges does masterfully in "The Library of Babel".
How do you explain the effects of random chance? Borges invented an all-powerful Lottery governing all possible events in life to help us think through it.
In “Pierre Menard, Author of the Quixote”, Borges plays with ideas of authorship and originality by inventing a French Symbolist poet who embarks on the impossible task of composing Don Quixote.
What would a world with no objective reality look like? How about a language with no nouns? Jorge Luis Borges explores these ideas in a fascinating thought experiment.
This section in A Universal History of Iniquity includes several interesting fragments, some of which could provide the basis for interesting stories but are not really developed.