Bring on the tough stuff - there’s not just one right answer.
What does the Library look like, really? See if you can draw a picture of it – we're still working on ours.
Where do baby librarians come from? No, seriously – how does the population of the Library reproduce? Are there any female librarians? Why aren't they mentioned in the story?
Is the Library completely silent? (It is a library, after all.) Or do you imagine there's some creepy elevator music playing all the time? Does music even exist in the Library?
How can we be sure that we understand each other's language? When two people communicate through writing, is there any way to know for sure that the reader understands exactly what the writer meant to say?
What do the librarians eat? Where do they cook their food? Can you think of any other daily necessities of life that Borges didn't account for in this story?