Sorry if I was unclear. By “mathematical” I meant looking for an underlying rule, a universal applicable to all particulars - which is essentially what the original essay is looking for.
Borges absolutely was extremely specific and analytical, but that’s not what I meant.
But since you mentioned Borges let me offer a counter-counterpoint: Borges was obsessive about his writings and can be considered "mathematical" about them. He chopped away anything that didn't fit and was very careful about the construction of sentences. He was so obsessed that he recalled -- or so I read somewhere -- something that was already printed in order to make corrections to it.
Poe claimed he was quite "mathematical" (or maybe the word is "methodical", or "analytical") about the construction of his famous poem The Raven. While this claim is disputed, or maybe he exaggerated, at least it's something he liked to claim about some of his work.