The Unreality of Son's Story

Borges' story is almost as artificial as the library of Babel itself was as a thought experiment. He's asking us to deal with the unreality of his story now, but presented it in an extremely real fashion at the outset. So he arrives at this guy's house, Steven Albert's house knocks on the door expecting this is a meeting of strangers. And sure enough, when Albert comes and sees that there's a Chinese person at the door, he starts speaking it to him in Chinese  and says, Oh, you must be here to see my famous garden of forking paths.