One of them is about mirrors. In "The Floating City," mirrors reflect the back of things, so that if you look into one, you see the back of your head instead of your face.
"In the floating city's mirrors you can't find any answers or forecast the
future. But you can know the past, and this is not necessarily a bad
thing. History can teach lessons, and this is one of the good things
about the mirrors in the floating city."
I wonder if this is a reference to the enlightenment philosophy of reason, knowledge and science, which focuses on describing things as they are in the here and now, and how they came to be that way, without divining about the future. This seems opposed to many other philosophies, including eastern and religious ones, with prophesies, oracles, astrology, etc, many of which contains a divination aspect.
If that is indeed the reference, it is a profound insight by Xi Xi.