> ...and a small book he kept, written primarily in an invented or "asemic" script, meaning it is unreadable or lacking specific semantic content.

Learned something new: https://en.wikipedia.org/wiki/Asemic_writing:

> ...asemic writing distinguishes itself among traditions of abstract art is in the asemic author's use of gestural constraint, and the retention of physical characteristics of writing such as lines and symbols.

Basically stuff that looks like writing but actually isn't. Another example is Xu Bing's A Book from the Sky, which is composed of things that look just like Chinese characters to someone who can't read them, but aren't.