As everyone knows, the Academy City's General Library is the largest building of its type on the entire Continent. After countless generations of effort by big Niu Chao, the amount of books inside is as vast as the sea. Even setting aside the contents in the forbidden book area that are not suitable for public viewing, the knowledge contained inside is overwhelmingly abundant, it can be said to be all-encompassing and universal.
Under this premise, the Book Spirit, who claims to 'know all the contents of the library', is definitely one of the most knowledgeable beings in the world, although strictly speaking, it does not count as a person.
In other words, for the Book Spirit, the threshold for 'unknown' is extraordinarily high.
