Nine old books, one shared copy of each. Everyone who visits reads the same pages.
Reading wears the ink away. Every time someone lingers on a page, its words fade a little. Some ink was always thinner than the rest, so the words go unevenly. When a word fades completely it is gone. It is not hidden, not stored somewhere, just gone from the page.
Copying brings it back. Take up the quill and write the damaged words out by hand. A faded word is easy to copy. A lost word can only be restored by someone who remembers it.
Which books survive is up to whoever visits.
Every word you restore is recorded in the margin of the page. How should you be remembered?