I need a clue!

[BurnedToast]

Kinda stuck on day3

I got the mission to go to the ship, and I talked to both keepers, but the objective to search the library for a clue about the dark age is still unchecked. I've been everywhere, looted everything in the forbidden library, and I even busted into the head keeper's study (allthough I got cought) and I can't seem to find whatever the clue is.