A book written by Xardas. It was written before the magic barrier was created, when Xardas was a member of the Circle of Fire and presumably lived in the monastery outside Khorinis. However, it is clear from the text, that he already came to a conclusion that his "brothers" are "fools" who would destroy all the records of the Beliar's temples, had they been given a chance.
This book is acquired for a moment in the third chapter, when Pyrokar at first refuses to help repair the Eye of Innos. Xardas wants the nameless hero to deliver this book to Pyrokar, as a sign of good will. However, the Sekob's farm, where this book is hidden inside a locked chest that can only be opened with Xardas' key, is already being searched by four Seekers when the hero arrives. Without doubt, they are looking for this book, trying to prevent anyone from reaching the Halls of Irdorath.
The nameless hero(and Pyrokar as well, in fact) is unable to read this book until the fifth chapter, when Xardas tells him the words which need to be spoken in order to open it. The book is by then stored in the monastery cellar and guarded by Talmon, Pyrokar however allows the hero access to it. The hero then successfully opens the book, finding inside a hidden key. He then descends into the secret library, where among other things he finds Xardas' notes about the Halls of Irdorath in a Dusty Book.
... and so I concealed the entrance to the library behind a secret door, to protect my records of Beliar's temples. If my brothers had known of these records, those fools would probably have destroyed them all.
Now, all they know is that these temples used to exist.
Just to be sure, I have sworn some servants to protect the library.
The key opens the last door.