It is the Book of the Dead. I cannot read any of it, of course, but you should be able to within the language that is most comfortable to you.

[ In fact, as he's saying this, the gibberish on the pages is now correcting itself into proper English. The book in itself is starting to feel warm, and... is it breathing? ]

Your dossier has emphasized that while you are an incredibly skilled mortal operative who is well-attuned to his "condition", you have not had many opportunities to explore more of your nature as one of the Bound. Studying that book will mitigate this weakness, and - given your work ethic - eventually remove it entirely.