The book quest is available for rank Count and up on the Fed Hud.
You will receive the book from the trader, than you need a key; you’ll receive that one from the fortune teller at the festival, after that you need the abbot to translate the book for you. It can take a long time (in real time) to fully complete this quest. Once completed you’ll receive 2g forevermore per acre.
You can speed up the quest by buying a Bronze potion from the alchemist.