Battle Instruction Encyclopedia

While in your home, Use the Encyclopedia and, every 60 seconds, you will gain an amount of Experience Points (XP).

Item expiration may be "1 Day", "7 Days", or "30 Days". For example, a Tier I Encyclopedia could be:

You will have one of four possible results, determining the amount of experience earned:
 * You fell asleep while reading. You waste so much time.
 * You quickly thumbed through it. There are still a lot of things you don't understand.
 * Your efforts result in steady results.
 * You're refreshed and learn doubly quick.

Since you have to be in your residence anyway, you should always switch to a class that is the lowest but still in the level range of the book. When you are ready for bed, remember to start reading and leave the game open overnight to maximize your experience gain from the book.