This is the big red book on the pedestal in the middle of the room in The Prologue of Defenders of the Realm.
It is called The Old Texts (subtitle: Everything a Wizard needs to know about Valdor, and managing the Realm).
It is a mish-mash of notes from previous Wizards of the Realm and has absolutely everything you ever wanted to know inside. Topics range from the extensive history of Valdor, to recipes on how to bake a wonderful cake. From how to kill an Undead, to what to wear to a Dwarf party (which are terribly hard to get into).
Every Wizard is born with a birthmark, of sorts, on their wrist, of The Old Texts. It is proof that they are going to be the next Wizard of Valdor.
(Sorry it's sideways). I feel no need to explain why that hand is giving you the 'live long and prosper' sign.
So there you have it. Some background information. I'm going to work on some characters now.
Live long and prosper!