That is the Book of Life. All the world is made of stories, and all of those stories are right here.
The Book of Life is a living, magical book containing all the stories and the events in the universe, the past the present, and the future. It is usually seen levitating around with the Candlemaker, and appears to have a mind of it's own. It also helps out in desperate situations.
The Book of Life also contains all mortal beings and all mortal creatures written life stories from the moment they are born all the way up to their deaths.
The book is brown. On the cover, it has a design of a read heart made of hearts, spitting flames. The design has golden detailing.