Adrian decided to open Cristobal's Journal to see what is inside. Just as he predicted, the journal is more of a grimoire as it has numerous spells and rituals written inside of it. Grimoires are different from skill books because of one thing.
Grimoires are basically a recording of all the knowledge of a mage in their lifetime. It contains all their knowledge and experience so that they can train their future apprentices. It also is a tangible representation of their determination and perseverance.
In some kingdoms, the grimoires of their famed royal wizards are placed in displays to inspire aspiring court mages. Grimoires are not only a symbol of mages but also a reminder for young mages to strive for the best. Adrian did not know why Cristobal created a grimoire, but he probably had an idea to get an apprentice if he succeeds in his experiment.