Merlin's book was a book so named because it was believed to have once belonged to the legendary Merlin himself. At some point, it came into the possession of one of the Heads of Hogwarts School of Witchcraft and Wizardry, and has since been kept in the Headmaster's study. A long line of successive headmasters and headmistresses of the school have presumably attempted to unlock its secrets, however, if any of them succeeded, its content might have proven either too mundane or too potentially dangerous for them to choose to divulge it, seen as the subject of the book is a mystery, with all that is known about it being it is handwritten in an unfamiliar runic alphabet.
Behind the scenes
- This mark is only mentioned as a possible answer to a hypothetical question posed during the sorting quiz on Pottermore. Therefore, it is unclear if this book does actually exist in historical canon.