Nicola Flannel's Grimoire

Throughout her life, Nicola Flannel wrote down all her alchemical recipes in this grimoire. When she sensed that the end was nigh, she concocted a potion that made the book as hard as metal, freezing it open ever so slightly. The only pages that can still be read contain a riddle. Some people believe that whoever manages to decipher it will gain the recipe to unfreeze the book and discover its secrets.