حجر الفلاسفة
The fictional Bernard Trevisan began his career as an alchemist at the age of fourteen. He had his family's permission, as they also desired to increase their wealth. He first worked with a monk of Cîteaux named Gotfridus Leurier. They attempted for eight years to fashion the Philosopher's stone out of hen eggshells and egg yolk purified in horse manure.