From the introduction: North of the city walls of Ur-Agnès, beyond the opalescent mansions of its princes, you will find the ruins of a school which was called the Black School. It was a school bellow ground, eternally dark and changeless, where you could learn a thorough and perfect knowledge of the Old Arts. It was pretty well known among the pupils that the devil himself was the master. The legend says that one of the rules of the school was that the owner should keep for himself that one of the students who would leave the school the last every year.