The ancient Tevinters did not originally consider blood magic a school of its own. Rather, they saw it as a means to achieve greater power in any school of magic. The name, of course, refers to the fact that magic of this type uses life, specifically in the form of blood, instead of mana. It was common practice, at one time, for a magister to keep a number of slaves on hand so that, should he undertake the working of a spell that was physically beyond his abilities, he could use the blood of his slaves to bolster the casting. —From The Four Schools: A Treatise, by First Enchanter Josephus.