Every class of objects and every concept is represented by a being of god-like power known as an Imperator. Each Imperator may govern from one to several of these Estates, and has effectively limitless control over them. The Imperators are engaged in a deadly struggle with the Excrucians, terrible beings from outside the Weirding Wall who wish to destroy reality; this struggle is known as the "Valde Bellum". This war keeps Imperators busy in the Spirit World, so in order to maintain their affairs on Earth and in the other worlds they invest a shard of their soul in a human (or occasionally another animal or object), creating a Nobilis. Each Nobilis represents one of the Imperator's Estates; the group of Nobilis this forms, known as a "Familia Caelestis", is typically loyal, both to each other and their Imperator.