Alarmed by his students' random use of causal language in their essays, James Edward Carroll resolved to help his students improve their understanding of causal processes. Carroll decided to introduce his students to the metaphors that historians use to describe causation in the historiography of the Salem witch trials. By modelling how historians use different types of metaphor to describe the conditions that allowed the witch trials to take place, Carroll showed his students how conditions of events differ from direct causes, and have a different causal role to play.