The central recommendation of this article is that philosophers trained in the analytic tradition ought to add the sensibilities and skills of the historian to their methodological toolkit. The value of an historical approach to strictly philosophical matters is illustrated by a case study focussing on the medieval origin of conceivability arguments and contemporary views of modality. It is shown that common metaphilosophical views about the nature of the philosophical enterprise as well as certain inference patterns found in thinkers from Descartes to Chalmers have their origin in the theological concerns of the Scholastics. Since these assumptions and inference patterns are difficult to motivate when shorn of their original theological context, the upshot is that much post-Cartesian philosophy is cast in an altogether unfamiliar, and probably unwelcome, light. The methodological point, however, is that this philosophical gain is born of acquaintance with the history of ideas.