In the 1260s, Humbert of Romans, former master general of the Dominican order, wrote an instruction book, De predicatione crucis, for aspiring preachers of the crusades.(1) His manual includes several passages of interest to art historians. Chapter 16--"On examples of ancestors, which inspire war against the Saracens"--documents the power of images to inflame the crusading passions of a medieval audience. First, Humbert advises, preachers should cite the valiant deeds of earlier ...