Although, early on, Bonaventure associates the basic threefold division of the Itinerarium with a biblical thema verse from Psalm 85:11, the Itinerarium is more famous for its use of the image of the six wings of the Seraph angel St. Francis saw in a vision on Mt. Alverna as a structuring device. Incorporating visual imagery into a theological treatise was not uncommon in the Middle Ages. The Victorines were especially adept at the practice, and Bonaventure was clearly influenced by them. But the way Bonaventure used the parts of a visual image as a structuring device was new. It resembled the way a sermo modernus-style preacher would use the parts a thema verse as a structuring device. As I will show in Chapter 6, “Imagery as a Structuring Device,” this skill was something Bonaventure learned during his training in writing sermo modernus-style prologues at the University of Paris. I provide several examples, but most prominently, I describe how Bonaventure used visual imagery to structure the amazingly complex and beautiful prologue to his Commentary on the Sentences of Peter Lombard.