Knightly Piety refers to a specific strand of Christian belief espoused by knights during the Middle Ages. The term comes from Ritterfrömmigkeit, coined by Adolf Waas in his book Geschichte der Kreuzzüge. Many scholars debate the importance of knightly piety, however it is apparent as an important part of the chivalric ethos based on its appearance within the Geoffroi de Charny's "Book of Chivalry" as well as much of the popular literature of the time.