After Constantine the Great recognized Christianity as one of the ofﬁcial religions of the Empire, it went on to be accepted by the end of the fourth century as the one true faith to the exclusion of all others. This section spans the time until the Reformation and the Religious Wars, which arguably began around 1400 with the Peasants’ Revolt in England (with its religious element) and the Hussite Wars in Bohemia. Historical periods are never neatly self-contained, and there is inevitably much overlap with the mentality of preceding and ensuing cultures. Thus the late Roman Empire and the Byzantine world carried important elements of ancient Greek philosophy and of the pagan Roman world. At the other end of this period, the Hundred Years’ War had much in common with the dynastic wars so typical of the Early Modern period. Nevertheless, comparing these strongly Christian cultures with those of the other periods covered in this book, what is striking is the intensity of men’s preoccupations with matters spiritual, with the afterlife of the soul. Thus it seems that more than in the other eras, the European Middle Ages are characterized by the particular religion that provided the systemic framework of reference for beliefs about the divinely ordained ordo mundis or world order, about good and evil, war and peace, friend and foe.