Looking back on the period between the fall of the empire in the West and Charlemagne, the following typology is discernible: The style of jurisprudence developed by Siricius and Innocent I, and in letters of Leo I and Gelasius I that echoed their themes, was carried on by the Dionysiana and (rearranged thematically) the Concordia Cresconius. This tradition remained a major influence. One may call it the legal type. A second type includes the first and also confines itself to conciliar canons and papal letters, but adds a good deal of Christology, through letters of Leo I about the ‘one nature’ theory; in this type, the Christological content makes the collection as a whole less like ‘positive’ law, more like a general collection of all kinds of papal letters, a hybrid of law and theology (as later understood). It could be called the hybrid type. The Hispana is a prime example. In the third type papal law is present but pushed into the background by much material, Patristic and from penitentials, that is neither obviously legal nor papal. The Hibernensis is a prime example. For want of a better formula it may be called the inclusive type.

Surveys the physical, social, religious, cultural and demographic changes which take place in the sixth and seventh centuries, preparing the stage for the detailed study from 700 CE onwards. The intention is to demonstrate that Rome in 700 was a ‘Byzantine’ city, a ‘Constantinople on the Tiber’ in the phrase coined by Per Jonas Nordhagen.