In the fifth century bishops had brought problems to the apostolic see, which replied by laying down what was lawful and unlawful (leaving the bishops to do what they wanted with these responses). Shortly after the end of the empire in the West, the first decretal age comes to an end and a new phase begins: one of synthesis and compilation. This meant deciding what to leave out and what to include. Two collections, the Frisingensis prima and the Quesnelliana, include debate on the humanity and divinity of Christ, alongside the papal responses. The Dionysiana, however, leaves out these themes, which are in any case absent from the decretals of Siricius and Innocent I. Christological themes are absent also from letters of Leo I selected by Dionysius and from the ‘hold-all’ decretal Necessaria rerum dispositione of Gelasius I, which draws together in a quasi-synthesis the principal issues addressed in the first century of papal jurisprudence. Gelasius’s summative decretal and the Dionysiana anticipate the boundary that would separate canon law from what would be called theology, while the Frisingensis prima and Quesnelliana anticipate collections which recognize no such boundary.