Clerics and monks were originally chalk and cheese. The clergy were an increasingly complex system committed to highly structured hierarchy – but there were unresolved uncertainties about the precise form it should take. The chapter discusses for instance the clerical cursus honorum, reactions against fast-track promotion, and the bigamia rule against clerics in higher orders marrying more than once and the rule’s relation to pagan marriage. The apostolic see was called in to clarify problems arising from these systems and also from the awkward relation between clerics and monks. Monasticism was an unstructured movement, sometimes out of control, at one point banned from towns by imperial law. The interpenetration of the clerical and monastic systems only intensified the challenge of integrating them. The problem would recur in different forms throughout the history of the Latin Church, and the difficulty of coordinating the two overlapping systems had the unintended consequence of strengthening the papacy, constantly called in to integrate monks within the religious legal system and adjust the differences between the two religious elites. The process is already in evidence with the earliest papal jurisprudence.

Episcopal elections furnish another example of the enlargement of legal meaning in the course of its application to new states of affairs. The conversation started by Celestine I in 428 when he sent Nullus invitis to Southern Gaul was continued with reference to situations and conditions different from those of the Roman Empire. Not in all respects. Just as monks from late Roman Lérins were leapfrogging over local clerics to bishoprics in Gaul, friars were being appointed as bishops in the thirteenth century. But clerical communities around late Roman bishops resembled neither the gamut of clergy spread over large thirteenth-century dioceses, nor the canons of thirteenth-century cathedrals. The slow transformation of the Western diocese and the Investiture Contest left a legacy of uncertainty about how to elect a bishop. In the thirteenth century, the efforts to create a transparently rational system for larger and more impersonal units were complicated both by uncertainties of the ‘greater and sounder part’ rule, and by the complexities of the concrete situations revealed by ‘modern’ rulings, from the second age of decretals, which glossators bring to bear on Celestine I’s decision.

That papal responses about Pelagianism belong to a specifically legal domain is a secondary conclusion of the chapter. The primary conclusion can be integrated with a central argument about the origins of the first papal jurisprudence, viz., that it was demand-driven, and that the demand was driven by uncertainty. We should not be surprised at uncertainty in late Antiquity about grace and free will when modern scholars write in such different terms about Augustine. Many modern people prefer Pelagius, but Augustine’s understanding of grace won the assent of intellectuals like Gottschalk in the ninth century, Bradwardine in the fourteenth, and Luther and Calvin in the sixteenth, and it continued to have adherents within Catholicism, even after the Council of Trent. Self-evident the solution to the argument was not. Given the violently opposed views, in this apparently purely Western controversy, it is not surprising that the apostolic see was asked for a response. Baffled by the paradox of divine omnipotence and human free will, it did what it would do in subsequent centuries: step back from acceptance of Augustine’s late views, without breathing a word of criticism against him.

Tensions arising from the establishment of monasteries in Gaul by John Cassian get associated in a long decretal of Celestine I with Cassian’s mild but firm critique of Augustine of Hippo’s views on grace and free will. These topics are the only core theological subjects discussed at length in the Dionysiana and Quesnelliana collections: the latter has three fascinating letters of Innocent I to African bishops, apparently endorsing their hard-line views on grace and (corrupted) nature, but in fact significantly silent on key points, stoppping short of some hard-line Augustinian positions.