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.

The complex interaction of different Christian systems created a series of uncertainties: about how to coordinate different ritual systems (e.g. baptism and the ritual year), about hierarchy (e.g. relation of the chain of command to status hierarchy), about the relation between the clerical elite and the monastic elite, and about the ritual status of heretics.

Leo I’s jurisprudence should be understood against the background of the earlier papal rulings available to him in the archive. He could not assume that these rulings would be generally known outside Rome, though they were being passed around. For that reason as well as for emphasis, repetition of earlier decisions was in order, but Leo I tended to draw out their logic and explain their rationale more fully than his predecessors had done. He worked within the already well-defined paradigm created by the first half-century of papal jurisprudence. Issues he dealt with included baptism’s relation to the liturgical year, the implication of penance for subsequent careers, indissolubility of marriage, pollution and celibacy, election of bishops and hierarchy.

As well as passing on or reaffirming decisions made at Nicaea, the apostolic see around 400 CE was dealing with issues the council had not addressed about who was entitled to administer a given ritual and when it was appropriate to do so. Questions arose notably about the ritual called consignatio, baptism, fast days in the week, a death ritual, and about marriage, adultery, and the Eucharist. These were problems without self-evident answers, and finding solutions might involve considerations both of principle and practicality.

In the late Roman Empire, complexity and uncertainty created demand for responsa from the apostolic see. After the eleventh-century papal turn, new legislation and a different society generated new complexities and uncertainties. Decretals were not the only way to resolve them, but given the prominence of the tradition launched by Siricius and Innocent I, they were an obvious way. An unbroken chain of communication links the first and second decretal ages. Late Antiquity and the central Middle Ages need not be kept in separate compartments.

The book attempts a long-range history which is about expansion of meaning in the course of reception, and the kind of social soil in which papal jurisprudence flourished in periods widely separated in time.

The apostolic see was asked how ritual systems, especially the system of clerical ordination, should be coordinated with the rules for the reception of repentant heretics. The main ritual system in question was clerical ordination, but baptism was drawn into the discussion. The main heresies in question were the Novatians, the followers of Bonosus and (less prominent) some Arians. The actual content of these theological heresies was hardly discussed in the papal responses. In terms of modern analytical ‘etic’ concepts, the responses are legal rather than theological. The last part of the chapter explains this conceptual distinction – between ‘legal’ and ‘theological’ – as it will be used throughout the book. Medievalists sometimes assume that canon law and theology were indistinguishable before the late twelfth century. It is true that they had constituted a continuum in the eleventh and twelfth centuries. When we look further back to late Antiquity, however, we find that a de facto distinction had emerged, even if around 1100 it would be submerged for a time.

The first and second decretal waves, c. 400 and c. 1200, both responded to unresolved complexities arising from the evolution of separate social systems. In the standard gloss on Gratian, ‘Gloss II’, decretals from the two ages are brought into conjunction. Innocent I’s ruling about pagan marriages was generating thoughtful discussion eight centuries after his death. The standard gloss discusses it together with a decretal of Innocent III. Between Innocent I and Innocent III, the ‘Pauline Privilege’ system emerges clearly into view, taken for granted by Innocent III after an evolution at which for want of evidence we can only guess. How to integrate the earlier Innocent’s ruling with the ‘Pauline Privilege’ system? This is an example of how the horizon of reflection about a text can be enlarged over time, without losing contact with the original meaning, as it is applied in new context and to complex scenarios not originally envisaged.

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.

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.

The focus of the chapter is on those features of the late Roman world in the West which were the environment of early papal jurisprudence. These include: the sheer number of clerics and monks, the heterogeneity of these two Christian elites, their relation to existing secular legislation on status and occupations, inconsistency in ritual systems, contested meanings of baptism and its place in the religious year, the symbolic significance of time, the disruption to society of the barbarian invasions, the two Christian systems of marriage (episcopal and imperial), and the spatial structures of empire and church. The chapter attempts to elucidate two overlapping sources of tension which played a part in generating the first papal jurisprudence: the multiplicity of semi-autonomous evolving systems, and uncertainty about where or whether to draw a line between non-negotiable principles and legitimate variation.

The chapter looks at period boundaries – c. 500, c. 1000 – and ways of transcending them. To position oneself on a boundary is one way, and another is to look for deep continuities. Here additional schemas have been proposed: the re-emergence of a half-submerged system with the recurrence of the conditions that gave rise to it originally, and, above all, the evolution of a sequence of communications (as opposed to a constant idea) like a conversation, from its origin through its twists and turns over many centuries. The history of the first papal jurisprudence’s reception over time can be a ‘part for the whole’, a synecdoche for the changes in history of Western Christianity. Tracing its reception helps to subvert the apartheid of periodization.

The three systems identified at the end of the previous chapter are all represented in the Carolingian and post-Carolingian period. The ‘inclusive’ system was renewed in the post-Carolingian period by the Decretum of Burchard. This left out a lot of the early papal jurisprudence studied in PJc.400. Secondly, produced over a century before Burchard’s Decretum and surviving in a multitude of manuscripts, there was the Pseudo-Isidorian corpus, consisting of conciliar canons and papal decretals, with boundaries closed against other genres of religious writings. It included all the papal material studied in PJc.400, but also material that would in a later period be classed as theology rather than canon law. More or less exclusive of such material, thirdly, were the Dacheriana, which included a non-trivial proportion of early papal jurisprudence, and the Dionysio-Hadriana, which was full of papal law. Charlemagne’s Admonitio generalis may be classified with them. It transmits only a modest amount of early papal jurisprudence, but this is attributed explicitly to the popes in question, and marked off, together with the conciliar canons, from the rest of his reform programme.