The pallium (or pall) is a liturgical vestment made of white wool, similar to a stole; in the mediaeval period, it took the form of a band that encircled the shoulders (affixed with pins), from which hung two strips falling down the front and back of the body, embroidered with crosses. Originally a garment worn exclusively by popes, from the sixth century onwards pallia acquired particular significance as insignia given by the papacy to other bishops (usually metropolitans) as a mark of authority and a symbol of their personal bond with the Church in Rome. The Code of Canon Law in the contemporary Catholic Church still specifies that a metropolitan ought to request a pallium from the Pope within three months of his accession, although he is no longer barred from exercising any archiepiscopal function before acquiring it, in order (the Code specifies) ‘to avoid giving the impression that the pallium itself conferred power’.

In the Middle Ages, this simple material object had much greater significance. Pallia were more than vestments; they were also contact relics, since the garment was customarily laid on the tomb of St Peter before being solemnly bestowed on the recipient. A precious gift and an impressive symbol of status and authority, the pallium was also, paradoxically, a symbol of control, imposed on a bishop. The recipient had not only to ask for it to be given but to accept the Pope's scrutiny before it was granted, and thus put himself directly under Rome's authority, constrained by the very sign that marked out his superior episcopal status.

In this learned and fascinating study, Steven Schoenig analyses the ways in which changes in the use of this single item of liturgical clothing between c 600 and 1300 cast important light on wider developments in the Latin Church that culminated in the reform of the eleventh and twelfth centuries. His method, which lays particular emphasis on the Carolingian period as a formative era in the shaping of the High Mediaeval papacy, requires engagement not only with the history of liturgy and liturgical dress but with a remarkably wide range of written sources including canon law, letters, diplomas and privileges, commentaries and polemics, chronicles and saints’ lives, as well as, to a lesser extent, visual imagery and surviving material evidence. Much more than a narrow study of one vestment's use, this book maps the papacy's exercise of power across western Europe.

For historians of the early English Church, the pallium has particular significance, for Pope Gregory the Great elected to grant the vestment to Augustine in support of his missionary work among the pagan Anglo-Saxons; in many ways, this laid the foundations for the developments of later centuries. English missionaries working among the pagan Continental Saxons, notably St Boniface, took their particular understanding of the relationship between local churches and Rome to the mission field, and also to the Carolingian Church, which had previously maintained some distance from the papacy. Yet, as Schoenig argues, the true story of the mediaeval pallium begins not in Canterbury but in Carolingian Frankia.

Part I of the study (‘Weaving the pattern’) defines the period from 741 to 882 as a turning point in the formation of Western Christendom. Most of the foundations of the wider project are laid here, in chapters that assess how to obtain, bestow and use the pallium, and then how it should be interpreted. The closely focused analysis is enlivened with numerous illustrative vignettes, discussing the careers of individual senior clerics, both those who found favour with the wider ecclesiastical establishment and those whose careers proved more stormy. Two further sections – ‘A well-worn garment, 882–1046’ and ‘The reformer's badge, 1046–1119’ – develop the narrative in similar style, in a way that necessarily involves a good deal of repetition. Readers of this Journal will find most interesting the lengthy epilogue, which addresses in detail the place of the pallium in classical mediaeval jurisprudence (1140–1271). In this period in which canon law was formally codified and ecclesiastical jurisprudence became a recognised intellectual discipline, earlier provisions and stipulations about the acquisition and use of the pallium were analysed forensically by canon lawyers. Schoenig divides this period into two distinct generations, which he defines as ‘the Decretum and the decretists’ and the ‘Decretals and decretalists’, showing how treatment of the pallium changed over this period.

Overall this is an impressive study, demonstrating how close attention to a single object can shed valuable light on a long period of mediaeval Church history, one in which the framing and revision of ecclesiastical law played a crucial role. It demonstrates conclusively the importance of the Carolingian era for laying the foundations of the Gregorian reform and it explains how and why, in the end, law proved more significant than material symbols or customary practice in defining and reinforcing the standing of the papacy. While once the popes had relied on the authority that the pallium itself bestowed, by the end of the period it was reduced to a simple symbol, lacking any real jurisdictional force; papal authority was rather expressed in the documentary privilege that accompanied the gift of the woollen liturgical band and in the legal prescriptions that surrounded its use.