‘All in all, perhaps the most important [source] for German history in the time of the investiture contest.’ This is Carl Erdmann (quoted here at p. vii), one of the greatest scholars of the period, on the so-called Codex Udalrici, a large early twelfth-century compilation of Latin letters, charters, poems and other short texts, which has now appeared in its first (virtually) complete modern edition, a splendid effort by Klaus Nass. Johann Georg Eccard first printed the Codex Udalrici in 1723, with numerous errors. Plans were first made for a scholarly edition in the Monumenta Germaniae Historica in 1831. In 1869 Philipp Jaffé, driven out of the Monumenta after years of suffering at the hands of the increasingly authoritarian president Georg Heinrich Pertz, published a reordered and abbreviated version in his own Bibliotheca Rerum Germanicarum series. Researchers with no access to the manuscripts have, until now, been forced to rely on a combination of Jaffé and Eccard. A series of eminent Germanophone medievalists have commented extensively on the Codex Udalrici and its making, but, for the uninitiated, the discussion has often been inaccessible. Now, however, thanks to Nass and the Monumenta, we have no excuse for not engaging seriously with this most fascinating witness to the intellectual, political and religious upheavals of the late eleventh and early twelfth centuries.

The Codex Udalrici was, manifestly, compiled at Bamberg Cathedral. The compiler named himself in a dedicatory poem to Bishop Gebhard of Würzburg (no. 1), dated to 1125. Udalrics abounded in twelfth-century Germany, but Nass is confident in his identification of the compiler with Udalric, custos of Bamberg (pp. xiv–xx). According to Nass's reconstruction (pp. xxi–xxv), the Codex Udalrici was compiled in phases, beginning no later than 1122 (or, probably, 1118), with a final Bamberg version, represented in this edition, completed in 1134, which included revisions postdating Udalric the custos’s death in 1127. There is no direct manuscript witness to this process, but two complete and five incomplete copies survive, all from the twelfth century.

Overall, the Codex Udalrici contains 395 texts: 22 poems, 113 charters, 228 letters and 32 miscellanea (formulas, synodal decrees, papal legislation, polemics, short narratives, oaths). Nass has left out only two of the lengthier Investiture Contest polemics (nos 34 and 196), both published elsewhere in the Monumenta. The compilation is roughly organised by genre, and chronologically within the letter section. The earliest texts date from the seventh century, but the clear majority are from time of the Investiture Contest. 161 texts survive only in the Codex Udalrici. For the rest, Nass has taken the trouble to record textual differences from relevant manuscripts outside of the Codex Udalrici tradition in his critical apparatus. This is important: it gives us a sense of the extent to which Udalric and his continuator(s) manipulated their source material. Nass is cautious here. Unlike several previous scholars he sees little evidence of extensive tendentious or stylistic alterations, for all that Udalric sometimes abbreviated or clarified his sources. Nass departs from previous scholarship in his assessment of the purpose and reception of the Codex Udalrici too. He argues that the selection of texts was based on content, not form or style. Some notaries at the twelfth-century imperial chancery knew a version of the Codex Udalrici, or at least its charter portion, but did not use it systematically. The Codex Udalrici was, Nass concludes, not a classroom or chancery book, but a collection of useful knowledge, likely intended for clergy striving for or destined to high office. It provided a comprehensive juridical and historical basis for dealing with the challenges that a provost or a bishop could face in the exercise of his duties.

Few might read these volumes from cover to cover, but the cumulative effect is fascinating. A world opens up, a world of men (mostly: ten texts – nos 4, 9, 11, 130, 136, 138, 182, 210, 280 and 383 – are addressed to or issued by women) flattering, patronising, bargaining, counselling and recommending their way through public life. This elite ecosystem of favours and sycophancy was disturbed by war, disagreement and excommunications en masse, but not shattered. One can see potential corruption everywhere, and the reformist obsession with simony begins to make perfect sense, as does the acute incentive – on all sides – to formalise public relationships, and to provide a legal basis for hierarchies, offices and landholding. Not only individuals, but communities as well (in the Codex Udalrici primarily cathedral chapters), emerge as confident participants, albeit with their own internal problems, often conceptualised as reflections of the larger disputes. Peter, a highly-recommended but disappointing new schoolmaster at Bamberg in around 1100, is a salient and very human example: he taught novelties and disobeyed his superiors, insisted on a canonical trial, and, following his suspension by the chapter, shouted back that he'd rather throw himself in the river than give up his prebends (nos 241–5).

The Codex Udalrici’s letter selection is studiedly bipartisan, alternating imperial and papal viewpoints. Udalric knew that most people caught in the middle of the investiture contest – like his bishop, Otto (1102–39) – had to be able to play both sides. His dedicatee, Gebhard of Würzburg, certainly needed well-weighed advice: appointed by Henry v whilst still a layman, just before the Concordat of Worms (nos 326–7), he spent the first twenty-eight years of his thirty-seven-year episcopate in dispute with his chapter and the papacy, with lengthy periods in excommunication. Gebhard's case is a reminder of how long and how much the papal-imperial dispute continued to resonate after its formal end. Today's medievalists have, with some exceptions, fallen out of love with the Investiture Contest. The grand old themes – Church versus State, the ‘de-sacralisation’ of kingship, and so on – have lost much of their lustre. Church reform is increasingly conceptualised primarily in a local context, anchored in the contingencies of power struggles and local economies, rather than as a centrally-directed intellectual movement. In the end, for this reader, the great value of the Codex Udalrici is that it allows us, better than any other document, to re-connect big ideas with small realities. As much as the grand chronicles and fierce polemics, it brings the period to life in all its complexity and relevance.