Codex 946 in the Troyes municipal library consists of 181 parchment folios, carrying about 150 miracles and visions, interspersed with short treatises, sermons and canonical texts. It was made in Clairvaux, almost certainly on the initiative of its prior John, between 1173 and 1181. (On dates: it only gives Bernard his ‘saint’ suffix half-way through, and he was canonised in 1174; Valdès of Lyons, whose conversion is first recorded here, had not yet broken with the Church). The codex was never copied, was kept at Clairvaux until the Revolution, yet has needed rebinding at least twice (the present binding dates from 1742 and there was one in 1472). The editor gives the work the unspecific title Collectaneum Clarevallense to reflect the heterogeneity of its contents. This heterogeneity reflects the volume's originality, and also serves as guide to the methods and minds of its makers. Of its visions and miracles, some two-thirds are of Cistercian provenance, from the contributor's own experience, or heard first-hand in Clairvaux or at general chapters. The other three-fifths are of various age, type and length, the two longest being a 79-page revised edition of Florus of Lyons's Expositio missae, and a 48-page excerpt from Elizabeth of Schönau's Liber visionum. Whatever the genre, three themes are prominent: the Other World, and relations between living and dead; the Virgin; and the Real Presence in the eucharist. Nuance is added by comparison with other early Cistercian collections. Herbert's Liber miraculorum, written in Clairvaux c. 1178, that is contemporaneously with the Collectaneum, shares only fifteen of the latter's stories, and never with identical words or details – a difference so striking that Brian McGuire – a previous student of the volume, and respected presence in the footnotes – thought it must be deliberate. Two Cistercian collections made soon after 1200, the unique florilegium in BN, ms lat. 15912, and Conrad of Eberbach's Exordium magnum, take over two dozen stories each from the Collectaneum, but alter them to make them ‘better stories’. The Exordium, for its part, adds a defensive note conspicuously absent from the Collectaneum, whose authors take serenely for granted the status of the Cistercian order as the path to salvation. This new jewel in the crown of the Corpus Christianorum will be invaluable not only to historians of the early Cistercians and their world, but, more generally, to all those students of pre-modern religious movements – the Franciscans, say, or for that matter the first Christians – who remain fascinated by the elusive process of transition by which lived experience finds its way, stage by stage, through oral report, into written record – changing the running water of history into the kind of ice we mortals can walk upon.