When Montaillou burst upon the French reading public in 1975 medieval heresy was, academically, a subject of marginal and somewhat esoteric interest to a handful of historians and theologians, and none at all to almost anybody else. Its rise to prominence, even centrality, in medieval studies, acknowledged in its selection as a major theme of the Leeds International Congress in 2009, has been due to a growing preoccupation not so much with heresy itself as with the many forms of conflict, transgression and dissent for which it, or its persecution, may seem to stand. That is also widely reflected in cultural life, and notably in fiction: there is no sign of slackening in the procession of successors to The name of the rose (1980; film, 1986), all the way from the almost sublime to the manifestly ridiculous. Andrew Roach has been unusually sensitive among Anglophone historians to the ever-growing gulf between the two. His and James Simpson's selection from the papers presented at Leeds embraces the range and diversity of issues and approaches that the idea of heresy is capable of evoking, ‘with the aim of exploring how orthodoxy and hence (European) identity have been and are shaped by responses to and negotiations with “the edge”, both cultural and topographic’.

All the heresies considered, real and alleged, are Christian, except Maribel Fierro's substantial, sophisticated and important account of developing conceptions and uses of orthodoxy as a condition of political legitimacy in Umayyad Spain. Most, indeed, are Latin Christian, except Timothy Ware's authoritative discussion of the ‘Rebaptism of heretics in the Eastern Orthodox tradition’, Igor Dorfman-Lazarev's account, through ‘The travels and studies of Stephen of Siwnik (c. 685–735)’ of the condition of Armenians under Islam, Peter Petkoff's of that of heretics in Byzantine civil and canon law through the late twelfth-century commentaries of Theodore Balsamon, and a thoughtful discussion by Maja Angelovska and Andrew Roach on the legitimacy of folk legends as sources on Bogomilism. Marilyn Dunne disposes of a long-serving myth by showing clearly that the ‘Arianism’ of the Lombards was a label imposed by others, but also gets behind it to a persuasive account of their religiosities. The much-hounded heretics of twelfth- and thirteenth-century Languedoc – whoever they were – are pursued a little further by Julien Bellarbre, Claire Taylor, James Given and Catherine Léglu, and their much less familiar counterparts in Milan usefully surveyed in a thorough and critical discussion by Faye Taylor. Eva Dolezalova finds that Dominican inquisitors sought Waldensians largely among the German population of Bohemia, who rejected the Wycliffite ideas that were welcomed among the Czechs – as Sieglinde Hartmann's analysis of Oswald von Wolkensein's ‘Song of Hell’ illustrates.

The papers range well beyond the formal category of heresy. Daniel Gerrard makes a strong case for treating the development of canon law as reactive rather than simply prescriptive, on the basis of the responses of English councils mainly of the early twelfth century to military activity on the part of senior clergy which might arise from real dilemmas. No reader will fail to learn from, or to enjoy, Alexander Murray on ‘the burning of heretical books’, or, perhaps, be altogether surprised that its goal was symbolic rather than practically destructive. Nor is it greatly surprising to hear from James Simpson on Béroul that poets, and presumably their audiences, were prone to lurid sexual fantasies, from Alessandra Beccarisi that the accusations of heresy levelled against Meister Eckhart must be understood in a political context, from Sarah Thomas that concubinage was not out of the way for clerics in the late medieval Hebrides, or illegitimacy a problem for their children, or from Georg Modestin that witch-hunting was used as a means of bolstering clerical rights in fifteenth-century Lausanne. Recent analogies and methodological resonances are discovered by Philip Tonner on ‘Heidegger, Deleuze and the Duns Scotus Affair’, John M. Bates on ‘Heresy and its afterlives in Communist-era Poland’ and Robert I Mochrie on ‘Scholastic economic theology and fair trade’.

Most of these papers contribute something – some a good deal – to the subject directly addressed. A few of them look beyond it, but since they originated in twenty-minute presentations it is understandable that no large picture or over-arching question emerges. By arranging them into sections (not followed above) on ‘The Wheat and the Tares’, ‘Inventing Heresies’, ‘Approaching Literary and Narrative Sources’, ‘Law and the Inquisition’, ‘Heresy, Place and Community’ and ‘Distant Mirrors: Heresies, Orthodoxies and Modernities’, the editors have brought some analytical structure beyond the particularities of time and place to the vast and miscellaneous assortment from which it was their thankless task to select. Its elaboration in their introduction provides a stimulating overview of the state of the field and a thoughtful assessment of the ways in which ‘dissenters and heretics, whether as convenient bogeymen or living social facts’ have shaped, and been used in the shaping of, European structures of power and culture. In doing so they challenge specialists who are presently in some danger of exclusive preoccupation with local disagreements, fundamental as some of them are, to situate their work in a larger set of problems, and to engage not only with each other but with issues of conviction, confrontation and identity very widely felt and too little understood. They might have gone further. It is not unusual to find popularisers of history refusing to take account even of very fundamental scholarly revision, but the relationship between religious conviction and ‘scientific’ historical method has again become difficult to avoid in the academic discussion of heresy at a time when it has also assumed a dangerous urgency in the wider world. Andrew Roach and James Simpson deserve credit, and attention, for a timely and stimulating reminder that ‘the problem of medieval heresy is too important to be left to medievalists’.