This excellent collection of essays deals with an exciting area of historical research that is badly in need of a slogan. The final essay in the volume, that by Marie Barral-Baron on Erasmus, sits ill with those that precede it, in that Erasmus slots comfortably into that recognised paradigm ‘the early modern republic of letters’: there is no comparable tag by which to identify the subjects that unite this collection. Michael Van Dussen and Pavel Soukup have done a superb job in gathering together a group of leading scholars working at the intersection of late medieval heresy studies, book history, textual transmission and intellectual history. The long fifteenth century saw the flourishing of new networks of religious learning, contemplation and textual production alongside important realignments of political, social and devotional trends, none of which can be written off as being merely a forerunner to sixteenth-century Reformation, let alone late medieval decline. But this has been the inevitable result of too many years spent studying ‘late medieval ideas’, ‘pre-Reformation religion’ and ‘communication before print’. How can we truly see things on their own terms? The period saw new ephemeral literary forms (manifestos, polemical tracts) emerge within arenas of intense debate ranging from radical local underground movements, to learned coteries centred on religious houses and the great church councils of Constance and Basle, to repeated contacts between university scholars and new audiences of literate lay people. The vernacular languages were being used for learned and polemical debate (English, Czech and Italian feature most prominently in this collection). This last context was probably the defining feature of the period. In the opening essay Robert Swanson introduces a number of issues, sources and potential analytical models within this field, several of which are well-known, other less so, but all of which would certainly repay further study. Anne Hudson shows that the concept of the opera omnia was present before print; collecting manuscript works was laborious and Hudson shows that it relied upon personal connections and dogged effort. Dealing with Czech collections of Wyclif's Latin works, she demonstrates how manuscript culture had a major impact on Reformation Europe: the Hussite copy of Wyclif's opera omnia was used to try to persuade Archduke Maximilian to adopt the reformed faith in the 1570s. Daniel Hobbins's innovative work on the distribution of Jean Gerson's works at the Council of Basle picks up similar themes, tracing manuscript collecting and production through inter-personal networks revolving around key hubs of transmission: the houses of the observant religious orders as well as church councils. At Basle there was such a demand for writing materials that local flax manufacture shifted entirely to the production of paper. Fiona Somerset's essay places valuable emphasis on the practices and circumstances of textual production, copying and circulation, providing an alternative angle to both Hudson's opera omnia focus and to the ‘whole book’ studies of particular manuscript codices that has been dominant for the past fifteen years or so. Somerset deals with the minute alteration or ‘variance’ (this seems to be the accepted translation of Zumthor's concept of mouvance, though that also conveys ‘variability’ or slipperiness) that defined dissenting engagement with orthodox pastoral texts in England. Lucie Doležalová pursues a similar line of enquiry in relation to Czech and Latin versions of an Utraquist poem on the spiritual benefits of the eucharist, but while Somerset seems occasionally willing to equate ‘lollard’ with non-clerical, Doležalová takes pains not to over-interpret signs of Hussitism. Marina Benedetti draws attention to the ‘little books’ (parvi libri) of Waldensian preachers. These were lent as well as carried in the hand during itinerant evangelism, and they included medical remedies for physical ailments alongside spiritual medicine for the soul. Georg Modestin presents an anti-Waldensian treatise known as Cum dormirent homines (‘while men are sleeping’), revealing much about the lines along which anti-heretical ideas and texts circulated. Michael Van Dussen's own contribution describes the self-conscious compilation known as the Tetragonus Aristotelis: a collection of ‘epistolary fictions’ in dialogic form intended to evoke a ‘potential literature’ in which grand visions of reform and idealised futures could be discussed. Form and content mirrored one another in this fascinating production. In an uncertain world storing, sifting and winnowing were not merely the means of collecting ideas in textual form, they were intellectual strategies for discovering consensus. As Kantik Ghosh puts it in his incisive essay, university learning was in this period ‘a tense discursive arena’ shot through with doubts about purpose and epistemology. He contrasts the panicked conservatism of Richard Fleming who, in founding Lincoln College in Oxford, deplored the desire to ‘feed the swinish maws of simple laypeople with the most precious pearls of the mysteries of the sacred page’, with Reginald Pecock's mid-century idealisation of a ‘lay party’ possessed of Aristotelian natural reason. Ultimately Pecock shared his predecessor's snobbishness about intellectual authority; though he wanted to knock down the barriers between clergy and laity, he could only envision the intellectual traffic flowing in one direction. Pavlína Rychterová, writing about Jan Hus's treatise on simony, argues that he too assumed his lay readers to possess innate reason. This was one of the key concepts in breaking down lay-clerical divisions and in creating a ‘reform-minded’ public across fifteenth-century Europe. Pavel Soukup surveys the possible sources of central European ideas about Islam as a prelude to discussion of the word ‘Mohammedan’ being used as an insult by Hussites against their Catholic opponents. Discursive space was defined by negative as well as positive illocutionary strategies. As this exciting field of research grows and develops it is becoming more international and more interdisciplinary. One challenge is to discover causal links between religious observance, clerical and lay educational movements, heresies spilling out of the academy, the growth of government and the laicisation of administration, and the changing parameters of social differentiation and ideology among a population decimated by plague. As for a slogan, we could do worse than ‘the fifteenth century public sphere’, but undoubtedly we could do a lot better too.