Gottschalk was a ninth-century Saxon monk whose views on predestination were judged heretical by two church councils, although they were rooted in a close reading of the works of St Augustine. Gottschalk was also, however, a talented poet, a rigorous grammarian, an intrepid missionary, a brilliant teacher and a man convinced of his own prophetic and indeed miraculous powers. By any standards, Gottschalk was a remarkable figure, and Matthew Gillis's book provides a very welcome fresh interpretation of him and his activities. Gillis's work is not exactly a biography, but, to borrow R.W.Southern's phrase, a portrait in a landscape. The book offers a contextualisation of the key phases in the renegade monk's life, with particular attention to how he negotiated his identity as a Saxon aristocrat in his struggle against the Frankish abbot Hraban Maurus in 829, and to how he circumvented – in fact flatly ignored – the perpetual silence that the Council of Quierzy imposed upon him in 849 after his theology of double predestination was declared heresy there. Gillis provides generous quotations from contemporary texts throughout (tutors and others too will be delighted that these are all helpfully translated into English). And the book brings out very clearly the appeal that Gottschalk held for many contemporaries, despite his official condemnation.

For Gillis, the story of Gottschalk's life opens up ‘some darker aspects of Carolingian history’ (p.232). The monk was physically beaten, forced to burn a book of his writings, and spent nearly twenty years in confinement at the monastery of Hautvillers. It is difficult not to admire the steadfastness of a man who refused even – or so it is said – on his deathbed a final offer of a decent burial in exchange for recantation. Yet Gottschalk was not necessarily less ambitious for power and influence than his opponents. After all, one of his stranger prophecies was that he would in due course become the archbishop of Reims, once its current incumbent had suffered the wrath of God. Conversely, those opponents were undoubtedly protecting their privileged position by disciplining the monk, but they were concerned too by the dangerous pastoral implications of double predestination.

And in some ways, what is more striking than the harshness of the treatment meted out to Gottschalk by the authorities of the Frankish Church – above all Archbishop Hincmar of Reims – is its moderation. Despite his long confinement, Gottschalk continued to write, and his works continued to circulate: indeed a large number of them survive to this day, including many that were composed after his formal conviction for heresy. As Gillis points out (p.150), his monastic cell walls were porous, perhaps surprisingly so given that Hautvillers was located in Hincmar's own diocese, only twenty miles from Reims itself. This was supposed to be monastic imprisonment, but to judge from the surviving sources, it came close to being something like an enforced writing retreat – in any case preferable to the fate suffered by the Byzantine monk Maximus, who after his conviction for heresy in 662 had his hand cut off and his tongue pulled out to stop him communicating his ideas, or to that of the heretics at Orléans in 1022 who were condemned to the pyre.

The difference is partly that the Carolingian authorities – in this instance, Hincmar of Reims – never gave up on trying to win the heretic around (and Hincmar personally visited him on several occasions). This was a strategy of inclusion rather than of exclusion, what Gillis calls ‘coercive reform’ (p.7), and there is no evidence that Hincmar ever contemplated more severe treatment, though he supported capital punishment for laymen engaged in political rebellions. But it is also because Gottschalk still had many open supporters within Francia. These supporters were often enemies of Hincmar, but they were also people at different levels of society who were convinced by the weight of Gottschalk's theological arguments for the elect and the damned. Even Gottschalk's jailors, the monks of Hautvillers, defied the authorities by including him in their necrology after his death in the late 860s, so that he could benefit from their prayers. Even when confronted by living heretics, Carolingian Francia was clearly not the ‘persecuting society’ that some have identified in later periods.

Indeed, Gillis's key and convincing point is that Gottschalk was not really opposed to ‘Carolingian Christianity’, but was rather very much a product of it. The monk's reading of Augustine depended on the work carried out in scriptoria across Francia, his stylistic abilities reflected a first-rate education at Fulda and perhaps Reichenau, and he was in contact with many of the bright lights of the Carolingian Renaissance – Lupus of Ferrières, Walafrid Strabo and Ratramnus of Corbie. As Gillis puts it, both he and his opponents ‘operated with a common set of theological expectations and goals’ (p.236). If Gottschalk's fate reminds us of the implicit violence of the Frankish Church under the Carolingian rulers, the monk's life and work also reveals its plurality, complexity and indeed creativity, as a network that was both multi-centred and, to a certain extent, open to debate. Set alongside the recent publication of Warren Pezé’s Le Virus de l'erreur, with its complementary focus on the wider predestination debate, Gillis's excellent book brings the life and ideas of this entrancing early medieval heretic to the attention of a new generation of scholars.