It is obviously impossible to do justice to a tome of over 600 pages in a short review, especially as this project took a few years to coalesce into a book. The book is one in a series of Companions to the Christian Tradition which reassesses previous studies on Byzantine iconoclasm with the aim of adding something new to the debate. I will use its introduction, authored by the editor Mike Humphreys (pp. 1–106), to highlight the foci of this useful book.

Although its importance in the history of Byzantium has been downplayed by major revisionist studies in the 1990s–2000s, Byzantine iconoclasm was indeed a major and disruptive controversy in the history of Byzantium and the medieval West because it challenged an established relation between image, text and belief. Indeed, recent and emerging studies, including this Companion, adopt a post-revisionist approach. They reject the view that iconoclasm was entirely a fabrication of eighth- and ninth-century iconophile authors, who systematically interpolated earlier sources in order to portray Byzantine emperors as iconoclasts and thus heretical – to oversimplify the matter.

Notwithstanding the fact that the Church Fathers had not engaged in lengthy expositions on the role of sacred images (pp. 51–2), the recourse to sacred images as objects mediating between earth and heaven was not a novelty in Christianity. Humphreys does question the view of a ‘rise of the icon’ in the late seventh century, agreeing instead with other scholars on the pervasiveness of images in Christian religious practices since at least the fifth–sixth centuries (pp. 53–4) – one might object that this was the case even earlier. Indeed, a growing attention toward sacred images is recorded in late sixth-century Latin sources and in late seventh-century Greek sources. However, during the iconoclastic controversy, ‘for the first time in Christian history’, art became ‘a central topic of importance’ (p. 2), and images became the object of extensive and heated debate. Their intrinsic nature was more precisely defined, as was their role in cult and devotional practices and their relation with their divine archetypes. Their limitations, too, were noted.

A (supposedly) increased importance of sacred images occuring in eastern religious practices during the late seventh and early eighth centuries, along with other factors which still remain elusive, such as the eventual influence of Islam and Judaism, may have spurred the Byzantine emperors to harness, rather than suppress, a common practice. In maintaining that the earliest attestations of Byzantine iconoclasm must be dated back to the mid-720s, as the most recent examinations of extant evidence suggest, Humphreys rejects the view that iconoclasm only began under Constantine v (741–75). Hence, he supports the importance of iconoclasm as an historical phenomenon which had a lasting impact on Byzantine and western Christianity up to today, since images are still widely implicated in the public cult and private devotion within many Christian communities.

The Companion has five parts and twelve chapters authored by recognised experts, who examine a range of issues including the role of images before iconoclasm; the sources about the controversy; and recent source criticism. Also covered are the historical developments of iconoclasm; its theology between the eighth and the ninth centuries, including the relation between images and relics; and the development of an iconoclastic attitude in Islam, including the effects of Byzantine iconoclasm in the West. The chapters are long and detailed, and cater for ‘both newcomers and specialists’ (p. vii). They respond to the editor's intention to offer ‘some idea of [the historical] context in which the debate took place’, which he himself obligingly does in his introduction (pp. 15–42), after usefully outlining the history of studies on Byzantine iconoclasm (pp. 3–15). The authors generally strive to offer a balanced approach to the scholarly debate on the many aspects of iconoclasm by, for example, supporting the view that the scarcity of material culture from this period was not the result of destruction on a wide scale but possibly because it was a period not so rich in material culture when compared to late antiquity.

The Companion openly declares that it does not aim to cover all the research about this controversy (p. vii). It leaves out, for example, liturgical texts to focus instead on historical narratives, hagiography, dogmatic and theological writings. In doing so, it follows Thomas Noble's approach in his investigation of the Carolingian West (Images, iconoclasm, and the Carolingians, Philadelphia, Pa 2009). Noble is also the author of the rich concluding chapter on the same topic. On the grounds that no Latin texts openly speak of the image controversy, this chapter intentionally excludes a discussion of the period between c.730 and 760. Yet, recent contributions from research into liturgical texts and practices as well as in material culture have demonstrated how, during those decades, the West answered the controversy through preaching, public processions and visual arts produced for, or in, the most prominent churches of Rome under the patronage of the popes (see, for example, Éamonn Ó Carragáin, ‘Interactions between liturgy and politics in Old Saint Peter's, 670–741: John the Archcantor, Sergius i and Gregory iii’, and Charles B. McClendon, ‘Old Saint Peter's and the Iconoclastic controversy’, in Rosamond McKitterick et al. [eds], Old Saint Peter's, Rome, Cambridge 2013, 177–89, 214–28, and Francesca Dell'Acqua, Iconophilia: politics, religion, preaching, and the use of images in Rome, c.680–880, London–New York 2020, esp. pp. 35–120).

From its extensive bibliography (pp. 571–616), the Companion leaves out a few recent contributions which are useful to an understanding of Byzantine iconoclasm (see, for example, Óscar Prieto Domínguez, Literary circles in Byzantine iconoclasm: patrons, politics and saints, Cambridge 2020). Possibly the book's long gestation and its mammoth size made it difficult to incorporate new insights during the final stages of its preparation for publication. It none the less remains a commendable effort and a useful instrument with which to approach the controversy over sacred images and its wider socio-political implications.