This slim volume, Tollefsen's third contribution to Oxford's Early Christian Studies series, ably shows the extent to which St Theodore the Studite made use of Greek philosophical logic and argumentation to sharpen his arguments against recrudescent iconoclasm (ad 815–43). The book thus represents a very useful contribution to the developing scholarly appreciation of the extent and richness of Byzantine philosophical culture and thinking. Tollefsen also sheds a good deal of light on some of the key aspects of Theodore's own thinking, notably in respect of Christology and image theory. There is, it must be said, a curious diffidence and understated quality to much of the book. The last paragraph of the conclusion is particularly underwhelming, amounting to little more than the claim that ‘Theodore is an interesting thinker’ (p. 149). This may perhaps be attributable to a certain Nordic sensibility, naturally averse to the grandstanding more common in Anglo-American academic discourse. Be that as it may, I am happy to applaud the appearance of a work which tangibly advances our understanding of the quality and sophistication of Theodore's anti-iconoclast works.

Theodore faced a somewhat more developed form of Byzantine iconoclasm than that addressed by St John of Damascus (to whom he obviously owes much). In particular, his focus is less on the issue of potential idolatry and Old Testament prohibition as on questions of Christological orthodoxy and the precise nature of a true image. It is worth emphasising that Theodore takes these more developed iconoclast arguments with utmost seriousness and that he resists mere ridicule or the setting up of straw men in the various dialogues that he constructs. In Theodore's hands, the argument against iconoclasm also takes on a forensic and avowedly logical character that amply merits the label ‘scholastic’ – not that Tollefsen uses this term. Chapter i details the various ways in which Theodore employs classical philosophical logic, both Aristotelian and Stoic but received within an overarching Aristotelian framework. Tollefsen does not suggest that Theodore is a great or particularly original logician but does claim for him a certain mastery of the art. Tollefsen is unable to explain quite how and where Theodore gained such a competence (understandable given the nature of the source material) but plausibly suggests some form of manual-based instruction and training.

Subsequent chapters move on to more avowedly theological topics – circumscription, relation and the nature of a true image. Here we encounter some quite excellent and suggestive probing of Theodore's remarkable Christology. The treatment of the notion of circumscription is perhaps Theodore's most abiding theological contribution. Granting, with the iconoclasts, that the divine nature itself cannot be circumscribed, Theodore goes on to present a sophisticated treatment of the circumscription operative in the incarnation and depictable in the icon. This is not simply a case of saying that the humanity is circumscribed whereas the divinity is uncircumscribed. Theodore cannot allow the icon to be representative only of Christ's humanity – precisely one of the charges adduced by the iconoclasts. Rather, the icon depicts the hypostasis of the second person of the Trinity incarnate embracing human nature in its totality. And because Christ has assumed all human nature, his humanity is irreducible to a single human hypostasis. What we are seeing in the icon is nothing less than the circumscription of the uncircumscribable divinity within a specific human form or individuated human existence but not – in line with the teaching of the ecumenical councils – a human hypostasis. While some of this may sound rather abstruse, Tollefsen admirably emphasises quite how grounded Theodore remains in the scriptural narrative and its presentation of a God who lived an authentically and indeed archetypally human existence – who was wrapped in swaddling-clothes and was seen, touched and crucified – while remaining uncircumscribable in his divinity. And while the mechanics and metaphysics of this paradoxical ‘mixture’ (as Theodore calls it) of the uncircumscribed and the circumscribed, the infinite and the finite, must remain obscure to mortal eyes and minds, Theodore is in no doubt as to the awe-fullness of the incarnation. As in John of Damascus before him, the icon of Christ becomes for Theodore an indispensable summation and visual representation of orthodox Christology presenting to the world the true face and form of God the Word incarnate.

Among the book's drawbacks, apart from its slimness, I must query the frequency of the appearance of SS Gregory of Nyssa and Maximus the Confessor, whose weight in modern theological discourse owes more to contemporary sensibilities and the success of the nouvelle théologie than a sober analysis of the tradition in which Theodore stood. While the various encounters between the thought of these ‘philosophical fathers’ and Theodore are fascinating, they go beyond what is warranted by Theodore's own text and adduced authorities. Concomitantly, we hear relatively little of John of Damascus, a more obvious reference point, while the whole monastic tradition in which Theodore lived and breathed remains curiously under-explored. On a more minor note, the argument for a veiled repudiation of Canon 82 of the Quinisext council at the iconoclast Council of Hieria (ad 754) seems to me a little stretched.

More positively, I must draw attention to the appendix in which Tollefsen admirably and eloquently argues for the ‘naturalness’ of the icon within Christianity – in other words the thesis that Christianity contains certain truths and principles that allow, inform and even positively elicit visual representation. As he states in his introduction, Tollefsen is concerned to repudiate the notion that the icon is some sort of quasi-pagan and crudely theurgic intrusion into the pure and originally image-less soil of Christianity. Tollefsen finds this attitude, which he traces back to von Harnack, still far too prevalent in modern scholarship. ‘It is high time’, he writes, ‘to rid ourselves of nineteenth-century prejudices about how primitive, spiritual Christianity was corrupted through its development into the early Byzantine Church’ (pp. 11–12). I could not agree more.