The schism between the Syrian Orthodox Church and the Byzantine and western Churches took a long time to develop and longer still to be recognised as irremediable by both sides; this book offers a closely focused study of a key period in this development, that from 518 to 553. It covers the vicissitudes of the non-Chalcedonian cause in Syria during this time, when despite oppression it proved ineradicable in its monastic bases, and also the personalities and events in Constantinople that were important for the situation in Syria. Menze makes full use of the Syriac material, notably John of Ephesus and Michael the Syrian, which provides an indispensable supplement to the more familiar material in Greek and Latin. On a whole series of issues Menze gives an account superior to anything yet available, even in German (although his analysis should be studied together with M. V. Grazianskij's Die Politik Kaiser Justinians I. gegenüber den Monophysiten, Stuttgart 2008). He argues convincingly that the breaking-point that frustrated all the attempts under Justinian to achieve church unity was the libellus of Pope Hormisdas, that demanded from the non-Chalcedonians the erasure from the diptychs of all their leaders since 451: this would have cut them off not only from their post-Chalcedonian past but also from the pre-Chalcedonian past to which they were connected by the non-Chalcedonian chain of succession. Equally disastrous, in Menze's plausible account, was the intervention of Pope Agapetus in 536, which shattered the unity plans of Justinian and Patriarch Anthimus of Constantinople; correcting previous accounts that followed the tendentious presentation in the non-Chalcedonian sources, Menze shows that Anthimus was not a Miaphysite but an exceptionally ‘ecumenical’ Chalcedonian. Equally insightful is Menze's treatment of the Empress Theodora: he shows that her adoption of the non-Chalcedonian cause occurred late (in 535/6) and abruptly and must be attributed to political manoeuvre, agreed to with Justinian, rather than to a long-standing religious conviction in opposition to her husband's policy. Menze is equally sceptical about the depth of Justinian's theological commitment, though here I find his position less persuasive. This admirable and important book suffers from one limitation: it keeps to its chronological limits rather too strictly. The situation in Syria under Justinian would be easier to place and interpret if more were said of the preceding period; and the statement that schism was irremediable and negotiations inevitably fruitless by the time of the Fifth Ecumenical Council (553) ignores the reopening of dialogue under Justin ii, when the discussions at Callinicum (567/8) came nearer to achieving unity than any of the attempts under Justinian. The volume concludes by pointing to the highly selective memory of this period in the non-Chalcedonian tradition (which stressed Byzantine oppression and played down the desire of both sides for reunion) as the ‘founding myth’ of the Syrian Orthodox Church. Menze's analysis of the convictions and anxieties of the Syrian Miaphysites remains a model of fair and sympathetic treatment.