This volume is the second (of two volumes in three) to appear of La Théologie byzantine et sa tradition, now edited by Carmelo Conticello on his own. The volumes, published by Brepols, if placed on a bookshelf near Geerard's Clavis Patrum Graecorum, might look like a Byzantine continuation of that venerable and immensely valuable work. But it is not: it is quite different, in some ways less and in some ways more than the Clavis. It is less in that it covers only a selection of theological writers for its period, whereas the Clavis aimed at being exhaustive, each volume having an index (‘Concordantia’) listing by column all the treatises contained in the relevant volumes of Migne's Patrologia Graeca, indicating where they are treated in the Clavis; not only that, the Clavis included many treatises (and some authors) not found in Migne at all. It is more in that those writers covered are discussed at much greater length: whereas the Clavis gave a brief indication of date for each author, followed by treatises ascribed to him with indication of discussion of the text and classified them as authentic, dubious, or spurious, La Théologie byzantine gives for each author a biography, a discussion of the works (much more than a list), an account of the theology of the author, a conclusion listing results, a detailed (and usually exhaustive) bibliography, and finally a translation of one of the author's works. Nor is La Théologie byzantine strictly any kind of successor to the Clavis: in this volume (i/1) and much of the next (i/2), still to appear, the authors are already included in the Clavis. The authors included in this first volume of the set are Justinian, Romanos Melodos, John Climacus, Isaac the Syrian, Maximos the Confessor and Anastasios of Sinai; there is a brief appendix on the author of the Makarian Homilies. The sections are of very different sizes, reflecting directly the relative importance of the writers and inversely the state of scholarship (much the longest article is that on Anastasios of Sinai by Karl-Heinz Uthemann, who has devoted his life to editions and studies of Anastasios: it runs to over 250 pages, a veritable monograph on its own). Justinian is perhaps the biggest surprise – as an emperor, his theology was something of a violin d'Ingres – but he is clearly important for the history of theology, precisely because he was emperor, calling an œcumenical council to endorse his theological nostrum which he hoped would bring union to the empire. The article brings out his importance for fostering the reading of the Chalcedonian Definition in the light of Cyril of Alexandria, usually known as Neo-Chalcedonianism; Alan Le Boulluec accomplishes his task with careful detail and conciseness. Romanos Melodos is treated by Johannes Koder. Here we find a careful discussion of the manuscripts, editions and translations, and a table of the enumeration of the hymns in the various editions; Romanos's place in the wider history of the kontakion, the verse sermon in which he excelled, is explained. There is a careful and illuminating discussion of Romanos's fundamental theological positions; what there is not, so far as I could see, is any discussion of the way in which his expressing himself through poetry influenced his theology. Next comes John Climacus, a joint article by Marie-Joseph Pierre (who contributes the Life), Conticello (who provides testimonies to Climacus: references to him, an inscription at the Sinai monastery, and an exhaustive list of information about his life from Daniel of Raithu's vita, to references in a multitude of places such as synaxaria, canons and the like, as well as the bibliography), and John Chryssavgis (who deals with his spiritual teaching, as well as providing a translation of his Letter to the Shepherd, on spiritual fatherhood). Altogether the information provided here is unparalleled elsewhere. Sebastian Brock treats Isaac the Syrian (Isaac of Nineveh) concisely and elegantly. In contrast to the other articles in the volume, the bibliography provided only covers the most important items in western European languages, as there already exists an extensive bibliography of Syriac ascetic and mystical literature (in Eastern Christian Studies xi [2011]) which covers Isaac. Brock also translates from the Syriac original three of the Ascetical Homilies, already available in a translation from the Greek version. The next article covers Maximos the Confessor, mainly composed by Peter Van Deun and Pascal Mueller-Jourdain (Van Deun having received some help from B. Markesinis and Conticello). Van Deun deals with the life, the works and the transmission of the text; Mueller-Jourdain with the Confessor's teaching. Like many scholars nowadays, Van Deun expresses some reservations about the Syriac vita by George of Rešai‘nā, and then continues to credit, more or less completely, the account it gives of Maximos's parents and early life – an account intended to discredit Maximos by an avowed opponent of his. It looks, given similar endorsement in the recent Oxford companion to Maximus the Confessor (2015), as if such trust in an invective against the Confessor is becoming the received opinion. No one claims much for the Greek vita, in any of its forms, but its assertion that Maximos was of Constantinopolitan origins and had served in the imperial chancery under Herakleios makes more sense of his serene composure in the trial scenes, and the claim that he was Palestinian in origin needs to explain why Maximos, in commenting on the story of the paralytic brought to Jesus, remarks that ‘those who have been eye-witnesses of those parts’ (i.e. Palestine) explain that the removal of the slates from the roof was possible because such slates are made of a very light stone (Quaestiones et dubia 162). Mueller-Jourdain's account of Maximos's teaching is of exceptional interest in that he approaches it, not as a theologian, but as a philosopher, deeply informed about late Neoplatonism; his substantial discussion of Maximos's teaching (over eighty pages) approaches many issues in a powerful and unique way. The longest section concerns Anastasios of Sinai: Karl Uthemann's account is extensive and covers all aspects of Anastasios, his life, his theological position and his influence. It is essential reading, and establishes Anastasios, a younger contemporary of Maximos (though his precise dates are difficult to establish), as a crucial figure of the seventh century, who can no longer be ignored, either for his own times or so far as his influence is concerned. It is not too much to say that this first half-volume of La Théologie byzantine et sa tradition puts our understanding of theology in the sixth and seventh centuries on a new, and more assured, footing: it is a masterly work, and an enormous debt it owed to Carmelo Giuseppe Conticello, whose careful editorial work is everywhere present in the volume.