The Council of Nicaea took place in 325, and canon lawyers are preparing to mark the 1700th anniversary of that event in various ways, not least the Ecclesiastical Law Society's conference ‘Nicaea Received: 1700 years of Canons, Councils and Ecumenism’, which is planned for June 2025 in Chichester, UK. The Cambridge Companion to the Council of Nicaea provides an admirable scholarly introduction to numerous aspects of the Council and its enduring legacy today, and can be recommended as good preparatory reading for the 2025 anniversary.

Nicaea gave us a creed and a canonical tradition, and left its imprint indelibly on a Christian church that was already becoming more international in extent and more public in character. Editor Young Richard Kim has taken a thoroughly interdisciplinary approach to this Companion. Theology, ecclesiology, history, archaeology and canon law are brought alongside one another, although each chapter tells its own story rather than contributing to a single narrative. The volume is not an introductory one, but should be mostly accessible for a non-specialist who has some existing knowledge of the period. In a few places Latin and Greek in footnotes have slipped through untranslated.

Part I considers the political and doctrinal background to the Council. Rebecca Lyman manages to make the deep complexity of the Arian controversy comprehensible, and (with reference to the work of Rowan Williams among others) gives some indication of what Arius and Arianism stood for. In Part II – focused on the Council itself – archaeologist Ine Jacobs offers a fascinating discussion of the material aspects of the Council, while Hal Drake presents a vivid portrayal of the Emperor Constantine, whose example was to have such far-reaching effects on subsequent Christian rulers.

Part III addresses outcomes. Mark Edwards writes on the creed, perhaps the most important ‘output’ of the Council. He also charts the subsequent and significant variations made after 325 which give us the ‘Nicene’ creed used liturgically today. Andreas Weckweth takes the reader through each of the 20 Canons of Nicaea. These ancient legal sources are brought alive by being placed in their historical context. For example, the purpose and scope of Canons 11–13, dealing with public penance, are explained with reference to the four orders of penitents, characteristic of the Eastern church at that time. Daniel P. McCarthy covers the controversy over the dating of Easter, and, interestingly, the extent to which the authority of Nicaea was determinative in later church practice.

Geoffrey Dunn's account of the Catholic reception of the Council includes a fascinating analysis of the Nicene antecedents of the 1983 Code of Canon Law. Similarly, Paul L. Gavrilyuk examines the legacy of Nicaea in the Orthodox Church, showing how the Council was ‘an inspired experiment in communal truth-seeking’ (p 345) which was imitated by later councils. It would be an interesting project for other churches to do something equivalent to these two chapters, and trace the influence of the Nicene canons on their own law and practice today.

Space precludes mentioning every chapter of the Companion, but each one brings a different perspective. The overall effect, as promised in the introduction, is to produce ‘a picture of the immediate, the middle, and the long-term impact of the Council of Nicaea’ (p 15). Those who are interested in the ancient antecedents of ecclesiastical law will find the Council brought to life in this Companion.