Cesare Santus’ book represents a welcome and outstanding addition to studies on the thorny relations between the Roman Catholic Church and the Orthodox Church during the early modern period. The author focuses his investigation on the activities of the Latin missionaries who operated amid the Orthodox communities located in three distinct areas: the Ionian islands, the Cyclades’ archipelago and Constantinople and eastern Anatolia between the seventeenth and the eighteenth century. Based on an impressive array of primary sources, Santus examines the forms of communication as well as the complex strategies adopted by the Latin missionaries who had to carry out their activities in a multifaceted reality. Structured in seven chapters, the pivotal theme which weaves all the book is how the Communicatio in sacris was implemented, affected and reshaped over the course of two centuries. The first chapter examines the peculiar features of the Catholic communities that resided in the eastern Mediterranean and how and to which extent they were integrated into the Ottoman Empire's political sphere. The second chapter explores the complex set of relations which existed between the Roman Catholic world and the Catholics of the East by focusing on the early attempts – made during the Middle Ages – to develop and carry on the strategy of the Communicatio in sacris.

The third chapter brings the reader into the heart of the question examined by the book and focuses on how the Catholic missionaries acted amid the eastern schismatics. This chapter investigates both the theological debates as well as the daily practical problems faced by the missionaries who operated on the ‘ground’. The fourth and the fifth chapters explore the context in which the Latin Catholics and the Orthodox lived in the Cyclades’ archipelago and in the Ionian islands. In these two parts the author reconstructs the cultural, political and religious milieu in which these communities lived, and the persistent difficulties faced by the Latin missionaries who worked amidst them. The sixth chapter examines the shifting religious context of Constantinople which was characterised by the efforts to find an agreement and by harsh quarrels between the Latin missionaries and the Armenian community who lived there. In this chapter the author reconstructs all the episodes during which, since the late seventeenth century, the missionaries sought to develop and carry out their strategies, but he also vividly displays the strong rivalry between the various orders as well as the long series of failed agreements with the Armenians.

Through a magisterial use of many sources – the majority of which are unedited and present difficult problems of interpretation – Santus has shed a new light on the world of the Catholic communities in the eastern Mediterranean and in the Ottoman Empire. From the theological disputes – including the elaborate but, most of the time, ineffective plans conceived in Rome – to the daily problems of communication faced by the missionaries, the book will satisfy both the specialised scholars and anyone who wants to know more about the world of the multifaceted Catholic communities of the eastern Mediterranean. The fact that the book has been published by the prestigious series on early modern history published by the École française de Rome is a further demonstration of the high scholarly level attained by this young scholar.