This volume, the author’s doctoral thesis, contains a detailed but concise study of Aphrahat’s Letters (i.e. Demonstrations). After an introduction dealing with Aphrahat’s life and writings, Chavanis moves into the main part of the book, which is divided into two parts. In the first, he looks at the historical situation against which Aphrahat’s works must be read, namely matters dealing with the Church in Persia, such as its ecclesiastical structure, the persecutions under Shapur II, and controversies with the Jews. In the second part, Chavanis examines the Demonstrations for the doctrines they present. He considers themes such as Scripture and tradition as sources for Aphrahat’s theology, God, Trinity, Angels, the World, Man, Original Sin, the Sacraments, the Church, and others. This volume, which is also suitable for non-specialists in Syriac, takes its place among others dealing specifically with this early Syriac author and stands out for its clarity and conciseness.