The exegesis of texts in Antiquity was determined by postulates that are often foreign to our conception of science. Following the analyses of Pierre Hadot, who showed how Neoplatonic commentaries could be both scholarly and based on misinterpretations, sometimes creative in terms of doctrine, this book studies in detail the mechanisms of misinterpretation in a Christian commentary on the Old Testament, written in Greek at the beginning of the 4th century AD, the Prophetic Extracts of Eusebius of Caesarea. Eusebius, known above all for his Ecclesiastical History , made his first steps as an exegete there. Driven by a single desire to show that the Jewish Bible announces Christ he deploys a knowledge of the text that is real and generally far superior to ours today, but, paradoxically, he constantly commits misinterpretations and condemns himself to not understanding the passages he comments on. Commenting on this commentary today allows us to identify the essential "places" of the misinterpretation: decontextualization, the absence of the original, hyperliteralism, spiritual exegesis, polemic against the adversary, modes of exposition. This work, devoted for the first time to the Prophetic Extracts one of the oldest Christian commentaries to have been transmitted to us analyzes in depth the methods of an exegete as much as it seeks to renew the traditional study of this literary genre. It constitutes the first part of an investigation into the logic of innovation at the end of Antiquity.