The uncovering of manuscripts over the last one hundred years has repeatedly changed how early Christian history is told. With no signs of this trend abating, this article seeks to take stock of how scholars respond to manuscript discoveries by focusing on three debates over the orthodoxy of an early Christian figure that extend over two hundred and fifty years. New manuscript evidence sparked no less than three debates over the christological views of the Syriac author Jacob of Serugh (d. 520/521) from the eighteenth through the twentieth centuries. In the first debate, the arrival of manuscripts in Western Europe led to a conflict between the Maronite scholars who viewed Jacob as a Chalcedonian thinker and certain textual evidence that suggested otherwise. The second debate began in the late nineteenth century after manuscripts from Egypt arrived in London that contained Jacob’s extensive epistolary corpus, which includes clear expressions of non-Chalcedonian, miaphysite christology. A new acquisition by the Vatican Library in the mid-twentieth century featured a previously unknown homily that included two lines that could be interpreted in a Chalcedonian manner. This inspired several Western scholars to dig yet deeper into the manuscripts to resolve this long-standing debate over his christological views. The focused analysis of the pendulum swings initiated by manuscript discoveries in the scholarly discourse surrounding Jacob of Serugh serves as a mirror for self-reflection on the way that scholars discuss a past whose many unknowns still await discovery.

For over a century, studies on Marcion have cited a quotation attributed to him in a fragmentary Syriac manuscript: London, British Library, Add. 17215 (fols. 30–3). An English translation of the relevant passage appeared in 1893, but no subsequent study has returned to the Syriac text itself. While this text has hitherto been cited as an anonymous Syriac source, this article identifies it as a letter by Jacob of Serugh (d. 520/1) and offers preliminary remarks on the implications of this identification for future research on Marcion's Gospel and his thought.