This chapter exposes the fundamental interpenetration of critical ideas and practices in the editing of texts of both classical and scriptural writings, one of the defining practices of philology, and shows a shared commitment to the return ad fontes. It focuses on one of the giants of philology, Karl Lachmann, and maps the ease with which the founding scholars of the modern discipline of classical philology moved between Greco-Roman texts and the bible. The chapter emphasizes the historical importance of that vast monument of Greek literature generally ignored in the modern discipline of classics, the Septuagint. It goes on to address the issue of authenticity, a key component not just of philology’s pursuit of the faked or corrupt, but also of theology’s commitment to the true word of God, and to show how the search for a source matches the idea of the godlike author.