An Unknown Opuscule by Barlaam of Calabria in Vaticanus Graecus 671 Misattributed to Theodore Prodromos

Abstract Codex Vaticanus graecus 671 (c. 1350), ff. 204–209 v , contains an anti-Latin treatise on the procession of the Holy Spirit that was erroneously attributed to Theodore Prodromos. Closer examination of the text reveals that the treatise is in fact a work by Barlaam of Calabria, composed in response to debates in Constantinople during the 1330s. This discovery is significant because Vaticanus graecus 671 preserves a fragment of the lost original version of Barlaam’s anti-Latin treatise – a version that triggered his disagreement with Gregory Palamas. The text under consideration includes two passages that were later reworked as two opuscules of Barlaam of Calabria’s Treatise against the Latins A , along with a previously unknown opuscule addressing Latin objections from the Holy Scriptures. This paper offers an edition and translation of this newly discovered opuscule, which has been reconstructed from a manuscript severely damaged by water.