De essentia et operatione Dei

De essentia et operatione Dei ("On the Essence and Activity of God") is a treatise by Prochorus Cydones, a Byzantine theologian and monk. Written around 1369, it was a significant work in Byzantine theology, as it vigorously disputed the mystical theology of Gregory Palamas, a prominent Athonite monk.1

Cydones, along with his brother Demetrius, advocated for Western Aristotelian thought and translated Latin Scholastic writings into Greek. In De essentia et operatione Dei, Prochorus applied Aristotelian logic to challenge the Neoplatonic aspects of Hesychasm, the contemplative prayer practice central to Palamas's teachings. The Cydones brothers accused Palamas of pantheism, but they were condemned by the Orthodox Synod of 1368, which canonized Palamas. This work represents a key moment in the intellectual and theological debates within the Byzantine Empire during the 14th century.21