Barlaam of Calabria, theologian; born Seminara, Calabria, ca.1290, died Avignon, June 1348. Born in southern Italy to an Orthodox family, he became a monk in his youth. In 1330 he moved to Constantinople, where he was hegoumenos of the Akataleptos monastery until 1341. A protégé of Andronikos III, he served as an Orthodox spokesman in Union negotiations in Constantinople and, in 1339, as imperial emissary to the courts of Naples and Paris. A brilliant but arrogant and contentious scholar, in the mid-1330s he began to attack hesychasm for both its theology and manner of prayer. He accused Gregory Palamas of Messalianism, and argued that the light on Mt. Tabor at the Transfiguration was created and not eternal. His intemperate criticism of the mystical exercises of the monks of Mt. Athos (whom he called omphalopsychoi, “with souls in their navels”) triggered the controversy over Palamism that was to divide the Byz. church for over a decade. The local council of Constantinople of 1341 condemned Barlaam and ordered his anti-hesychast writings burned. He returned to the West, converted to Catholicism at Avignon in 1342, and became bishop of Gerace in Calabria (1342–48). At Avignon Barlaam met Petrarch, who was later to study Greek with him. Barlaam was anathematized by the Orthodox church in 1351.
Bilingual, Barlaam left writings in both Latin and Greek. Most of his anti-Palamite works (except for his letters and an unedited disputation with Gregory Akindynos) were destroyed, so his views are known primarily from the rebuttals of his opponents. His 21 anti-Latin treatises on the Procession of the Holy Spirit and papal primacy do survive (in Latin), but are mostly unpublished. Barlaam was also interested in astronomy and wrote treatises on solar eclipses and the astrolabe.