The life of St Kallistos I of Constantinople
From that formation he rose to occupy the throne of Constantinople across two separate terms, 1350 to 1353 and then 1354 until his death in 1363, throwing his full weight behind Gregory Palamas and the Hesychast cause: a synod he convened in 1351 formally settled the Orthodoxy of that teaching, after which he worked to press the same doctrine on patriarchates and sees well beyond his own. He also moved to tighten the patriarchate's authority over the wider Church, at one point excommunicating Stephen Dušan of Serbia for having set the Serbian archbishop up as an independent patriarch on his own authority.
In 1363 Kallistos joined an imperial embassy traveling to seek Serbian military aid against the advancing Ottomans. Tradition holds that the ascetic Maximos, meeting him on Mount Athos along the way, foretold his coming death. At Serres, Kallistos fell ill and died there in August, the sickness described at the time as infectious, though some contemporaries suspected poison instead. He was buried in a chapel of that city's Cathedral of the Holy Theodores.
