John of Damascus

John of Damascus was born around 675 AD in Damascus to a prominent Arab Christian family that had served in the administration of the Umayyad caliphate. He himself may have held a fiscal position under the caliphs before retiring to the monastery of Mar Saba near Jerusalem, where he spent the rest of his life as a monk and priest. He died around 749 AD.

John was the last of the great Greek Church Fathers and one of the most important theologians of the Eastern Church. His principal work, the Fount of Knowledge, comprises a philosophical introduction, a catalogue of heresies, and the Exact Exposition of the Orthodox Faith — a systematic theology that synthesised the work of the preceding centuries and became the standard theological textbook of Eastern Christianity.

The Vita Barlaam et Joasaph (Life of Barlaam and Josaphat), traditionally attributed to John, is a Christianised version of the legend of the Buddha. A prince is sheltered from the world, discovers suffering, and renounces his throne for the ascetic life. The story passed from Sanskrit to Arabic to Georgian to Greek, acquiring Christian theology along the way. Whether John himself or a later monk at Mar Saba was responsible for the Greek version is debated, but the work was enormously popular in the medieval world.