 Bessarion was born in Trebizond between 1399 and 1408, and baptized Basil. At a young age, he went to Byzantium, where he studied with John Cortasmenos (d. 1431/7). He changed his name to Bessarion when he became a monk in 1423. Pursuing his ecclesiastical career, Bessarion engaged in diplomatic activity in the service of the emperor John VIII Palaiologos. This put him in contact with the court of the Despot of Mistra, a city where he had the opportunity to deepen his philosophical and mathematical training under the guidance of Gemistos Pletho (d. 1454). The decisive year in the life of Bessarion was probably 1437, when he was made metropolitan of Nicea (hence the common epithet of Cardinal Nicenus) and left for Italy as member of the Greek delegation to the Council of Ferrara-Florence.