→Lives: add link
Constantine (later Cyril) and Michael (later Methodius) were born early in the 9th century in Thessalonika into a senatorial family. The years of their birth are uncertain. Constantine, the older, may have been born in 826, while Methodius is believed to have been born in 827. Their father, Leon, was Drungarios of the Byzantine Roman Thema of Thessalonika, which position included the Slavs of Macedonia. Their mother is believed to have been Slavic. Being raised in an area with both Greek and Slavic speakers endowed the brothers with a good knowledge of the two languages. As befitting their family's position, they were well educated.
At a young age the brothers lost their father and they were raised under the protection of their uncle Theoctistos, who was a powerful official in the Byzantine government, responsible for postal services and diplomatic relations of the empire. In 843, he invited Constantine to Constantinople to continue his studies at the university there. He was [[ordain]]ed a [[deacon]] in Constantinopole. As Constantine was knowledgeable in theology and had a good command of the Arabic and Hebrew languages, his first state mission to the Abbasid Caliph Al-Mutawakkil was to discuss the principle of the [[Holy Trinity]] with Arab theologians and thus improve the Empire's diplomatic relations with the Abbasid Caliphate.