From the Prologue of Ochrid
Brothers by birth, from Thessalonica, born of distinguished and wealthy parents, Leo and Maria. The elder brother Methodius served as an officer for ten years among the Slavs (Macedonian) and thus learned the Slavonic language. Afterward Methodius withdrew to Mount Olympus and gave himself to monastic struggle. There he was later joined by Cyril (Constantine). But when the Khazar King, the Khagan, sought from Emperor Michael preachers of the faith of Christ, then by the emperor's command these two brothers were found and sent among the Khazars. Having convinced the Khagan of the faith of Christ, they baptized him together with a great number of his chieftains and an even greater number of the people. After some time they returned to Constantinople, where they composed a Slavonic alphabet of thirty-eight letters and began to translate Church books from Greek into Slavonic. At the invitation of Prince Rastislav they went to Moravia, where they spread and strengthened the pious faith, multiplied books, and gave them to the priests to teach the youth. At the invitation of the Pope they went to Rome, where Cyril fell ill and died on February 14, 869. Then Methodius returned to Moravia and labored until his death in the strengthening of the faith of Christ among the Slavs. After his death — for he reposed in the Lord on April 6, 885 — his disciples, the Five Disciples, with Saint Clement as bishop at their head, crossed the Danube and descended southward into Macedonia, where from Ohrid they continued among the Slavs the work begun by Cyril and Methodius in the north.
