The Holy Equal-to-the-Apostles first teachers and enlighteners of the Slavic, brothers Cyril and Methodius, came from a noble and pious family who lived in the Greek city of Thessalonica. Saint Methodius was the eldest of the seven brothers, Saint Constantine (Cyril is his monastic name) was the youngest. Saint Methodius was at first in military rank and was the ruler of one of the Slavic principalities subordinate to the Byzantine Empire, apparently Bulgarian, which gave him the opportunity to learn the Slavic language. 
After staying there for about 10 years, Saint Methodius then became a monk in one of the monasteries on Mount Olympus. Saint Constantine was distinguished by great abilities from an early age and studied with the young Emperor Michael with the best teachers of Constantinople, including Photius, the future Patriarch of Constantinople. Saint Constantine perfectly comprehended all the sciences of his time and many languages, he studied the works of St. Gregory the Theologian especially diligently. For his intelligence and outstanding knowledge, Saint Constantine was nicknamed the Philosopher (wise). Upon completion of the teaching, St. Constantine took the rank of priest and was appointed keeper of the patriarchal library at the Church of St. Sophia, but soon left the capital and secretly entered a monastery. Found there and returned to Constantinople, he was identified as a philosophy teacher at the Higher School of Constantinople. The wisdom and power of faith of the still very young Constantine were so great that he managed to defeat the leader of the iconoclastic heretics Annius in the debate. After this victory, Constantine was sent by the emperor to debate the Holy Trinity with the Saracens (Muslims) and also won. Upon returning, Saint Constantine retired to his brother Saint Methodius on Olympus, spending time in incessant prayer and reading the works of the holy fathers.
Soon the emperor summoned both holy brothers from the monastery and sent them to the Khazars for evangelical preaching. On the way, they stopped for a while in the city of Korsun, preparing for the sermon. There the holy brothers miraculously found the relics of the Holy Martyr Clement, Pope of Rome (commemoration November 25). Russian Russian-speaking Saint Konstantin also found the Gospel and the Psalter in Korsun, written in "Russian letters", and a man who spoke Russian, and began to learn from this man to read and speak his language. After that, the holy brothers went to the Khazars, where they won the debate with Jews and Muslims, preaching the Gospel teaching. On the way home, the brothers visited Korsun again and, taking the relics of St. Clement there, returned to Constantinople. Saint Constantine remained in the capital, and Saint Methodius received the abbacy in the small monastery of Polychron, near Mount Olympus, where he had previously asceticized.
Soon ambassadors from the Moravian prince Rostislav, oppressed by the German bishops, came to the emperor with a request to send teachers to Moravia who could preach in the native language of the Slavs. The emperor called Saint Constantine and told him: "It is necessary for you to go there, because no one will do it better than you." Saint Constantine began a new feat with fasting and prayer. With the help of his brother Saint Methodius and disciples Gorazd, Clement, Savva, Nahum and Angelyar, he compiled the Slavic alphabet and translated into Slavic the books without which Worship could not be performed: the Gospel, the Apostle, the Psalter and selected services. It was in 863.
After completing the translation, the holy brothers went to Moravia, where they were received with great honor, and began to teach Worship in the Slavic language. This provoked the anger of the German bishops, who celebrated Divine services in Latin in the Moravian churches, and they rebelled against the holy brothers, arguing that Worship could be performed only in one of three languages: Hebrew, Greek or Latin. Saint Constantine replied to them: "You recognize only three languages worthy of praising God in them. But David cries out: Sing to the Lord, all the earth, praise the Lord with all your tongues, let every breath praise the Lord! And in the Holy Gospel it says: "Go teach all languages.." The German bishops were ashamed, but became even more embittered and filed a complaint with Rome. The holy brothers were called to Rome to resolve this issue. Taking with them the relics of St. Clement, the pope, Saints Constantine and Methodius went to Rome. Having learned that the holy brothers were carrying holy relics with them, Pope Adrian and the clergy went out to meet them. The holy brothers were greeted with honor, the Pope approved the divine service in the Slavic language, and ordered the books translated by the brothers to be placed in Roman churches and to celebrate the liturgy in the Slavic language.
While in Rome, Saint Constantine fell ill and, in a miraculous vision, informed by the Lord of his approaching death, accepted the schema with the name Cyril. 50 days after the adoption of the schema, on February 14, 869, Equal-to-the-Apostles Cyril died at the age of 42. Departing to God, Saint Cyril commanded his brother Saint Methodius to continue their common cause - the enlightenment of the Slavic peoples with the light of the true faith. Saint Methodius begged the pope to allow his brother's body to be taken away for burial in his native land, but the pope ordered the relics of St. Cyril to be placed in the church of St. Clement, where miracles began to be performed from them.
After the death of Saint Cyril, the pope, following the request of the Slavic prince Kotsel, sent Saint Methodius to Pannonia, ordaining him Archbishop of Moravia and Pannonia, to the ancient throne of the Holy Apostle Andronikos. In Pannonia, Saint Methodius, together with his disciples, continued to spread Worship, writing and books in the Slavic language. This again provoked the fury of the German bishops. They achieved the arrest and trial of St. Methodius, who was exiled to imprisonment in Swabia, where he suffered many sufferings for two and a half years. Released by order of Pope John VIII and restored to the rights of archbishop, Methodius continued evangelical preaching among the Slavs and baptized the Czech Prince Borivoy and his wife Lyudmila (September 16), as well as one of the Polish princes. For the third time, the German bishops persecuted the saint for not accepting the Roman doctrine of the descent of the Holy Spirit from the Father and from the Son. Saint Methodius was summoned to Rome, but justified himself before the pope, keeping the Orthodox teaching pure, and was again returned to the capital of Moravia, Velegrad.
Here, in the last years of his life, Saint Methodius, with the help of two priest-disciples, translated into Slavic the entire Old Testament, except for the Maccabean books, as well as the Nomocanon (Rules of the Holy Fathers) and patristic books (Paterik).
Sensing the approach of death, Saint Methodius pointed to one of his disciples, Gorazd, as a worthy successor. The saint predicted the day of his death and died on April 6, 885, at the age of about 60 years. The funeral service of the saint was performed in three languages - Slavic, Greek and Latin; he was buried in the cathedral church of Velegrad.