information:extraction, linguistic:paraphrasing, linguistic:voice_change
Great Moravia

In 862, the brothers began the work which would give them their historical importance. That year Prince Rastislav of Great Moravia requested that Emperor Michael III and the Patriarch Photius send missionaries to evangelize his Slavic subjects. His motives in doing so were probably more political than religious. Rastislav had become king with the support of the Frankish ruler Louis the German, though he subsequently sought to assert his independence from the Franks. That Cyril and Methodius might have been the first to bring Christianity to Moravia is a common misconception; Rastislav's letter to Michael III states clearly that his people "had already rejected paganism and adhere to the Christian law." Rastislav is said to have expelled missionaries of the Roman Church and instead turned to Constantinople for ecclesiastical assistance and, presumably, a degree of political support. The Emperor quickly chose to send Cyril, accompanied by his brother Methodius. The request provided a convenient opportunity to expand Byzantine influence. Their first work seems to have been the training of assistants. In 863, they began the task of translating the Gospels and essential liturgical books into what is now known as Old Church Slavonic, and travelled to Great Moravia to promote it. This endeavour was amply rewarded. However, they came into conflict with German ecclesiastics, who opposed their efforts to create a specifically Slavic liturgy.

For the purpose of this mission, they devised the Glagolitic alphabet, the first alphabet to be used for Slavonic manuscripts. The Glagolitic alphabet was suited to match the specific features of the Slavic language. Its descendant script, the Cyrillic, is still used by many languages today.

The brothers wrote the first Slavic Civil Code, which was used in Great Moravia. The language derived from Old Church Slavonic, known as Church Slavonic, is still used in the liturgy by several Orthodox Churches, and also in some Eastern Catholic churches.

Exactly how much the brothers translated is impossible to say for certain. The New Testament and the Psalms seem to have been the first, followed by other lessons from the Old Testament. The "Translatio" speaks only of a version of the Gospels by Cyril, and the "Vita Methodii" only of the "evangelium Slovenicum", though other liturgical selections may also have been translated.

Nor is it known for sure which liturgy, whether of Rome or of Constantinople, they took as a source. They may well have used the Roman alphabet, as hinted by liturgical fragments adhering closely to the Latin type. This view is confirmed by the "Prague Fragments" and by certain Old Glagolitic liturgical fragments brought from Jerusalem to Kyiv and discovered there by Izmail Sreznevsky —probably the oldest document in the Slavonic tongue; examples of where they resemble the Latin type include the words "Mass," "Preface," and the name of one Felicitas. Regardless, the circumstances were such that the brothers could have hoped for no lasting success without having had authorization from Rome.