The two holy brothers were missionaries in the 9th century, and are considered to be the Apostles to the Slavic people.
The eastern church calls them “Equal to the Apostles,” and they are credited with creating an alphabet, called Glagolitic, which was used to transcribe the ancient language of the area now known as Old Church Slavonic.
They were born Constantine and Michael, and took the names Cyril and Methodius on being received into the monastic life.
I also read somewhere that in earlier centuries, French monks went to eastern Europe hoping to convert the Slavs, but were thwarted by their own limitations. Much to the monks’ frustrations, nobody else spoke French or Latin.
After confusing everybody they came across during their very unsuccessful missionary efforts, most of them turned around went back to France.
In their own time, the holy brothers came across the remnants of those French monks, who gave the two of them a hard time. The brothers went to Rome, and argued for the use of a language other than Hebrew, Greek, or Latin in prayer and liturgy. It was on this trip that Cyril died in Rome, while Methodius returned after being named archbishop.
He continued on alone, oftentimes coming into conflict with French and German bishops, and always taking his case to Rome. He died 18 years after his brother, and is buried in the cathedral church of Great Moravia.
One thousand years later, in 1880, Pope Leo XIII introduced the feast of Cyril and Methodius into the General Roman Calendar on July 5, and then seven years later, it was moved to July 7. It stayed there for over 80 years until the reform of the liturgy in 1969, where it was moved to February 14 – today.
In 1980, Pope St. John Paul II named the brothers as co-patrons of Europe – along with St. Benedict of Nursia.
