Saints Cyril and Methodius (826-869, 815-885; ; Old Church Slavonic: ) were two Byzantine Christian theologians and Christian missionaries who were brothers. Through their work they influenced the cultural development of all Slavs, for which they received the title "Apostles to the Slavs". They are credited with devising the Glagolitic alphabet, the first alphabet used to transcribe Old Church Slavonic. After their deaths, their pupils continued their missionary work among other Slavs. Both brothers are venerated in the Orthodox Church as saints with the title of "equal-to-apostles". In 1880, Pope Leo XIII introduced their feast into the calendar of the Roman Catholic Church. In 1980, Pope John Paul II declared them co-patron saints of Europe, together with Benedict of Nursia.