Today is St. Valentine's day, but our current calendar commemorates Saints Cyril and Methodius on this day.
The ninth century Slavs sought political and ecclesiastical independence from their dominating Germanic neighbors. St. Cyril invented an alphabet (Cyrillic) and translated most of the New Testament and the liturgy to meet the needs of the Slavonic culture and the new growing church. Methodius finished the task by translating the entire Bible into Slavonic (well almost, he didn't finish 2 Maccabees).
Cyril and Methodius established a principle that cultures need not employ a Latin-only liturgy. These two holy men were persecuted for their conviction, but Pope Adrian II vindicated their efforts. We might even say that St. Cyril and St. Methodius are the patron saints of vernacular liturgy and the AUTHENTIC liturgical reforms of the Second Vatican Council.