Slavorum Apostoli §22

²² In the historical development of the Slavs of Eastern Rite, this language played a role equal to that of the Latin language in the West. It also lasted longer than Latin in part until the nineteenth century-and exercised a much more direct influence on the formation of the local literary languages, thanks to its close kinship with them. These merits vis-a-vis the culture of all the Slav peoples and nations make the work of evangelization carried out by Saints Cyril and Methodius in a certain sense constantly present in the history and in the life of these peoples and nations.