17 We can say without fear of contradiction that such a traditional and at the same time extremely up-to-date vision of the catholicity of the Church-like a symphony of the various liturgies in all the world's languages united in one single liturgy, or a melodious chorus sustained by the voices of unnumbered multitudes, rising in countless modulations, tones and harmonies for the praise of God from every part of the globe, at every moment of history-this vision corresponds in a particular way to the theological and pastoral vision which inspired the apostolic and missionary work of Constantine the Philosopher and of Methodius, and which sustained their mission among the Slav nations. In Venice, before the representatives of the ecclesiastical world, who held a rather narrow idea of the Church and were opposed to this vision, Saint Cyril defended it with courage. He showed that many peoples had already in the past introduced and now possessed a liturgy written and celebrated in their own language, such as " the Armenians, the Persians, the Abasgians, the Georgians, the Sogdians, the Goths, the Avars, the Tirsians, the Khazars, the Arabs, the Copts, the Syrians and many others". Reminding them that God causes the sun to rise and the rain to fall on all people without exception, he said: "Do not all breathe the air in the same way? And you are not ashamed to decree only three languages (Hebrew, Greek and Latin), deciding that all other peoples and races should remain blind and deaf! Tell me: do you hold this because you consider God is so weak that he cannot grant it, or so envious that he does not wish it?". To the historical and logical arguments which they brought against him Cyril replied by referring to the inspired basis of Sacred Scripture: "Let every tongue confess that Jesus Christ is Lord, to the glory of God the Father"; "All the earth worships you; they sing praises to you, sing praises to your name"; "Praise the Lord, all nations! Extol him, all peoples!".
Source: Slavorum Apostoli (Vatican.va)