Why the Latin Mass still opens with a prayer in Greek
In the middle of the Latin Mass sits a scrap of Greek: Kyrie eleison, meaning Lord, have mercy. It survives because Rome first worshipped in Greek, and the plea was kept when Latin took over. Composers from chant to polyphony have since made it the opening movement of countless Mass settings.
The words come straight from scripture. The Greek translation of the Hebrew Psalms repeatedly uses a cry for the Lord's mercy, and in Matthew's gospel it appears three times: from a Canaanite woman, from a father pleading for his son, and from two blind men by the road. In the Bible the plea always names who needs mercy, me or us or my son; in worship it widens into a general statement of trust in God's love.
Eastern Christianity uses the phrase constantly. Orthodox litanies answer each petition with it, sometimes once, sometimes three times, and some petitions draw twelve or even forty repetitions. Coptic services in Egypt keep it in Greek, and it is the seed of the Jesus Prayer, a cornerstone of private devotion in the East that is spreading among Western Christians too. The liturgist Josef Jungmann saw the Roman Kyrie as the leftover of an opening litany like those still sung in Eastern churches.
Differences were noticed early. In the sixth century Pope Gregory the Great observed that Eastern congregations sang it together, while in the West clergy sang and people answered, adding Christe eleison as often as Kyrie. The older Roman form uses three sets of three invocations, nine in all, said to join worshippers' prayers to the nine choirs of angels. Anglicans have used English since 1549, and the 1552 Prayer Book wove the Kyrie into a reading of the Ten Commandments.
Musically, the text's symmetry often yields a three-part ABA shape, and some polyphonic settings alternate with chant or organ. Modern theologians such as Mark Francis argue its stress falls on God's mercy rather than human sin, almost a way of declaring that the Lord is merciful.
Source: Kyrie
