Litany of the Saints
As the ritual dating back to the medieval era proceeded, Gregorian chants were sung by several religious orders with the people responding to each verse with the ancient Greek prayer, "Lord, have mercy" or "Kyrie eleison." The Litany of the Saints was sung. After each name of a martyr or saint was chanted, invoking his or her intercession between God and the people, participants in the procession sang the Latin words, "Ora pro eo," meaning "Pray for him." This is a departure from the traditional, "Pray for us" or "Ora pro nobis."