KYRIE ELEISON. — “Lord, have mercy!” is a Greek expression in language and origin, in use in sacred and profane contexts since ancient times in the East, among Greeks and Romans. It is often found (not in the compound sense) in the Bible (especially in Ps. 6:3; 30:10; 40:5, 11; 55:2; 85:3; 118:29; 122:3; Is. 33:2; Bar. 3:2; Mt. 15:22; 17:15; 20:30–31). It appears in the liturgy no earlier than the end of the 4th century in Antioch (s. Giovanni Crisostomo, in Mt. hom., 71,4; PG 58, 666; hom. 6,1 in I Tim.; PG 62, 530; Constit. Apost., VIII, 6,4.9 and c. 35, ed. Funck, I, 478.480.544) and in Jerusalem (Eteria c. 24: CSEL, 39, 72). At Rome it was introduced
toward the end of the 5th century, and in the time of s. Gregorio I (d. 604), perhaps already by s. Benedetto (d. 547), it was recited alternately with “Christe eleison.” From Rome it spread into Gaul (Council of Vaison of 529), etc.; in Milan, already earlier, under Greek influence.
In the Eastern liturgy, the K. e. is used as the people’s response to the deacon’s invitation in the litanies of intercession (ektenies); it is said without addition, separately from the other supplication, but is also often repeated on other occasions.
In the Roman Mass it was recited in the form of the “Deprecatio Gelasii,” similar to the Greek ekteny, perhaps introduced into the “Missa catechumenorum” by Gelasius I (492–96) as a substitute for the “Oratio fidelium” (which was omitted because the prayers of intercession had entered the Canon), still used in the Ambrosian liturgy. Following the example of the Roman liturgy, s. Benedetto prescribed the “litaniae” for Lauds and Vespers; for the Minor Hours, instead, an abbreviated form, the “supplicatio litaniae, id est K. e.,” perhaps
already alternated with “Christe eleison.” s. Gregorio I likewise distinguishes two forms: the greater in the solemn Mass, the lesser in daily Masses, alternated with “Christe eleison” (Ep., 9,2, ad Ioann. ep. Syrac.). The greater was omitted; it is no longer found in the Roman Orders. The number 9 (documented in the Ordo of Giovanni Archicantor, ed. Silva-Tarouca, p. 196) was sometimes increased and ended at the pontiff’s signal. Then the sacred number of 9 (three times three) was fixed, interpreted by Amalarius as having been established in honor of the Most Holy Trinity, though in reality all the cries are directed to Christ. The shorter form occurs, outside the Mass, in the Preces of the Office and, placed at the beginning and end of the litanies, is repeated in processions. Outside liturgical usage, especially in the Middle Ages in France and Germany (Lais, Leisen), it was added to religious songs. Formerly it was recited or sung, by Greeks and Romans, between the deacon and the people; the celebrant did not recite it, but already from Giovanni Archicantor (Silva-Tarouca, p. 205) it is known that the priest recited it in private Masses (“... singulus... sacerdos ... novem tantum vicibus”), and in sung or solemn Masses from the 13th century onward (Ordo Rom., XIV, n. 61. 68. 71).
In the 9th century the so-called tropes began to be inserted, a custom that lasted until the reform of Pius V (1570).