The Kyrie Eleison offers an interesting distinction between old Mass and New, but its history also provides an interesting challenge to contemporary myths about liturgical development. It is often supposed today that the Kyrie is a remnant of a time when the Mass was said in Greek, and thus a sign for us that just as the Mass was changed from Greek to Latin, it should be changed to the vernacular of the people. Nothing could be further from the truth.
The Kyrie Eleison was not introduced into the Roman liturgy until after it had been celebrated in Latin for many years. It appears nowhere in the account of St. Justin Martyr, and it is not present in the North African liturgy which followed the Roman rite very closely. None of the old Latin writers such as Tertullian nor St. Cyprian mention it, neither does a later writer St. Augustine. Where did it come from then? It was a saying of St. John Chrysostom which he introduced into the liturgy of Constantinople (if it was not already in use), and from there it was popularized and introduced into other liturgies. Because it was Greek, rather than translate it into the Latin it was imported directly as it was received. It appears first in the Gallican liturgies, which were an Eastern liturgy brought to the west by the patriarchs of Milan, and appears in the Roman liturgy first in the 6th century. In the Greek rites it was apart of a litany, whereas in the West the manner of its introduction was alternating with the invocation "Christe eleison", something not seen in the Greek liturgy, or any other Western liturgy save the Mozarabic.
The myth that it is left over from a time when the Roman liturgy was said in Greek liturgy nothing more than an instance of bad scholarship and false assumptions made by those eager to push a vernacular liturgy on the Church at the expense of her tradition, and should be dispensed with because it is nonsense. It was an influence from a foreign Greek liturgy once the Roman Liturgy had already acquired its Latin form.
Secondly, the Kyrie in the Novus Ordo represents a retrograde development, not to the early Church as is also supposed (born of a mythical concept that the Novus Ordo is the restoration of primitive Christianity), but rather ironically, as we shall see in a moment to the high Middle Ages. The traditional Latin Mass revised by St. Pius V removed all sorts of local creations with respect to the Kyrie, and restored the ancient usage in the Roman Rite of 3 Kyrie Eleisons to God the Father, 3 Christe Eleisons to God the Son, and 3 Kyrie Eleisons for God the Holy Ghost, no invocations, no farcing, no additions to the prayer to fill in the chant. This is fitting also for the Trinitarian aspect of the prayers. Now the medieval custom which the reform of Pius V put to rest was a musical device called "farcing". Farcing a text means that where the notes are long, the text will be filled in with other words or invocations.
This was not limited to the Kyrie but also found realization in the Gloria, Agnus Dei, and many of the Church's antiphons and sequences (which themselves were an innovation although useful at their inception). The style would go something like this: Kyrie eleison, redemptor mundi et rex creationis, Christe eleison filius David, etc. Or it would work the other way Princeps pacis qui salvare nos venire, Kyire eleison, Redemptor mundi Kyrie eleison, or again Precamur te Domine, Christe eleison, etc. It is possible that this grew out of the litany tradition of the Gallican rite which continued uninterrupted in some places in spite of Charlemagne. Although it ought to be noted that the names for certain Kyries, such as Orbis factor come from the first farcing of the Kyrie chants of the middle ages.
In the event one is curious about the Byzantine sounding nature of the chant, that is generally because all northern European chant was founded on the Eastern rite tradition imparted to the west in the Gallican rite, which is an eastern liturgy, probably from Antioch according to most sources, and later melds with the Roman tradition spread by Charlemagne. Nevertheless, by the high and late middle ages the practice of farcing was getting out of control, the number and enormity of the texts were ridiculous and even some heresies were beginning to be introduced. Since the character of the Roman Rite is noble simplicity, St. Pius V's reform eliminated from the use of the Church the farcing of texts. In might justly be said the reform imposed the Roman usage (which never made use of it) to the whole Church.
Now forgetting ICEL, or the manifold abuses existing with respect to the Kyrie, we will go straight to the Latin of the Novus Ordo. There are several options for it. The first: Kyrie eleison twice, Christe eleison twice, Kyrie Eleison twice. Why only twice? If we are going to speak of time, how much time does it really save to take away one extra invocation each to the Holy Trinity? Not only is one reducing the honor paid to the Holy Trinity, he is also reducing the beautiful symbolism for the faithful. Moreover there is simply no good reason for this change. Second, let us look at the options for the Kyrie in the Novus Ordo:
Postea sacerdos, vel diaconus vel alius minister, sequentes, vel alias, invocationes cum Kyrie, eléison profert: Qui missus es sanáre contrítos corde: Kyrie, eléison.
Populus respondet: Kyrie, eléison. Sacerdos: Qui peccatóres vocáre venísti: Christe, eléison. Populus: Christe, eléison. Sacerdos: Qui ad déxteram Patris sedes, ad interpellándum pro nobis: Kyrie, eléison. Populus: Kyrie, eléison.
Thus what the Novus Ordo has done is to re-introduce a foreign element to the Roman Rite, namely textual farcing, which was expunged during the middle ages, something that the apologists for the right claim it is supposed to be doing! Where it was something added to the rite in the medieval period, it has become apart of the official text of the new roman rite today, a clear novelty in the tradition.
In either case, if a priest was to choose the more traditional option, he is not able to say it the way it has nearly always been done in the Roman Rite, three each, or even to have it chanted three each, which is even the case in the medieval farced Kyries.
This post by Ryan Grant originally appeared on the blog Athanasius Contra Mundum on January 29, 2010 under the title "Forgetting ICEL: The Kyrie"