[Question]{.underline}: Why is it that in the celebration of Mass the Psalm ‘Judica me’ is said before the “Kyrie Eleison’?
[Answer]{.underline}: The ordering of the parts of the Mass is essential historical in its origin. The Mass did not come into being because somebody sat down and figured out a logical sequence of prayers. Different circumstances were involved in the introduction of the different elements.
Neither the Kyrie Eleison nor the Psalm 42 were a part of the primitive Roman rite. The Kyrie Eleison was added in during the fifth and sixth centuries, coming from Antioch in the East, through Gaul. It was certainly firmly a part of the Roman Mass in the time of St. Gregory the Great at the end of the sixth century. It is the insistent importuning of God’s mercy by those who are aware of their unworthiness.
The Psalm “Judica me, Deus”, which is Psalm 42, began to be used in the celebration of Mass, together with the other prayers at the foot of the altar, in the 11^th^ century. However, for several centuries, it remained a local custom, becoming more universal as time went on, but not obligatory. It was originally a private preparation of the priest before the celebration of Mass, which is why it was not a part of the Mass prayers properly speaking. Still in 1550 Pope Paul III simply ordered that this Psalm be said aloud or silently in the sacristy before the priest went to the altar. It was St. Pius X with the Tridentine Mass who ordered that it be recited at the foot of the altar.
This Psalm is a messianic Psalm, referring in its literal sense to David asking God’s deliverance and protection from his rebellious son Absalom. It refers, however, in its messianic sense, to Christ’s offering himself on the altar of the Cross, the accomplishment of His Father’s will, the joy of his life. The relevance to the priest in his preparation for Mass is very clear. To mount the altar of God is the joy of his youth, the realization of his every desire, for this altar, on which Christ’s sacrifice is reactualized, is the source of all light and truth. With what alacrity does he repeat this Psalm, that identifies him with Christ Himself, sinner though he is, confident that he will be judged, not on his own merits, but on those of the all-Holy Savior in whose person he stands.
Consequently, it might seem a little strange that Psalm 42 precedes the Kyrie Eleison, and also the Confiteor, but when understood as the final preparation for going to the altar, it can be seen how this joyful, confident Psalm can precede these professions of sinful unworthiness.
Answered by Father Peter Scott, SSPX.