CHAPTER XVIII. In What Order the Psalms Are to Be Said
21 Feb. 22 June. 22 Oct.
First of all let this verse be said: “O God, come to my assistance; O Lord, make haste to help me,” and the Gloria, followed by the hymn proper to each Hour. At Prime on Sunday four parts of the hundred and eighteenth Psalm are to be said. At the other Hours, that is, Tierce, Sext and None, let three parts of the same Psalm be said. At Prime on Monday let three Psalms be said, namely, the first, second and sixth and so in the same way every day until Sunday let three Psalms be said at Prime in order, up to the nineteenth; the ninth and seventeenth, however, being divided into two Glorias. It will thus come about that at the Night-Office on Sunday we shall always begin with the twentieth Psalm.

Saint Benedict reserves Psalm 118 (Beati immaculati) to Sunday, the Day of the Lord, the day par excellence of lectio divina, with the overflow of verses being chanted on Monday. Psalm 118 is a long, rapturous litany in praise of the Law. It was by means of the Law that God made known His Heart — the splendour of His truth, the glory of His beauty, the immensity of His goodness — to Israel. The psalmist cannot find enough words to describe the munificent self-revelation of God to Israel. With the mystical accents of a lover, the psalmist sings of the word of the Lord, of His precepts, His commandments, His ordinances, His statutes, His laws, His will, His righteousness, His justice, His mercy, and His utterances. Having exhausted all that he can say, he fails even to begin to approach the splendour of what God has revealed to Israel!

Beati sumus, Israël, quia quæ Deo placent manifesta sunt nobis.
We are happy, O Israel: because the things that are pleasing to God, are made known to us. (Baruch 4:4)

The rabbis of old referred to the Torah, the Law, as “the way, the truth, and the life.” When the Lord Jesus applied these three words to Himself, saying, “I am the Way, the Truth, and the Life” (John 124:6), He was revealing Himself as the true Torah, the fulfillment of the Law and of the Prophets, the One and Only Way to the Father. In this light, Psalm 118 becomes a litany of love addressed to the Word, a long contemplation of of the glory of God shining on the Face of His Christ, a confession of His holiness, His beauty, His goodness, and His mercy.

For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God, in the face of Christ Jesus. (2 Corinthians 4:6)

Saint Athanasius says that Psalm 118 describes the life of the saints: spiritual combat; demonic assaults; the remedy of the Divine Word; patience in suffering; joy in God; unfailing help from heaven; and light, happiness, and consolation in the way. Beati immaculati in via. The via of Psalm 118 is also the via crucis, the way of the Cross. Not for nothing was this very psalm chanted in the ancient Roman liturgy of Good Friday when the pontiff  would make his way, barefoot, from Saint John Lateran to the basilica of Santa Croce in Gerusalemme. Psalm 118 accompanies a monk from the first day of his life in the monastery until, in death, he is carried by his brethren to the cemetery, and there laid to rest.

Psalm 118 is most fittingly associated with Lex Domini immaculata, the second part of Psalm 18:

The law of the Lord is unspotted, converting souls: the testimony of the Lord is faithful, giving wisdom to little ones. (Psalm 18:8)

There is true spiritual joy in the weekly return of Psalm 118. It is an integral part of the Day of the Lord, spilling over into the feria secunda, the second day of the week. Of all the psalms, it is the one that each of us can pray most directly to Christ, offering Him verse after verse in adoration and in love. In the Byzantine liturgy, Psalm 118:26 is the verse by which the deacon announces to the priest at the altar that it is time for Divine Sacrifice to begin:

Tempus faciendi, Domine.
It is time for the Lord to act.

or as Monsignor Knox puts it:

Put off the hour, Lord, no more.

All of Psalm 118, effectively, announces the Incarnation of the Word in the womb of the Blessed Virgin Mary, the very mystery that Saint Luke describes as happening under the overshadowing of the Holy Ghost:

The Holy Ghost shall come upon thee, and the power of the most High shall overshadow thee. And therefore also the Holy which shall be born of thee shall be called the Son of God. (Luke 1:35)

At the same time, all of Psalm 118 points to the adorable Mystery of the Most Holy Eucharist. The whole psalm, in some way, leads a man, step by step, in via, to the Verba Verbi, the Words of the Word by which bread becomes the very Body of Christ and the chalice containing wine mixed with water becomes the chalice of His very Blood.  As Saint Thomas says, Nil hoc verbo Veritatis verius, “Truth himself speaks truly or there’s nothing true” (G.M. Hopkins).