This page is an unfinished work. Greater detail of the text and written explanations sure would be nice additions. Feedback is welcome at cormacmjones@gmail.com.

Not to be read on a narrow screen!

PART Β.
 Have Mercy on Me, O God (41–71)

PART O.
 Bless the Lord, O My Soul (89–105)

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The chiastic arrangement may be original to me, but the division of the Psalter into five books is from St. Gregory of Nyssa:

          “The entire treatise of the Psalms has been separated into five sections, and there is a systematic arrangement and division in these sections. The circumscription of the sections is obvious, since they conclude in a similar manner with certain ascriptions of praise to God. We must recognize these ascriptions of praise in relation to the division which we show to exist in the Psalms.
          “The number of psalms in each section is as follows: forty in the first section, thirty-one in the second, seventeen in the third, the same number also in the fourth, and forty-five in the fifth. The first part, then, concludes with the fortieth Psalm after the first, and ends with the words, ‘Blessed be the Lord God of Israel forever and ever. So be it. So be it.’ The second part concludes with the seventy-first Psalm, the ending of which is, ‘Blessed be the Lord, the God of Israel, who alone does marvellous things. And blessed be the name of his glory for ever and ever. The whole earth will be filled with his glory. So be it. So be it.’ The third part ends with the eighty-eighth Psalm, and this part too concludes in similar fashion, for it ends as follows: ‘Blessed be the Lord for ever. So be it. So be it.’ The one hundred and fifth Psalm completes the fourth section. Its ending resembles the others. ‘Blessed be the Lord the God of Israel from everlasting to everlasting. And all the people shall say, So be it, so be it.’ The fifth part extends from this psalm to the last one, whose ending is, ‘Let every breathing creature praise the Lord’ (Gregory of Nyssa’s Treatise on the Inscriptions of the Psalms, td. by Ronald E. Heine (Oxford: Clarendon Press, 1995), pp. 95–96).”

The holy father then goes on for several pages about the general meaning of the five main Parts in the context of the Psalter. It’s needless to say if you're reading this, but the work — Treatise on the Inscriptions of the Psalms — is highly recommended.

As for the names I’ve given the five Parts, they come from what I call the “fractal sweet spots.” For example, Psalm 1 is the first Psalm of the first section of the first Part; it begins “Blessed Is the Man,” and so PART Α is called that. Psalm 50 is the second Psalm of the second section of the second Part; thus PART Β is called “Have Mercy on Me, O God.” The navel of the whole Psalter is Psalm 80, wherein is found the declaration, “I Am the Lord Thy God” — that’s PART Χ’s name. The fourth section of the fourth Part consists of Psalms 102 and 103, both of which begin, “Bless the Lord, O My Soul”; hence PART Ο’s name. The whole Psalter ends with Psalms 148–150, known as the “Praises,” which begin and end with the phrase “Praise the Lord.” Rightfully then does PART Ω take its name from the book’s final words.

Χ.

      ς.

      ς. Psalm 118:1–64 (א–ח)

   ζ. Psalm 118:57–120 (ח–ס)

η. Psalm 118:113–176 (ס–ת)

Notes

Thrice I pair two Psalms together as one based on their liturgical use in the Orthodox Church. Psalms 19 and 20 are read together as part of the royal beginning of Matins. Psalms 134 and 135 comprise the Polyeleos sung at Matins on feast days. And Psalms 140 and 141 are read consecutively as “Lord I Have Cried” daily at Vespers.