“Have mercy on me, O God, according to thy great mercy.” In the Douay-Rheims that line is Psalm 50, verse 3. In Crampon’s French Bible the same line is Psalm 51, verse 3. In the World English Bible it is Psalm 51, verse 1. Three different references for one sentence, and none of them is a misprint. Each Bible is counting correctly; they are counting different things.
Two books of Psalms
The psalms reached the Church by two roads. One is the Hebrew text, copied and vocalized by the Masoretes and printed today in editions based on manuscripts such as the Leningrad Codex. The other is the Septuagint, the Greek translation of the Hebrew Scriptures, made over the centuries before Christ and begun in Alexandria, which was the Old Testament many of the first Christians read.
Both hold the same hundred and fifty psalms, but they do not divide them the same way.
The Latin West took its count from the Greek. Saint Jerome made three Latin psalters: a light revision of the Old Latin, a translation from the Greek corrected against Origen’s Hexapla, and a fresh translation from the Hebrew. It was the second, the one made from the Greek and known as the Gallican Psalter, that ended up in the Vulgate, carrying the Greek division with it. The Church’s Latin liturgical books keep that count to this day, and lectionaries often print both numbers, so “The Lord is my shepherd” appears as Psalm 22 or as Psalm 23 (22).
Where the counts part, and where they meet again
The two divisions agree for the first eight psalms. Then the Greek reads the Hebrew Psalms 9 and 10 as a single psalm, and from that point almost every psalm in the Greek and Latin count carries a number one lower than in the Hebrew.
The gap does not run to the end. The Greek joins Hebrew 114 and 115 into one psalm, then splits Hebrew 116 into two, and later splits Hebrew 147 into two as well. The second split closes the gap, and the last three psalms carry the same number everywhere.
| Hebrew | Greek and Latin |
|---|---|
| 1–8 | 1–8 |
| 9–10 | 9 |
| 11–113 | 10–112 |
| 114–115 | 113 |
| 116 | 114–115 |
| 117–146 | 116–145 |
| 147 | 146–147 |
| 148–150 | 148–150 |
Only eleven psalms, then, have the same number in both counts: the first eight and the last three. For the other hundred and thirty-nine, the number on the page says which tradition the edition follows before it says anything about the psalm.
Which division is right?
Neither is right every time. The psalms were written as separate songs, gathered over centuries, and divided by the people who copied them. Where two of those songs met, a copyist could read one poem or two, and the two traditions did not always decide the same way.
Sometimes the Greek has the stronger case. Psalms 9 and 10, as the Hebrew numbers them, are held together by an alphabetic acrostic: successive sections begin with successive letters of the Hebrew alphabet, and the sequence starts in Psalm 9 and carries on through Psalm 10. The Catholic Encyclopedia of 1911 put it bluntly: it is “generally admitted” that the two were “originally a single acrostic poem,” wrongly separated in the Hebrew and rightly united by the Septuagint and the Vulgate. Psalm 10 also has no title of its own, which is unusual in that part of the Psalter.
Sometimes neither count seems right. Psalms 42 and 43 in the Hebrew numbering (41 and 42 in the Latin) share a refrain, “Why are you cast down, O my soul?”, which appears twice in the first and again at the end of the second. Psalm 43, too, has no title. Both traditions print them as two psalms; many commentators who notice the refrain read them as one.
And sometimes the evidence is older than either Bible. The Babylonian Talmud asks why the prayer “May the words of my mouth” follows “eighteen” psalms when it is drawn from the nineteenth, and answers that the first two psalms are “a single chapter.” It reasons that the first opens with “Happy is the man” and the second closes with “Happy are those who take refuge in him”: “every chapter that was dear to David,” it says, he began and ended with “happy.” By that reckoning, every number in the Psalter would be one lower again.
Then the verses move too
The numbers inside a psalm differ as well, and for a separate reason. Many psalms open with a title: “Unto the end, a psalm of David, when Nathan the prophet came to him after he had sinned with Bethsabee,” as the Douay-Rheims has it. The Hebrew text counts a title like that as verse 1, sometimes as verses 1 and 2. The Vulgate does the same, and so do most of the translations made from either. Most modern English Bibles print the title above the psalm and begin counting with the first line that follows it.
That is why the line this article began with is verse 3 in two of those Bibles and verse 1 in the third. The difference affects dozens of psalms, by one verse or by two, and it is independent of the psalm’s own number: two Bibles can agree that a psalm is 51 and still disagree about where in it a verse falls.
Psalm 151, “outside the number”
The Septuagint carries one psalm more than the hundred and fifty. Its title marks it as written by David “outside the number,” after his fight with Goliath. The Vulgate leaves it out, and the Catholic canon does not count it; the Eastern Orthodox churches do.
For a long time it was known only in Greek and in the versions made from it. Then, among the Dead Sea Scrolls, the great Psalms scroll from Cave 11, copied in the first century, turned out to contain two short Hebrew poems on the same subject, which the Greek psalm appears to draw on and join together. The psalm that was outside the number had Hebrew roots after all.
Which Bibles use which
Catholic Bibles have used both counts. The older translations, made from the Vulgate, keep its numbering: the Douay-Rheims in English, Matos Soares in Portuguese, and Martini in Italian. Translations made from the Hebrew mostly follow the Hebrew count: Crampon in French, the Petrus Canisius Bible in Dutch, and Šarić in Croatian. The World English Bible follows the Hebrew as well. Straubinger’s Spanish Bible shows that the number follows a tradition rather than the source text: his psalms were translated from the Hebrew, yet they keep the Latin number, with the Hebrew one printed beside it. Many modern Catholic translations do the opposite, giving the Hebrew number and the Latin one beside it, while the liturgy goes on saying Psalm 22.
None of this is a matter of one Bible being right and another wrong. It is two old and careful ways of dividing the same text, each with a long tradition behind it.
Reading them side by side
Collatio lines the psalms up by their text, not by the number printed above them. Ask for the shepherd psalm, in any edition and under either number, and every column shows the shepherd psalm; ask for “Have mercy on me, O God,” and every column opens on the same line, whatever verse each edition calls it.
Sources
- Psalms — Walter Drum, Catholic Encyclopedia (1911), on the two numberings, Psalms 9 and 10 as one acrostic poem, and Jerome’s three Latin psalters
- Book of Psalms — Wikipedia, on the table of correspondences and the verse offset caused by psalm titles
- Berakhot 9b–10a — Babylonian Talmud, William Davidson edition on Sefaria, on Psalms 1 and 2 as a single chapter
- Making sense of psalm numbering — Fiona M. Dyball, The Summit, Catholic Archdiocese of Melbourne (2025), on the Greek numbering in the Lectionary
- Psalm 151 — Wikipedia, on its title, its place in the canons, and the Hebrew text in the Psalms scroll from Qumran Cave 11