People often get confused by Psalm numbering, because there are two different arrangements.

This is because the traditional Christian numbering of the Psalms (as found in the Greek Septuagint and Latin Vulgate) differ from the Hebrew numbering of the Psalms. Most modern bibles have the Hebrew numbering.

It all starts going wrong with Psalm 9, because Psalms 9 and 10 in Hebrew are joined together as a single Psalm 9 in the Greek/Latin versions. 

• Psalms 9 and 10 in the Hebrew are combined into Psalm 9 in the Greek 
• Psalms 114 and 115 in the Hebrew are combined into Psalm 113 in the Greek 
• Psalm 116 in the Hebrew is divided into Psalms 114 and 115 in the Greek 
• Psalm 147 in the Hebrew is divided into Psalms 146 and 147 in the Greek

Still confused? Most people continue to be so. As a rule of thumb, the numbering in our Bibles is one ahead of those used in the Liturgy, except at the beginning and the end of the Psalter.

I will try to quote the Hebrew/Bible numbering, with the Greek/Latin/Liturgical numbering in Brackets. 

THE LETTER OF ATHANASIUS TO MARCELLINUS (extract)

My dear Marcellinus, 

YOUR steadfastness in Christ fills me with admiration. Not only are you bearing well your present trial, with its attendant suffering; you are even living under rule and, so the bearer of your letter tells me, using the leisure necessitated by your recent illness to study the whole body of the Holy Scriptures and especially the Psalms. Of every one of those, he says, you are trying to grasp the inner force and sense. Splendid! I myself am devoted to the Psalms, as indeed to the whole Bible; and I once talked with a certain studious old man, who had bestowed much labour on the Psalter, and discoursed to me about it with great persuasiveness and charm, expressing himself clearly too, and holding a copy of it in his hand the while he spoke. So I am going to write down for you the things he said. 

You see, then, that the grace of the one Spirit is common to every writer and all the books of Scripture, and differs in its expression only as need requires and the Spirit wills. Obviously, therefore, the only thing that matters is for each writer to hold fast unyieldingly the grace he personally has received and so fulfil perfectly his individual mission. And, among all the books, the Psalter has certainly a very special grace, a choiceness of quality well worthy to be pondered; for, besides the characteristics which it shares with others, it has this peculiar marvel of its own, that within it are represented and portrayed in all their great variety the movements of the human soul. It is like a picture, in which you see yourself portrayed, and seeing, may understand and consequently form yourself upon the pattern given. 

Elsewhere in the Bible you read only that the Law commands this or that to be done, you listen to the Prophets to learn about the Saviour's coming, or you turn to the historical books to learn the doings of the kings and holy men; but in the Psalter, besides all these things, you learn about yourself. You find depicted in it all the movements of your soul, all its changes, its ups and downs, its failures and recoveries. Moreover, whatever your particular need or trouble, from this same book you can select a form of words to fit it, so that you do not merely hear and then pass on, but learn the way to remedy your ill. Prohibitions of evil-doing are plentiful in Scripture, but only the Psalter tells you how to obey these orders and abstain from sin. Repentance, for example, is enjoined repeatedly; but to repent means to leave off sinning, and it is the Psalms that show you how to set about repenting and with what words your penitence may be expressed. 

Again, Saint Paul says, Tribulation worketh endurance, and endurance experience, and experience hope, and hope maketh not ashamed [Rom 5:3, 5]; but it is in the Psalms that we find written and described how afflictions should be borne, and what the afflicted ought to say, both at the time and when his troubles cease: the whole process of his testing is set forth in them and we are shown exactly with what words to voice our hope in God. Or take the commandment, In everything give thanks. [1 Thess 5:18] The Psalms not only exhort us to be thankful, they also provide us with fitting words to say. We are told, too, by other writers that all who would live godly in Christ must suffer persecution;[2 Tim 3:12] and here again the Psalms supply words with which both those who flee persecution and those who suffer under it may suitably address themselves to God, and it does the same for those who have been rescued from it. We are bidden elsewhere in the Bible also to bless the Lord and to acknowledge Him: here in the Psalms we are shown the way to do it, and with what sort of words His majesty may meetly be confessed. In fact, under all the circumstances of life, we shall find that these divine songs suit ourselves and meet our own souls' need at every turn. 

And herein is yet another strange thing about the Psalms. In the other books of Scripture we read or hear the words of holy men as belonging only to those who spoke them, not at all as though they were our own; and in the same way the doings there narrated are to us material for wonder and examples to be followed, but not in any sense things we have done ourselves. With this book, however, though one does read the prophecies about the Saviour in that way, with reverence and with awe, in the case of all the other Psalms it is as though it were one's own words that one read; and anyone who hears them is moved at heart, as though they voiced for him his deepest thoughts. 

For he who reads those books is clearly reading not his own words but those of holy men and other people about whom they write; but the marvel with the Psalter is that, barring those prophecies about the Saviour and some about the Gentiles, the reader takes all its words upon his lips as though they were his own, and each one sings the Psalms as though they had been written for his special benefit, and takes them and recites them, not as though someone else were speaking or another person's feelings being described, but as himself speaking of himself, offering the words to God as his own heart's utterance, just as though he himself had made them up. Not as the words of the patriarchs or of Moses and the other prophets will he reverence these: no, he is bold to take them as his own and written for his very self. Whether he has kept the Law or whether he has broken it, it is his own doings that the Psalms describe; every one is bound to find his very self in them and, be he faithful soul or be he sinner, each reads in them descriptions of himself. 

It seems to me, moreover, that because the Psalms thus serve him who sings them as a mirror, wherein he sees himself and his own soul, he cannot help but render them in such a manner that their words go home with equal force to those who hear him sing, and stir them also to a like reaction. Sometimes it is repentance that is generated in this way, as by the conscience-stirring words of Psalm 51; another time, hearing how God helps those who hope and trust in Him, the listener too rejoices and begins to render thanks, as though that gracious help already were his own. Psalm 3, to take another instance, a man will sing, bearing his own afflictions in his mind; Psalms 11 and 12 he will use as the expression of his own faith and prayer; and singing the 54th, the 56th, the 57th, and the 142nd, it is not as though someone else were being persecuted but out of his own experience that he renders praise to God. 

And every other Psalm is spoken and composed by the Spirit in the self-same way: just as in a mirror, the movements of our own souls are reflected in them and the words are indeed our very own, given us to serve both as a reminder of our changes of condition and as a pattern and model for the amendment of our lives. 

From the Ancient Christian Writers series, published by Paulist Press

What is a good commentary to have on the Psalms?

First of all ourselves - they are prayers, and are written to give expression of our stuggles and our joys. We need to let them speak to us.

There are many, many books written on the Psalms, serving different purposes, but for the  the general reader, and anyone who experiences the Psalms in the liturgy, a practical one-volume book is the following, written by the Abbot Primate of the Benedictines, Gregory Polan, who is a Scripture Scholar and has worked on the new translation for the liturgy. For each psalm there is an introduction, the text and a prayer. Just enough to get us started.

The Psalms: Songs of Faith and Praise. 

Gregory J. Polan, Paulist Press, 2014

I generally use the Grail Translation, which we use in our liturgy. However a new translation is being adopted, The Revised Grail Psalms, prepared by Abbot Gregory and the monks of Conception.

Over the years Walter Brueggemann has written a number of things on the Psalms:

Spirituality of the Psalms, 2001, Fortress Press, is a condensed version of the following:

The Message of the Psalms: A Theological Commentary,  Augsburg Press, 1984.

Praying the Psalms, Cascade Books, 2007

Also of note is a fresh and lively translation and commentary by Robert Alter.

The Book of Psalms: A Translation with Commentary, Norton & Co. 2009

There are commentaries and reflections by Thomas Merton, C.S. Lewis and Tom Wright.

There are many excellent commentaries out there!

Examples of these are:

Psalm 1, 8, 24, 33, 104, 119, 133, 145. 

These are the psalms we are most comfortable with. These are psalms of gratitude for God’s ordering of life. These psalms reflect life the way it is expected to be: full of blessing for the saints. These are psalms where the Torah is celebrated and the God of creation is praised. 

See several works by Walter Brueggemann, eg The Message of the Psalms,  1984; Spirituality of the Psalms, 2002

In Hebrew, this is an  acrostic/alphabetical psalm, meaning each verse begins with the sucessive character of the Hebrew Alphabet. This contruction is invisible in this translation. 

I will give you glory, O God my King,

I will bless your name for ever.

I will bless you day after day

and praise your name for ever.

The Lord is great, highly to be praised,

his greatness cannot be measured.

Age to age shall proclaim your works,

shall declare your mighty deeds,

shall speak of your splendour and glory,

tell the tale of your wonderful works.

They will speak of your terrible deeds,

recount your greatness and might.

They will recall your abundant goodness;

age to age shall ring out your justice.

The Lord is kind and full of compassion,

slow to anger, abounding in love.

How good is the Lord to all,

compassionate to all his creatures.

All your creatures shall thank you, O Lord,

and your friends shall repeat their blessing.

They shall speak of the glory of your reign

and declare your might, O God,

to make known to men your mighty deeds

and the glorious splendour of your reign.

Yours is an everlasting kingdom;

your rule lasts from age to age.

The Lord is faithful in all his words

and loving in all his deeds.

The Lord supports all who fall

and raises all who are bowed down.

The eyes of all creatures look to you

and you give them their food in due time.

You open wide your hand,

grant the desires of all who live.

The Lord is just in all his ways

and loving in all his deeds.

He is close to all who call him,

who call on him from their hearts.

He grants the desires of those fear him,

he hears their cry and he saves them.

The Lord protects all who love him;

but the wicked he will utterly destroy

Let me speak the praise of the Lord,<187>

let all mankind bless his holy name

for ever, for ages unending.

Jean-Pierre Prévost notices many similarities between this psalm and the Lord's Prayer. 

Read through the Psalm and make those connection:

• Sanctification of God's Name
• The Coming of the kingdom
• The Giving of the daily bread
• Help against temptation.

But he notes that there are two things missing in the Psalm that is new in the Our Father.  What might they be? 

• The name 'Father' - expressing the absolute confidence of the Christian in God;
• The insistence on forgiveness.

Happy indeed is the man

who follows not the counsel of the wicked;

nor lingers in the way of sinners

nor sits in the company of scorners,

but whose delight is in the law of the Lord

and who ponders his law day and night.

He is like a tree that is planted

beside the flowing waters,

that yields its fruit in due season

and whose leaves shall never fade;

and all that he does shall prosper.

Not so are the wicked, not so!

For they like winnowed chaff

shall be driven away by the wind.

When the wicked are judged they shall not stand,

nor find room among those who are just;

for the Lord guards the way of the just

but the way of the wicked leads to doom.

(Grail Translation)

Bless the Lord, my soul!

Lord God, how great you are,

clothed in majesty and glory,

wrapped in light as in a robe!

You stretch out the heavens like a tent.

Above the rains you build your dwelling.

You make the clouds your chariot,

you walk on the wings of the wind,

you make the winds your messengers

and flashing fire your servants.

You founded the earth on its base,

to stand firm from age to age.

You wrapped it with the ocean like a cloak:

the waters stood higher than the mountains.

At your threat they took to flight;

at the voice of your thunder they fled.

They rose over the mountains and flowed down

to the place which you had appointed.

You set limits they might not pass

lest they return to cover the earth.

You make springs gush forth in the valleys:

they flow in between the hills.

They give drink to all the beasts of the fields;

the wild asses quench their thirst.

On their banks dwell the birds of heaven;

from the branches they sing their song.

From your dwelling you water the hills;

earth drinks its fill of your gift.

You make the grass grow for the cattle

and the plants to serve man's needs,

that he may bring forth bread from the earth

and wine to cheer man's heart;

oil, to make his face shine

and bread to strengthen man's heart.

The trees of the Lord drink their fill

the cedars he planted on Lebanon;

there the birds build their nests:

on the tree top the stork has her home.

The goats find a home on the mountains

and rabbits hide in the rocks.

You make the moon to mark the months;

the sun knows the time for its setting.

When you spread the darkness it is night

and all the beasts of the forest creep forth.

The young lions roar for their prey

and ask their food from God.

At the rising of the sun they steal away

and go to rest in their dens.  

Man goes forth to his work,

to labour till evening falls.

How many are your works, O Lord!

In wisdom you have made them all.

The earth is full of your riches.

There is the sea, vast and wide,

with its moving swarms past counting,

living things great and small.

The ships are moving there

and the monsters you made to play with.

All of these look to you

to give them their food in due season.

You give it, they gather it up:

you open your hand, they have their fill.

You hide your face, they are dismayed;

you take back your spirit, they die,

returning to the dust from which they came.

You send forth your spirit, they are created;

and you renew the face of the earth.

May the glory of the Lord last for ever!

May the Lord rejoice in his works!

He looks on the earth and it trembles;

the mountains send forth smoke at his touch.

I will sing to the Lord all my life,

make music to my God while I live.

May my thoughts be pleasing to him.

I find my joy in the Lord.

Let sinners vanish from the earth

and the wicked exist no more.

Bless the Lord, my soul.

Grail Translation

How great is your name, O Lord our God,  

through all the earth! 

Your majesty is praised above the heavens;

on the lips of children and of babes  

you have found praise to foil your enemy,

to silence the foe and the rebel. 

When I see the heavens, the work of your hands,  

the moon and the stars which you arranged,

what is man that you should keep him in mind,  

mortal man you care for him? 

Yet you have made him little less than a god;  

with glory and honour you crowned him,

gave him power over the works of your hands, 

put all things under his feet. 

All of them, sheep and cattle, 

yes, even the savage beasts,

birds of the air, and fish 

that make their way through the waters. 

How great is your name, O Lord our God,

through all the earth! 

Grail Translation

O Lord, my heart is not proud

nor haughty my eyes.

I have not gone after things too great

nor marvels beyond me.

Truly I have set my soul

in silence and peace.

A weaned child on its mother's breast,

even so is my soul.

O Israel, hope in the Lord

both now and for ever.

Grail Translation