Psalm 127 - Verse 6: Peace and prosperity

Bellini, Christ Blessing
Source: Wiki art

St Alphonsus Liguori supplies a nice summary of the last two verses of Psalm 127:

In these last two verses...the Holy Ghost promises the just man supreme blessing, the only true and perfect happiness, which consists in seeing and possessing the sovereign Good in the heavenly Jerusalem during all eternity.

6	V/NV/JH	Benedícat tibi Dóminus ex sion: et vídeas bona Jerúsalem ómnibus diébus vitæ tuæ.
		εὐλογήσαι σε κύριος ἐκ Σιων καὶ ἴδοις τὰ ἀγαθὰ Ιερουσαλημ πάσας τὰς ἡμέρας τῆς ζωῆς σου

Benedícat (He may bless) tibi (to you) Dóminus (the Lord) ex (from) Sion: et (and) vídeas (may you see) bona (good) Jerúsalem omnibus (all) diébus (the days) vitæ (of the life) tuæ (your)

video, vidi, vlsum, ere 2,  to see, behold; consider; experience, undergo, suffer, realize; keep watch, look for, meditate on

bonus, a, um, good;  the good; Of things that which is good as opposed to what is evi; good things, possessions, prosperity

DR	May the Lord bless you out of Sion: and may you see the good things of Jerusalem all the days of your life.
Brenton	May the Lord bless thee out of Sion; and mayest thou see the prosperity of Jerusalem all the days of thy life.
MD	Now the Lord bless thee from Sion, and mayest thou see Jerusalem prosper all the days of thy life
RSV	The LORD bless you from Zion! May you see the prosperity of Jerusalem all the days of your life!
Cover	The Lord from out of Sion shall so bless thee, that thou shalt see Jerusalem in prosperity all thy life long
Knox	May the Lord who dwells in Sion bless thee; mayest thou see Jerusalem in prosperity all thy life long.
Grail	May the Lord bless you from Zion in a happy Jerusalem all the days of your life!

St Augustine points out that some of the blessings already described, such as having children, while a blessing, is not always all that great a one, something more is needed, namely the good: 

Even to the birds was it said, Be fruitful and multiply. Do you wish to hold as a great blessing what was given unto birds? Who can be ignorant, that it was given indeed by the voice of God? But use these goods, if you receive them; and rather think how you may nourish those who have been born, than that others may be born. For it is not happiness to have children, but to have good ones.

Most of the modern translations use prosperity' for 'bona', but it really has a very broad meaning, as St John Chrysostom explains:

A different translator says, "And see the goods of Jerusalem." As good things he means the city, wealth, appearance, victories, honors, prosperity, good seasons, security, peace. All the days of your life.

Cassiodorus also develops this theme, saying:

By Jerusalem is meant "vision of peace," peace here being the invisible quality which will be visible when its Author the Lord Christ is beheld with blessed mind. So he prays that he may see in Jerusalem all the things that are good; for there the Lord Himself is beheld, and He makes those who gaze on Him eternal, revealing Himself in unbroken continuity. So in the spirit of prophecy he prays on the saints' behalf for what he knows can accrue to them...

It is important to note, too, that the phrase 'All the days of thy life' has an eschatological connotation, as St Robert Bellarmne explains:  

that you may see God, in whom are all the good things of Jerusalem, "all the days of thy life," forever, unto ages of ages; for as the soul is immortal, as is the body, too, after the short sleep of death, when it will rise immortal, unquestionably the good things we see here are not seen all the days of our life...the good things of the Jerusalem above are possessed by seeing them, as perfect happiness consists purely of the beatific vision as St. John, in his first Epistle says, "We shall be like to him," most blessed and happy, and almost gods, "because we shall see him as he is.

Psalm 127

Vulgate	Douay-Rheims
Canticum graduum.
1 Beáti omnes, qui timent Dóminum,* qui ámbulant in viis ejus.	Blessed are all they that fear the Lord: that walk in his ways.
2  Labóres mánuum tuárum quia manducábis: * beátus es, et bene tibi erit.	2 For you shall eat the labours of your hands: blessed are you, and it shall be well with you.
3  Uxor tua sicut vitis abúndans: * in latéribus domus tuæ.	3 Your wife as a fruitful vine, on the sides of your house.
4  Fílii tui sicut novéllæ olivárum: * in circúitu mensæ tuæ.	Your children as olive plants, round about your table.
5  Ecce sic benedicétur homo, * qui timet Dóminum.	4 Behold, thus shall the man be blessed that fears the Lord.
6  Benedícat tibi Dóminus ex Sion: *  et vídeas bona Jerúsalem ómnibus diébus vitæ tuæ.	5 May the Lord bless you out of Sion: and may you see the good things of Jerusalem all the days of your life.
7  Et vídeas fílios filiórum tuórum: * pacem super Israël.	6 And may you see your children's children, peace upon Israel.
Gloria Patri et Filio et Spiritui Sancto.	Glory be to the Father, and to the Son, and to the Holy Ghost
Sicut erat in principio, et nunc, et semper, et in saecula saeculorum. Amen.	As it was in the beginning, is now, and ever shall be, world without end. Amen.

And you can find the final part in this series here.