Ps 139 v13: Blessed are the poor in spirit

The second last verse of Psalm 139 reaffirms the faith of the psalmist that God will set things right in the end.

Looking at the Latin

Cognóvi quia fáciet Dóminus judícium ínopis:  et vindíctam páuperum

I know that the Lord will do justice to the needy, and will revenge the poor.

The key vocabulary for the verse is:

cognosco, gnovi, gnitum, ere 3, to know, see, learn, perceive, be come acquainted with

judicium, i, n.  judgment, decrees; law, commandment; the power, or faculty of judging wisely; justice.

inops, opis, without means or resources; poor, needy, indigent, destitute

reddo, didi, ditum, ere. to restore, return, give back; to requite, repay, reward, render; 

egenus i n (substantive) needy, necessitous, in want, destitute

ius, iuris that which is binding, right, justice, duty

vindicta, ae, f. vengeance, punishment

pauper, eris, ., poor, needy, indigent, helpless, destitute, wretched.

Word by word:

Cognóvi (I have known) quia (that) fáciet (he will make/do) Dóminus (the Lord) judícium (justice) ínopis (the poor/needy/destitute) et (and) vindíctam (revenge/vengeance) páuperum (to the poor/helpless).

This is a verse where the Pian looks quite different to the Vulgate, without the changes adding much obvious value in meaning:

13	V	Cognóvi quia fáciet Dóminus judícium ínopis: * et vindíctam páuperum.
	OR	cognovi quoniam faciet Dominus iudicium inopum et vindictam pauperum
	NV	Cognovi quia faciet Dominus iudicium inopis et vindictam pauperum.
	Pian	Novi Dominum ius reddere egeno, iustitiam pauperibus.
	JH	Scio quod faciet Dominus causam inopis, iudicia pauperum.
	Sept	ἔγνων ὅτι ποιήσει κύριος τὴν κρίσιν τοῦ πτωχοῦ καὶ τὴν δίκην τῶν πενήτων

[Abbreviations: V=Vulgate; OR=Old Roman; NV=Neo-Vulgate; JH=St Jerome's translation from the Hebrew; Sept=Septuagint]

The English translations offer a variety of synonmyms for those God will help:

DR	I know that the Lord will do justice to the needy, and will revenge the poor.
Brenton	I know that the Lord will maintain the cause of the poor, and the right of the needy ones.
MD	I know the Lord secureth justice for the poor and defendeth the cause of the needy
RSV	I know that the LORD maintains the cause of the afflicted, and executes justice for the needy.
Cover	Sure I am that the Lord will avenge the poor, and maintain the cause of the helpless.
Knox	Can I doubt that the Lord will avenge the helpless, will grant the poor redress?
Grail	I know that the Lord will avenge the poor, That he will do justice for the needy.

[Abbreviations: DR=Douay-Rheims Challoner; MD=Monastic Diurnal; RSV=Revised Standard Version; Cover=Coverdale]

The knowledge gained by faith

The word cognovi, indicating the perfect tense, can be interpreted as a strong conviction that God will help the needy.  It is both a statement of faith in God's goodness, and a description of the appropriate thoughts of the just man.

And the use of the word cognovi here, is meant, I would suggest, to stand in contrast to the evil thoughts and actions of  plotters described earlier in the psalm:

2 Qui cogitavérunt iniquitátes in corde: tota die constituébant prælia.	3 Who have devised iniquities in their hearts: all the day long they designed battles.
5 Qui cogitavérunt supplantáre gressus meos: abscondérunt supérbi láqueum mihi:	Who have proposed to supplant my steps: 6 The proud have hidden a net for me.
9 Ne tradas me, Dómine, a desidério meo peccatóri: cogitavérunt contra me, ne derelínquas me, ne forte exalténtur.	9 Give me not up, O Lord, from my desire to the wicked: they have plotted against me; do not forsake me, lest they should triumph.

Who are the poor?

Although the verse can obviously also be interpreted literally, the tradition emphasises that the most important type of poverty is not material.  St Augustine, for example, pointed to the beatitudes in his analysis of the verse:

He is needy of whom it is said, Blessed are they which do hunger and thirst after righteousness, for they shall be filled. 

Building on this, St Robert Bellarmine argued that even a nominally rich man can be poor in this sense:

I am convinced, both from my own experience, from the records of my ancestors, as well as from a knowledge of God’s promises and of his justice, that he regards the humble and the poor; which include those abounding in the wealth of the world, yet, by reason of their not looking upon such wealth as their own, but as so much entrusted to them by God to dispense, as being but so many stewards, are still really poor in spirit. 

Vulgate	Douay-Rheims
In finem. Psalmus David.	Unto the end, a psalm of David.
1 Eripe me, Dómine, ab hómine malo: * a viro iníquo éripe me.	Deliver me, O Lord, from the evil man: rescue me from the unjust man.
2 Qui cogitavérunt iniquitátes in corde: * tota die constituébant prælia.	3 Who have devised iniquities in their hearts: all the day long they designed battles.
3 Acuérunt linguas suas sicut serpéntis: * venénum áspidum sub lábiis eórum.	4 They have sharpened their tongues like a serpent: the venom of asps is under their lips.
4 Custódi me, Dómine, de manu peccatóris: * et ab homínibus iníquis éripe me.	5 Keep me, O Lord, from the hand of the wicked: and from unjust men deliver me.
5 Qui cogitavérunt supplantáre gressus meos: * abscondérunt supérbi láqueum mihi:	Who have proposed to supplant my steps: 6 The proud have hidden a net for me.
6 Et funes extendérunt in láqueum: * juxta iter scándalum posuérunt mihi.	And they have stretched out cords for a snare: they have laid for me a stumbling block by the wayside.
7. Dixi Dómino : Deus meus es tu: * exáudi, Dómine, vocem deprecatiónis meæ.	7 I said to the Lord: You are my God: hear, O Lord, the voice of my supplication.
8 Dómine, Dómine, virtus salútis meæ: * obumbrásti super caput meum in die belli.	8 O Lord, Lord, the strength of my salvation: you have overshadowed my head in the day of battle.
9 Ne tradas me, Dómine, a desidério meo peccatóri: * cogitavérunt contra me, ne derelínquas me, ne forte exalténtur.	9 Give me not up, O Lord, from my desire to the wicked: they have plotted against me; do not forsake me, lest they should triumph.
10 Caput circúitus eórum: * labor labiórum ipsórum opériet eos.	10 The head of them compassing me about: the labour of their lips shall overwhelm them.
11 Cadent super eos carbónes, in ignem dejícies eos: * in misériis non subsístent.	11 Burning coals shall fall upon them; you will cast them down into the fire: in miseries they shall not be able to stand.
12 Vir linguósus non dirigétur in terra: * virum injústum mala cápient in intéritu.	12 A man full of tongue shall not be established in the earth: evil shall catch the unjust man unto destruction.
13 Cognóvi quia fáciet Dóminus judícium ínopis: * et vindíctam páuperum.	13 I know that the Lord will do justice to the needy, and will revenge the poor.
14 Verúmtamen justi confitebúntur nómini tuo: * et habitábunt recti cum vultu tuo.	14 But as for the just, they shall give glory to your name: and the upright shall dwell with your countenance.

And you can find notes on the last verse of the psalm here.