St. Augustin on the Psalms.
1. This Psalm, belonging to the number of the Songs of Degrees, teacheth us, while we ascend and raise our minds unto the Lord our God in loving charity and piety, not to fix our gaze upon men who are prosperous in this world, with a happiness that is false and unstable, and altogether seductive; where they cherish nothing save pride, and their heart freezeth up against God, and is made hard against the shower of His grace, so that it beareth not fruit....
2. "They that put their trust in the Lord shall be even as the mount Sion: they shall not be removed for ever" (ver.1).
3. Who are these? "They shall stand fast for ever, who dwell in Jerusalem" (ver.2). If we understand this earthly Jerusalem, all who dwelt therein have been excluded by wars and by the destruction of the city: thou now seekest a Jew in the city of Jerusalem, and findest him not. Why then will "they that dwell in Jerusalem not be moved for ever," save because there is another Jerusalem, of which ye are wont to hear much? She is our mother, for whom we sigh and groan in this pilgrimage, that we may return unto her....They then who dwell therein "shall never be moved." But they who dwelt in that earthly Jerusalem, have been moved; first in heart, afterwards by exile. When they were moved in heart and fell, then they crucified the King of the heavenly Jerusalem herself; they were already spiritually without, and shut out of doors their very King. For they cast Him out without their city, and crucified Him without.  He too cast them out of His city, that is, of the everlasting Jerusalem, the Mother of us all, who is in Heaven.
4. What is this Jerusalem? He briefly describes it. "The mountains stand around Jerusalem" (ver.2). Is it anything great, that we are in a city surrounded by mountains? Is this the whole of our happiness, that we shall have a city which mountains surround? Do we not know what mountains are? or what are mountains save swellings of the earth? Different then from these are those mountains that we love, lofty mountains, preachers of truth, whether Angels, or Apostles, or Prophets. They stand around Jerusalem; they surround her, and, as it were, form a wall for her. Of these lovely and delightful mountains Scripture constantly speaketh....They are the mountains of whom we sing: "I lifted up mine eyes unto the mountains, from whence my help shall come:"  because in this life we have help from the holy Scriptures.  And through the mountains that receive peace, the little hills received righteousness: for what saith he of the mountains themselves? He said not, they have peace from themselves, or they make peace, or generate peace; but, they receive peace. The Lord is the source, whence they receive peace. So therefore lift up thine eyes to the mountains for the sake of peace, that thy help may come from the Lord, who hath made heaven and earth. Again, the Holy Spirit mentioning these mountains saith this: "Thou dost light them wonderfully from Thy everlasting mountains."  He said not, the mountains light them: but, Thou lightest them from Thy everlasting mountains: through those mountains whom Thou hast willed to be everlasting, preaching the Gospel, Thou lighting them, not the mountains. Such then are the "mountains that stand around Jerusalem."
5. And that ye may know what sort of mountains these be that stand around Jerusalem; where Scripture hath mentioned good mountains, very rarely, and hardly, and perhaps never, doth it fail instantly to mention the Lord also, or allude to Him at the same moment, that our hopes rest not in the mountains....Lest thou again shouldest tarry in the mountains, he at once addeth, "Even so the Lord standeth round about His people:" that thy hope might not lie in the mountains, but in Him who lighteth the mountains.  For when He dwelleth in the mountains, that is, in the Saints, He Himself is round about His people; and He hath Himself walled His people with a spiritual fortification, that it may not be moved for evermore. But when Scripture speaketh of evil mountains, it addeth not the Lord unto them. Such mountains, we have already told you often, signify certain mighty, but evil, souls. For ye are not to suppose, brethren, that heresies could be produced through any little souls. None save great men have been the authors of heresies; but in proportion as they were mighty, so were they evil, mountains. For they were not such mountains as would receive peace, that the hills might receive righteousness; but they received dissension from their father the devil. There were therefore mountains: beware thou fly not to such mountains. For men will come, and say unto thee, There is a great hero, there is a great man! How great was that Donatus! How great is Maximian! and a certain Photinus, what a great man he was! And Arius too, how illustrious he was! All these I have mentioned are mountains, but mountains that cause shipwreck.  ...
6. But love such mountains, in whom the Lord is. Then do those very mountains love thee, if thou hast not placed hope in them.  See, brethren, what the mountains of God are. Thence they are so called in another passage: "Thy righteousness is like the mountains of God."  Not their righteousness, but "Thy righteousness." Hear that great mountain the Apostle. "That I may be found in Him, not having mine own righteousness, which is of the law, but that which is through the faith of Christ."  But they who have chosen to be mountains through their own righteousness, as certain Jews or Pharisees their rulers, are thus blamed: "Being ignorant of God's righteousness, and going about to establish their own righteousness, they have not submitted themselves unto the righteousness of God."  But they who have submitted themselves are exalted in such a manner as to be humble. In that they are great, they are mountains; in that they submit themselves unto God, they are valleys: and in that they have the capacity of piety, they receive the plenteousness of peace, and transmit the copious irrigation to the hills, only beware, at present, what mountains thou lovest. If thou wish to be loved by good mountains, place not thy trust even in good mountains. For how great a mountain was Paul? where is one like him found? We speak of the greatness of men. Can any one readily be found of so great grace? Nevertheless, he feared lest that bird should place trust in him: and what doth he say: "Was Paul crucified for you?"  But lift up your eyes unto the mountains, whence help may come unto you: for, "I have planted, Apollos hath watered:" but, your help cometh from the Lord, who hath made Heaven and earth; for, "God gave the increase."  "The mountains," therefore, "stand around Jerusalem." But as "the mountains stand around Jerusalem, even so standeth the Lord round about His people, from this time forth for evermore." If therefore the mountains stand around Jerusalem, and the Lord standeth round about His people, the Lord bindeth His people into one bond of love and peace, so that they who trust in the Lord, like the mount Sion, may not be moved for evermore: and this is, "from this time forth for evermore."
7. "For the Lord will not leave the rod of the ungodly upon the lot of the righteous, lest the righteous put forth their hands unto wickedness" (ver.3). At present indeed the righteous suffer in some measure, and at present the unrighteous sometimes tyrannize over the righteous. In what ways? Sometimes the unrighteous arrive at worldly honours: when they have arrived at them, and have been made either judges or kings; for God doth this for the discipline of His folk, for the discipline of His people; the honour due to their power must needs be shown them. For thus hath God ordained His Church, that every power ordained in the world may have honour, and sometimes from those who are better than those in power. For the sake of illustration I take one instance; hence calculate the grades of all powers. The primary and every day relation of authority between man and man is that between master and slave. Almost all houses have a power of this sort. There are masters, there are also slaves; these are different names, but men and men are equal names.  And what saith the Apostle, teaching that slaves are subject to their masters? "Servants, be obedient to them that are your masters according to the flesh:" for there is a Master according to the Spirit. He is the true and everlasting Master; but those temporal masters are for a time only. When thou walkest in the way, when thou livest in this life, Christ doth not wish to make thee proud. It hath been thy lot to become a Christian, and to have a man for thy master: thou wast not made a Christian, that thou mightest disdain to be a servant. For when by Christ's command thou servest a man, thou servest not the man, but Him who commanded thee. He saith this also: "Servants, be obedient to them that are your masters according to the flesh."  Behold, he hath not made men free from being servants, but good servants from bad servants. How much do the rich owe to Christ, who orders their house for them! so that if thou hast had an unbelieving servant, suppose Christ convert him, and say not to him, Leave thy master, thou hast now known Him who is thy true Master: he perhaps is ungodly and unjust, thou art now faithful and righteous: it is unworthy that a righteous and faithful man should serve an unjust and unbelieving master. He spoke not thus unto him, but rather, Serve him: and to confirm the servant, added, Serve as I served; I before thee served the unjust....If the Lord of heaven and earth, through whom all things were created, served the unworthy, asked mercy for His furious persecutors, and, as it were, showed Himself as their Physician at His Advent (for physicians also, better both in art and health, serve the sick): how much more ought not a man to disdain, with his whole mind, and his whole good will, with his whole love to serve even a bad master! Behold, a better serveth an inferior, but for a season. Understand what I have said of the master and slave, to be true also of powers and kings, of all the exalted stations of this world. For sometimes they are good powers, and fear God; sometimes they fear not God. Julian was an infidel Emperor, an apostate, a wicked man, an idolater; Christian soldiers served an infidel Emperor; when they came to the cause of Christ, they acknowledged Him only who was in heaven. If he called upon them at any time to worship idols, to offer incense; they preferred God to him: but whenever he commanded them to deploy into line, to march against this or that nation, they at once obeyed. They distinguished their everlasting from their temporal master; and yet they were, for the sake of their everlasting Master, submissive to their temporal master.
8. But will it be thus always, that the ungodly have power over the righteous? It will not be so. The rod of the ungodly is felt for a season upon the lot of the righteous; but it is not left there, it will not be there for ever. A time will come, when Christ, appearing in his glory, shall gather all nations before Him.  And thou wilt see there many slaves among the sheep, and many masters among the goats; and again many masters among the sheep, many slaves among the goats. For all slaves are not good—do not infer this from the consolation we have given to servants—nor are all masters evil, because we have thus repressed the pride of masters. There are good masters who believe, and there are evil: there are good servants who believe, and there are evil. But as long as good servants serve evil masters, let them endure for a season. "For God will not leave the rod of the ungodly upon the lot of the righteous." Why will He not? "Lest the righteous put forth their hand unto wickedness:" that the righteous may endure for a season the domination of the ungodly, and may understand that this is not for ever, but may prepare themselves to possess their everlasting heritage....
9. And he therefore addeth, "Do well, O Lord, unto those that are good and true of heart" (ver.4). They who are right in heart, of whom I was speaking a little before,—they who follow the will of God, not their own will,—reflect upon this. But they who wish to follow God, allow Him to go before, and themselves to follow; not themselves to go before, and Him to follow; and in all things they find Him good, whether chastening, or consoling, or exercising, or crowning, or cleansing, or enlightening; as the Apostle saith, "We know that all things work together for good to them that love God." 
10. Whence the Psalmist at once addeth: "As for such as turn aside, the Lord shall lead them forth unto strangling with the workers of unrighteousness" (ver.5): that is, those whose deeds they have imitated; because they took delight in their present pleasures, and did not believe in their punishments to come. What then shall they have, who are righteous in heart, and who turn not back? Let us now come to the heritage itself, brethren, for we are sons. What shall we possess? What is our heritage? what is our country: what is it called? Peace. In this we salute you, this we announce to you, this the mountains receive, and the little hills receive as righteousness.  Peace is Christ: "for He is our peace, who hath made both one, and hath broken down the middle wall of partition between us."  Since we are sons, we shall have an inheritance. And what shall this inheritance be called, but peace? And consider that they who love not peace are disinherited. Now they who divide unity, love not peace. Peace is the possession of the pious, the possession of heirs. And who are heirs? Sons....Since then Christ the Son of God is peace, He therefore came to gather together His own, and to separate them from the wicked. From what wicked men? From those who hate Jerusalem, who hate peace, who wish to tear unity asunder, who believe not peace, who preach a false peace to the people, and have it not. To whom answer is made, when they say,  "Peace be with you," "And with thy spirit:" but they speak falsely, and they hear falsely. Unto whom do they say, Peace be with you? To those whom they separate from the peace of the whole earth. And unto whom is it said, "And with thy spirit"? To those who embrace dissensions, and who hate peace. For if peace were in their spirit, would they not love unity, and leave dissensions? Speaking then false words, they hear false words. Let us speak true words, and hear true words. Let us be Israel, and let us embrace peace; for Jerusalem is a vision of peace, and we are Israel, "and peace is upon Israel."
 Lat. CXXIV. A discourse to the people.  John 19:17, 18.  Psalm 121:1, 2.  [Observe in our author passim this implication that the laity as well as the clergy were filled with the knowledge and comfort of the Scriptures.--C.]  Psalm 76:4.  [Evidence against saint-worship.--C.]  [So Jude 16..--C.] Vinc. Lir. Common. 17-20.  [Evidence against saint-worship.--C.]  Psalm 36:6.  Philip. iii. 9.  Romans 10:3.  1 Corinthians 1:13.  1 Corinthians 3:6.  [The Epistle to Philemon is here reflected. See A.N.F. vol. viii. p. 782, note 1, and p. 784; also vol. vii. p. 425.--C.]  Ephesians 6:5.  Matthew 25:32, 33.  Romans 8:28.  Psalm 72:3.  Ephesians 2:14.  [In the Liturgy.--C.]
 John 19:17, 18.
 Psalm 121:1, 2.
 [Observe in our author passim this implication that the laity as well as the clergy were filled with the knowledge and comfort of the Scriptures.--C.]
 Psalm 76:4.
 [Evidence against saint-worship.--C.]
 [So Jude 16..--C.] Vinc. Lir. Common. 17-20.
 [Evidence against saint-worship.--C.]
 Psalm 36:6.
 Philip. iii. 9.
 Romans 10:3.
 1 Corinthians 1:13.
 1 Corinthians 3:6.
 [The Epistle to Philemon is here reflected. See A.N.F. vol. viii. p. 782, note 1, and p. 784; also vol. vii. p. 425.--C.]
 Ephesians 6:5.
 Matthew 25:32, 33.
 Romans 8:28.
 Psalm 72:3.
 Ephesians 2:14.
 [In the Liturgy.--C.]