St. Augustin on the Psalms.
1. ...We are not Christians, except on account of a future life: let no one hope for present blessings, let no one promise himself the happiness of the world, because he is a Christian: but let him use the happiness he hath, as he may, in what manner he may, when he may, as far as he may. When it is present, let him give thanks for the consolation of God: when it is wanting, let him give thanks to the Divine justice. Let him always be grateful, never ungrateful: let him be grateful to his Father, who soothes and caresses him: and grateful to his Father when He chasteneth him with the scourge, and teacheth him: for He ever loveth, whether He caress or threaten: and let him say what ye have heard in the Psalm: "It is a good thing to give thanks unto the Lord; and to sing praises unto Thy Name, Thou Most Highest" (ver.1).
2. This Psalm is entitled, a Psalm to be sung on the Sabbath day. Lo, this day is the Sabbath, which the Jews at this period observe by a kind of bodily rest, languid and luxurious. They abstain from labours, and give themselves up to trifles; and though God ordained the Sabbath, they spend it in actions which God forbids. Our rest is from evil works, theirs from good; for it is better to plough than to dance. They abstain from good, but not from trifling, works. God proclaims to us a Sabbath. What sort of Sabbath? First consider, where it is. It is in the heart, within us; for many are idle with their limbs, while they are disturbed in conscience....That very joy in the tranquillity of our hope, is our Sabbath. This is the subject of praise and of song in this Psalm, how a Christian man is in the Sabbath of his own heart, that is, in the quiet, tranquillity, and serenity of his conscience, undisturbed; hence he tells us here, whence men are wont to be disturbed, and he teaches thee to keep Sabbath in thine own heart.
3. ...Accuse thyself, and thou receivest indulgence. Besides, many do not accuse Satan but their fate. My fate led me, saith one when you ask him, why did you do it? why did you sin? he replies, by my evil fate. Lest he should say, I did it; he points to God as the source of his sin: with his tongue he blasphemes. He saith not this indeed openly as yet, but listen, and see that he saith this. You ask of him, what is fate: and he replies, evil stars. You ask, who made, who appointed the stars; he can only answer, God. It follows, then, that whether he doth so directly or indirectly,  still he accuseth God, and when God punisheth sins, he maketh God the author of his own sins. It cannot be that God punishes what He hath wrought: He punisheth what thou doest, that He may set free what He hath wrought. But sometimes, setting aside everything else, they attack God directly: and when they sin, they say, God willed this; if God had not willed it, I should not have sinned. Does He warn thee for this, that not only He may not be listened to, to keep thee from sin, but even be accused because thou dost sin? What then doth this Psalm teach us? "It is a good thing to confess  unto the Lord." What is to confess unto the Lord? In both cases: both in thy sins, because thou hast done them; and in thy good works, confess unto the Lord, because He hath done them. Then shalt thou "sing unto the Name of God, the Most Highest:" seeking the glory of God, not thine own; His Name, not thine. For if thou seekest the Name of God, He also seeketh thy name; but if thou hast neglected the Name of God, He also doth blot out thine....
4. "To tell of Thy mercy early in the morning, and of Thy truth in the night season" (ver.2). What is the meaning of this; that the mercy of God is to be told us in the morning, and in the night the truth of God? The morning is, when it is well with us; the night, the sadness of tribulation. What then did he say in brief? When thou art prosperous, rejoice in God, for it is His mercy. Now, perhaps thou wouldest say, If I rejoice in God, when I am prosperous, because it is His mercy; what am I to do when I am in sorrow, in tribulation? It is His mercy, when I am prosperous; is it then His cruelty, when I am in adversity? If I praise His mercy when it is well with me, am I then to exclaim against His cruelty when it is ill? No. But when it is well, praise His mercy: when ill, praise His truth: because He scourgeth sins, He is not unjust....During the night Daniel confessed the truth of God: he said in his prayer, "We have sinned, and committed iniquity, and have done wickedly. O Lord, righteousness belongeth unto Thee: but unto us confusion of face."  He told of the truth of God during the night-season. What is it to tell of the truth of God in the night-season? Not to accuse God, because thou sufferest aught of evil: but to attribute it to thy sins, His correction: to tell of His loving-kindness early in the morning, and of His truth in the night-season. When thou doest this, thou dost always praise God, always confess to God, and sing unto His Name.
5. "Upon a psaltery of ten strings, with a song, and upon the harp" (ver.3). Ye have not heard of the psaltery of ten strings for the first time: it signifies the ten commandments of the Law. But we must sing upon that psaltery, and not carry it only. For even the Jews have the Law: but they carry it: they sing not...."And upon the harp." This means, in word and deed; "with a song," in word; "upon the harp," in work. If thou speakest words alone, thou hast, as it were, the song only, and not the harp: if thou workest, and speakest not, thou hast the harp only. On this account both speak well and do well, if thou wouldest have the song together with the harp.
6. "For Thou, Lord, hast made me glad through Thy works; and I will rejoice in giving praise for the operations of Thy hands" (ver.4). Ye see what he saith. Thou hast made me living well, Thou hast formed me: if by chance I do aught of good, I will rejoice in the work of Thy hands: as the Apostle saith, "For we are His workmanship, created unto good works."  For unless He formed thee to good works, thou wouldest not know any works but evil....Because thou canst not have truth from thy own self, it remains that thou drink it thence, whence it floweth: as if thou hast gone back from the light, thou art in darkness: as a stone glows not with its own heat, but either from the sun or fire, and if thou withdraw it from the heat, it cools: there it appears, that the heat was not its own; for it became heated either by the sun or by fire: thus thou also, if thou withdraw from God, wilt become cold; if thou approach God, thou wilt warm: as the Apostle saith "fervent in spirit."  Also what saith he of the light? If thou approach Him, thou wilt be in light; therefore saith the Psalm, "Look upon Him, and be lightened; and your faces shall not be ashamed."  Because therefore thou canst do no good, unless lightened by the light of God, and warmed by the spirit of God; when thou shalt see thyself working well, confess unto God, and say what the Apostle saith; say unto thyself, that thou be not puffed up, "For what hast thou that thou didst not receive?"  ...
7. That wretched man who doeth good, and suffereth evils, seeth him, becometh disturbed, and saith, O God, the wicked, I imagine, please Thee, and Thou hatest the good, and lovest those who work iniquity....The Sabbath being now lost in the inner man, and the tranquillity of his heart being shut out, and good thoughts repelled, he now beginneth to imitate him whom he seeth flourishing amid his evil deeds; and turneth himself also to evil works. But God is long-suffering, because He is eternal,  and he knoweth the day of His own judgment, where He weigheth all things.
8. Teaching us this, what saith he? "O Lord, how glorious are Thy works: Thy thoughts are made very deep" (ver.5). Verily, my brethren, there is no sea so deep as these thoughts of God, who maketh the wicked flourish, and the good suffer: nothing so profound, nothing so deep: therein every unbelieving soul is wrecked, in that depth, in that profundity. Dost thou wish to cross this depth? Remove not from the wood of Christ's Cross: thou shalt not sink: hold thyself fast to Christ. What do I mean by this, hold fast to Christ? It was for this reason that He chose to suffer on earth Himself. Ye have heard, while the prophet was being read, how He "did not turn away His back from the smiters, and His face from the spittings of men," how "He turned not His cheek from their hands;"  wherefore chose He to suffer all these things, but that He might console the suffering? He could have raised His flesh at the last day: but then thou wouldest not have had thy ground of hope, since thou hadst not seen Him. He deferred not His resurrection, that thou mightest not still be in doubt. Suffer then tribulation in the world with the same end as that which thou hast observed in Christ: and let not those who do evil, and flourish in this life, move thee. "Thy thoughts are very deep." Where is the thought of God? Rejoice not as the fish who is exulting in his bait: the fisherman hath not drawn his hook: the fish hath as yet the hook in his jaws. And what seemeth to thee long, is short; all these things pass over quickly. What is the long life of man to the eternity of God? Dost thou wish to be of long-suffering? Consider the eternity of God. For thou regardest thy few days, and in thy few days thou dost wish all things to be fulfilled. What things? The condemnation of all the wicked: and the crowning of all the good: dost thou wish these things to be fulfilled in thy days? God fulfilleth them in His own time. Why dost thou suffer weariness? He is eternal: He waiteth: He is of long-suffering: but thou sayest, I am not of long-suffering, because I am mortal. But thou hast it in thy power to become so: join thy heart to the eternity of God, and with Him thou shalt be eternal....
9. For this reason, after saying, "Thy thoughts are very deep," he at once subjoins: "An unwise man doth not well consider this, and a fool doth not understand it" (ver.6). What are the things which an unwise man doth not well consider, and which a fool doth not understand? "When the ungodly are green as the grass." What is, "as the grass"? They flourish when it is winter, but they will wither in the summer. Thou observest the flower of the grass? What more quickly passeth by? What is brighter? What is greener? Let not its verdure delight thee, but fear its withering. Thou hast heard of the ungodly being green as the grass: hear also of the righteous: "For lo." In the mean while, consider the ungodly; they flourish as the grass; but who are they who understand it not? The foolish and unwise. "When the ungodly are green as the grass, and all men look upon the workers of iniquity" (ver.7). All who in their heart think not aright of God, look upon the ungodly when they are as green as grass, that is, when they flourish for a time. Why do they look upon them? "That they may be destroyed for ever." For they regard their momentary bloom, they imitate them, and wishing to flourish with them for a time, perish for evermore: this is, "That they may be destroyed for ever."
10. "But Thou, Lord, art the Most Highest for evermore" (ver.8). Waiting above in Thy eternity until the season of the wicked be past, and that of the just come. "For lo." Listen, brethren. Already he who speaketh (for he speaketh in our person, in the person of Christ's body, for Christ speaketh in His own body, that is, in His Church), hath joined himself unto the eternity of God: as I a little before was saying unto you, God is long-suffering and patient, and alloweth all those evil deeds which He seeth to be done by wicked men. Wherefore? because He is eternal, and seeth what He keepeth for them. Dost thou also wish to be long-suffering and patient? Join thyself to the eternity of God: together with Him wait for those things which are beneath thee: for when thy heart shall have cleaved unto the Most Highest, all mortal things will be beneath thee: say then what follows, "For lo, thine enemies shall perish." Those who now flourish, shall afterwards perish. Who are the enemies of God? Brethren, perhaps ye think those only enemies of God who blaspheme? They indeed are so, and those wicked men who neither in tongue nor in thought cease to injure God. And what do they do to the eternal, most high God? If thou strike with thy fist upon a pillar, thou art hurt: and thinkest thou that where thou strikest God with thy blasphemy, thou art not thyself broken? for thou doest nothing to God. But the enemies of God are openly blasphemers, and daily they are found hidden. Beware of such enmities of God. For the Scripture revealeth some such secret enemies of God: that because thou knowest them not in thy heart, thou mayest know in God's Scriptures, and beware of being found with them. James saith openly in his Epistle, "Know ye not that the friendship of the world is enmity with God?"  Thou hast heard. Dost thou wish not to be an enemy of God? Be not a friend of this world: for if thou art a friend of this world, thou wilt be an enemy of God. For as a wife cannot be an adulteress, unless she be an enemy to her own husband: so a soul which is an adulteress through its love of worldly things, cannot but be an enemy to God. It feareth, but loveth not: it feareth punishment but is not delighted with righteousness. All lovers of the world, therefore, are enemies of God, all the curious after trifles, all consulters of diviners astrologers, and evil spirits. Let them enter, or not enter, Churches: they are enemies of God. They may flourish for a season like grass, but they will perish, when He beginneth to visit them, and pronounce His sentence upon all flesh. Join thyself to the Scripture of God, and say with this Psalm, "For lo, thine enemies shall perish" (ver.9). Be not found there, where they shall perish. "And all the workers of iniquity shall be destroyed."
11. ..."But mine horn shall be exalted like the horn of an unicorn" (ver.10). Why did He say, "like the horn of an unicorn"? Sometimes an unicorn signifies pride, sometimes it means the lifting up of unity; because unity is lifted up, all heresies shall perish with the enemies of God. And "mine horn shall be exalted like an unicorn." When will it be so? "And mine old age shall be in the fatness of mercy."  Why did he say, "my old age"? He means, my last days; as our old age is the last season in our lives, so the whole of what the body of Christ at present suffereth in labours, in cares, in watchings, in hunger, in thirst, in stumbling-blocks, in wickednesses, in tribulations, is its youth: its old age, that is, its last days, will be in joy. And beware, beloved, that ye think not death meant also, in that he hath spoken of old age: for man groweth old in the flesh for this reason, that he may die. The old age of the Church will be white with good works, but it shall not decay through death. What the head of the old man is, that our works will be. Ye see how the head groweth old, and whiteneth, as fast as old age approacheth. Thou sometimes dost seek in the head of one who groweth old duly in his own course a black hair, yet thou findest it not: thus when our life shall have been such, that the blackness of sins may be sought, and none found, that old age is youthful, is green, and ever will be green. Ye have heard of the grass of sinners, hear ye of the old age of the righteous: "My old age shall be in the fathers of mercy."
12. "And Mine eye hath beheld on mine enemies" (ver.11). Whom doth he call his enemies? All the workers of iniquity. Do not observe whether thy friend be wicked: let an occasion come, and then thou provest him. Thou beginnest to go contrary to his iniquity, and then thou shalt see that when he was flattering thee, he was thy enemy; but thou hadst not yet knocked, not to raise in his heart what was not there, but that what was there might break out. "Mine eye also hath looked upon mine enemies: and mine ear shall hear his desire of the wicked that rise up against me." When? In my old age. What is, in old age? In the last times. And what shall our ear hear? Standing on the right hand, we shall hear what shall be said to them that are on the left. 
13. The grass withereth, the flower of sinners dieth away: what of the righteous? "The righteous shall flourish like a palm tree" (ver.12). The ungodly are green as grass; "The righteous shall flourish like a palm tree." By the palm tree he signifieth height. Possibly he had also this meaning in the palm, that in its extremities it is beautiful: so that thou mayest trace its beginning from the earth, its end in its topmost branches, wherein its whole beauty dwelleth. The rough root appeareth in the earth, the beautiful foliage toward the sky. Thy beauty too, then, shall be in the end. Thy root is fixed fast: but our root is upward. For our root is Christ, who hath ascended into heaven. Humbled, he shall be exalted; "he shall spread abroad like a cedar in Libanus." See what trees he spoke of: the righteous shall flourish like a palm-tree: and shall spread abroad like a cedar in Libanus. When the sun hath gone forth, doth the palm-tree wither? Doth the cedar die? But when the sun hath been glowing for some hours, the grass drieth up. The judgment, therefore, shall come, that sinners may wither, and the faithful flourish.
14. "Such as are planted in the house of the Lord, shall flourish in the courts of the house of our God" (ver.12). "They shall be yet more increased in fruitful old age, and shall be quiet, that they may show it forth" (ver.13). Such is the Sabbath, which but a little while ago I commended unto you, whence the Psalm hath its title. "They shall be quiet, that they may show it forth." Wherefore are they quiet that show it forth? The grass of sinners moveth them not: the cedar and palm-tree not even in tempests are bent. They are therefore quiet, that they may show it forth: and with reason, since at present they must show it forth even unto men who mock at it. O wretched men, who are lovers of the world! Those who are planted in the house of the Lord, show it to you: those who praise the Lord with song and lute, in word and deed, show it forth to you, and tell you. Be not seduced by the prosperity of the wicked, admire not the flower of grass: admire not those who are happy only for a season, but miserable unto eternity....If ye wish to flourish like a palm-tree, and to spread abroad like a cedar in Libanus, and not to wither like grass when the sun is hot; as those who appear to flourish when the sun is absent. If then ye wish not to be as grass, but as the palm-tree and the cedar, what will ye show forth? "How true the Lord my strength is: and that there is no unrighteousness in Him." How is it there is no unrighteousness? A man committeth so great crimes; he is well, he hath sons, a plentiful house, he is full of pride, is exalted by his honours, is revenged on his enemies, and doeth every evil deed; another man, innocent, attending to his own affairs, not robbing another's goods, doing nothing against any one, suffereth in chains, in prison, tosseth and sigheth in poverty. How is it that there is no unrighteousness in Him? Be quiet, and thou shalt know: for thou art disturbed, and in thy chamber thou dost darken thy light. The eternal God doth wish to shine upon thee: do not then make thee cloudy weather from thy own disturbed mind. Be quiet within thyself, and see what I say unto thee. Because God is eternal, because for the present He spareth the bad, bringing them to repentance: He scourgeth the good, instructing them in the way unto the kingdom of heaven: "There is no unrighteousness in Him:" fear not....What, if He leaveth this man unpunished now, because he is doomed to hear, "Depart into everlasting fire." But when? when thou shalt be placed at the right hand, then shall it be said to those placed on the left, "Depart into the everlasting fire, which is prepared for the devil and his angels." Let not therefore those things move thee: Be quiet, keep Sabbath, and show "how true the Lord my strength is: and that there is no unrighteousness in Him."
 Lat. XCI. A sermon to the people, preached on Saturday.  Sive per transennam sive per cannam longam, sive per proximum.  Confiteri.  Daniel 9:5, 7.  Ephesians 2:10.  Romans 12:11.  Psalm 34:5, Bible Version.  1 Corinthians 4:7.  [Deus autem patiens est quia æternus est. One of those felicitous maxims in which our author abounds.--C.]  Isaiah 50:6.  James 4:4.  So LXX.  [The words "my desire" are not in the Hebrew: what the Hebrew implies is the patient expectation of a just judgment, by which truth shall at last be vindicated. See Revelation 6:10.--C.]
 Sive per transennam sive per cannam longam, sive per proximum.
 Daniel 9:5, 7.
 Ephesians 2:10.
 Romans 12:11.
 Psalm 34:5, Bible Version.
 1 Corinthians 4:7.
 [Deus autem patiens est quia æternus est. One of those felicitous maxims in which our author abounds.--C.]
 Isaiah 50:6.
 James 4:4.
 So LXX.
 [The words "my desire" are not in the Hebrew: what the Hebrew implies is the patient expectation of a just judgment, by which truth shall at last be vindicated. See Revelation 6:10.--C.]