The interpretation timeline
Isaiah 48:18 Douay-Rheims

O that thou hadst hearkened to my commandments: thy peace had been as a river, and thy justice as the waves of the sea,

A.D. 397 – 1871 5 witnesses 6 excerpts

Patristic

before A.D. 750
397
A.D.
Ambrose of Milan Patristic
A.D. 339–397
“Set before yourself any river. It springs from its fountain but is of one nature, of one brightness and beauty. And you assert rightly that the Holy Spirit is of one substance, brightness and glory with the Son of God and with God the Father. I will sum up everything in the oneness of the qualities without any dispute over degrees of greatness. For in this point also Scripture has provided for us. For the Son of God says, "Whoever shall drink of the water that I will give him, it shall become in him a well of water springing up unto everlasting life." This well is clearly the grace of the Spirit, a stream proceeding from the living Fountain. The Holy Spirit, then, is also the fountain of eternal life.You observe, then, from his words that the unity of the divine greatness is pointed out and that Christ cannot be denied to be a fountain even by heretics, since the Spirit, too, is called a fountain. The Spirit is called a river, too, just as the Father said, "Behold, I come down on you like a river of peace, and like a stream overflowing the glory of the Gentiles." And who can doubt that the Son of God is the river of life from whom the streams of eternal life flowed forth?”
Source
“This water is good, then. I mean here the grace of the Spirit. Who will give this Fountain to my heart? Let it spring up in me, let that which gives eternal life flow on me. Let that Fountain overflow on us and not flow away. For Wisdom says, "Drink water out of your own vessels and from the fountains of your own wells, and let your waters flow abroad in your streets." How shall I keep this water so that it does not seep out or glide away? How shall I preserve my vessel, lest any crack of sin penetrating it should let the water of eternal life exude? Teach us, Lord Jesus, teach us as you taught your apostles, saying, "Lay not up for yourselves treasures on the earth, where rust and moth destroy and where thieves break through and steal."8Our rust is wantonness, our rust is lust, our rust is luxury, which dim the keen vision of the mind with the filth of vices. Again, our moth is Arius, our moth is Photinus, who rend the holy vesture of the church with their impiety, and desiring to separate the indivisible unity of the divine power, gnaw the precious veil of faith with sacrilegious tooth. The water is spillled if Arius has imprinted his tooth, it flows away if Photinus has planted his sting in anyone's vessel.… If you seek Jesus, forsake the broken cisterns, for Christ did not make it his custom to sit by a pool but by a well. There that Samaritan woman found him, she who believed, she who wished to draw water. Although you ought to have come in early morning, nevertheless if you come later, even at the sixth hour, you will find Jesus wearied with his journey. He is weary, but it is because of you, because he has long looked for you, your unbelief has long wearied him. Yet he is not offended if you only come now. He asks to drink who is about to give. But he drinks not the water of a stream flowing by, but your salvation. He drinks your good dispositions. He drinks the cup, that is, the passion that atoned for your sins, that you, drinking of his sacred blood, might quench the thirst of this world.”
Source

Scholastic

c. 1100 – 1500
1167
A.D.
Ibn Ezra Jewish
1089–1167
לוא Oh that. The א is paragogic; comp. ההלכוא that went (Jos. 10:24). ויהי Then had been. The ו has here the same meaning as فَ in Arabic. Thy peace had been as a river, that does not cease to flow. And thy righteousness, etc. And thy righteousness had been continuous as the waves of the sea.”
1256
A.D.
Thomas Aquinas Catholic
1225–1274
“Hear this, O house of Jacob, etc. Here he promises the liberation of the people. And it is divided into two parts. In the first he promises the liberation; in the second he carries out the order of the liberation, below, chapter 49: Hear, O islands, etc. The first is divided into two. In the first he arouses attention, calling to mind three things in which they gloried: namely, the dignity of their lineage, because they were from holy fathers: "of the waters," that is, of the seed. Against which, Matthew 3: "Do not think to say," etc.; the privilege of the knowledge of God: "who swear" — calling upon his name — "and remember" — as to the knowledge of him — "in truth," of heart, "nor in justice," of work. Above, chapter 29: "This people, with their lips, me," etc.; the worship of sacred religion: "from the city" — namely Jerusalem, in which was the worship of sacrifices — "they are called" — men of Jerusalem — 2 Maccabees 5: "not for the sake of the place, the nation," etc. Secondly he promises the liberation: "the former things, from that time," and concerning this he does three things. First he shows the majesty of God who promises; secondly, the prosperity of Cyrus who carries it out: "Assemble yourselves, all of you," etc.; thirdly he promises the liberation: "Come near to me," etc. Concerning the first, two things. First he shows the majesty of God from the foretelling of future things; secondly from the creation of things: "Hearken to me, Jacob," etc. Concerning the first, three things. First he assigns the reason for the foretelling of certain future things, setting down the foretelling itself: "the former things" — namely those which have already passed — "from that time," when they were still future, "suddenly," as regards others to whom they were not foretold. Ecclesiasticus 42: "declaring the things that have passed," etc.; setting down also the reason for this, which is taken from their condition — which he first states, "for I knew," from eternity. "That thou art hard" — hard to come to one's senses from evils; "thy neck" — that is, the stiffness of one's own judgment; "a sinew of iron," which cannot be bent; "thy forehead" — on account of shamelessness. Acts 5: "stiff-necked," etc.; Deuteronomy 31: "I know the contention," etc.; Jeremiah 3: "the forehead of a harlot," etc.; and then from this he draws out the reason, "I foretold," etc., as if to say: because thou wert prone to idolatry, I foretold it to thee, lest thou shouldst ascribe my benefits to idols. Hosea 2: "I will go after lovers," etc.; setting down also the manifestation of the things foretold: "which thou hast heard" — foretold to thee by me — "behold," fulfilled. Psalm 47: "As we have heard, so have we seen," etc. Secondly he assigns the reason for the concealment of certain future things, setting down first the concealment itself. As has been said, certain future things I foretold to thee; but certain future things have been kept in my foreknowledge, which thou dost not know, because I have not revealed them to thee. "Now" — that is, in time — "they are created," that is, brought forth in effect, and not from that time when I foreknew them; and "before the day" of their fulfillment, "thou hast not heard" of them, neither from me nor from the idols. 4 Kings 4: "the Lord hath hid it from me," etc. He also assigns the reason for this: "lest perhaps," as if to say: I did not reveal it for this reason, that thou mightest perceive thy own defect, and that of thy gods, in that thou canst not foreknow future things except those which I reveal to thee. "I have known" — by my own effort — "nor hast thou heard" — from the idols — the things opened by me. Psalm 63: "Man shall come to a deep heart," etc. He also sets down their condition, from which the aforesaid reason is drawn: "for I know." "From the womb" — that is, from the time when I carried thee through the desert as in a womb. Exodus 32: "I see that this people," etc.; above, chapter 24: "by the transgression of the transgressors," etc. Thirdly he excludes a certain objection: "for my name's sake." For someone could ask: since they are so hard, why then dost thou promise them good things, and hast done so? And to this objection he first sets down the response, recalling three benefits shown to them: "for my name's sake" — not on account of thy merit — "I will put far off," or have put far off, freeing them from punishments. Ezekiel 36: "Not for your sakes will I do this," etc., and "for my praise" — that is, I bound thee to my ceremonies and my praises, lest, offering sacrifices to idols, thou shouldst perish. Psalm 31: "with bit and bridle," etc. "I have refined," wishing to purge thee through tribulations, "but not as silver," which is purged. But thou hast not been corrected. Jeremiah 6: "in vain hath he melted," etc. "I have chosen," purging thee, namely, through poverty, punishing thee by the spoiling of goods. Gregory: "those whom the infirmity of their conduct wounds, the medicine of poverty heals." And this by correcting as a father. Secondly he sets down the exposition of the response: "for my own sake" — that I not be blasphemed, as though powerless to save the people whom I have chosen for myself; and "my glory" — namely, that the idols be judged stronger than I. Above, chapter 42: "my glory," etc. Hearken to me. Here he shows the divine majesty from the creation of things. "I will call," imposing upon each thing its proper work: "they shall stand," ready to obey. Above, chapter 40: "who hath weighed with three fingers," etc. Assemble yourselves, etc. Here he foretells the prosperity of Cyrus himself; and first he shows the concealment of this deed from others: "who among them?" — namely, among the idols — as if to say: none. Above, chapter 41: "who hath declared from the beginning," etc. Secondly he himself foretells his prosperity: "the Lord hath loved him" — namely Cyrus — advancing him into the kingdom; "in Babylon," capturing it; "his arm" — that is, by his own power slaying them. 1 Kings 27: "and indeed doing," etc. Thirdly he assigns the reason for his prosperity from divine aid: "I, I," etc.; "directed," not absolutely, but to this end, that he might destroy Babylon; otherwise it could not be expounded of Cyrus, but only of Christ, as Jerome says, because he was an idolater. Psalm 106: "he led them into the way," etc. Come near to me, etc. Here he promises liberation; and concerning this he does three things. First he arouses attention, setting down the divine authority: "in secret" — yet all the people saw the voices: Exodus 20. "From the beginning" — of the law given. "From the time," past, before they came to pass — the things which I foretell — "there I was," present to those future things, remaining, through the same "now" of eternity, throughout the whole succession of time. Or in the person of the Son, "there I was" — namely, in the Father according to his divinity — Proverbs 8: "when he weighed the foundations," etc.; setting down the truth of the prophet — who was sent by God — "and now, me": Isaiah, or me, Christ made man; "God," the Father; whence the three Persons are designated. Below, chapter 61: "the spirit of the Lord is upon me," etc. Secondly, there, "thus saith the Lord," he sets down the reason for the captivity, showing on God's part the help that was prepared. "Teaching" — against ignorance — and "governing in the way," of works, against weakness in acting. Psalm 31: "I will give thee understanding, and I will instruct," etc.; showing also the harm arising from the fault of the Jews. "O that thou hadst hearkened" — keeping them — "as an abundant river," "as the waves." The same, Psalm 80: "if my people had heard," etc. Thirdly, there, "go forth," he foretells the liberation; and concerning this he does three things. First he announces to them the departure from captivity, as certain of the liberation as if it were already present. "Go ye forth," etc.; Apocalypse 18: "go out from her," etc.; and he charges them to announce the benefit of God. "Declare ye," etc.; Jeremiah 50: "the voice of them that flee, and of them that have escaped," etc. Secondly he designates the benefit of consolation bestowed on those freed: "they thirsted not" — that is, the Lord will provide for them in all things just as when they went out from Egypt. Psalm 77: "he struck the rock, and they flowed," etc.; Numbers 21. Thirdly he takes away from the wicked the solace of peace: "there is no peace," below, chapter 57; 4 Kings 9: "what hast thou to do with peace," etc. (Collations, chapter 48) Poverty confers: the recognition of sins: "if they shall be bound," etc.; the preservation of virtues, Ecclesiasticus 10: "the poor man glorieth," etc.; quiet of heart, Tobit 5: "it was enough for us," etc.; the fulfillment of desire, Psalm: "the desire of the poor," etc.; participation in the divine sweetness, Psalm: "thou hast prepared in sweetness," etc.; exaltation, 1 Kings 2: "raising up from the dust," etc.; the heavenly inheritance, Matthew 5: "blessed are the poor," etc. The words of God are useful: for the illumination of the understanding, Proverbs 6: "the commandment is a lamp," etc.; for the delight of the affections, Psalm: "how sweet to the jaws," etc.; for the kindling of love, Jeremiah 20: "it came to be in the heart," etc.; Psalm: "the word of the Lord"; for the rightness of work, Psalm: "direct me in truth," etc.; for the attainment of glory, Proverbs 3: "keep the law"; for the instruction of others, 2 Timothy 3: "all doctrine divinely," etc.”

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“O that thou hadst hearkened to my commandments,.... Which the Jews did not, but slighted and despised them, and were not obedient to them. So, in the times of Christ, they disregarded his doctrines, though so profitable; and despised his ordinances and commands, which were not grievous; they neither hearkened to them themselves, nor would suffer others; wherefore our Lord expresses his great concern at it, and his desire, as man, after their welfare; see Mat 23:13, then had thy peace been as a river: their prosperity, temporal and spiritual, had been abundant, and would have always continued, have been increasing and ever flowing, yea, overflowing, like the waters of a river. The Targum is, the river Euphrates, a river which ran through Babylon: but they had no regard to the things which related to their temporal, spiritual, and eternal peace, these were hid from their eyes, Luk 19:42, and thy righteousness as the waves of the sea: large, abundant, numerous as the waves of the sea; which may regard acts of justice and righteousness, which are the support of a people and state, and blessings the fruit thereof; and which God of his goodness bestows on such a people, as all kind of prosperity, protection, safety, and continuance.”
Source
1871
A.D.
1871
“peace-- (Psa 119:165). Compare the desire expressed by the same Messiah (Mat 23:37; Luk 19:42). river-- (Isa 33:21; Isa 41:18), a river flowing from God's throne is the symbol of free, abundant, and ever flowing blessings from Him (Eze 47:1; Zac 14:8; Rev 22:1). righteousness--religious prosperity; the parent of "peace" or national prosperity; therefore "peace" corresponds to "righteousness" in the parallelism (Isa 32:17).”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.