18 In that day shall five cities in the land of Egypt speak the language of Canaan, and swear to the LORD of hosts; one shall be called, The city of destruction.
[AD 420] Jerome on Isaiah 19:18
(Verse 18.) On that day there shall be five cities in the land of Egypt that speak the language of Canaan and swear by the Lord of hosts. One of these cities shall be called the city of the sun. Concerning the city of the sun, the LXX translated 'asedec,' not knowing exactly what it meant. Some of our people interpret it as the city of justice, and due to a mistake, they think that it is written in Hebrew as 'Ares,' which means 'land' in other letters. Symmachus translated it better as 'the city of the sun shall be called one,' for 'Ares' is an ambiguous word and is used for both 'clay pot' and 'sun,' because both dry and heat. Not understanding this place, Onias built a temple in Egypt in the city of Heliopolis. Read Josephus' Histories (Joseph. lib. XII, cap. 9). Others want Ares, that is, a shell, that is, a testa, to be understood as the city of Ostracinem, and other cities near Rhinocorura and Casium, which until today it is evident that they speak in Egypt in the Canaanite language, that is, Syrian. And they think that the Syrians and Arabs came from neighboring places to that land under Nabuchodonosor's rule. Moreover, those who speak of the coming of Christ and the Roman empire prophecy, understand either the five cities or the law of the Lord, which was first interpreted in Alexandria, or the five orders of the Church, bishops, presbyters, deacons, believers, catechumens: or certainly the spiritual understanding of the law, of which the Apostle also says: I want to speak five words in the Churches in my understanding, rather than ten thousand words in a tongue (1 Cor. XIV): and that the one city of the five cities is called the city of the sun, namely justice, in whose wings there is healing.

[AD 420] Jerome on Isaiah 19:18
(Verse 18.) On that day there will be five cities in the land of Egypt speaking the language of Canaan and swearing by the Lord of hosts. One city shall be called the City of the Sun. The raised and shaking hand of the Lord over Egypt greatly benefits, so that the land of Judah may be in fear of Him, and everyone who remembers Him may tremble. At that time, five cities in the land of Egypt will speak the language of Canaan, which our five senses understand: sight, hearing, smell, taste, and touch. When we see a woman to be desired, our sight speaks in the Egyptian language. When we hear a judgment of blood, with the Lord saying: You shall not entertain a vain hearing (4 Kings 12:21, according to the Septuagint), our hearing speaks in the Egyptian language. When we live in luxury according to the prophet, and lie on ivory beds, and anoint ourselves with the best ointments, our sense of smell speaks in the Egyptian language. When our God is present (Philippians III), our taste speaks the Egyptian language. If we do not hear what the Apostle says: It is good for a man not to touch a woman (I Corinthians VII); but on the contrary, let us join with the harlot, our touch speaks the Egyptian language. But if, on the contrary, we lift up our eyes and see that the fields are already white for harvesting, and we have not bowed down to the ground, but according to the Gospel, with a woman who for eighteen years could not look up to heaven (Luke XIII), we lift up our eyes and say, To you I lift up my eyes, who dwell in heaven (Psalm CXXII, 1), our eye and sight speak the Canaanite language. If we cut off our ears and hear the Lord speaking, those who have ears to hear shall listen (Luke 8:8). Our hearing speaks the language of the Canaanite. Whoever can say to the bridegroom: After you we run for the fragrance of your ointments (Song of Songs 1:3), and: We are the sweet odor of Christ in every place (1 Corinthians 2:15), his sense of smell speaks the language of the Canaanite. The taste is also received in a good manner by the one who eats the bread that came down from heaven, the living and not the dead bread, and hears this: Taste and see how sweet the Lord is (Psalm 34:9), immediately his tongue speaks the language of the Canaanite. But there is also a spiritual touch, of which the Apostle John says: Our hands have touched the Word of life (1 John 1:1); and whoever touches Jesus in faith, so that the Savior can say about him: Someone has touched me, for I know power has gone out from me (Luke 8:46). We have learned how great blessings the elevated hand of the Lord bestows; let us seek why the five cities of Egypt speak not in the Hebrew tongue, but in the language of Canaan. To this, we will attempt to respond as follows: the Hebrew word 'περάτην' means 'transitor', one who travels from one place to another. Therefore, even though we are holy as long as we are in Egypt and surrounded by the darkness of this world, we cannot speak in the Hebrew language, but in the language of Canaan, which is intermediate between Egyptian and Hebrew and closely related to Hebrew. Canaan, in translation, means 'commotion' or 'response.' Therefore, when we depart from Egypt and desire to leave the power of Pharaoh, so that our land and our fearful confession belongs to Egypt, then we are moved and as if we respond to the will of the Lord, and yet because we are still in the present age, we cannot yet speak the Hebrew language. And what follows: swearing by the Lord of hosts five cities, this signifies that even here, placed in no way among demons, but among the rememberers of almighty God. Out of the five cities, while the names of four others are not mentioned, one is called the city of the sun, which seems to me to refer to sight. Just as a city needs the sun and moon to be seen, so our eyes need the sun of righteousness to be enlightened.

[AD 500] Aponius on Isaiah 19:18
Like one body has five senses and five movements by which all of its works are performed, so also are five different personas typified in this Canticle, each through the image of a spouse, not counting the “sixty queens” and “eighty concubines” and “adolescents without number,” or “daughters,” and “the only child of her mother,” who calls herself a “wall,” and she who “has no breasts.”These five personas, I believe, denote five languages. Hebrew, the first of all languages, was the language of those from among whom the church was first assembled at the coming of Christ and to whom the first Gospel was addressed in Hebrew through the apostle Matthew. Greek is the language of those collaborators of the apostles, the Evangelists Mark and Luke, who are shown to be the first after the Hebrews to have gone on their missions. Egyptian, with which Mark the disciple of the apostles was not unfamiliar, is the tongue of those to whom he was sent as a teacher; the example he left them flowers still today with holy piety. Latin, which the ancients called Auxonian after King Auxonius, is the language of the one who has Peter, prince of the apostles, as its teacher and patron; decorated with the jewels of his doctrine, it is united by participation in Christ. It is to it, we believe, that it was said, “How beautiful are your feet in sandals, daughter of the prince!” Fifthly, Assyrian, also called Syriac, is the tongue of the country to which the nation of ten tribes, the kingdom of Ephraim, was led away captive. By proclaiming the merit of its religion through this tongue, the people were made one body. Assyrian, then, represents the nation which was led by the Word of God “out of the wilderness” where Christ was not honored and out of the thorny conduct of humanity, to be settled in the delightful garden of sanctity.
After or apart from these languages, all the others under heaven, once converted to Christ, will be grafted into them like a limb onto a body. For everyone who believes in one omnipotent God and confesses one Redeemer, Christ, the Son of God, and receives the one Holy Spirit who proceeds from both, together constitutes the one body of the church, which is unified, as we have said, as though by the five senses. And it was prophesied quite clearly in mystery through the prophet Isaiah, I believe, that these five languages would become one language rejoicing in the praises of its one Creator by holding firm to the one faith. The coming of such a time was predicted when he said, “There will be in that day,” the day when the Lord will break the chains of his people, “five cities in the land of Egypt speaking the language of Canaan, one of which will be called the city of the sun.”
We know that “Egypt” means “obscurity” or “darkness,” which characterized the entire world before the incarnation of Christ, as blessed John the Evangelist taught when he said, “The light shone in the darkness, and the darkness has not overtaken it.” Zechariah also taught that Christ came “to illuminate those who were sitting in darkness and the shadow of death.” And the Savior himself declared, “I am the light of the world.” “Canaan,” on the other hand, means “glowing chalice.” Who else are we able to understand as a glowing chalice except the Holy Spirit, who, after the ascension of the Lord, was first sent by the Father and the Son to the apostles while their faith was still cold? Of him it is said in the Acts of the Apostles that “he rested upon each one like a flame.” He filled those who spoke the one praise of the one God in the tongue of every nation, such that they appeared intoxicated to the unaware. Having received from this chalice, the five prophesied cities now speak the marvels of the omnipotent God with one mouth or one tongue, “that our Lord Jesus Christ,” as Paul, teacher of the Gentiles, shows, “is to the glory of God the Father,” and that “no one can say that Jesus Christ is Lord except in the Holy Spirit.”
The name “city of the sun” designates the one Hebrew language itself, whose kingdom is seated in Jerusalem. There is the throne, there is the temple, the holy place of worship, and there is the kingdom of Judah, whence came Christ, the Sun of Justice. It is from Jerusalem, which was previously called Heliopolis, meaning “city of the sun,” that light is shed throughout the entire, darkened body of the world. From it, a healing balm is applied to every member of the church. And it was of this sun that the prophet predicted, “For you who fear the Lord, the sun of justice will rise, and healing is in its rays; and you will leap like young bulls in the middle of the herd, and you will trample your enemies until they become like the dust under your feet.”

[AD 735] Bede on Isaiah 19:18
The servant is “faithful in very little” who does not defile the word of God but speaks as though he were speaking from God and with God in Christ. For whatever gifts we receive at present are very little and very poor in comparison with those of the future, since “now we know only partially and prophesy only partially, but when the perfect comes, the partial will pass away.” The ten cities are souls coming to the grace of the gospel through the word of the law. And because he must be glorified, the one who will invest the money of the word worthily for God is placed over them. Hence one successful investor addressed the cities over whom he presided, that is, the souls whose governance he had accepted, asking, “What is our hope or joy or crown of glory? Is it not you before the Lord Jesus?”20“And another came, saying, ‘Lord, your mina has made five minas.’ ” This servant is representative of those who were sent to evangelize the uncircumcised. The Lord had given him one mina for preaching, which means one and the same faith which is also believed by the circumcised. He made five minas because people who had previously been enslaved to their bodily senses he converted to the grace of evangelical faith. “And he said to him, ‘You will be over five cities,’ ” that is, you will shine greatly and on high with the faith and conversion of those souls whom you imbued. Isaiah also spoke mystically about this: “In that day there will be five cities in the land of Egypt who speak the language of Canaan.” The five cities in the land of Egypt are the five senses of the body we use in this world, namely, vision, hearing, taste, smell and touch. He who looks at a woman with concupiscence, he who shuts his ears not to hear the poor, he who gets drunk with wine, which is dissipation, he who delights in crowning himself with fresh roses, whose hands are covered with blood and whose right hand is filled with bribes, represents the five cities that speak the language of Egypt, that is, that perform the works of darkness with all of their senses, for Egypt sings of the darkness. But he who blocks his ears not to hear of blood and closes his eyes not to see evil, he who tastes and sees how sweet is the Lord, who castigates his body and makes it his slave, who is able to say with the apostle “we are the fragrance of Christ to God,” represents the cities of those who speak the altered language of Canaan. And the one who delivered them from darkness by his teaching is rightly rewarded with the leadership of five cities because he is being honored not only for his own progress but also for that of those whom he called to the light.