The interpretation timeline
2 Timothy 4:20 Douay-Rheims

Erastus remained at Corinth. And Trophimus I left sick at Miletus.

A.D. 407 – 1871 5 witnesses

Patristic

before A.D. 750
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“"Erastus abode at Corinth: but Trophimus have I left at Miletum sick." This Trophimus and Tychicus, we know from the book of the Acts, sailed away with him from Judea, and were everywhere his companions, perhaps as being more zealous than the rest. "Trophimus I have left at Miletum sick." Why then didst thou not heal him, instead of leaving him? The Apostles could not do everything, or they did not dispense miraculous gifts upon all occasions, lest more should be ascribed to them than was right.”
Source

Scholastic

c. 1100 – 1500
1273
A.D.
Thomas Aquinas Catholic
1225–1274
“He asks to be visited, and first he calls him to himself; second he indicates his own condition, at "Alexander"; third he concludes the epistolary greeting, at "they greet you." Again, first he commands that he come; second he assigns him a companion, at "take Mark"; third he shows what he should bring, at "the cloak." Concerning the first he does two things, for first he calls him; second he assigns the cause of the calling, at "Demas." He says therefore: because I am soon to depart from the world, hasten to come to me quickly. And this, that they might console one another, and that he might help him in the preaching of the Gospel, for which he was anxious, being in chains. Prov. 18:19: A brother who is helped by a brother is like a strong city. The cause of the calling is that he was deprived of the fellowship due to him. And first by one who had departed on account of his own fault; second, because he had sent certain ones to preach. He says therefore "for Demas," etc., that is, he preferred the love of this age to love of me. 1 John 2:15: If anyone loves the world, the charity of the Father is not in him. Crescens, a certain disciple, went into Galatia, sent by the apostle. Titus also, sent by him, went into Dalmatia, where in the end he is said to have been bishop. Job 38:35: Will you send lightnings, and will they go? "Luke alone is with me" — this one he retained in the preaching of the Gospel, in which he was gracious. 2 Cor. 8:18: whose praise is in the Gospel throughout all the Churches. Then when he says "Take Mark, and bring him," he assigns him a companion; and concerning this he does two things. First he assigns him a companion; second, the reason for this. This Mark is called by another name John, and is the cousin of Barnabas. Acts 15:37f. it is said that Barnabas wanted to take Mark, but Paul was unwilling. And on account of this a dissension arose between them, so that he departed from them. Col., last chapter: Mark, the cousin of Barnabas. The reason is, "because he is useful to me," etc. Then when he says "the cloak," etc., he says what he should carry. Carpus is a certain saint. The "penula" according to Jerome was a scroll of the law, which they had on paper in the manner of a roll, and this he calls the "penula." Or "penula" is said to be some garment; but, according to Chrysostom, it was a common garment. And because the apostle at Rome was poor, not receiving from others, therefore he wanted a garment to be brought to him. Haymo says that it was a special garment as a sign of nobility. Hence in Acts 22:25, Paul said that he was a Roman citizen. For Paul's father served the Romans at Tarsus of Cilicia; and from this he was made a Roman citizen: and the "penula" was a garment as a sign of the consul. And perhaps his father was consul there. Or "penula" is said to be a satchel where the books were, which seems to be the case, because there follows "and the books." But what need had the apostle, full of the Holy Spirit, of books? Again, his dissolution was at hand. I respond. It must be said that it was on account of two things. First, that in reading he might have comfort. 1 Macc. 12:9: having the holy books for comfort. For in books there is a remedy against tribulations. Or he says this lest they be lost, but might remain for the faithful. Again, the more he was approaching death, the more he pressed on with the service of the Scriptures; just as it is said of Ambrose that up to his last illness he did not cease to write; hence, while writing that Ps. 47:2: "Great is the Lord, and greatly to be praised," etc., he died. "But especially the parchments." Parchments are unwritten papers, or leaflets, where he had written his letters, or his sermons. Then when he says "Alexander," etc., he shows what things were with him, and what things are with him. And first on the part of men; second on the part of God, at "but the Lord stood by me." Again the first is divided into two; for first he tells him about a certain one who was against him; second about the negligence of those who did not help him, at "in my first defense," etc. Again, first he sets forth the fault of the one wickedly attacking; second he shows his future punishment, at "the Lord will repay him," etc.; third he shows how he is also to be punished according to the Church, at "whom you also avoid." It seems that this Alexander was a coppersmith, or a keeper of the treasury; and he was one of those who said that the legal observances were to be kept as necessary for salvation. 1 Tim. 1:19: concerning the faith they have made shipwreck, of whom is Hymenaeus and Alexander. And some say that this is the one about whom it is said in Acts 19:24, because he stirred up a sedition against the apostle; but the name disagrees, because that one was Demetrius, this one Alexander, and Luke; because that one was at Ephesus, this one at Rome. And he adds "he showed me many evils." And note that he does not say "he did," but that "he showed," because the wicked can show their intent against the just, but do not always carry it out, Jer. 1:19. Jer. 15:20: They will fight against you, and will not prevail, because I am with you. Job 5:12: who scatters the thoughts of the malicious, so that their hands cannot accomplish what they have begun. Who catches the wise in their own cunning, and scatters the counsel of the wicked. Then when he says "the Lord will repay him," etc., he sets down his future punishment. But note that he does not put the optative verb, "may he repay," but says "he will repay"; because it is signified that the punishment has been prepared by God, which the apostle foresaw from his obstinacy. Ps. 61:13: because you will repay each one according to his works. Yet, together with the fact that punishment is reserved for him in the future, the Church ought also to punish him by excommunicating him. Hence he adds "whom you also avoid," namely as a heretic. Titus 3:10: A heretical man, after one and a second correction, avoid. Of this saying he also gives the reason, saying "for he greatly withstood our words." Acts 7:51: You have always resisted the Holy Spirit. Consequently he sets down the negligence of those not helping him; and first he reproves their fault; second he asks pardon for them, at "may it not be imputed to them." He says therefore "in my first," etc. The Gloss says that the apostle often fought against Alexander who taught wrongly, and in person no one stood by him. But this does not seem to be his meaning here, because this Alexander was not so great that the apostle needed others to dispute with him. But it must be said that, as it is said in Acts 25:21: "Paul, appealing, was sent to Rome," and therefore it was necessary that he be presented to Caesar, that the cause of his mission be examined, and the Jews came against him. And this the apostle calls his first defense. In which the disciples were absent to him, fearing lest they be punished by the cruel Nero. Ecclus. 51:10: I was looking for the help of men, and there was none. Is. 63:3: I have trodden the winepress alone, and of the nations there is no man with me. But it could be said that this was because from the beginning no one knew. But this is false; rather, they withdrew out of a certain faintheartedness. Ps. 87:19: You have put far from me friend and neighbor, and my acquaintances, because of misery. Job 6:15: My brothers have passed by me, etc. But because they did it out of weakness, he prays for them, and does not excommunicate, saying "may it not be imputed to them." Luke 6:28: Pray for those who slander you. Then when he says "but the Lord," he shows what is done concerning him on the part of God, whose help he first sets down; second, the effect of this, at "and let them hear." He says therefore: all have forsaken me, but where man is lacking, God offers himself. Ps. 24: for my father and my mother have forsaken me, but the Lord has taken me up. Hence he says "the Lord stood by me," namely to help me. Jer. 20:11: The Lord is with me like a mighty warrior. Ps. 15:8: I foresaw the Lord always in my sight, because he is at my right hand, that I be not moved. And how? "And he strengthened me," giving fortitude of soul, so that I would not be stunned before Caesar. Ezek. 3:14: the hand of the Lord was with me, strengthening me. And this "that through me," etc., which is fulfilled when it is spread to many, and when what is said by mouth is fulfilled by deed. Acts 9:15: a vessel of election, etc. Then when he says "and let them hear," the effect of the divine help is set down. And first as to the past; second as to the future; third he gives thanks. But the benefit regarding the past is twofold, namely deliverance from fault and from punishment. He says therefore: the Lord stood by me, and therefore in that summons I was delivered, because I was not condemned by Caesar; but it was permitted to me that I might go where I wished. And therefore he says "and let all the nations hear," namely that others might be encouraged along with him to come. Ps. 95:5: Declare his glory among the nations. And that the insult of the Jews might be put down. And he adds "I was delivered from the mouth of the lion," that is, from the cruelty of Nero. Prov. 19:12: As the roaring of lions, so is the wrath of a king. Prov. 28:15: A roaring lion and a hungry bear is a wicked prince over a poor people. Second, he was delivered from fault; hence he says "the Lord delivered me from every evil work." But some are delivered from punishment, falling into the fault of denial of the faith. Ps. 17:18: He rescued me from my most powerful enemies, and from those who hated me, etc. And this through God. Wis. 8:21: I cannot be continent unless God grants it. "In the future he will save me." Is. 45:17: Israel is saved in the Lord with an eternal salvation. And he says "into the heavenly kingdom." Luke 22:29: I dispose to you, as my Father has disposed to me, a kingdom. Matt. 5:12: your reward is abundant in heaven. And therefore he gives thanks, "to whom be glory." 1 Tim. 1:17: to the king of ages. Then when he says "greet," etc., he enjoins on him the greeting of others; second he greets him on the part of others; third on his own part. Again, concerning the first, first he enjoins the greeting of others; second he determines the time of coming. He says therefore "greet Prisca," namely who is the woman, "and Aquila," the husband of Prisca, whom he puts first because perhaps they were more devout, "and the household of Onesiphorus." But why not him, but the household? Because perhaps he was dead, and therefore he greets the family; or perhaps because he was with him at Rome. Determining the time of coming, first he shows the necessity; second he pursues his purpose. The necessity is on account of others remaining in other places. Again, on account of the disturbance of the sea. Then he sets down the persons greeting, as is evident. And in the usual manner, lest the letter be corrupted, he writes in his own hand: "Grace be with you. Amen."”

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“The Lord Jesus Christ be with thy spirit,.... To counsel and advise in every difficult matter; to comfort under every distress; to supply with all grace in every time of need; and to strengthen and fit for every part and branch of duty. Grace be with you, Amen: which is the apostle's common salutation in all epistles. The Syriac version renders it, "grace be with thee"; but the Greek copies read in the plural, "with you"; which shows that the epistle was designed for the use of the whole church, as well as of Timothy. The subscription follows, which is not in many ancient copies, and is not to be depended on. The second epistle unto Timotheus; so far is right; this is certainly the second epistle to Timothy: ordained the first bishop of the church of the Ephesians: this is omitted in the Syriac version; nor is it likely, much less certain, that he ever was bishop of Ephesus, or ordained as a bishop of any place, but was rather an evangelist, Ti2 4:5, was written from Rome: this is evident from his being a prisoner when he wrote it, Ti2 1:8. And yet in the Alexandrian copy it is said to be written from Laodicea: when Paul was brought before Nero the second time; but whether he was before Nero at all is a question, or only before a Roman governor or judge. Next: Titus Introduction”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“Erastus abode at Corinth - He was treasurer of that city, as we learn from Rom 16:23 (note). The apostle had sent him and Timothy on a mission to Macedonia, Act 19:22, whence it is probable he returned to Corinth, and there became finally settled. Trophimus have I left at Miletum sick - Even the apostles could not work miracles when they pleased; that power was but rarely given, and that for very special purposes. Trophimus was an Ephesian. See Act 20:4, and the note there. Miletus was a maritime town of Ionia, not far from Ephesus; but there was another Miletus, in Crete, which some learned men think to be intended here. It appears that St. Paul went from Macedonia to Corinth, where he left Erastus; from Corinth he proceeded to Troas, where he lodged with Carpus: from Troas he went to Ephesus, where he visited Timothy; from Ephesus he went to Miletus, where he left Trophimus sick; and having embarked at Miletus, he went by sea to Rome. See Calmet. It is most likely, therefore, that the Miletus of Ionia is the place intended.”
Source
1871
A.D.
1871
“In order to depict his desertion, he informs Timothy that Erastus, one of his usual companions (Act 19:22, possibly the same Erastus as in Rom 16:23, though how he could leave his official duties for missionary journeys is not clear), stayed behind at Corinth, his native place, or usual residence, of which city he was "chamberlain," or city steward and treasurer (Rom 16:23); and Trophimus he left behind at Miletus sick. (On his former history, see on Act 20:4; Act 21:29). This verse is irreconcilable with the imprisonment from which he writes being the first: for he did not pass by Corinth or Miletus on his way to Rome when about to be imprisoned for the first time. As Miletus was near Ephesus, there is a presumption that Timothy was not at Ephesus when Paul wrote, or he would not need to inform Timothy of Trophimus lying sick in his immediate neighborhood. However, Trophimus may not have been still at Miletus at the time when Paul wrote, though he had left him there on his way to Rome. Prisca and Aquila were most likely to be at Ephesus (Ti2 4:19), and he desires Timothy to salute them: so also Onesiphorus' household (Ti2 1:18). Paul had not the power of healing at will (Act 19:12), but as the Lord allowed him.”
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.