The interpretation timeline
Galatians 1:18 Douay-Rheims

Then, after three years, I went to Jerusalem, to see Peter, and I tarried with him fifteen days.

A.D. 220 – 1871 9 witnesses

Patristic

before A.D. 750
220
A.D.
Tertullian Patristic
c. A.D. 150–220
“But the fact is, having been converted from a persecutor to a preacher, he is introduced as one of the brethren to brethren, by brethren-to them, indeed, by men who had put on faith from the apostles' hands. Afterwards, as he himself narrates, he "went up to Jerusalem for the purpose of seeing Peter," because of his office, no doubt, and by right of a common belief and preaching.”
Source
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“"Then after three years I went up to Jerusalem to visit Cephas." What can be more lowly than such a soul? After such successes, wanting nothing of Peter, not even his assent, but being of equal dignity with him, (for at present I will say no more,) he comes to him as his elder and superior. And the only object of this journey was to visit Peter; thus he pays due respect to the Apostles, and esteems himself not only not their better but not their equal. Which is plain from this journey, for Paul was induced to visit Peter by the same feeling from which many of our brethren sojourn with holy men: or rather by a humbler feeling for they do so for their own benefit, but this blessed man, not for his own instruction or correction, but merely for the sake of beholding and honoring Peter by his presence. He says, "to visit Peter;" he does not say to see, but to visit and survey, a word which those, who seek to become acquainted with great and splendid cities, apply to themselves. Worthy of such trouble did he consider the very sight of Peter; and this appears from the Acts of the Apostles also. For on his arrival at Jerusalem, on another occasion, after having converted many Gentiles, and, with labors far surpassing the rest, reformed and brought to Christ Pamphylia, Lycaonia, Cilicia, and all nations in that quarter of the world, he first addresses himself with great humility to James, as to his elder and superior. Next he submits to his counsel, and that counsel contrary to this Epistle. "Thou seest, brother, how many thousands there are among the Jews of them which have believed; therefore shave thy head, and purify thyself." Accordingly he shaved his head, and observed all the Jewish ceremonies; for where the Gospel was not affected, he was the humblest of all men. But where by such humility he saw any injured, he gave up that undue exercise of it, for that was no longer to be humble but to outrage and destroy the disciples. "And tarried with him fifteen days." To take a journey on account of him was a mark of respect; but to remain so many days, of friendship and the most earnest affection.”
Source
430
A.D.
Augustine of Hippo Patristic
A.D. 354–430
“If, when Paul had evangelized Arabia, he subsequently saw Peter, it was not so that he might learn the gospel from Peter himself (for then he would have seen him before) but so that he might enhance familial love by being with the apostles.”

Scholastic

c. 1100 – 1500
1273
A.D.
Thomas Aquinas Catholic
1225–1274
“After the Apostle has shown that he himself did not receive the Gospel from man before his conversion, he now proves here that he did not receive it from man after his conversion either. And concerning this he does two things. First he shows that he did not receive the Gospel from man at the time of his conversion; second, that he did not receive it after his conversion either, at the place, then after three years, and so on. Concerning the first he does two things. For first he shows that he did not receive the Gospel from the apostles, nor was he taught by them; second, that he did not receive it from other believers either, at the place, but I went away into Arabia, and so on. Concerning the first he does three things. First he shows the efficient cause of his conversion; second, the end, at the place, that he might reveal, etc.; third, the manner, at the place, immediately I did not yield, and so on. Concerning the first, he notes the cause of his conversion, which is twofold, namely the good pleasure of God, which is the divine election, and the calling of the one who converts him. As to the first he says when it pleased, namely God — not when I willed, but when it was pleasing to him, because it is not of him who wills nor of him who runs, etc., as is said in Romans 9:16. Psalm 146:11: the good pleasure is with the Lord, and so on. Philippians 2:13: it is God who works in us, and so on. Who, namely God, me — namely a rebel, 1 Corinthians 15:9: I am the least of the apostles, etc., because I persecuted, and so on; Acts 9:1: Saul still breathing threats, and so on — a persecutor: Saul, Saul, why do you persecute me, etc. — a blasphemer, 1 Timothy 1:13: who was a blasphemer, and so on. Me, such as I was, I say, he set apart from my mother's womb. Or according to the letter: who caused me to be born from my mother's belly. And it is truly said that God sets apart from the womb, although this is the work of nature, which is as it were the instrument of God, because our works too are attributed to God as to the principal author, Isaiah 26:12: for all our works you have wrought in us, etc., just as effects are also attributed to the principal agent. Hence it is said in Job 10:11: you have clothed me with skin and flesh, and so on. And from this womb he was set apart unto justification, because it belongs to the same one to justify to whom it belongs to create. Psalm 21:11: from my mother's womb, and so on. Or: from my mother's womb, namely of the synagogue, whose womb is the college of the Pharisees, who nourished others in Judaism. Matthew 23:15: you go about sea and land to make, and so on. Thus, then, his mother was the synagogue. Song of Songs 1:5: the sons of my mother fought against me, and so on. Her womb is the Pharisees. From this womb, then, he was set apart through the Holy Spirit unto the faith of the Gospel. Romans 1:1: set apart unto the Gospel of God. Or his mother is the Church of Christ; her womb, the college of the apostles. God, then, set him apart from the womb of the Church, that is, from the college of the apostles, into the office of apostleship and preaching to the gentiles, when he said to the apostles, Acts 13:2: set apart for me Barnabas and Paul, and so on. Now he calls the synagogue his mother because he was a Pharisee, being as it were great in it, since it is said, a Pharisee, and of the Pharisees, because he was a zealot of the law. Above: but being more abundantly a zealot, and so on. As to the other cause he says, and called, and so on. Now there is a twofold calling. One is exterior, and thus he says: he called me with a heavenly voice. Acts 9:4: Saul, Saul, why do you persecute me? and so on. Go into the city, and so on. Thus he also called the other apostles. The other is interior, and thus he called through a certain interior instinct, by which God through grace touches the heart, that it may be converted to him, and thus he called him from the evil way into the good, and this through his grace, not by our merits. Romans 8:30: whom he predestined, these he also called, and so on. Isaiah 45:13: I have raised him up unto justice, and so on. Amos 5:8: who calls the waters of the sea, and so on. Now the end of his conversion is set down when he says, that he might reveal his Son, etc., which end indeed is Christ. Now his conversion is ordered to Christ in two ways: namely by deed, and thus he says that he might reveal his Son, that is, in that which he did concerning me, converting me and forgiving me my sins, he might reveal how great a mercy had been done to me. 1 Timothy 1:15ff: Christ Jesus came into this world to save sinners, and so on. But I obtained the mercy of God because ignorant, and so on. Thus, then, he revealed his Son in his conversion, and this insofar as the Son is called the grace of God. Likewise he revealed him in his working; whence he himself said, Romans 15:18: for I do not dare to speak of any of those things which Christ has not wrought through me unto the obedience of the gentiles, in word, in deeds, and in power, and so on. And this insofar as the Son is the power of God. Likewise he revealed him in his preaching; whence he himself said, 1 Corinthians 1:23: we preach, etc., down to and the wisdom of God. And this insofar as his Son is called the wisdom of God. Likewise his conversion is ordered to Christ by word, and thus he says that I might preach him among the gentiles, because, while the other apostles were preaching Christ to the Jews, Paul, by the command of the Lord, went to the gentiles to convert them. Isaiah 49:6: for it is a small thing that you should be my servant, etc., I have given you as a light, and so on. Acts 13:47: for thus he has commanded, and so on. Below: behold I have given him as a witness to the peoples, a leader and teacher to the gentiles. Now the manner of his conversion is perfect, both as to its effect; whence he says immediately I did not yield to flesh and blood, that is, at once I was so perfectly converted that every carnal affection withdrew from me. Ecclesiasticus 11:23: for it is easy in the eyes of the Lord suddenly to enrich the poor man. And here flesh and blood is taken for carnal vices. 1 Corinthians 15:50: flesh and blood shall not possess the kingdom of God, and so on. Below, 5:17: the flesh lusts, and so on. Or for the affection and love toward those carnally joined to oneself. Matthew 16:17: flesh and blood has not revealed it to you, and so on. Thus the Apostle both overcame his own vices and despised his own Jews. Likewise as to the intellect; because he was so instructed by Christ that it was not necessary for him to be instructed by the apostles. And therefore he says, nor did I go to Jerusalem, namely so as to be instructed by them. Likewise it was not necessary for him to be instructed by other believers. And therefore he says, but I went away into Arabia, etc., as if to say: I did not go to places where other believers were, so that they might instruct me, but I went into Arabia, where there were none instructed in the faith, but unbelievers. And again I returned to Damascus, namely to my kinsfolk. Job 38:25: who has given a course to the most violent rain shower, and so on. But against this it is said in Acts 9:25 that they let him down from the wall in a basket, and so on. And when he had come to Jerusalem, he tried to join himself to the disciples. He came, then, to Jerusalem. It must be said that he came, but not so as to be instructed. Or, better, it must be said that he did not come at once, but after some time, and therefore there follows, then after years, and so on.”

Reformation

c. 1500 – 1650
1637
A.D.
1567–1637
“Then after three years I went up to Jetusalem to see Peter . Chrysostom and Theophylact remark on the distinction between ISeiv and the word loroprjo-ai , used here. This latter is used of those who visit and go round splendid cities, like Rome, and carefully inspect its monuments, its Pontiff, its Cardinals, its clergy, and holy men. I came to Jerusalem, says S. Paul, to see Peter, not to learn anything from him (though Erasmus thinks that Urroprj<rat connotes this), for I had been taught from above, but merely to see and pay my respect to the chief of the Apostles (Theodoret, Chrysostom, Ambrose, Jerome). In Gal it 2 Paul gives another reason for his visit S. Chrysostom writes : “ Peter was the chief and the mouth of the Apostles , and therfore Paul went up to see him especially ” ( Horn . in foan . 87). And S. Jerome on this passage: “ Paul came to see Peter — not to gaze on his eyes , cheeks , and countenance — to see if he was fat or lean , if he had a hooked or a straight nose , whether he had hair on his head or was (as Clement relates) bald headed Nor is it to be S. PAUL AND S. PETER 233 Supposed consistent with apostolical dignity , that after such a preparation of three years he should wish to see anything in Peter that was merely human . Paul saw Cephas with those same eyes with which he himself is seen still by those who have power to see him . If this does not seem clear to any one , let him compare this sentence with the one before , in which it is said that the Apostles conferred nothing on him . For he went to Jerusalem , that he might see an Apostle , not to learn anything from him— for both had the same authority for their preaching — but to do honour to one who was an Apostle before him.” From this it is clear that Paul did not see Peter that he might be taught by him, as Erasmus and Vatablus think. For this is contradicted by Gal ii. 6 : “ They added nothing to me,” and by Gal. i. 11, 12, where he expressly says that he had been taught not by man but by God”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Then after three years I went up to Jerusalem,.... Not three years after his return to Damascus, but after his conversion; and now it was that he moved to become a member of the church at Jerusalem; but they did not care to admit him, fearing that he was not a disciple, till such time that Barnabas took him, and brought him to the Apostles Peter and James, and related his conversion and his boldness in preaching the Gospel at Damascus: his view in going up to Jerusalem at this time was partly his own safety, being obliged to fly from Damascus, but chiefly to see Peter. The Alexandrian copy, and another, read "Cephas", and so does the Ethiopic version, the same with Peter: not to see what sort of a man he was, but to pay him a Christian visit; to converse with him about spiritual things; to know how the work of God went on under him, as the minister of the circumcision; and to relate to him, what success he had met with as the minister of the uncircumcision; but not to receive the Gospel from him, or to be ordained a preacher of it by him; for he had been three years already in the work of the ministry, before he made him this visit; and besides, his stay with him was very short, nor could he have received much from him, in so short a time, in an ordinary way: and abode with him fifteen days; and even all this time was not wholly spent in conversation with him; for he was, during this time, coming in and going out at Jerusalem, where he preached boldly in the name of Christ, and disputed against the Grecians.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“After three years I went up to Jerusalem to see Peter - These three years may be reckoned either from the departure of Paul from Jerusalem, or from his return from Arabia to Damascus. To see Peter - Ιστορησαι Πετρον, to become personally acquainted with Peter; for this is the proper import of the verb ἱστορειν, from which we have the word ἱστορια, history, which signifies a relation of things from personal knowledge and actual acquaintance. How far this is, now, from the sense in which we must take the word, ninety-nine of every hundred of our histories sufficiently show. They are any thing but true relations of facts and persons. And abode with him fifteen days - It was not, therefore, to get religious knowledge from him that he paid him this visit. He knew as much of the Jewish religion as Peter did, if not more; and as to the Gospel, he received that from the same source, and had preached it three years before this.”
Source
1849
A.D.
1774–1849
“Then three years after, I came to Jerusalem to see (and as St. Chrysostom says, out of respect to make a visit to) Peter, but staid only at Jerusalem fifteen days, and saw none of the apostles except him, and James, the brother, or cousin of our Lord; so that I was yet unknown by face to the Christian churches in Judea. (Witham)”
Source
1871
A.D.
1871
“after three years--dating from my conversion, as appears by the contrast to "immediately" (Gal 1:16). This is the same visit to Jerusalem as in Act 9:26, and at this visit occurred the vision (Act 22:17-18). The incident which led to his leaving Damascus (Act 9:25; Co2 11:33) was not the main cause of his going to Jerusalem. So that there is no discrepancy in the statement here that he went "to see Peter"; or rather, as Greek, "to make the acquaintance of"; "to become personally acquainted with." The two oldest manuscripts read, "Cephas," the name given Peter elsewhere in the Epistle, the Hebrew name; as Peter is the Greek (Joh 1:42). Appropriate to the view of him here as the apostle especially of the Hebrews. It is remarkable that Peter himself, in his Epistles, uses the Greek name Peter, perhaps to mark his antagonism to the Judaizers who would cling to the Hebraic form. He was prominent among the apostles, though James, as bishop of Jerusalem, had the chief authority there (Mat 16:18). abode--or "tarried" [ELLICOTT]. fifteen days--only fifteen days; contrasting with the long period of three years, during which, previously, he had exercised an independent commission in preaching: a fact proving on the face of it, how little he owed to Peter in regard to his apostolical authority or instruction. The Greek for "to see," at the same time implies visiting a person important to know, such as Peter was. The plots of the Jews prevented him staying longer (Act 9:29). Also, the vision directing him to depart to the Gentiles, for that the people of Jerusalem would not receive his testimony (Act 22:17-18).”
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.