The interpretation timeline
2 Corinthians 13:12 Douay-Rheims

Salute one another with a holy kiss. All the saints salute you.

A.D. 108 – 1849 8 witnesses

Patristic

before A.D. 750
108
A.D.
c. A.D. 50–107
“I salute Cassian and his partner in life, and their very dear children. Polycarp, that most worthy bishop, who is also deeply interested in you, salutes you; and to him I have commended you in the Lord. The whole Church of the Smyrnaeans, indeed, is mindful of you in their prayers in the Lord. Onesimus, the pastor of the Ephesians, salutes you. Damas, the bishop of Magnesia, salutes you. Polybius, bishop of the Trallians, salutes you. Philo and Agathopus, the deacons, my companions, salute you, "Salute one another with a holy kiss."”
Source
220
A.D.
Tertullian Patristic
c. A.D. 150–220
“But when is peace more to be concluded with brethren than when, at the time of some religious observance, our prayer ascends with more acceptability; that they may themselves participate in our observance, and thereby be mollified for transacting with their brother touching. their own peace? What prayer is complete if divorced from the "holy kiss? " Whom does peace impede when rendering service to his Lord? What kind of sacrifice is that from which men depart without peace? Whatever our prayer be, it will not be better than the observance of the precept by which we are bidden to conceal our fasts; for now, by abstinence from the kiss, we are known to be fasting.”
Source
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“Then to lead them on unto it, he says, "Salute one another with a holy kiss." What is "holy?" not hollow, not treacherous, like the kiss which Judas gave to Christ. For therefore is the kiss given, that it may be fuel unto love, that it may kindle the disposition, that we may so love each other, as brothers brothers, as children parents, as parents children; yea, rather even far more. For those things are a disposition implanted by nature, but these by spiritual grace. Thus our souls bound unto each other. And therefore when we return after an absence we kiss each other, our souls hastening unto mutual intercourse. For this is that member which most of all declares to us the workings of the soul. But about this holy kiss somewhat else may yet be said. To what effect? We are the temple of Christ; we kiss then the porch and entrance of the temple when we kiss each other. See ye not how many kiss even the porch of this temple, some stooping down, others grasping it with their hand, and putting their hand to their mouth. And through these gates and doors Christ both had entered into us, and doth enter, whensoever we communicate. Ye who partake of the mysteries understand what I say. For it is in no common manner that our lips are honored, when they receive the Lord's Body. It is for this reason chiefly that we here kiss. Let them give ear who speak filthy things, who utter railing, and let them shudder to think what that mouth is they dishonor; let those give ear who kiss obscenely. Hear what things God hath proclaimed by thy mouth, and keep it undefiled. He hath discoursed of the life to come, of the resurrection, of immortality, that death is not death, of those other innumerable mysteries. For he that is about to be initiated comes to the priest's mouth as it were an oracle, to hear things full of awe. For he lost his life even from his forefathers, and comes to seek it again, and to ask how he may haply find and get it back. Then God announceth to him how it may be found, and that mouth becomes more awful than the very mercy-seat. For that mercy-seat never sent forth a voice like this, but spake much of lesser things, of wars and such peace as is here below: but this speaks all about heaven and the life to come, and things new and that pass understanding.”
Source

Scholastic

c. 1100 – 1500
1272
A.D.
Thomas Aquinas Catholic
1225–1274
“In what precedes, the Apostle rebuked those seduced by the false apostle; here, however, he consoles those persisting in the faith and his teaching. And first he sets down an admonition; second he appends a greeting, where he says, greet with a kiss, et cetera. Concerning the first, first he sets down the admonition; second, the reward of the fulfilled admonition, where he says, and the God of peace, et cetera. Now he admonishes them concerning three things. First, how they should conduct themselves in themselves; second, how they should conduct themselves toward their neighbors; third, how all should be toward one another. In themselves, moreover, they ought to have two goods. First, joy over the good possessed, and as to this he says, for the rest, brothers, who have been steadfast, rejoice, in those things which you do for the service of God. And this is necessary in order that you be just and virtuous, because no one is virtuous, or just, who does not rejoice in just and virtuous activity. And therefore it is said in Ps. 99:2: shout with joy to God, all the earth, serve the Lord in gladness; Phil. 4:4: rejoice in the Lord always; again I say, rejoice, et cetera. And truly one must always rejoice, because joy preserves a man in a good disposition, since no one can remain long in that which saddens him. Second, the good ought to have in themselves an emulation of perfection, and as to this he says, be perfect, that is, always strive toward advancement. Hebr. 6:1: wherefore, leaving behind the discourse of the beginning of Christ, unto perfection, et cetera. Now this, what is said here, is not a precept, namely that a man be perfect, but this, that he always strive toward perfection. And this is necessary, because he who does not study to advance is in danger of falling short. For we see that unless the rowers strive to go upward, the ship always goes downward. And therefore the Lord said, Mc. ult.: be perfect, et cetera. To neighbors, however, exhortation to good things is to be extended. And as to this he says, exhort, et cetera. Eccli. 17:12: God has commanded each one concerning his neighbor, et cetera. Rom. c. 12:8: he who exhorts, in exhorting; Apoc. ult.: let him who hears say, come. Two things, moreover, ought to be common to all, namely that they think the same thing, and therefore he says, think the same thing, and that they have peace, and therefore he says, have peace. And these two stand thus, that one is exterior, the other interior. For it is agreed that bodies cannot be preserved and ordered unless the members are ordered to one another. Likewise neither the Church, nor the members of the Church, unless they are ordered and united to one another. Now there is a twofold union necessary for uniting the members of the Church. One is interior, namely that they think the same thing through faith, as to the intellect, believing the same thing, and through love, as to the affection, loving the same thing. And therefore he says, think the same thing, that is, that you feel the same about the faith, and that you love with the affection of charity the same thing. Because then there is true wisdom, when the operation of the intellect is perfected and consummated through the quieting and delight of the affection. Whence wisdom is called, as it were, a savory knowledge. Rom. 15:6: that thus, of one mind, with one mouth you may honor God, et cetera. I Cor. 1:10: that you say the same thing, et cetera. Phil. c. 2:2: think the same thing, et cetera. The other is exterior, namely peace, and therefore he says, have peace among yourselves. Hebr. 12:14: follow after peace, et cetera. Ps. 33:15: seek peace. II Thess. 3:16: may the God of peace himself give you everlasting peace in every place. Consequently, when he says, and the God of peace and of love will be with you, he sets down the reward that is given to those fulfilling the aforesaid admonition; as if he were saying: if you keep peace among yourselves, the God of peace and of love will be with you. Concerning which it should be noted that among the gentiles it was customary that some named gods from gifts, because although there was only one God, nevertheless they named their individual gifts gods from those gifts, just as from the gift of peace they named the God of peace, and from the gift of health, the God of health. Alluding to this usage, the Apostle says, God of peace, et cetera. Not that peace is one God, as they said, but Christ is called the God of peace for this reason, that he is the giver of peace and its lover. Io. 14:27: my peace I give you, et cetera. I Cor. 14:33: God is not a God of dissension, but of peace. Rom. 5:5: the charity of God is poured out in our hearts, et cetera. He himself is also the author of peace. Io. 16:33: in me you will have peace, et cetera. He himself dwells in peace. Ps. 75:3: in peace his place has been made, et cetera. Likewise, he is not only the God of peace, but also of love. And therefore he says, the God of peace and of love will be with you. And this is so because he who is in true peace of heart and body is in charity, and he who abides in charity abides in God and God in him, as is said in I Io. 4:16, and because man does not merit save through peace and love. Io. 14:23: if anyone loves me, et cetera. Consequently, when he says, greet one another with a kiss, etc., he sets down the greeting, and concerning this, first he enjoins on them a mutual greeting; second he greets them on behalf of others, where he says, all greet you, etc.; third he greets them on his own behalf, where he says, the grace of God, et cetera. The mutual greeting he enjoins to be done by a kiss. Whence he says, greet one another, you yourselves, with a holy kiss. Here it should be noted that a kiss is a sign of peace. For through the mouth, in which the kiss is given, a man breathes. And therefore when men give one another mutual kisses it is a sign that they unite their spirit to peace. Now there is a feigned peace, and this is that of those who speak peace with their neighbor, but evil things are in their hearts, etc., as is said in Ps. 27:3. Which indeed is brought about through the deceit of a kiss. Prov. 27:6: better are the wounds of one who loves, et cetera. There is also an evil and shameful peace, namely when men come together to do evil. Sap. 14:22: living in a great war of ignorance, et cetera. And this is brought about through a lustful kiss. Prov. 7:13 it is said of the evil woman, that having caught the young man she kisses him, et cetera. There is also a holy peace which God makes. Phil. c. ult.: and the peace of God, which surpasses, et cetera. And this is brought about through a holy kiss, because it unites the spirit to holiness. And of this kiss it is said here, with a holy kiss. And from this the custom grew up, that the faithful and holy men, in sign of charity and union, kiss one another, and peace is given in the churches with a holy kiss. On behalf of others, moreover, he greets them, saying, all the saints greet you, because all the saints and faithful hope and desire, and by their prayers procure, our salvation; whence all the faithful of Christ hope and desire salvation for one another. Ps. 118: make me a partaker, O God, et cetera. On his own behalf, however, the Apostle greets them, saying, the grace of our Lord, et cetera. Here it should be known that there is a twofold manner of appropriating something to the divine persons. One is essential, the other causal; essentially, indeed, power is appropriated to the Father, because he is essentially power, inasmuch as he is the principle; wisdom to the Son, inasmuch as he is the Word; love to the Holy Spirit, inasmuch as he is goodness. Here, however, the Apostle does not appropriate these things in this manner, namely through essence, because thus all would be appropriated to the Holy Spirit, but he appropriates through cause. And therefore, since grace is the gift by which our sins are forgiven, Rom. c. 3:24: justified freely, etc., and the remission of sins was made for us through the Son, who, taking on our flesh, made satisfaction for our sins, Io. 1:17: grace and truth came through Jesus Christ, etc.; for this reason the Apostle attributes grace to Christ. Whence he says, the grace of our Lord, et cetera. Charity, however, is necessary for us, because we must be united to God. I Io. 4:16: he who abides in charity abides in God, et cetera. And because this is from God the Father, inasmuch as he so loved the world that he gave his only-begotten Son, as is said in Io. 3:16, Rom. 5:8: but God commends his own charity, therefore he attributes charity to himself, as the principle of this charity, when he says, and the charity of God, namely of the Father. The communication of divine things, however, comes about through the Holy Spirit, because he is the distributor of spiritual gifts. I Cor. 12:11: all these things the one and the same Spirit works. And therefore he attributes communication to the Holy Spirit, when he says, and the communication of the Holy Spirit. Or he attributes this to him because he himself is common to the other two persons. Thus, then, the Apostle in his greeting wishes for all necessary things, when he says, the grace of our Lord Jesus Christ, and the charity of God, and the communication of the Holy Spirit, be always with you all. Amen. The grace of Christ, by which we are justified and saved; the charity of God the Father, by which we are united to himself; and the communication of the Holy Spirit, distributing to us divine gifts. Amen.”

Reformation

c. 1500 – 1650
1637
A.D.
1567–1637
“Greet one another with an holy kiss . What was this kiss? Xenophon (Cyropoedia, lib. i.) and Herodotus (Clio) testify that it was a heathen custom to salute one another with a kiss at meeting, in token of friendship. Suetonius says that Tiberius tried in vain to put an end to the practice. The Jews had the same custom. C i 2 Sam. xx. 9. Judas, too, was but conforming to what was usual when he betrayed Christ with a kiss. It was a still more solemn and common custom with the early Christians, both on other occasions, and especially when they met for Holy Communion, to salute one another with a kiss, or other familiar salutation, saying, “Peace be with you.” This was a symbol of goodwill towards those about to communicate, of the forgiveness of all injury, and of pure charity. Cf, Cyril (Cat. Myst. 5). Tertullian (de Orat.) calls this kiss " the symbol of prayer.” S. Chrysostom gives the mystical meaning to be, that through our mouth enters the body of Christ We, therefore, kiss it, just as the early Christians, out of reverence for the sacred building, used to kiss the doors of the church. He gives directions how to guard this mouth against all that defiles, and to consecrate it to the praises of God. In some churches, even now, it is the custom for the canons to give this kiss before the Holy Communion. When some men, though the sexes sat apart, secretly crept in among the women and kissed them, the kissing the tablet of peace, as it is called, took the place of the kiss of peace. A holy kiss, therefore, is not one that is heathen, carnal, fraudulent, but one that is devout, pure, and sincere, as a Christian’s should be (Chrysostom). Cf. S. Augustine (Serm. 83 de Diversis ) and Baronius (Annals, a.d. 45). The author of the work “ on Friendship,” included among the writings of S. Augustine, gives four reasons why 208 SECOND EPISTLE TO THE this holy kiss is given : (i.) as a sign of reconciliation between those who have been enemies ; (2.) in sign of peace, as in the sacrifice of the Mass ; (3.) m sign of joy and of renewed love, as when a friend returns after a long absence; (4.) in sign of Catholic communion, as when a guest is welcomed with a kiss. But in all such matters the custom of the place is to be followed, and care must be taken that this kiss do not degenerate into a merely sensual delight”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Greet one another with an holy kiss. See Gill on Rom 16:16. . 2 Corinthians 13:13 co2 13:13 co2 13:13 co2 13:13All the saints salute you. Being all interested in the same divine favour, redeemed by the same blood, and sanctified by the same grace, they have a common concern for each other's welfare; See Gill on Rom 16:16.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“Greet one another with a holy kiss - Use every means by which a good understanding may be brought about. Let the spirit of friendship live among you, and encourage its continuance by every friendly act. See the note on Rom 16:16.”
1849
A.D.
1774–1849
“This was customary with both Jews and Persians, as we learn from Xenophon and Herodotus, and with other oriental nations. And in process of time, from the custom of common life, it was introduced into ecclesiastial assemblies. The ancients were in the habit before they began their meal to embrace each other, to manifest by that sign their mutual cordiality and friendship; then they contributed their alms, that they might give a substantial proof of what was represented by their kiss of charity. (Pastorini)”
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.