Catena Aurea by St. Thomas Aguinas
CHAP. 12
12:49–53
49. I am come to send fire on the earth; and what will I, if it be already kindled?
50. But I have a baptism to be baptized with; and how am I straitened till it be accomplished!
51. Suppose ye that I am come to give peace on earth? I tell you, Nay; but rather division:
52. For from henceforth there shall be five in one house divided, three against two, and two against three.
53. The father shall be divided against the son, and the son against the father; the mother against the daughter, and the daughter against the mother; the mother in law against her daughter in law, and the daughter in law against her mother in law.
AMBROSE.
To stewards, that is, to Priests, the preceding words seem to have been addressed, that they may thereby know that hereafter a heavier punishment awaits them, if, intent upon the world’s pleasures, they have neglected the charge of their Lord’s household, and the people entrusted to their care. But as it profiteth little to be recalled from error by the fear of punishment, and far greater is the privilege of charity and love, our Lord therefore kindles in men the desire of acquiring the divine nature, saying, I came to send fire on earth, not indeed that He is the Consumer of good men, but the Author of good will, who purifies the golden vessels of the Lord’s house, but burns up the straw and stubble.
CYRIL OF ALEXANDRIA. 
Now it is the way of holy Scripture to use sometimes the term fire, of holy and divine words. For as they who know how to purify gold and silver, destroy the dross by fire, so the Saviour by the teaching of the Gospel in the power of the Spirit cleanses the minds of those who believe in Him. This then is that wholesome and useful fire by which the inhabitants of earth, in a manner cold and dead through sin, revive to a life of piety.
CHRYSOSTOM. 
For by the earth He now means not that which we tread under our feet, but that which was fashioned by His hands, namely, man, upon whom the Lord pours out fire for the consuming of sins, and the renewing of souls.
TITUS BOSTRENSIS. And we must here believe that Christ came down from heaven. For if He had come from earth to earth, He would not say, I came to send fire upon the earth.
CYRIL OF ALEXANDRIA.
But our Lord was hastening the kindling of the fire, and hence it follows, And what will I, save that it be kindleda? (nisi ut accendatur) For already some of the Jews believed, of whom the first were the holy Apostles, but the fire once lighted in Judæa was about to take possession of the whole world, yet not till after the dispensation of His Passion had been accomplished. Hence it follows, But I have a baptism to be baptized with. For before the holy cross and His resurrection from the dead, in Judæa only was the news told of His preaching and miracles; but after that the Jews in their rage had slain the Prince of life, then commanded He His Apostles, saying, Go and teach all nations. (Matt. 28:19.)
GREGORY. (in Ezech. lib. i. Hom. 2.) 
Or else, fire is sent upon the earth, when by the fiery breath of the Holy Spirit, the earthly mind has all its carnal desires burnt up, but inflamed with spiritual love, bewails the evil it has done; and so the earth is burnt, when the conscience accusing itself, the heart of the sinner is consumed in the sorrow of repentance.
BEDE. 
But He adds, I have a baptism to be baptized with, that is, I have first to be sprinkled with the drops of My own Blood, and then to inflame the hearts of believers by the fire of the Spirit.
AMBROSE.
But so great was our Lord’s condescension, that He tells us He has a desire of inspiring us with devotion, of accomplishing perfection in us, and of hastening His passion for us; as it follows, And how am I straitened till it be accomplished?
BEDE.
Some manuscripts have, “And how am I anguished,” (coangor) that is, grieved. For though He had in Himself nothing to grieve Him, yet was He afflicted by our woes, and at the time of death He betrayed the anguish which He underwent not from the fear of His death, but from the delay of our redemption. For he who is troubled until he reaches perfection, is secure of perfection, for the condition of bodily affections not the dread of death offends him. For ho who has put on the body must suffer all things which are of the body, hunger, thirst, vexation, sorrow; but the Divine nature knows no change from such feelings. At the same time He also shews, that in the conflict of suffering consists the death of the body, peace of mind has no struggle with grief.
BEDE.
But the manner in which after the baptism of His passion and the coming of the spiritual fire the earth will be burnt, He declares as follows, Suppose ye that I am to give peace, &c.
CYRIL OF ALEXANDRIA.
What sayest thou, O Lord? Didst thou not come to give peace, Who art made peace for us? (Eph. 2:14.) making peace by Thy cross with things in earth and things in heaven; (Col. 1:20.) Who saidst, My peace I give unto you. (John 14:27.) But it is plain that peace is indeed a good, but sometimes hurtful, and separating us from the love of God, that is, when by it we unite with those who keep away from God. And for this reason we teach the faithful to avoid earthly bonds. Hence it follows, For from henceforth there shall be five in one house divided, three against two, &c.
AMBROSE.
Though the connexion would seem to be of six persons, father and son, mother and daughter, mother in law and daughter in law, yet are they five, for the mother and the mother in law may be taken as the same, since she who is the mother of the son, is the mother in law of his wife.
CHRYSOSTOM. (non occ.)
Now hereby He declared a future event, for it so happened in the same house that there have been believers whose fathers wished to bring them to unbelief; but the power of Christ’s doctrines has so prevailed, that fathers were left by sons, mothers by daughters, and children by parents. For the faithful in Christ were content not only to despise their own, but at the same time also to suffer all things as long as they were not without the worship of their faith. But if He were mere man, how would it have occurred to Him to conceive it possible that He should be more loved by fathers than their children were, by children than their fathers, by husbands than their wives, and they too not in one house or a hundred, but throughout the world? And not only did he predict this, but accomplish it in deed.
AMBROSE.
Now in a mystical sense the one house is one man, but by two we often mean the soul and the body. But if two things meet together, each one has its part; there is one which obeys, another which rules. But there are three conditions of the soul, one concerned with reason, another with desire, the third with anger. Two then are divided against three, and three against two. For by the coming of Christ, man who was material became rational. We were carnal and earthly, God sent His Spirit into our hearts, and we became spiritual children. (Gal. 4:6.) We may also say, that in the house there are five others, that is, smell, touch, taste, sight, and hearing. If then with respect to those things which we hear or see, separating the sense of sight and hearing, we shut out the worthless pleasures of the body which we take in by our taste, touch, and smell, we divide two against three, because the mind is not carried away by the allurements of vice. Or if we understand the five bodily senses, already are the vices and sins of the body divided among themselves. The flesh and the soul may also seem separated from the smell, touch, and taste of pleasure, for while the stronger sex of reason is impelled, as it were, to manly affections, the flesh strives to keep the reason more effeminate. Out of these then there spring up the motions of different desires, but when the soul returns to itself it renounces the degenerate offspring. The flesh also bewails that it is fastened down by its desires (which it has borne to itself,) as by the thorns of the world. But pleasure is a kind of daughter in law of the body and soul, and is wedded to the motions of foul desire. As long then as there remained in one house the vices conspiring together with one consent, there seemed to be no division; but when Christ sent fire upon the earth which should burn out the offences of the heart, or the sword which should pierce the very secrets of the heart, then the flesh and the soul renewed by the mysteries of regeneration cast off the bond of connection with their offspring. So that parents are divided against their children, while the intemperate man gets rid of his intemperate desires, and the soul has no more fellowship with crime. Children also are divided against parents when men having become regenerate renounce their old vices, and younger pleasure flies from the rule of piety, as from the discipline of a strict house.
BEDE.
Or in another way. By three are signified those who have faith in the Trinity, by two the unbelievers who depart from the unity of the faith. But the father is the devil, whose children we were by following him, but when that heavenly fire came down, it separated us from one another, and shewed us another Father who is in heaven. The mother is the Synagogue, the daughter is the Primitive Church, who had to bear the persecution of that same synagogue, from whom she derived her birth, and whom she did herself in the truth of the faith contradict. The mother in law is the Synagogue, the daughter in law the Gentile Church, for Christ the husband of the Church is the son of the Synagogue, according to the flesh. The Synagogue then was divided both against its daughter in law, and its daughter, persecuting believers of each people. But they also were divided against their mother in law and mother, because they wished to abolish the circumcision of the flesh.