63 And inasmuch as the Lord is admonishing us in this passage with respect to rash and unjust judgment,— for He wishes that whatever we do, we should do it with a heart that is single and directed toward God alone; and inasmuch as, with respect to many things, it is uncertain with what intention they are done, regarding which it is rash to judge; inasmuch, moreover, as those parties especially judge rashly respecting things that are uncertain, and readily find fault, who love rather to censure and to condemn than to amend and to improve, which is a fault arising either from pride or from envy; therefore He has subjoined the statement: “And why do you behold the mote that is in your brother's eye, but considerest not the beam that is in your own eye?” So that if perchance, for example, he has transgressed in anger, you should find fault in hatred; there being, as it were, as much difference between anger and hatred as between a mote and a beam. For hatred is inveterate anger, which, as it were simply by its long duration, has acquired so great strength as to be justly called a beam. Now, it may happen that, though you are angry with a man, you wish him to be turned from his error; but if you hate a man, you cannot wish to convert him.
64. “Or how will you say to your brother, Let me pull out the mote out of your eye; and, behold, a beam is in your own eye? Thou hypocrite, first cast out the beam out of your own eye; and then shall you see clearly to cast out the mote out of your brother's eye;” i.e., first cast the hatred away from you, and then, but not before, shall you be able to amend him whom you love. And He well says, “Thou hypocrite.” For to make complaint against vices is the duty of good and benevolent men; and when bad men do it, they are acting a part which does not belong to them; just like hypocrites, who conceal under a mask what they are, and show themselves off in a mask what they are not. Under the designation hypocrites, therefore, you are to understand pretenders. And there is, in fact, a class of pretenders much to be guarded against, and troublesome, who, while they take up complaints against all kinds of faults from hatred and spite, also wish to appear counsellors. And therefore we must piously and cautiously watch, so that when necessity shall compel us to find fault with or rebuke any one, we may reflect first whether the fault is such as we have never had, or one from which we have now become free; and if we have never had it, let us reflect that we are men, and might have had it; but if we have had it, and are now free from it, let the common infirmity touch the memory, that not hatred but pity may go before that fault-finding or administering of rebuke: so that whether it shall serve for the conversion of him on whose account we do it, or for his perversion (for the issue is uncertain), we at least from the singleness of our eye may be free from care. If, however, on reflection, we find ourselves involved in the same fault as he is whom we were preparing to censure, let us not censure nor rebuke; but yet let us mourn deeply over the case, and let us invite him not to obey us, but to join us in a common effort.
65. For in regard also to what the apostle says—“Unto the Jews I became as a Jew, that I might gain the Jews; to them that are under the law, as under the law (not being under the law), that I might gain them that are under the law; to them that are without law, as without law (being not without law to God, but under the law to Christ), that I might gain them that are without law. To the weak became I as weak, that I might gain the weak: I am made all things to all men, that I might gain all,”— he did not certainly so act in the way of pretence, as some wish it to be understood, in order that their detestable pretence may be fortified by the authority of so great an example; but he did so from love, under the influence of which he thought of the infirmity of him whom he wished to help as if it were his own. For this he also lays as the foundation beforehand, when he says: “For although I be free from all men, yet have I made myself servant unto all, that I might gain the more.” And that you may understand this as being done not in pretence, but in love, under the influence of which we have compassion for men who are weak as if we were they, he thus admonishes us in another passage, saying, “Brethren, you have been called unto liberty; only use not liberty for an occasion to the flesh, but by love serve one another.” And this cannot be done, unless each one reckon the infirmity of another as his own, so as to bear it with equanimity, until the party for whose welfare he is solicitous is freed from it.
66. Rarely, therefore, and in a case of great necessity, are rebukes to be administered; yet in such a way that even in these very rebukes we may make it our earnest endeavour, not that we, but that God, should be served. For He, and none else, is the end: so that we are to do nothing with a double heart, removing from our own eye the beam of envy, or malice, or pretence, in order that we may see to cast the mote out of a brother's eye. For we shall see it with the dove's eyes—such eyes as are declared to belong to the spouse of Christ, whom God has chosen for Himself a glorious Church, not having spot or wrinkle, i.e. pure and guileless.
Source: Our Lord's Sermon on the Mount (New Advent)