Ambrosiaster : It is true, and no one is unaware of it, that if we consider honestly our acts and thoughts we find ourselves superior to no one and cannot easily pass judgment on another. For the person who is puffed up as if he were something special is misled, since he does not know that humility becomes a means of growth. For he does not have before his eyes the words and deeds of the Savior, who, though he be Lord of all, humbled himself so as to give us a pattern that we might follow should we wish to grow. If we were to exalt ourselves, we would stumble as a result of the ignorance of a heart elated by the hope of presuming to be more worthy of praise. — EPISTLE TO THE Galatians 6.4.1 Jerome : This [verse] can be read in two distinct ways.… The sense of the first is "If someone thinks he is something when he is nothing, he deceives himself." The second is deeper and more meaningful to me: "If someone thinks he is something, by the very fact of thinking himself something and judging himself, not from his love toward his neighbors but from his own work and labors, contented with his own virtue, he himself becomes nothing through this very arrogance and is his own deceiver." … The meaning of this passage is also linked to circumcision and the law in the following way: One who is spiritual yet has no compassion for his neighbor, despising the lowly because of his own self-elevation, is his own deceiver, not knowing that the spirit of the law adds up finally to loving one another. — EPISTLE TO THE Galatians 3.6.3 Jerome : (Verse 3) For if anyone thinks that they are something when they are nothing, they deceive themselves. If anyone does not want to bear the burdens of others, and is merciless, satisfied only with their own work and virtue, not seeking what is of others but what is their own, that is, a lover only of themselves and not of God, they deceive themselves. However, it can be read and distinguished in two ways: Either, if anyone thinks that they are something when they are nothing, or in this way: If anyone thinks that they are something, as we will explain later, when they are nothing, they deceive themselves. And this difference resonates more in Greek than in Latin. The first sense of this distinction is: Whoever considers themselves to be something, and is nothing, deceives themselves. The second sense is deeper, and is more pleasing to us: If someone considers themselves to be something, in that they think they are something, not out of kindness towards their neighbor, but out of their own work and effort, judging themselves only by their own virtue, this person, out of this very arrogance, becomes nothing, and deceives themselves: which is better expressed in Greek as φρεναπατᾷ, which means, they deceive their own mind: for which the Latin interpreter has used the phrase, they deceive themselves. But he deceives his own mind, who thinks himself wise, and according to Isaiah, he is wise in himself and understands in his own sight (Isa. V). The understanding of this passage is connected to circumcision and the Law: Whoever is spiritual and does not have mercy on his neighbor, despising the humble because he himself is higher, deceives himself, not knowing that this is the law of the spirit, that we should love one another. — Commentary on Galatians John Chrysostom : "For if a man thinketh himself to be something, when he is nothing, he deceiveth himself." Here again he reflects on their arrogance. He that thinks himself to be something is nothing, and exhibits at the outset a proof of his worthlessness by such a disposition. — Homily on Galatians 6 Oecumenius : "For if anyone seems to himself to be something," that alone is nothing of what he appears to be. Therefore he is deceiving himself in nothing. — [PHOTIUS] "he deceives his own mind." For if anyone were to approve his own work, and to examine himself exactly, he would have his boasting rather in himself and not against another; that is, he would have boasting against himself, or he would condemn himself, and not another: that is, seeing himself inferior and needy, he will accuse himself, and refrain from condemning others, since he will know that his conduct does not always observe the right way, but meanwhile even falls away from it. [end of the Photius excerpt] — — Commentary on Galatians