8 Let us beware therefore of saying anything about ourselves, for this renders us both odious with men and abominable to God. For this reason, the greater the good works we do, the less let us say of ourselves; this being the way to reap the greatest glory both with men and with God. Or rather, not only glory from God, but a reward, yea, a great recompense. Demand not therefore a reward that you may receive a reward. Confess yourself to be saved by grace, that He may profess Himself a debtor to you; and not for your good works only, but also for such rightness of mind. For when we do good works, we have Him debtor for our good works only; but when we do not so much as think we have done any good work, then also for this disposition itself; and more for this, than for the other things: so that this is equivalent to our good works. For should this be absent, neither will they appear great. For in the same way, we too, when we have servants, do then most approve them when, after having performed all their service with good will, they do not think they have done anything great. Wherefore, if you would make your good deeds great, do not think them to be great, and then they will be great.
It was in this way that the centurion also said, “I am not fit that you should enter under my roof;” because of this, he became worthy, and was “marvelled at” above all Jews. On this wise again Paul says, “I am not meet to be called an apostle;” because of this he became even first of all. So likewise John: “I am not meet to loose the latchet of His shoe;” because of this he was the “friend of the Bridegroom,” and the hand which he affirmed to be unworthy to touch His shoes, this did Christ draw unto His own head. So Peter too said, “Depart from me, for I am a sinful man;” because of this he became a foundation of the Church.
For nothing is so acceptable to God as to number one's self with the last. This is a first principle of all practical wisdom. For he that is humbled, and bruised in heart, will not be vainglorious, will not be wrathful, will not envy his neighbor, will not harbor any other passion. For neither when a hand is bruised, though we strive ten thousand times, shall we be able to lift it up on high. If therefore we were thus to bruise our heart likewise, though it were stirred by ten thousand swelling passions, it could not be lifted up, no, not ever so little. For if a man, by mourning for things pertaining to this life, drives out all the diseases of his soul, much more will he, who mourns for sins, enjoy the blessing of self-restraint.
Source: Homilies on the Gospel of St. Matthew (New Advent)