Luke 5:8

But mystically, those whom Peter takes by his word, he claims not as his own booty or his own gift. Depart, he says, from me, O Lord. Fear not then also to ascribe what is thy own to the Lord, for what was His He has given to us.

Say thou also, Depart from me, for I am a sinful man, O Lord, that God may answer, Fear not. Confess thy sin, and the Lord will pardon thee. See how good the Lord is, who gives so much to men, that they have the power of making alive. As it follows, From henceforth thou shalt catch men.

(de Quaest. Ev. lib. ii. c. 2.) Or, Peter speaks in the character of the Church full of carnal men, Depart from me, for I am a sinful man. As if the Church, crowded with carnal men, and almost sunk by their vices, throws off from it, as it were, the rule in spiritual things, wherein the character of Christ chiefly shines forth. For not with the tongue do men tell the good servants of God that they should depart from them, but with the utterance of their deeds and actions they persuade them to go away, that they may not be governed by the good. And yet all the more anxiously do they hasten to pay honours to them, just as Peter testified his respect by falling at the feet of our Lord, but his conduct in saying, Depart from me.

For calling back to his consciousness the crimes he had committed, he is alarmed and trembles, and as being unclean, he believes it impossible he can receive Him who is clean, for he had learnt from the law to distinguish between what is defiled and holy.

For this reason also Peter, carried back to the memory of his former sins, trembles and is afraid. As an impure man, he does not dare to receive the one who is pure. His fear was praiseworthy, because he had been taught by the law to distinguish between the holy and the profane.

Mathois said, 'The nearer a man comes to God, the more he sees himself to be a sinner. Isaiah the prophet saw the Lord and knew himself to be wretched and unclean (Is. 6:5).'

When Simon Peter saw this, he fell at Jesus' knees, saying: Depart from me, for I am a sinful man, O Lord. For the carnal ones in the Church somehow repel the governance of the spiritual ones in whom the persona of Christ clearly shines. They do not say this with the voice of the tongue to the good ministers of God, to repel them, but they advise with the voice of their morals and deeds to withdraw, lest they be governed by the good ones, and the more vehemently as they show them honor. Yet, they admonish with their deeds to withdraw, just as Peter signified this honor falling at the feet of the Lord; but showed the morals in what he said: Depart from me, Lord, for I am a sinful man. However, since the Lord did not do this – He did not depart from them but led them to the shore with the drawn-up boats – it signifies that in good and spiritual men there should not be this will, to be so disturbed by the sins of the crowds that, to live as if more securely and peacefully, they abandon the ecclesiastical duty.

Peter was astonished at the divine gift, and the more he feared, the less did he now presume; as it is said, When Simon Peter saw it, he fell down at Jesus' knees, saying, Depart from me; for I am a sinful man, O Lord.

When Simon Peter saw this. After the instruction of the people and the working of the miracle, there follows the calling of Peter and the sons of Zebedee. For the perfection of which, four things are shown to have concurred, namely the humiliation of Peter, disposing him to grace; wonder, elevating him to understanding; the reassurance of Christ, establishing him in confidence; the imitation of the Master, leading him to perfect righteousness.

First, therefore, there is set forth the humiliation of Peter disposing him to grace, when it says: When Simon Peter saw this, he fell down at the knees of Jesus. From the miracle he had seen, he was humbled, by magnifying the divine majesty; and rightly so, because in Philippians chapter two, "at the name of Jesus every knee should bow," etc.; and Isaiah chapter forty-five: "Every knee shall bow to me, and every tongue shall swear." And Peter did this as if inviting others to do likewise, so that he might say that word of the Psalm: "Come, let us adore and fall down," etc.

He was also humbled by recoiling into his own littleness; whence he adds: Saying: Depart from me, Lord, for I am a sinful man, as if to say: I am not such that I am worthy to be together with you. He said this from faith and reverence, just as that centurion in Matthew chapter eight: "Lord, I am not worthy that you should enter under my roof." But Peter said this because he saw the power and did not perceive the clemency, by which he said in Matthew chapter nine: "I came not to call the just, but sinners." Whence Augustine says: "Peter speaks as a fisherman: he had God and the Lord of salvation with him and was saying: Depart from me—as if a sick man were to say to a physician wishing to cure him: withdraw from me, for I am ill." And Gregory says: "Peter, on the contrary, if you consider yourself a sinner, it is needful that you not drive the Lord from you." But certainly by humbling himself thus he was not driving him away, but drawing him near: Isaiah the last chapter: "To whom shall I look, but to the poor and contrite in spirit and him who trembles at my words?"