1 Now the publicans and sinners drew near unto him to hear him.
Gloss: That is, those who collect or farm the public taxes, and who make a business of following after worldly gain.
Ambrose: Thou hadst learnt by what went before not to be occupied by the business of this world, not to prefer transitory things to eternal. But because the frailty of man can not keep a firm step in so slippery a world, the good Physician has shewn you a remedy even after falling; the merciful Judge has not denied the hope of pardon.
Theophylact: This was His wont, for the sake whereof He had taken upon Him the flesh, to receive sinners as the physician those that are sick.
2 And the Pharisees and the scribes murmured, saying: This man receiveth sinners, and eateth with them.
Gregory: True justice feels compassion, false justice scorn, although the just are wont rightly to repel sinners. But there is one act proceeding from the swelling of pride, another from the zeal for discipline. For the just, though without they spare not rebukes for the sake of discipline, within cherish sweetness from charity. In their own minds they set above themselves those whom they correct, whereby they keep both them under by discipline, and themselves by humility. But, on the contrary, they who from false justice are wont to pride themselves, despise all others, and never in mercy condescend to the weak; and thinking themselves not to be sinners, are so much the worse sinners.
3 And he spoke to them this parable, saying:
Ambrose: St. Luke has given three parables successively; the sheep which was lost and found [Luke 15:4-7], the piece of silver which was lost and found [vv. 8-10], the son who was dead and came to life again [vv. 11-32], in order that invited by a threefold remedy, we might heal our wounds. Christ as the Shepherd bears thee on His own body, the Church as the woman seeks for thee, God as the Father receives thee, the first, pity, the second, intercession, the third, reconciliation.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. III (London: Rivington, 1843).