Here are excerpts from three sermons in which St. Augustine explored the richness of today's Gospel:

With this Psalm we have exhorted you to practice mercy, for that is how you will ascend, and you know that it those who sing the song of steps who ascend. Remember this: do not choose to go down and not to go up; think rather about going up. The one who went down from Jerusalem to Jericho fell among robbers. If he hadnt gone down, he wouldnt have fallen among them. Adam went down and fell among thieves, for we all are Adam. A priest went by and ignored him; a Levite went by and ignored him: the Law could not heal him. A certain Samaritan went by, that is, Our Lord Jesus Christ. It was said to him, "Are we not right to say that you are a Samaritan and have a devil?" He did not say, "I am not a Samaritan," but rather "I do not have a devil" (John 8:48-49). "Samaritan" means "Guardian," and if he had said, "I am not a Samaritan," he would have been saying, "I am not a guardian." And who else would guard us? "A Samaritan went by and took pity on him," as you know. He was lying wounded in the road because he had gone down. The Samaritan going by did not ignore us: he took care of us; he lifted us up onto his beast, in our flesh; he brought us to an inn, that is, to the Church; he entrusted us to the innkeeper, the Apostle; he gave him two denarii for our care, the love of God and the love of neighbor, for on these two commandments the entire Law and the prophets depend" (Mt 22:37-40).... If we have gone down and been wounded, let us now go up and make progress so that we may finally arrive. (Augustine, Enar. in Ps 125,15)The inn is the Church. Its an inn now because as long as we live we are on the way; it will be a house from which we will never move when we have been healed and reach the Kingdom of heaven. Meanwhile, let us gladly be healed in the inn; let us not boast of being healed while we are still ill. (Sermon 131, 6)Who is so distant and yet so near except the one who by his mercy became a neighbor to us? ... The man who went down was an Israelite.... The priest who passed by was a neighbor by birth or race, but he left the man lying there. The Levite who went by was also a neighbor by birth or race, but he too ignored the man lying there. A Samaritan came by, distant by birth, but a neighbor by mercy, and did what you know from the parable. ... The Lord is near, because he became a neighbor to us (Sermon 171, 1-2)