Dominica XIII post Pentecosten: "Go, show yourselves unto the priests."

From the Holy Gospel according to Luke
Luke 17:11-19
It came to pass, as Jesus went to Jerusalem, that He passed through the midst of Samaria and Galilee. And, as He entered into a certain village, there met Him ten men that were lepers. And so on.

Homily by St. Augustine, Bishop of Hippo
Bk. ii. Gospel Questions, ch. 40.

"The ten lepers 'lifted up their voices and said: Jesus, Master, have mercy on us.' And when He saw them, He said unto them 'Go, show yourselves unto the Priests'. And it came to pass that, as they went, they were cleansed." Question why did the Lord send them unto the Priests, that, as they went, they might be cleansed. Lepers were the only class among those upon whose bodies He worked mercy, whom we find that He sent unto the Priests. It is written in another place that He said to a leper whom He had cleansed: 'Go, and show thyself to the Priest, and offer for thy cleansing according as Moses commanded, for a testimony unto them' Luke v. 14, Lev. xiv. seq. We ask then, of what leprosy was a type, whereof they that were ridded were called, not 'healed,' but 'cleansed.' It is a disease which doth first appear in the skin, but destroyeth not immediately the strength, nor the use of feeling and the limbs.

"The lepers maybe taking mystically for those who, having no knowledge of the true faith, profess various erroneous doctrines. For they do not conceal their ignorance, but blazen it forth as the highest wisdom, making a vain show of it with boasting words. But since leprosy is a blemish in color, when true things appear clumsily mixed up with false in a single discourse or narration, as in the color of a single body, they represent a leprosy streaking in disfiguring as it were with true and false dyes the color of the human form. Now these lepers must be so put away from the church being as far removed as possible they may with the loud shouts call upon Christ.  But by either calling him teacher I think it is playing the implied the leprosy is truly the false doctrine which the good teacher may wash away.

"Now we find that of those upon whom our Lord bestowed bodily mercies, not one did He send to the priests, save the lepers, for the Jewish priesthood was a figure of that priesthood which is in the Church. All vices our Lord corrects and heals by His own power working inwardly in the conscience, but the teaching of infusion by means of the Sacrament, or of catechizing by word of mouth, was assigned to the Church.

"And as they went they were cleansed; just as the Gentiles to whom Peter came, having not yet received the sacrament of baptism, whereby we come spiritually to the priests, are declared cleansed by the infusion of the Holy Spirit. Whoever then follows true and sound doctrine in the fellowship of the Church,  proclaiming himself to be free from the confusion of lies, as it were a leprosy, yet still  ungrateful to his Cleanser does not prostrate himself with pious humility of thanksgiving, is like to those of whom the Apostle says, 'that when they knew God, they glorified him not as God, nor were thankful.'"