I.Concerning the plague of leprosy we may observe in general, 1. That it was rather an uncleanness than a disease; or, at least, so the law considered it, and therefore employed not the physicians but the priests about it. Christ is said to cleanse lepers, not to cure them. We do not read of any that died of the leprosy, but it rather buried them alive, by rendering them unfit for conversation with any but such as were infected like themselves. Yet there is a tradition that Pharaoh, who sought to kill Moses, was the first that ever was struck with this disease, and that he died of it. It is said to have begun first in Egypt, whence it spread into Syria. It was very well known to Moses, when he put his own hand into his bosom and took it out leprous. 2. That it was a plague inflicted immediately by the hand of God, and came not from natural causes, as other diseases; and therefore must be managed according to a divine law. Miriam's leprosy, and Gehazi's, and king Uzziah's, were all the punishments of particular sins: and, if generally it was so, no marvel there was so much care taken to distinguish it from a common distemper, that none might be looked upon as lying under this extraordinary token of divine displeasure but those that really were so. 3. That it is a plague not now known in the world; what is commonly called the leprosy is of a quite different nature. This seems to have been reserved as a particular scourge for the sinners of those times and places. The Jews retained the idolatrous customs they had learnt in Egypt, and therefore God justly caused this with some others of the diseases of Egypt to follow them. Yet we read of Naaman the Syrian, who was a leper, Kg2 5:1. 4. That there were other breakings-out in the body which did very much resemble the leprosy, but were not it, which might make a man sore and loathsome and yet not ceremonially unclean. Justly are our bodies called vile bodies, which have in them the seeds of so many diseases, by which the lives of so many are made bitter to them. 5. That the judgment of it was referred to the priests. Lepers were looked upon as stigmatized by the justice of God, and therefore it was left to his servants the priests, who might be presumed to know his mark best, to pronounce who were lepers and who were not. All the Jews say, "Any priest, though disabled by a blemish to attend the sanctuary, might be a judge of the leprosy, provided the blemish were not in his eye. And he might" (they say) "take a common person to assist him in the search, but the priest only must pronounce the judgment." 6. That it was a figure of the moral pollution of men's minds by sin, which is the leprosy of the soul, defiling to the conscience, and from which Christ alone can cleanse us; for herein the power of his grace infinitely transcends that of the legal priesthood, that the priest could only convict the leper (for by the law is the knowledge of sin), but Christ can cure the leper, he can take away sin. Lord, if thou wilt, thou canst make me clean, which was more than the priests could do, Mat 8:2. Some think that the leprosy signified, not so much sin in general as a state of sin, by which men are separated from God (their spot not being the spot of God's children), and scandalous sin, for which men are to be shut out from the communion of the faithful. It is a work of great importance, but of great difficulty, to judge of our spiritual state: we have all cause to suspect ourselves, being conscious to ourselves of sores and spots, but whether clean or unclean is the question. A man might have a scab (Lev 13:6) and yet be clean: the best have their infirmities; but, as there were certain marks by which to know that it was a leprosy, so there are characters of such as are in the gall of bitterness, and the work of ministers is to declare the judgment of leprosy and to assist those that suspect themselves in the trial of their spiritual state, remitting or retaining sin. And hence the keys of the kingdom of heaven are said to be given to them, because they are to separate between the precious and the vile, and to judge who are fit as clean to partake of the holy things and who as unclean must be debarred from them.

II.Several rules are here laid down by which the judgment of the priest must be governed. 1. If the sore was but skin-deep, it was to be hoped it was not the leprosy, Lev 13:4. But, if it was deeper than the skin, the man must be pronounced unclean, Lev 13:3. The infirmities that consist with grace do not sink deep into the soul, but the mind still serves the law of God, and the inward man delights in it, Rom 7:22, Rom 7:25. But if the matter be really worse than it shows, and the inwards be infected, the case is dangerous. 2. If the sore be at a stay, and do not spread, it is no leprosy, Lev 13:4, Lev 13:5. But if it spread much abroad, and continue to do so after several inspections, the case is bad, Lev 13:7, Lev 13:8. If men do not grow worse, but a stop be put to the course of their sins and their corruptions be checked, it is to be hoped they will grow better; but if sin get ground, and they become worse every day, they are going downhill. 3. If there was proud raw flesh in the rising, the priest needed not to wait any longer, it was certainly a leprosy, Lev 13:10, Lev 13:11. Nor is there any surer indication of the badness of a man's spiritual state than the heart's rising in self-conceit, confidence in the flesh, and resistance of the reproofs of the word and strivings of the Spirit. 4. If the eruption, whatever it was, covered all the skin from head to foot, it was no leprosy (Lev 13:12, Lev 13:13); for it was an evidence that the vitals were sound and strong, and nature hereby helped itself, throwing out what was burdensome and pernicious. There is hope in the small-pox when they come out well: so if men freely confess their sins, and hide them not, there is no danger comparable to theirs that cover their sins. Some gather this from it, that there is more hope of the profane than of hypocrites. The publicans and harlots went into the kingdom of heaven before scribes and Pharisees. In one respect, the sudden breakings-out of passion, though bad enough, are not so dangerous as malice concealed. Others gather this, that, if we judge ourselves, we shall not be judged; if we see and own that there is no health in us, no soundness in our flesh, by reason of sin, we shall find grace in the eyes of the Lord. 5. The priest must take time in making his judgment, and not give it rashly. If the matter looked suspicious, he must shut up the patient seven days, and then seven days more, that his judgment might be according to truth. This teaches all, both ministers and people, not to be hasty in their censures, nor to judge any thing before the time. If some men's sins go before unto judgment, the sins of others follow after, and so men's good works; therefore let nothing be done suddenly, Ti1 5:22, Ti1 5:24, Ti1 5:25. 6. If the person suspected was found to be clean, yet he must wash his clothes (Lev 13:6), because he had been under the suspicion, and there had been in him that which gave ground for the suspicion. Even the prisoner that is acquitted must go down on his knees. We have need to be washed in the blood of Christ from our spots, though they be not leprosy-spots; for who can say, I am pure from sin? though there are those who through grace are innocent from the great transgression.

And the Lord spake unto Moses and unto Aaron,.... Aaron is addressed again, though left out in the preceding law, because the laws concerning leprosy chiefly concerned the priests, whose business it was to judge of it, and cleanse from it; and so Ben Gersom observes, mention is made of Aaron here, because to him and his sons belonged the affair of leprosies, to pronounce unclean or clean, to shut up or set free, and, as Aben Ezra says, according to his determination were all the plagues or strokes of a man, who should be declared clean or unclean:

saying; as follows.