If the leprosy have covered all his flesh, he shall pronounce him clean - Why is it that the partial leper was pronounced unclean, and the person totally covered with the disease clean? This was probably owing to a different species or stage of the disease; the partial disease was contagious, the total not contagious. That there are two different species or degrees of the same disease described here, is sufficiently evident. In one, the body was all covered with a white enamelled scurf; in the other, there was a quick raw flesh in the risings. On this account the one might be deemed unclean, i. e., contagious, the other not; for contact with the quick raw flesh would be more likely to communicate the disease than the touch of the hard dry scurf. The ichor proceeding from the former, when brought into contact with the flesh of another, would soon be taken into the constitution by means of the absorbent vessels; but where the whole surface was perfectly dry, the absorbent vessels of another person coming in contact with the diseased man could imbibe nothing, and therefore there was comparatively no danger of infection. Hence that species or stage of the disease that exhibited the quick raw rising was capable of conveying the infection for the reasons already assigned, when the other was not. Dr. Mead thus accounts for the circumstance mentioned in the text. See on Leviticus 13:18 (note). As the leprosy infected bodies, clothes, and even the walls of houses, is it not rational to suppose that it was occasioned by a species of animalcula or vermin burrowing under the skin? Of this opinion there are some learned supporters.

Then the priest shall consider,.... Look wistly upon it, and well weigh the matter in his own mind, that he may make a true judgment and pronounce a right sentence:

and, behold, if the leprosy have covered all his flesh; from head to foot, so that no quick, raw, or sound flesh appear in him:

he shall pronounce him clean that hath the plague; not clean from a leprosy he is covered with; but that he is free from pollution by it, and under no obligation to bring his offering, or to perform, or have performed on him any of the rites and ceremonies used in cleansing of the leper:

it is all turned white; his skin and flesh with white bright spots, scabs and swellings, and no raw and red flesh appears:

he is clean; in a ceremonial sense: this may seem strange, that one that had a bright spot, or a white swelling, or a scab that spreads, a single one of these, or here and there one, should be unclean, and yet, if covered over with them, should be clean; the reason in nature is, because this shows a good healthful inward constitution, which throws out all its ill humours externally, whereby health is preserved; as we see in persons that have the measles or smallpox, or such like distempers, if they stick in the skin, and only here and there one rises up in a tumour, and to an head, it is a bad sign; but if they come out kindly and well, though they cover the whole body, things are very promising: the mystical or spiritual meaning of this is, that when a man sees himself to be a sinful creature, all over covered with sin, and no part free, and disclaims all righteousness of his own to justify him before God, but wholly trusts to, and depends upon the grace of God for salvation, and the righteousness of Christ for his acceptance with God; he becomes clean through the grace of God and the blood and righteousness of Christ.

Then the priest shall consider: and, behold, if the leprosy have covered all his flesh, he shall pronounce him {e} clean that hath the plague: it is all turned white: he is clean.

(e) For it is not that contagious leprosy that infects, but a form of scales which does not leave the skin raw as leprosy does.

13:13 All his flesh - When it appeared in some one part it discovered the ill humour which lurked within, and withal the inability of nature to expel it; but when it overspread all, it manifested the strength of nature conquering the distemper, and purging out the ill humours into the outward parts.

13:1-17 The plague of leprosy was an uncleanness, rather than a disease. Christ is said to cleanse lepers, not to cure them. Common as the leprosy was among the Hebrews, during and after their residence in Egypt, we have no reason to believe that it was known among them before. Their distressed state and employment in that land must have rendered them liable to disease. But it was a plague often inflicted immediately by the hand of God. Miriam's leprosy, and Gehazi's, and king Uzziah's, were punishments of particular sins; no marvel there was care taken to distinguish it from a common distemper. The judgment of it was referred to the priests. And it was a figure of the moral pollutions of men's minds by sin, which is the leprosy of the soul, defiling to the conscience, and from which Christ alone can cleanse. The priest could only convict the leper, (by the law is the knowledge of sin,) but Christ can cure the sinner, he can take away sin. It is a work of great importance, but of great difficulty, to judge of our spiritual state. We all have cause to suspect ourselves, being conscious of sores and spots; but whether clean or unclean is the question. As there were certain marks by which to know it was leprosy, so there are marks of such as are in the gall of bitterness. The priest must take time in making his judgment. This teaches all, both ministers and people, not to be hasty in censures, nor to judge anything before the time. If some men's sins go before unto judgment, the sins of others follow after, and so do men's good works. If the person suspected were found to be clean, yet he must wash his clothes, because there had been ground for the suspicion. We have need to be washed in the blood of Christ from our spots, though not leprosy spots; for who can say, I am pure from sin?