So infinitely important is the doctrine of being convinced of a leprous state, and of the impossibility of being cleansed by anything short of divine power; that the HOLY GHOST prosecutes in these verses the same subject. The leper is here shown the dreadful state of being shut out, while the disease remained uncured, from all civil or religious communion. And as an evidence that he himself is conscious of it, he is continually to keep in mind and as frequently to cry out, by way of deterring any from approaching him, unclean, unclean. And what was all this designed to show, but that, in a gospel sense, when the heart is thoroughly awakened by almighty grace, to a knowledge of its own sinfulness and loathsomeness before GOD, to manifest by retirement from the world, and lying low in the dust under a deep sense of humiliation, that the unhumbled heart is at length subdued, and the man accepts the punishment of his iniquity. Covering the upper lip, renting the clothes, dwelling alone, and walking with the head bare; all these are so many outward signs, of an inward sorrow of soul. The church is represented as speaking this language of penitence by the prophet, when confessing we are all as an unclean thing. Isaiah 64:6.
Leviticus 13:38-46
38 If a man also or a woman have in the skin of their flesh bright spots, even white bright spots;
39 Then the priest shall look: and, behold, if the bright spots in the skin of their flesh be darkish white; it is a freckled spot that groweth in the skin; he is clean.
40 And the man whose hair is fallen off his head, he is bald; yet is he clean.
41 And he that hath his hair fallen off from the part of his head toward his face, he is forehead bald: yet is he clean.
42 And if there be in the bald head, or bald forehead, a white reddish sore; it is a leprosy sprung up in his bald head, or his bald forehead.
43 Then the priest shall look upon it: and, behold, if the rising of the sore be white reddish in his bald head, or in his bald forehead, as the leprosy appeareth in the skin of the flesh;
44 He is a leprous man, he is unclean: the priest shall pronounce him utterly unclean; his plague is in his head.
45 And the leper in whom the plague is, his clothes shall be rent, and his head bare, and he shall put a covering upon his upper lip, and shall cry, Unclean, unclean.
46 All the days wherein the plague shall be in him he shall be defiled; he is unclean: he shall dwell alone; without the camp shall his habitation be.