Leviticus 13:13

Overview - Leviticus 13
The laws and tokens whereby the priest is to be guided in discerning the leprosy.
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Leviticus 13:13  (King James Version)
Then the priest shall consider: and, behold, if the leprosy have covered all his flesh, he shall pronounce him clean that hath the plague: it is all turned white: he is clean.

if the leprosy
It may seem strange that the partial leper should be 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 being contagious, the total not. That there are two different species, or degrees, of the disease described here, is sufficiently evident: in one, the person 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 was deemed unclean, or 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 constitution by means of the absorbent vessels; but where the surface was perfectly dry; the absorbent vessels of another, coming in contact with the diseased man, could imbibe nothing, and there was consequently but little or no danger of infection. This is the learned Dr. Mead's view of the subject; who thus accounts for the circumstances mentioned in the text.

he is clean
Isaiah 64:6 ; John 9:41