The priest is here instructed what judgment to make if there was any appearance of a leprosy, either, 1. In an old ulcer, or bile, that has been healed, Lev 13:18, etc. When old sores, that seemed to be cured, break out again, it is to be feared there is a leprosy in them; such is the danger of those who, having escaped the pollutions of the world, are again entangled therein and overcome. Or, 2. In a burn by accident, for this seems to be meant, Lev 13:24, etc. The burning of strife and contention often proves the occasion of the rising up and breaking out of that corruption which witnesses to men's faces that they are unclean. 3. In a scall-head. And in this commonly the judgment turned upon a very small matter. If the hair in the scall was black, it was a sign of soundness; if yellow, it was an indication of a leprosy, Lev 13:30-37. The other rules in these cases are the same with those mentioned before. In reading of these several sorts of ailments, it will be good for us, 1. To lament the calamitous state of human life, which lies exposed to so many grievances. What troops of diseases are we beset with on every side! and they all entered by sin. 2. To give thanks to God if he has never afflicted us with any of these sores: if the constitution is healthful, and the body lively and easy, we are bound to glorify God with our bodies.

A plague upon the head or the beard - This refers to a disease in which, according to the Jews, the hair either on the head or the chin dropped out by the roots.

And in the seventh day the priest shall look on the plague,.... To see whether it has got any deeper, or spread any further, and has any hair growing in it, and of what colour, that he might be also able to judge whether it was a leprosy or not:

and, behold, if the scall spread not; was neither got into the flesh, nor larger in the skin:

and there be in it no yellow hair; that is, a thin yellow hair, for such only, as Ben Gersom observes, was a sign of leprosy in scalls, as in Lev 13:30; and the same writer observes, that "and" is here instead of "or", and to be read, "or there be in it no yellow hair"; since a scall was pronounced unclean, either on account of thin yellow hair, or on account of spreading:

and the scall be not in sight deeper than the skin; but be just as it was when first looked upon.

if the rising be white--This BRIGHT WHITE leprosy is the most malignant and inveterate of all the varieties the disease exhibits, and it was marked by the following distinctive signs: A glossy white and spreading scale, upon an elevated base, the elevation depressed in the middle, but without a change of color; the black hair on the patches participating in the whiteness, and the scaly patches themselves perpetually enlarging their boundary. Several of these characteristics, taken separately, belong to other blemishes of the skin as well; so that none of them was to be taken alone, and it was only when the whole of them concurred that the Jewish priest, in his capacity of physician, was to pronounce the disease a malignant leprosy. If it spread over the entire frame without producing any ulceration, it lost its contagious power by degrees; or, in other words, it ran through its course and exhausted itself. In that case, there being no longer any fear of further evil, either to the individual himself or to the community, the patient was declared clean by the priest, while the dry scales were yet upon him, and restored to society. If, on the contrary, the patches ulcerated and quick or fungous flesh sprang up in them, the purulent matter of which, if brought into contact with the skin of other persons, would be taken into the constitution by means of absorbent vessels, the priest was at once to pronounce it an inveterate leprosy. A temporary confinement was them declared to be totally unnecessary, and he was regarded as unclean for life [DR. GOOD]. Other skin affections, which had a tendency to terminate in leprosy, though they were not decided symptoms when alone, were: "a boil" (Lev 13:18-23); "a hot burning,"--that is, a fiery inflammation or carbuncle (Lev 13:24-28); and "a dry scall" (Lev 13:29-37), when the leprosy was distinguished by being deeper than the skin and the hair became thin and yellow.