13:18-44 The priest is told what judgment to make, if there were any appearance of a leprosy in old sores; and such is the danger of those who having escaped the pollutions of the world are again entangled therein. Or, in a burn by accident, ver. 24. The burning of strife and contention often occasions the rising and breaking out of that corruption, which proves that men are unclean. Human life lies exposed to many grievances. With what troops of diseases are we beset on every side; and thy all entered by sin! If the constitution be healthy, and the body lively and easy, we are bound to glorify God with our bodies. Particular note was taken of the leprosy, if in the head. If the leprosy of sin has seized the head; if the judgment be corrupted, and wicked principles, which support wicked practices, are embraced, it is utter uncleanness, from which few are cleansed. Soundness in the faith keeps leprosy from the head.
9-37. 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" (Le 13:18-23); "a hot burning,"—that is, a fiery inflammation or carbuncle (Le 13:24-28); and "a dry scall" (Le 13:29-37), when the leprosy was distinguished by being deeper than the skin and the hair became thin and yellow.