In the skin thereof, was a boil - Scheuchzer supposes this and the following verse to speak of phlegmonic, erysipelatous, gangrenous, and phagedenic ulcers, all of which were subjected to the examination of the priest, to see whether they were infectious, or whether the leprosy might not take its origin from them. A person with any sore or disposition to contagion was more likely to catch the infection by contact with the diseased person, than he was whose skin was whole and sound, and his habit good.

The flesh also, in which, even in the skin thereof, was a boil,.... Or hot ulcer, by which, says Maimonides (n) you may understand any stroke by a stone, stick, or iron, or any other thing: and in the Misnah (o), it is asked, what is an ulcer (or boil)? a stroke by wood, stone, pitch, or hot water; all that is from the force of fire is an ulcer:
and is healed; by the use of medicine, and the part, in all appearance, as well and as sound as ever.
(n) In Misn. Negaim, c. 6. sect. 8. (o) Ib. c. 9. sect. 1.

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, Leviticus 13:24. 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.