In this chapter, the LORD shares with Moses the process for identification and treatment of skin diseases and mold in garments.
This chapter is an interesting change of pace from what we have been reading. While early Leviticus is devoted to the laws governing ceremonial offerings, we are now reading a set of rules for how to identify skin diseases. This is rather unexpected, to me at least. It seems strange that this would be in the book of priestcraft, but as we can see, the priests are responsible for identifying skin diseases. Once again, this shows that the role of the priest is steadily expanding beyond simply maintaining the tabernacle and offering sacrifices. Expanding might not be the right word, since all of these books were probably written contemporaneously, but it's hard to deny that they are steadily accruing more responsibilities as move away from their simple appointment back in Ex 28.
Anyway, it's now clear that the priests are also supposed to be doctors. This seems fitting to me, given the variegated nature of the Mosaic law, which itself traverses many realms of life.
This chapter further supports what I call the "desert living" hypothesis, which is that many of the ceremonial laws of Leviticus are designed to teach the new nation of Israel how to survive through their desert wanderings while heading to the promised land. It is easy to explain this chapter as the LORD establishing laws of hygiene, since it so obviously relates to communicable diseases. From this, we can infer that chapter 12 (motherhood laws) and possibly even chapter 11 (food laws) were also predominantly interested in preventing disease or otherwise assisting the Israelites as they become a newly independent nation.
Throughout this chapter, the Hebrew word used to describe the skin diseases and mold is Hebrew "tsaraath", literally "mark" or "stroke"; figuratively, "blow" or "infliction". The traditional translation of "tsaraath" is leprosy, based on the Septuagint, and that's how the KJV translated it. The NASB inherited the KJV translation in this instance, even though a more thorough investigation shows that tsaraath is not specifically describing leprosy as we understand it today. Other bible translations call it a "leprous disease" (Amp, ESV), a "serious skin disease" (Message), a "defiling skin disease" (NIV), etc. To my surprise, there is an entire wikipedia page devoted to this term, which contains a tremendous amount of information about what it means and how it is treated by various authorities.
In this chapter, "tsaraath" is broadly used to mean an "infliction" upon both people's bodies and clothing (and later, homes). From our perspective, this blurs the distinction between infectious skin diseases and mold, but from the author's perspective, these are all "infectious surface diseases", so bundling them makes sense from that point of view.
I'm not going to discuss the processes of how skin diseases are to be identified and quarantined, because it's relatively straightforward and should be easy for most people to understand. In broad terms, we can see that the priest generally isolates his patient for seven days, observing for any change or growth in the "mark", which would indicate that it is an active infection and not a scar or whatever. If the person is infected, then they are unclean and are sent out of the camp. This seems like a fairly rational approach to communicable diseases, and doesn't seem to have any religious content other than the role of the priest-as-doctor. There are a few details that I would like to highlight however.
The first is in verses 12 and 13, which is that if the skin disease spreads over a man's whole body so that he is entirely covered, then he is clean. This is pretty hard to explain, since one would think being entirely infected would make the patient extremely infectious. Some commentaries suggest that the white stuff covering a person is not the infectious part, but rather that the most infectious part of the illness is the "raw flesh". I don't know enough about the disease to comment (indeed, the disease being described here is unclear).
The "spiritual" explanations for this verse generally note that being totally covered in white stuff is a metaphor for fullness of sin, or awareness of total depravity. Being aware of the fullness of sin in one's life, the patient is supposed to repent, and thus is declared clean. I'm a bit skeptical of this logic myself. Though I think it's fair to compare this skin disease as a metaphor for sin, going from there to "he is clean" seems like a big stretch, since the text simply says that the person is clean without having to take any particular action. It is simply by being fully covered in "leprosy", with the examination of the priest, that he becomes clean.
The next detail I would like to highlight is how a person is isolated if they are unclean, in v. 45-46. I would like to first point out that we are only told this is the process for "the leper who has the infection", and so this doesn't necessarily apply to other types of impurity (such as the post-birth bleeding of Lev 12). Still, we can see the difficulty of having an infectious skin disease: the person is forced to live outside the camp, shouting a warning to all those who come near that he is ritually impure, both because he is clinically infectious and because ritual impurity is transmissible as well, as I have previously emphasized. Being ejected from the community must have been difficult, but it was also temporary: upon being healed of the condition, the person could return to the camp. This is not meant as a punishment; the emphasis is clearly on protecting the integrity of the community.
The diagnosis of moldy garments is similar to the diagnosis of skin diseases with a series of examinations and quarantines. Unlike for people, the final result of "leprous" garments is destruction because a moldy garment is probably cheaper to destroy than to cure (if a cure is even possible). I don't expect my readers to have a hard time understanding this section.
Next chapter, we will learn what are the rituals for "cleansing" a cured person.