Our parashah specifies the signs and discusses the laws of tzaraas, a supernatural disease that resembles natural diseases, but which can be told apart by signs described in the Torah. Ramban (v. 47) explains that when the Jewish people are righteous and the Divine presence rests amongst them, their bodies, clothes, and houses have a good appearance. If, however, the Jewish people are unworthy and the Divine presence leaves them, its absence is manifest in the form of ugly tzaraas. Tzaraas can only come when the Jewish people dwell in Eretz Yisrael because then the Divine presence rests to a greater degree and the effects of sin are more evident. The Kabbalists explain that tzaraas comes about when inner Divine energies depart from a body that is no longer worthy to host them (Shem MiShmuel, Tazria 5671; see also Rabbeinu Bachaye to 13:2).

Hashem finds it difficult to smite a person. He first inflicts one’s house with tzaraas, and if that warning does not suffice, He proceeds to inflict garments, and only if that measure fails He inflicts the body (Tanchuma §10). For the same reason, an infliction usually requires weeks of quarantine before it can be identified as tzaraas, to give the inflicted person time to repent and avoid the tzaraas. Even once a person has already been stricken with tzaraas, if he repents it will immediately become healed (Tanna D’vei Eliyahua §16).Since tzaraas is a means of helping the Jewish people to rectify their ways, we find that Hashem announced to the Jewish people that He would inflict them with tzaraas as if He were sharing good news (Midrash HaGadol 14:34).

Ramban explains that when Hashem wants to mark the clothes of a sinner with tzaraas, He will specifically do so upon a white garment where the mark is clearly tzaraas, and not upon a colored garment, where the mark might be attributed to a discoloration caused by the dye within the fabric. Thus, a colored garment is not subject to the impurityof tzaraas.

Tzaraas has many varieties. There are numerous shades of paleness, which indicate the loss of spiritual life and the severity of the sin. Some create restrictions that last for a week, some for two, and some for a lifetime. Some are revealed and some are hidden beneath clothing. Sometimes the inflicted person must leave the city and live in solitude, and sometimes he may remain. Hashem created the possibility for different levels of stringency corresponding to different levels of sinfulness (Hagahos Rabbi Elyashiv to Arachin 16a).

A person may be inflicted with tzaraas due to a severe violation of any one of the following sins: Lashon hara (evil speech), bloodshed, false oaths, sexual immorality, arrogance, theft, and miserliness (Arachin 16a; see also Tanchuma 14:2). Hashem rebukes a person by inflicting him with a type of tzaraas that alludes to the fault that he needs to correct (Maharsha to Arachin 16a). It is therefore possible for a person to infer the cause of his tzaraas based on its characteristics, as follows:

1. Miserliness: Tzaraas on one’s house corresponds to miserliness. As the Sages expound, when a person avoids lending items to others by claiming that he does not possess them, Hashem reveals that man’s miserliness by smiting his house with tzaraas, compelling him to remove all his possessions out to the street so that they will not become contaminated along with the house (Tanna D’vei Eliyahu §16; see also Tanchuma §10).
2. Theft: Tzaraas on one's clothing alludes to theft (ibid.; see also Arachin ibid.), for it suggests that he does not deserve to wear his own clothing as a punishment for taking away the property of others.
3. Lashon hara: Metzora is an acronym for motzi shem ra, a slanderer(Vayikra 16:1). This reflects the idea that the main cause of tzaraas is lashon hara (Sefer HaChinuch). Since a slanderer creates disunity and separation in society, he is inflicted with tzaraas on his body and becomes separated from society. The purification process involves chirping birds to remind the metzora to be careful even regarding chirp-like chatter since it often leads to harmful gossip.
4. False oaths: A person who cannot be trusted even when he takes an oath undermines the quality of society, which is built on trust, so he is stricken with bodily tzaraas as well (see Tanna D’vei Eliyahu ibid.). Gechazi’s skin was smitten with snow-white tzaraas when he swore falsely to Naaman. The Torah states that Hashem will not cleanse someone who swears falsely in His name (Shemos 20:7), and this may explain why Gechazi’s tzaraas lasted permanently.
5. Arrogance:One who acts arrogantly is stricken with bodily tzaraas (Tanna D’vei Eliyahu); he must live in solitude until he learns how to relate to others. Maharsha suggests that Karachas v’Gabachas,a type of tzaraas that appears on the scalp (the highest point of the body), corresponds to arrogance. King Uziah was smitten this way when he brazenly sought to take up the role of Kehunah and offer incense. The purification ritual for tzaraas involves wood from a cedar tree, which is tall, as well as hyssop and a thread, which are small, to indicate the penitent must henceforth humble his arrogant nature.
6. Bloodshed: When Yoav killed Avner, David cursed that tzaraas should fall upon “his head.” Maharsha sees this as an allusion to the type of tzaraas called “nesek,” which involves hair loss and skin discoloration that is not related to natural causes. We may note that one of the signs of a nesek is a pair of short reddish hairs (Onkelos),which may symbolize the redness of blood and a life cut short.
7. Sexual immorality: There is a type of tzaraas that appears on a burn or a boil. Alshich sees burn-tzaraas as an allusion to sexual immorality, because a verse states that anyone who sins in this matter will invariably suffer burning (Mishlei 6:28), presumably because it is caused by unbridled burning passion. We may suggest that boil-tzaraas alludes to the same sin, for we find that Pharaoh was punished with tzaraas of boils when he abducted Sarah, which also served to prevent him from sinning(Yalkut Shimoni §69).

*Nowadays, we are no longer worthy of Hashem rebuking us through tzaraas. Nevertheless, the Sages teach that if a person notices troubles coming upon him, he should scrutinize his deeds. Hashem is speaking to him (see Berachos 5a).