In this parashah, the Torah continues to describe the methods of purification for skin lesions and also when corrosive blotches appear on the walls of houses or on clothing. The biblical text uses the same word in both cases, tzaraat. Maimonides explains (Mishneh Torah, Hilchot Negaim, 16: 13-19) that skin lesions are natural, bodily reactions in those who defame and slander, while deteriorations on material objects are supernatural phenomena. But they are always the result of the same corrosive action against others.
The relationship between the corporeal tzaraat and transgressive behavior is explicitly found in the cases of Miriam (Numbers 12; Deuteronomy 24:9), who was punished with tzaraat, for having spoken badly about her brother Moses; of Jeroboam, king of Israel, for having introduced paganism into his kingdom (1 Kings 13: 4-6); and of Uzziah, king of Judah, for his arrogance (2 Chronicles 26: 18-21).
The prophet Ezekiel (36: 16-38) declares that the land of Israel itself became impure because of the evil conduct of its inhabitants. But God would cause the people to be purified by the acts of justice and mercy they would perform once God replaced their hearts of stone with hearts of flesh.
It can be concluded from these parashot that destructive actions against others lead to self-destructive reactions, both in the body as well as in surrounding objects. Although people could always be on watch for such indications, the fragility of memory, personal ambition and baser instincts can quickly make people forget to pay heed to them.
Shabbat Shalom!