The parashah deals with the laws of impurity (tumah) and purity (taharah) in relation to the metzora - the tzara'at sufferer.
Mishnah Taharot states that the most severe form of tumah is conveyed by a human corpse. Similarly, the white lesion on the skin of the metzora signals something has died or gone subtly wrong in the micro-systems of the body. The tumah of the menstruant woman (Leviticus 15:19) is caused by the disintegration of potential life in the natural destruction of the unfertilised egg; as male sperm cells carrying possible life, are lost in a seminal emission (15:10]. The abnormal genital flow of the zav (15:2-3) and zavah (15:25) manifests the tumah of impaired life force, perhaps sexually transmitted, or caused by the trauma of altered life state.
Maimonides looks beyond the physiology of tzara'at to its spiritual significance. "The Torah's reference to such discoloration of clothing or buildings and such pathology is not natural. It was a marvel and a sign to Israel to warn them away from lashon ha'ra, evil speech. One who would so speak would find the walls of his house discolouring. If he changed his ways, the house would recover" (Mishneh Torah, Hilchot Tumat Tzara'at, 16:10).
Bad-mouthing someone chokes the healthy flow of interpersonal life force, poisons our own spirituality and invokes tumah.
