In the book of Leviticus, there are three primary sources of impurity that are addressed: corpses/carcasses, scale disease, and genital discharges. What is the rationale for focusing on these three sources?
This rationale comes to light once it is perceived that there is a common denominator to the three above-mentioned sources of impurity – death. Genital discharge from the male is semen, and from the female, blood. They represent the life force; their loss represents death…. So too the few varieties of scale disease afflicting the human body: their appearance is that of approaching death.
[The dietary laws also] serve a larger, extrinsic purpose…animal life is inviolable except for a few edible animals, provided they are slaughtered properly (i.e., painlessly) and their blood (i.e., their life) is drained and thereby returned to God.
Because impurity and holiness are antonyms, the identification of impurity with death must mean that holiness stands for life…. The quintessential source of holiness resides with God, and therefore Israel is enjoined to control the occurrence of impurity lest it impinge on his realm. The forces pitted against each other in a cosmic struggle are no longer the benevolent and the demonic deities who populate the mythologies of Israel’s neighbors, but the forces of life and death set loose by persons themselves through their obedience to or defiance of God’s commandments. (Milgrom, Leviticus)
Milgrom identifies holiness (kedushah) as life force. Tamara Eskenazi sees it more as an extremely powerful and potentially dangerous force, which she likened to nuclear energy. Like nuclear energy, it can be a great force for good, but it also is dangerous if improperly approached. Impurity is thus not necessarily the domain of death but more like a “spill” which must be cleaned up. One of the korbanot (near-offerings, or more commonly sacrifices) called a chatat offering acts as purification, cleaning up the spill. Another korban, the asham offering, repairs the damage done by the spill.