The book of Vayikra makes a sudden shift from the world of the Mishkan to the laws of purity (taharah) and impurity (tum’ah). In a sense, these are two sides of the same coin: Those who encounter tum’ah are banished from the Mishkan; we may say that tum’ah is the antithesis of what the Mishkan stands for. Therefore, a person in the state of tum’ah must separate from the place of holiness. What is this state of impurity? Where does it come from and how is it resolved? As is the case with many technical terms, translation can only produce an approximation of the concept we call tum’ah. In general terms, tum’ah may be associated with death or quasi-death experiences. Even childbirth generates tum’ah: Although it is the most basic, most immediate experience of life, childbirth is part of the cycle of mortality that is part and parcel of the human experience. The newborn child will, inevitable, inescapably, “suffer” from the same mortality that lies at the base of all tum’ah.
Similarly, if not somewhat strangely, a person who suffers from “living death,” from the physiological manifestation of the spiritual disease known as tzara’at (often lamely translated as leprosy) is considered more profoundly impure than a person who comes into contact with actual death. The leper is sequestered, quarantined, removed completely from all three concentric rings that made up the Israelite camp. Not only is the leper completely isolated, he or she must warn one and all of the affliction, alert everyone they encounter to keep a safe distance – by calling out “tameh! tameh!”. On the other hand, when a person dies, family members who became tameh in the course of the burial must leave the Mishkan, but the community comes to them. The mourners are not sequestered, not isolated. They are cared for, consoled and comforted, gently reintroduced into the community and, eventually, the sacred confines of the Mishkan. Not so lepers: Until they are completely healed, they remain personae non grata.
There is an unmistakable linguistic parallel that may bring this contrast into sharper focus. Describing the leper, the Torah states:
The … kohen must declare him unclean. When a person has the mark of the leprous curse, his clothing must be torn, he must go without a haircut, and he must cover his head down to his lips. ‘Tameh! Tameh!’ (Unclean! Unclean!) he must call out. As long as he has the mark, he shall remain unclean. Since he is unclean, he must remain alone, and his place shall be outside the camp. (Vayikra 13:44-46)
Some of the terms here are familiar to us from an earlier narrative: The sons of Aharon, Nadav and Avihu, died suddenly in the Mishkan itself, and Moshe instructs the family not to mourn:
Moshe said to Aharon and his sons, Elazar and Itamar, ‘Do not go without a haircut and do not tear your vestments; otherwise you will die, bringing Divine wrath upon the entire community. As far as your brothers are concerned, let the entire family of Israel mourn for those whom God burned. (Vayikra 10:5)
Here, then, is the inverse of the leper: The leper is completely estranged from the Mishkan and all of society, while the Kohen Gadol and his sons are commanded not to leave the Mishkan. The leper must comport himself like a mourner, letting his hair grow long and tearing his clothes, while Aharon’s family is forbidden to show any of these outward signs of mourning.
A concise comment in the Talmud may shed light on this inverse relationship. We noted above that the leper must call out and declare to all he is tameh (spiritually impure). The simple understanding of this behavior is pragmatic: The leper suffers from a severe spiritual malady, and his condition may be highly contagious – especially according to the Talmudic opinion that connects leprosy with speaking gossip (Erachin 16b). It becomes eminently clear why this person must be removed from society. Yet the Talmud sees the leper’s cry as something else altogether: The Talmud teaches that the leper’s cry “tameh, tameh” is, in fact, a call to anyone who hears his cries to pray for him (Shabbat 67a). The leper must ask the very people whom he may have slighted to show greatness of spirit, to forgive him, to have compassion and pray for him. The leper’s plea to his community serves to teach him to value the very people he had slandered, those for whom he had shown disregard and disrespect.
This contrasts starkly with Moshe’s instructions to Aharon and his remaining sons in their time of pain and mourning: The task with which they had been entrusted, the position of kohen, was not one they could walk away from. Aharon was given both the responsibility and the power to pray for the entire nation; he no longer had the luxury of private time. The Kohen Gadol is not only the representative of the people before God, he is also the servant of the people. Aharon would no longer have the luxury of “time off,” even to mourn his personal loss. Whereas the kohen embodies the greatness, the power and the holiness of the community, the leper is forced to beg the community to pray for him, teaching him to value his community as the first step towards reconciliation and rejoining the community.
For a more in-depth analysis see: http://arikahn.blogspot.co.il/2016/04/audio-and-essays-parashat-tazria.html