"This will be the law of the leper on the day he is purified and he is brought to the priest." (Leviticus 14:2)
This could apply to any person who wants to return to G-d and purify himself. This main type of repentence is to return measure for measure. This means that he repents through the very thing that he sinned with, using those very things to serve G-d. Not every person is worthy to this level. If someone who is not able to actually do this attempts it it can sometimes cause problems. One has to worry that while he is trying to elavate those things which he sinned with earlier to the holiness of serving G-d he might, G-d forbid, fall back into his old sins. The Torah gives us advice that if a person wants to accomplish this he should attatch himself to a Tzaddik. This is because the Tzaddik is a true servant of G-d, and he fulfills G-d's Will even with physical objects. Furthermore, the Tzaddik does all of his actions with a connection to the entire Jewish people, lifting them up together with his own piety. This is how a person who is attatched to the Tzaddik is able to truly return to G-d, and can make a tikkun for all of the things with which he sinned to elavate them to holiness. This is the meaning of "on the day he is purified", which is a reference to repentance. Then "and he is brought to the priest" means that he is attatched to the Tzaddik. "And the priest should go outside the camp", meaning that the Tzaddik has the power to "go outside of the of the camp", meaning the Tzaddik can elavate even the lowest things in the world and use them to serve G-d. This is the was a person can fix all of the things he has sinned with, and perform complete repentance, measure for measure. This can only be done with certainty with the strength of the work of the Tzaddik. Futhermore, "and he shall go outside of the camp" means that the Tzaddik should see to it that this other person, who is trying to repent and purify himself, that he should follow the good straight path in all of his character traits, because if one serves G-d, through study and prayer, it is worthless unless he follows the good path in all of his character traits as well. This is the meaning of "and he shall go outside of the camp". He must know that he must be a servant of G-d even outside of the walls of the synagogue or yeshivah, by being of good character. "If the plague of leprosy is healed from the leper", meaning the person has repented fully and has turned all of his exterior traits as well as his interior also to goodness. Then "and the priest shall command that the one who is purified should take two pure, living birds." Rashi explains that this is because Biblical leprosy comes for the sin of speaking evil, slanderous talk, for he sins through words of chattering. Therefore he must bring a sacrifice of birds in order to be purified, because birds are constantly chirping. This means that the Tzaddik can fix him and teach him that all of his words, whether in prayer or Torah study, or whether in mundane activity, that they should all be on the level of "living birds", meaning that his speach should be imbued with the liveliness of holiness and purity. This is the reason for two living birds. The bird must be a "free bird" who can live both in a house or in a field. This hints to the fact that a person must be pious both in private matters and in public matters.
(Divrei Binah - Parshas Metzorah p. 44)
"When you come into the land of Canaan which I give to you to possess, I will place the plague of leprosy upon the houses of the land" (Leviticus 14:34)
Rashi teaches that this is good news, because when there are plagues on the walls of a house, the walls must be destroyed. The Amorites used to hide their treasures in the walls of their houses, so when the walls are destroyed the Israelites will find the gold and silver.
Elsewhere, Rashi teaches that plagues come upon the walls of a house on account of being miserly.
It would seem that these two teachings contradict one another. However, it seems that they are talking about two types of wealth, one coming from holiness and one coming from evil. Holy wealth is filled with a spirit of mercy, selflessly giving with an open and loving heart to one's fellow. When a person is worthy to have holy wealth, he often becomes a philantropist, giving charity and doing acts of kindness, so that others may benefit from his generosity.
However there is also a type of wealth which comes from the side of evil. Such wealth makes a person miserly and very cruel, to the point where his wealth makes him arrogant and only seeking personal honor. Sometimes a person can have a little bit of both types of money mixed together, both miserly money and holy money. When this happens, he needs tremendous protection to make sure he does not lose his money, even that which comes from holiness.
The Amorites were very wicked people, and all of their gold and silver was filled with a spirit of miserliness and harsh cruelty. When the Israelites came into the Land, they took the money of the Amorites. However, they were able to transform this wicked money into sacred money by coming into the hands of the Holy People. This is what is meant by the good news of the plagues. The fact that the Amorites hid their gold in the interior of the walls of their houses hints to the fact that all of their posessions were filled with an aura of miserliness and wickedness. However, when the Israelites destroyed the walls, which were affected by the plagues, they removed the hidden gold and silver of the Amorites, which were filled with this aura of miserliness. The Israelites were able to spiritually repair these places to the point where even this wealth, which was until now a source of wicked miserliness and cruelty, was transformed into holy wealth, which was now used for kindness and charity. Even this very money was brought into holiness through the attributes of generosity. This is really good news to the Israelites concerning the plagues, for there is no greater joy than turning a source of darkness into a source of light, turning bitterness into sweetness, turning evil around to good.
Understand this well.
(Divrei Binah - Parshas Metzorah p. 51)