The Torah describes the procedure for a metzora (a person afflicted with tzara'at) upon conclusion of his isolation. This process extends for a week and involves korbanot and immersions in the mikveh. Then, a kohen must pronounce the metzora pure. A metzora of limited financial means may substitute lesser offerings for the more expensive animals. Before a kohen diagnoses that a house has tzara'at, household possessions are removed to prevent them from also being declared ritually impure. The tzara'at is removed by smashing and rebuilding that section of the house. If it reappears, the entire building must be razed. The Torah details those bodily secretions that render a person spiritually impure, thereby preventing his contact with holy items, and the Torah defines how one regains a state of ritual purity.
"and cedar wood, crimson thread, and hyssop" (14:4)
"For leprous-looking lesions result from conceit and haughtiness. What is the cure? A person should lower himself like the worm and the hyssop." (Rashi)
The Baal Shem Tov once arrived in Polana for Shabbat in a beautiful carriage. In that town was a certain individual who loved to create trouble. He accused the Baal Shem Tov of lording it up and behaving in a conceited fashion.
The Baal Shem replied to him:
"Once there was a king who let it be known that he was searching for the elixir of eternal life. Hearing about the kings quest, a wise man came to him and said, "I have the elixir of eternal life." "Where is it? Where is it?" said the king in great excitement. "I will pay you anything for it!" Replied the wise man "You need pay me nothing for it But it will certainly cost you."
The kings brow furrowed. "Where is the potion?" he demanded.
Said the wise man: "If you humble yourself and distance yourself from all conceit, you will have imbibed the elixir of life."
The king took the wise mans words and fulfilled them to the letter. He behaved like the epitome of humility, to the extent that he actually ceased riding in the royal carriage and followed behind it on foot along with his servants.
However, the more he did to humiliate himself, the more he heard this little voice in his head saying, "You are the MOST incredibly HUMBLE person in the whole world. Look at you! You are a great king and yet you walk on foot behind your carriage. You speak in whispers, carefully weighing your each and every word. Your shoulders are hunched unassumingly. Your glance is always downward and diffident. You are truly FANTASTIC!"
He sought out the wise man and told him of his problem. The wise man explained, "Walking behind the royal carriage was not what I had it mind. I meant you to go up and sit in your carriage, that everyone should continue bowing to you and treating you with royal deference, and, in spite of all that, in your heart of hearts, you should still feel humble and small. Thats a much more difficult thing to do."
But that is true humility.