Halakhah for Arakhin 32:3

However we should not be called from the group of fools, in our spending all of our breath on [empty] words; as in much waste, a little food can sometimes be found. Also because we have seen our Rabbis, may their memory be blessed, saying [words] similar to our words: As they said about the sacrifice of a sotah (a suspect of adultery) (Sotah 14a), "She did an animal act, therefore she should bring barley (animal food)"; and with the sacrifice of a metsora (Vayikra Rabbah 16, Arakhin 16b), "He did an act of chatter, he should bring birds." And similar to this, they, may their memory be blessed, said regarding the matter of a menstruant woman, "Why did the Torah say that she sit seven clean days? That she be most dear to him." And in truth, none of all this is in their opinion the ultimate intent of the things. Rather, it is to inform that the matter of the commandment includes many hints, besides the great and strong fundamentals.

The commandment of purification from tsaraat that it be with certain species: That purification from tsaraat - whether tsaraat of a person, a garment or a house - be with cedar wood, hyssop, wool dyed red, two birds and living water, and that he do with them everything that is written about the matter, as it is stated (Leviticus 14:2), "This is the law of the metsora, etc." to the end of the section. And three types of purifications are mentioned in the Torah, and these are them: Water, and this type, by water, includes the purification of every impurity - meaning to say it is impossible for any impure thing to emerge from impurity without water; and the second type is sprinkling water, and that is the type that is specific for the impurity of a dead body; and the third type, the cedar wood, hyssop, wool dyed red, two birds and living water, and it is the type that is specific for tsaraat. The Sages informed us of a bit of a hint in the matters of the purification of the metsora with these things. As they, may their memory be blessed, said (Pesikta D'Rav Kahanna 14) that the matter is to fix in the soul of the metsora that if, before the illness came to him, he was haughty-hearted like the cedar - by way of metaphor, since it is a tall tree - he should lower himself like the hyssop. It is said about the reason of the birds (Arakhin 16b) [that] he did an act of chattering - meaning to say, he spoke many words of evil speech - therefore, he must sacrifice birds that constantly chirp. And with the wool dyed red (shani tolaat), I do not know or remember anything that they, may their memory be blessed, said about it. And it is possible that it is also a hint that he should lower himself; and it would be a hint from its name [as it is called,] worm (tolaat).