Tazria, Vayikra 13:3. A Kohen Must See the Tzara'as.

The Torah says that if a nega appears, only a kohen may pasken whether it is Tzara'as. If he is not a Talmid Chacham, he has to take a lamden with him to tell him what to pasken. But the Kohen has to examine the nega'im, and, ultimately, he has to pasken.

Rabbi Dr. Gary Schreiber pointed out that the avoda of the miluim, the process by which the Kohanim were inaugurated, has similarities to the tahara process of the metzora. If you carefully compare the two, you will find that they have avodos in common which are rarely found elsewhere. He said an excellent, and, I think, new, pshat that explains both connections of Kehuna to Tzara'as.

A kohen is subject to the temptation of gaavah, because of his entitlements (the twenty four Matnos Kehuna) and his kedusha (which enables him to do the avodah and requires him to be tahor). Also, Kohanim are aware of everyone’s sins, because whoever brings a korban chatas has to be misvadeh; furthermore, when someone brings a chatas, he has to clearly explain to the Beis Din of the Kohanim why he is bringing it, so they can be sure that the Korban Chatas is indeed required and that it is not chulin ba'azara. So he might say lashon hora. This is a dangerous position to be in: you are born with superior kedusha, Klal Yisrael has to sweat to wrest a living from the earth while you sit at home and get your food-- grain, fruit and meat-- delivered tied with a bow, and you are privy to all their embarrasing failures and sins. It would not be surprising if Kohanim viewed the rest of Klal Yisrael as if they were a bunch of donkeys. This natural tendency to ga'avah and lashon hara can bring Tzara'as.

So the Torah says that the kohanim must personally look at nega’im. They need to see what the result of gaavah and lashon hara are. This constant visual reinforcement will help them control their yetzer hora. Very few oncologists smoke, and many dermatologists obssesively avoid exposure to sunlight, because day after day they see the deadly results of irresponsible and self destructive behavior; so, too, Kohanim are obligated to closely examine the nega'im of Tzara'as, and this will remind them to eschew the traits that bring Tzara'as - Ga'avah and Lashon Hara.

And this explains why the Avodas HaMilu'im recalls Taharas Metzora. The foundation ritual of Kehuna mirrors the taharas metzora process, so that every kohen will read this parsha and remember that the superior status he was granted brought with it a concomitant danger, and that every day he must be on guard against the temptations of ga'avah and lashon hara. Indeed, this concept is found in the Bracha the Kohanim give Klal Yisrael: Yevarechacha Hashem Veyishmerecha: every blessing brings along a heightened risk and the need for shemira. Kohanim, too, are blessed with many things, and these blessings create the need for greater shemira.

(Dr. Schreiber's words:
"...the similarity between the avoda of the taharas hametzora and the miluim of the kohanim which requires blood placed on the the bohanos of each of them. The kohen will hopefully carry the initial impression with him through his years of avodah and refrain from the failings that lead to one becoming a metzora.")

Update 2017: R Avrohom Bukspan sent a comment that connects a Medrash on this inyan. Vayikra Rabba 15.

רבי בשם רבי חמא בר חנינא: 

צער גדול היה לו למשה בדבר, כך הוא כבודו של אהרן אחי להיות רואה את הנגעים?! 

אמר ליה הקב"ה: לא נהנה (אותו) מהם כ"ד מתנות? 

מתלא אמר: דאכיל בהדי קורא ילקה בהדי קילא, (= האוכל מן הקור לוקה מן הקורה).

There are too many pshatim on the words דאכיל בהדי קורא so we won't go into that, but, as I responded to Reb Avrohom, 

Very interesting pshat in the Medrash. Pashtus, it means that if a person shares his blessings with you, you can't turn your back on him when he's suffering and say it has nothing to do with you, you have to share his pain as well. But the way you're connecting it to this pshat, it's Chazal's way of describing what Gaavah is all about- that when it comes to taking, you think you're entitled, so that when the man needs sympathy, you don't feel any obligation to him. "I took because I deserve, and it's an honor for him to give me. I owe nothing to him!" So the Torah says, no. It was a gift, and you should be makir tov to the extent that his pain is your pain.

Update 2021:

Just to outline the similarities between Taharas Metzora and Chinuch Kohanim and Leviim. Chinuch Leviim is in Behaaloscha, and Kohanim is in Tzav.

1. Taglachas: 

Metzora, (ויקרא יד, ט) 

וְהָיָה בַיּוֹם הַשְּׁבִיעִי יְגַלַּח אֶת כׇּל שְׂעָרוֹ אֶת רֹאשׁוֹ וְאֶת זְקָנוֹ וְאֵת גַּבֹּת עֵינָיו וְאֶת־כׇּל־שְׂעָרוֹ יְגַלֵּחַ 

Leviim וְהֶעֱבִירוּ תַעַר עַל כָּל בְּשָׂרָם" (במדבר ח, ז)

2. Kibus:

Metzora וְכִבֶּס אֶת בְּגָדָיו" (ויקרא יד, ט) 

Leviim וְכִבְּסוּ בִגְדֵיהֶם וְהִטֶּהָרוּ" (במדבר שם)

3. Tevilla.

4. Tenufa, by Metzora on his living Korban, by the Leviim on them personally.

5. Dam and Shemen on the persons:

Metzora  וְלָקַח הַכֹּהֵן מִדַּם הָאָשָׁם וְנָתַן הַכֹּהֵן עַל תְּנוּךְ אֹזֶן... וכו" (ויקרא יד, יד, י'ז)

וּמִיֶּ֨תֶר הַשֶּׁ֜מֶן אֲשֶׁ֣ר עַל־כַּפּ֗וֹ יִתֵּ֤ן הַכֹּהֵן֙ עַל־תְּנ֞וּךְ אֹ֤זֶן הַמִּטַּהֵר֙ הַיְמָנִ֔ית וְעַל־בֹּ֤הֶן יָדוֹ֙ הַיְמָנִ֔ית וְעַל־בֹּ֥הֶן רַגְל֖וֹ הַיְמָנִ֑ית עַ֖ל דַּ֥ם הָאָשָֽׁם׃

Kohanim, (ויקרא ח, כד-ל)וישחט ויקח משה מדמו ויתן על־תנוך אזן־אהרן הימנית ועל־בהן ידו הימנית ועל־בהן רגלו הימנית

ויקרב את־בני אהרן ויתן משה מן־הדם על־תנוך אזנם הימנית ועל־בהן ידם הימנית ועל־בהן רגלם הימנית

Shemen, by the Kohanim, ויקח משה משמן המשחה ומן־הדם אשר על־המזבח ויז על־אהרן על־בגדיו ועל־בניו ועל־בגדי בניו אתו ויקדש את־אהרן את־בגדיו ואת־בניו ואת־בגדי בניו אתו 

UPDATE 2022.

I just saw an email from R Zweig's yeshiva in Miami. He says that the lesson of davka these three limbs is that a kohen, elevated to Keser Kehuna, holier than every other Jew, needs to be reminded that his is a position of service, not self-aggrandizement. So you put the dam on his hand, leg and ear - The kohen is charged with the work of doing for others, and going to others, and listening to others.  The same lesson is taught the Metzora, who needs to change from self centered to sympathetic.

His words:

In this week’s parsha, we find Hashem giving Moshe instructions for the official installation of Aharon and his sons as kohanim – the priestly class of Bnei Yisroel. Moshe then gathers all of Bnei Yisroel to watch as he follows a step-by-step process for initiating Aharon and his sons as the kohanim.

Aside from the steps that might be expected in the process of elevating their status – immersion in a mikveh, dressing them in priestly vestments, applying and sprinkling the special anointing oil to all the vessels in the Mishkan and to Aharon and his sons as well, etc. – we find a very unusual ritual.

Several sacrifices were offered: a bull was brought as a sin offering, a ram was brought as a burnt offering, and a second ram was brought as a peace offering (see 8:22 and Rashi ad loc). Moshe then applied the blood of the peace offering to Aharon’s and his sons’ right ear lobes, right thumbs, and right big toes.

This ritual is only performed in one other place in the Torah: by the purification of a person who has been struck by tzora’as – commonly (and incorrectly) translated as leprosy.

hat is the meaning of this enigmatic ritual and what is the relationship between initiating the kohanim and cleansing one who has recovered from tzora’as?

Aharon and his sons were being elevated to a new status over the rest of the Jewish people. They were now receiving forevermore one of the three crowns that Hashem gifted to this world; they were receiving the crown of kehuna. Without proper perspective, being crowned can be a dangerous affair as it can easily lead one to harbor false notions of self-importance. A person can actually begin to believe that he is receiving this honor because there is something intrinsically great about himself.

The unique ritual of placing the blood on the ear lobe, thumb, and big toe is intended to address this issue. The unifying connection between all of these parts of the body is that the ears, fingers, and toes represent the person’s extremities. When a person gets cold, the first parts that are affected are the extremities – namely the ears, fingers, and toes – because they are the furthest from the core of the body. Yet, when a person is asked to point to himself, he always points to his core. Thus, by emphasizing the extremities, this ritual demonstrates that the position is not about them personally, it’s about what they can do for others.

The message they receive is that while being anointed a kohen is an honor, it is more significantly a great and awesome responsibility. The Talmud has a dispute about whether the kohanim are agents of the people to Hashem or agents of Hashem to the people, but everyone agrees that they are merely agents. In other words, they are facilitators not principals. This is the message conveyed by placing the blood on the extremities.

This is also true of a person who has been struck by tzora’as. This punishment comes as a consequence of speaking loshon hora. The core motivating force of one who speaks loshon hora is the desire to elevate oneself by putting others down. While every sin contains an element of self-centered behavior, loshon hora is the sin of focusing on the perceived importance of oneself and trying to elevate the opinions of others regarding one’s own self-importance. This is why a person needs a kohen to declare them unclean and the process of purification is the same as the kohen’s initiation. The message they are supposed to receive and internalize is that they need to focus less on themselves and their own importance.

ADDITIONAL UPDATE 2022

Dr. R' Hertzka Grinblatt offered another very good explanation for the commonality among Metzora and Kohen and Levi. He said that all three need to be kovei'a themselves in a machaneh.

The Metzora needs to be allowed into Machane Yisrael; the Levi into Machane Levi'ah; the Kohen into Machane Shechina.

This is a case of תן לחכם ויחכם עוד, and also an application of די לחכימה ברמיזה. Because you can cavil that the Metzora was already muttar to enter the machane after the Shtei Tziporim; and the Levi? He doesn't need any hetter to go into the Har HaBayis. But the point is still excellent. There are three machanos. Each of the three is the place of the parts of Klal Yisrael. For all three of these people, it is part of the process that is KOVEI'A them into their machane position. Again, I can explain it for you, I can not understand it for you.