Why Aaron Was Chosen
"And Moshe said to Aaron, Approach the altar…and atone" (Vayikra 9:7) Rashi says that Aaron was afraid and embarrassed to approach the Altar. Moshe responded, "Why are you embarrassed? For this you were appointed!" Two questions can be posed here on Rashi. Why was Aaron embarrassed? And how did Moshe's answer to him help?
The Ben Ish Chai explains why Aaron was both embarrassed and afraid. The sacrifices of that day were to atone for the sin of the Golden Calf. Since Aaron was unintentionally involved in the making of the calf, he first had to bring a sacrifice for himself, and he was embarrassed. He was also afraid that other Leviim might use the fact that Aaron was involved in the sin to undermine his authority, like Korach later did.
However, with just two words (L'kach nivcharta - for this you were chosen), Moshe changed Aaron's perspective. Moshe knew that, rather than being a handicap, it is essential that a leader have some sort of embarrassing episode in his past, so that he does not become arrogant.
The source of this idea is in the Talmud (Yoma 22b). The Sages explain why King David's royal dynasty will last all the way until Mashiach, as opposed to King Shaul's, which ended. David's lineage was "controversial" - his maternal grandmother, Ruth, was a Moabite convert. The Torah states that a man from Moav may not convert to Judaism, and there was great debate among the rabbis about whether a Moabite woman may enter the Jewish nation (the halacha is that she may). Also, because of his different hair color and other reasons for suspicion, his brothers rejected him and called him a mamzer, and he was relegated to the role of shepherding in places where he was in danger of attack by wild animals. Because of all this, David remained humble and never felt that he deserved to be a King.
King Shaul on the other hand, had a perfectly respectful background and complexion to be a leader. Therefore, the Talmud concludes that we only appoint a leader who has a "Kupa shel Sheratzim" - some type of background and past that will remind him "go back to where you belong" if he gets haughty.
Moshe told Aaron that, especially as Kohen Gadol, his sin wasn't something to be embarrassed about, and was no cause for fear. In fact, it was his ticket to being a successful leader! Any of the other Leviim wouldn't have qualified for this position because the entire tribe remained clean. This is a phenomenal perspective which can be perceived from many viewpoints. First, a lesson can be derived about the importance of humility as a leader. This can only be brought about by someone who recognizes that he is not worthy. Modesty is one of the exceptional traits of Jews. It is not a social handicap; it means recognition of where one's place is.
Another concept that can be derived is that even failure and weaknesses can be "traded in" for assets and strengths after proper recognition of faulty judgment. Repentance can only work when one realizes that he can actually turn his weaknesses into strengths. When one does not recognize this, he still might see himself as an eternally doomed sinner. Even after he comes to terms with his faults and he goes through the proper elements of change and repentance, he will still feel he has a skeleton in the closet which can't have proper burial. This feeling is destructive and counter-productive.
By merely focusing on one's past misbehavior, one does not gain the power to stand up against a future tide of challenges or to release himself from a guilty, negative mindset. There was truth to Aaron's feelings that his mistake left him unworthy of being a leader. However, a more positive belief and perception would have been to take this opportunity to learn how to empathize with others who have made mistakes and want to repent.
Consider the following parable: Morris, an observant Jew, wore tefillin every day. When he was 80 years old, he decided to have his tefillin checked to see if they were kosher. One day, a well-known scribe passed through his town and put up a stand in shul offering to check tefillin. To his dismay, Morris discovered that his tefillin were not kosher. Morris was beside himself. He approached his rabbi with a choked voice and watery eyes, unable to accept the bitter news that he had never properly fulfilled the mitzvah of tefillin. The rabbi suggested that Morris should offer to donate money for others to get their tefillin checked and fixed for free, and that he could donate kosher tefillin to Bar Mitzvah boys who either didn't have the money or didn't understand the importance of having kosher tefillin. Instead of focusing on the past that he was unable to change, Morris found in this piece of advice a way to rectify his loss and help many other people to wear kosher tefillin for the rest of their lives.
Moshe taught Aaron how to find the positives in everything, even in his own mistakes. We can experience great joy and transform ourselves if we can internalize this message as well.