After Moses counted the tribe of Levi as a whole, G‑d told him to count each of the three Levite clans separately, appointing each clan to carry specific components of the Tabernacle when the Jewish people would travel.
The Power of Peace
בְּגִשְׁתָּם אֶת קֹדֶשׁ הַקֳּדָשִׁים אַהֲרֹן וּבָנָיו יָבֹאוּ וְשָׂמוּ אוֹתָם אִישׁ אִישׁ עַל עֲבֹדָתוֹ וְאֶל מַשָּׂאוֹ: (במדבר ד:יט)
[G‑d told Moses,] “When [the members of the tribe of Levi’s son Kehat] approach the holiest of the holy things, Aaron and his sons must [first] come and appoint each man to his task.” Numbers 4:19

It often happens that when we strive to reach our potential in spiritual matters, we encounter forms of opposition. Sometimes other people ridicule us or are hostile to us; sometimes we are assaulted by inner voices of self-doubt. The Torah teaches us here that the proper response to these challenges is not to battle them but to use the power of Aaron, who dedicated his to being a peacemaker. Our loving-kindness will then either neutralize the negativity or eliminate it altogether. And transforming an adversary into an ally is the most complete and effective victory possible.1