Following this majestic path, we will now proceed to explain why the privilege and mitzvah of Birkas Kohanim was bestowed specifically upon Aharon and his descendants. It states in the Zohar hakadosh (Metzora 53b):"מֹשֶׁה שׁוּשְׁבִינָא דְּמַלְכָּא, אַהֲרֹן שׁוּשְׁבִינָא דְּמַטְרוֹנִיתָא" —Moshe is the companion of the king, and Aharon is the companion of the queen. In other words, Moshe represents HKB”H, while Aharon represents Kenesses Yisrael.
The Zohar hakadosh explains that Moshe Rabeinu always strived to appease HKB”H and draw Him closer to Yisrael. This was evident in the aftermath of the “cheit ha’eigel,” when Moshe beseeched Hashem (Shemos 32, 32): "ועתה אם תשא חטאתם, ואם אין מחני נא מספרך אשר כתבת"—and now, if You would but bear their sin; but if not, erase me from Your book that You have written. Aharon, on the other hand, worked from the opposite direction. He always strived to draw Yisrael closer to their Father in Heaven, This is taught in the Mishnah (Avos 1, 12): "הלל אומר, הוי מתלמידיו של אהרן, אוהב שלום ורודף שלום, אוהב את הבריות ומקרבן לתורה"—Hillel says: Be among the disciples of Aharon—love peace and promote peace, love your fellow creatures, and bring them closer to Torah.
Now, the Torah attests to the special relationship that existed between Aharon and the people (Bamidbar 20, 29): "ויראו כל העדה כי גוע אהרן ויבכו את אהרן שלשים יום כל בית ישראל"—the entire assembly witnessed that Aharon had perished; they wept for Aharon thirty days—the entire house of Yisrael. Rashi comments: Everyone grieved over Aharon’s death, both men and women alike, since he was the ultimate peacemaker—he promoted shalom and amity among disputants, and between husbands and wives. He also promoted shalom between HKB”H and the people of Yisrael.
Therefore, Aharon HaKohen was privileged to be imbued with “ruach hakodesh” and ascertain Birkas Kohanim specifically on the day of the inauguration of the Mishkan. For, it was the day on which HKB”H united exclusively with the people of Yisrael, fulfilling the directive: “They shall make Me a sanctuary, so that I may dwell among them.” Hence, it was the propitious time to initiate the mitzvah of Birkas Kohanim comprised of fifteen words representing the name י"ה indicating the presence of HKB”H between a husband and a wife; it also contains sixty letters representing the sixty masechtos that are the ring with which HKB”H betrothed Yisrael. Aharon earned this privilege for promoting shalom between husbands and wives and, similarly, between HKB”H and the congregation of Yisrael.
