The Love Of The Kohanim

לזכות ידיד נפשי ר' אברהם יצחק בן אסתר לברכה והצלחה ברוח וגשם הוא ביתו וכל אשר לו

Summary of a recent shiur [מבוסס בחלקו עפ"י דברי מו"ר שליט"א]:

The Torah never commands the kohanim to bless the Jews. It just says what the blessing is [יברכך השם וישמרך etc.]. Why?

Why is birkas kohanim the only bracha where it says that the mitzva must be done  באהבה - with love?

The Sfas Emes explains that a kohen should be so filled with love for his fellow Jews that he doesn't need a commandment to bless them. The bracha must come from a place of strong innate love. The Zohar says that if the kohen doesn't love the congregation [and vice versa] the bracha will not be effective. This answers both questions. They don't need a commandment because they are so naturally filled with love [or at least should be].

The Rambam asks how the bracha of the kohanim works? How can mere mortals effectively bless?? He answers that the bracha comes from Hashem and the kohanim are just the conduit for the Divine blessing.

The Rambam's premise seems to fly in the face of a gemara in Brachos that says that the bracha of a simple person counts! So why is he bothered by the fact that the bracha of the kohanim is effective?

The sefer להעיר להורות ולהשכיל explains the Rambam based on the Sforno [בראשית לב א] that Lavan's blessings to his family were so effective because they were given with love. [Yitzchak asked Esav to bring him food before his bracha so as to increase his feeling of fondness for Esav. That is also why we physically touch the person being blessed. Touch increases the feeling of connection and care]. The Rambam is thus bothered by the question of how can the kohanim's blessing be effective in the absence of their love.

However, the Sfas Emes would answer the Rambam's question by questioning his premise and saying that of course the Kohen loves the people he is blessing. Otherwise he wouldn't get up there [as per the Zohar]. 

The medrash says that in the zchus of Yitzchak about whom the Torah says [before the Akeida] the word כה we merited the mitzva of birkas kohanim where it says כה [ko sivarchu es bnei yisrael]. What is the thematic connection? Avraham KNEW that Yitzchak would willingly give up his life because he loved Hashem so much. This love carries over to the Jews who love each other and thus the mitzva of birkas kohanim. [הערה - אחרי העקידה כתוב "עתה ידעתי כי ירא אלקים אתה", ירא ולא אוהב] 

The yesod in Avodas Hashem is to constantly go around giving Yidden brachos. It is nothing less than a fulfillment of ואהבת לרעך כמוך and the more love the greater the odds of the bracha being fulfilled.