We now turn to Birkat Kohanim.
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The Mechaber (Orach Chayim 128:10) states that kohanim cannot begin reciting the blessing before Birkat Kohanim until the chazzan finishes Modim. The Tur (ad loc.) explains that this means that the kohanim must not only wait for the congregation to answer “Amen” to “hatov shimcha u’lcha na’eh l’hodos,” but they also have to wait until the chazzan calls out to them to proceed with their blessing. This is the procedure that is commonly followed nowadays when there is more than one kohen present. However, if there is only one kohen present, the chazzan should not call out to him; rather, the kohen should begin the blessing on his own. The Mechaber and Tur are based on the Gemara in Sotah (38-39).
The Gemara, in turn, is based on the passage in Parshat Naso (Numbers 6:22-27), where Hashem instructs Moses to speak to Aaron and his sons and tell them, “Koh tevarchu et Bnei Yisrael, amor lahem – so shall you bless the children of Israel, say to them.”
The Klei Yakar (Parshat Naso ad loc.) further clarifies the role of the chazzan in Birkat Kohanim: “Amor lahem – say to them”: From here our sages deduced that the chazzan calls upon the kohanim (in a responsive manner), saying the text of the blessing word for word. He does so because he is the intermediary who starts the process of bringing closer the overflow of blessing from the source of blessings to the spout, to the kohen. Thus, when he intones “Yevarechecha Hashem,” he is in effect fashioning the kohen into a vessel that is full and overflowing with the blessings of Hashem. Then, when the kohen intones the same to the congregation, he pours from that overflowing blessing into the empty vessel, i.e., the congregation. However, if the chazzan didn’t call upon the kohen, the kohen would in effect be pouring from one empty vessel into another empty vessel.
How does the Klei Yakar’s explanation fit situations where there is only one kohen and the chazzan does not call upon him to start? We might suggest that even in these cases, the chazzan initiates the blessing. The kohen must technically begin because the text of the prayer refers to kohanim in the plural; the chazzan, therefore, cannot start: “Elokeinu Ve’lokei avoteinu barecheinu ba’beracha ha’meshulet baTorah haketuva al yedei Moshe avdecha ha’amurah mipi Aharon u’banav Kohanim… – Our G-d and the G-d of our fathers, bless us with the three verse blessing in the Torah that was written by the hand of Moses, your servant, that was said by Aaron and his sons.” In theory, however, the blessing still originates with the chazzan, who is in effect serving as Hashem’s representative. A proof to the fact that the chazzan is still beginning Birkat Kohanim lies in the halacha that the kohen has to wait before he proceeds with Birkat Kohanim for the chazzan to conclude Modim, which serves as his cue to begin. In effect, then, the chazzan still calls upon him to bless.
Birkat Kohanim is unique in that it is placed in chazarat hashatz, but is recited by the kohanim, not the chazzan. This mitzvah is for kohanim. However, if there are no kohanim available, the chazzan recites this blessing. Indeed, other than the Yomim Tovim, bnei Ashkenaz in the diaspora do not have the Kohanim duchan. Rather, the chazzan recites the Birkat Kohanim.
Now, one might ask: Is the chazzan a kohen that he may recite this blessing? But that is the din. The Shulchan Aruch Harav (Orach Chayim 127:2, citing the Rambam, Hilchot Tefillah 15:10) writes that when we do not duchan (either because it is a non-duchaning day or because no kohen is present), the chazzan recites Birkat Kohanim. He notes that when no kohanim are present the chazzan introduces Birkat Kohanim with the words “Elokeinu vE’lokei avoteinu…” as we noted above. Thus, we see that the chazzan, even though he may be a yisrael, has the right to recite Birkat Kohanim. He says “Elokeinu vElokei avoteinu…” because this short tefillah establishes that the source for the blessing of the congregation is Hashem.
The Abudarham (Seder Shacharit Shel Chol, Birkat Kohanim, Hotza’at Usha edition, p.116) notes as follows: “An individual is prohibited from reciting Birkat Kohanim in his [private Amidah] because it was enacted for the congregation [chazarat hashatz] to correspond to nesiyyat kappayyim, and only when there is the minimum quorum of ten, does the chazzan recite it [if there is no kohen present].”