Birchas Kohanim is undoubtedly the central blessing administered to Klal Yisroel. This is the formula that HKB"H Himself has given to the kohanim to utter every day. If we examine it closely, we see that it has a peculiar structure. It starts with a blessing, followed by Hashem's name, and then ends with another blessing. Regarding the first of the blessings, Rashi explains the structure:
The L-rd bless you- that your property may increase. And may He guard you - that no robbers come upon you to take your property. For, a human being who gives a present to his servant cannot guard him against everybody, and if a band of robbers attack him and take it away, what pleasure can he, then, derive from this present?! The Holy One, Blessed be He, however, both gives and guards - against everybody.
If we take a closer look at the other berachos, we will discover a very similar pattern. The second beracha bestows "hearos panim" which is a sense of Hashem being favorably disposed towards us, which is then followed by "viy'chunekah" meaning that Hashem will endow us with chen, a type of charm which makes one more easily favored. And finally, we are told that Hashem will act towards us in ways that we receive better than we deserve, and then it says that He will bless us with peace. This too goes hand in hand, for when someone is given preferential treatment it tends to arouse the ire and jealousy of one's neighbors. Thus the passuk is telling us that despite the fact that Hashem is endowing us with extraordinary favors, He will still make sure that no one becomes jealous and fights us on that account.
How are we to understand all of these gifts and the guarantees? Do we look at them as two blessings? Do we say that Hashem is giving us both the blessing for wealth and also a blessing that he will guard it? The answer is that these are not two separate but related blessings, rather Hashem is bestowing upon us two complimentary parts that form a stable and complete whole.
Let us explain this with the words of the Rabbeinu Bachya in Parshas Mishpatim, concerning the words, "I am Hashem your Healer". He points at a grammatical difference between the word "refuah" when it is used regarding Hashem as Healer vs. its use regarding a human doctor. He says that any human medical intervention is perforce harmful in some way, whereas Hashem's healing is perfect. The reason is that when man heals, he intervenes. Every medication must therefore have some negative effect as well. But when HKB"H heals, He fixes the problem from within. And just as the world was perfectly balanced when Hashem created it, so too when He rights the world, it is perfectly balanced as well. Hashem's healing does not disrupt the order, rather it rebalances it.
This then is the meaning of the berachos of Birchas Kohanim. When a human gives a gift to someone, he is "upsetting" the natural order [see, for example, what happened when Yaakov Avinu gave an extra coat to Yosef], and that is why jealousy sets in and the possibility of robbery exists. But when Hashem bestows a blessing, it means that He has changed the very economic order. Hashem's name in the middle of each beracha, implies that both blessings emanate from HKB"H simultaneously, with each blessing complementing the other and, together, creating a new order. They are not two distinct blessings, but two halves of one great all-inclusive beracha.