Baal HaSulam, “Arvut”: “A holy nation” is the reward in its final form of Dvekut [adhesion] with Him, which includes all the rewards that can even be conceived.
There is a part of humanity that receives spiritual awakening—the group (Bnei Baruch). These people are obligated to carry out the correction inside of them, to acquire the force of the mutual guarantee, and by virtue of that force, to begin bestowing to everyone else.
Besides, they have to observe the law that is described by the verse, “You will be a kingdom of priests unto Me.” Stated differently, this is talking about the state of Hafetz Hesed: Priests do not have their own property. Like Bina, they aspire only to bestowal. This is the quality we must acquire as well.
As for the quality of “the holy nation,” this is already a receiving desire that we use and raise to the level of holiness. Thus, it acquires an intention for the sake of bestowal and reaches adhesion.
This unity, this force, or this state has to reign in the group. There are no other possibilities here. We are talking about the laws of nature. If we don’t want to carry them out the good way, we will be forced to do it the bad way—through suffering. There are no compromises here, but a program that becomes realized with just one parameter of free choice: You can accelerate your development before you are obligated to this by the special, systematic force.
At every phase, this obligatory force descends to us and begins advancing us forward. However, we can move faster than it, and in that case we will reach the goal by the good and fast path, without blows from behind.
Thus, we have two possibilities to choose the means of advancement. But the advancement itself is immutable because in the final state, the program of development is already realized in full. The two phases of this realization are “the kingdom of priests” and “a holy nation.” They demand for us to attain mutual bestowal, love for the neighbor as oneself, and thereby, adhesion with the upper Light, the Creator.
From the 5th part of the Daily Kabbalah Lesson 7/26/11, “Arvut”