Likutei Moharan 21:9/ליקוטי מוהר"ן כ״א:ט׳

19. For we are called “am segulah” (a special nation) (Deuteronomy 7:6). This is like a segulah used for healing. Even though the dictates of nature would not necessitate that this should induce healing, nevertheless, this thing is propitious for curing. It is supernatural, something which the human mind cannot fathom.

2<Israel, too, is in the category of segulah. It cannot be understood why and how the Holy One chose us as “a special nation” from amongst the other nations.> As at the splitting of the Red Sea, when Judgment accused: “These serve idolatry [and these serve idolatry]” (Shemot Rabbah 21:7), even so, the Holy One chose us as an < am segulah>.

3Thus, this thing [being chosen] is like a segulah. It is supernatural and beyond human comprehension. This is the concept of encircling, explained above. And someone who has merited to these transcendent intellects, giving birth to them and internalizing them, will thus have merited to understand the segulah. It is therefore only fitting that the “specialness” be revealed to the nation that is special.

4And so, each and every person, commensurate with his level, has an immanent and transcendent intellect. And commensurate with his level, that which God has granted him, to have the transcendent become immanent and to understand and originate something—it is only right that [every individual] reveal and give over this comprehension of “specialness.” That which was a segulah for him, he should disclose to the “special nation” and share his good with others.