Service of the Kohen Gadol: One & One
“One. one and one, one and two…” (Artscroll Yom Kippur Machzor Ashkenaz, Page 564) On Yom Kippur the Kohan Gadol is crowned with the crowns of the upper worlds, crowns of light and achievement. He stands between the upper worlds and the lower and brings atonement for himself from the Midah of Chochma, for his house and family from Binah, for the Kohanim from Chesed, for the Beit Hamikdash from Malchut, and for the entire Jewish People from Tiferet. We learned that at the time the Kohan enters the Kodesh Kodshim with the blood of the bull, he would concentrate on the world of אצילות, or transcendance, and would sprinkle the blood, as it says, “And he should sprinkle it (the blood) on the Kaporet (the cover of the Ark),” this refers to one sprinkle high, “and in front of the Kaporet,” refers to seven below. How would the Kohen do this? He would dip the tips of his fingers into the blood, and he would whip his fingers forward as if giving lashes that begin on the shoulder and go down, so too, the Kohen would begin high and then go down. With each sprinkle the Kohen would concentrate on the appropriate Sefirah. And the he would count; One; God’s Highest form above even the Highest World, the One that includes all things and is the root of all, the One most praised, the One to whom all turn to receive, the One Who is the head of all forms of being in the Highest World.
One and One; The One and the perception of God as Father and Mother joined as One in love and will not separate one from the other.
One and Two; One with Chesed and Gevurah.
One and Three: ..w/Tiferet
and Four; …w/Netzach
And so the light of Yom Kippur comes from two worlds, The Highest World with the light of First Existence, and the light of Malchut of the Lower Worlds. This is why it is called Yom Kippurim, in the plural, because it has both lights .