Baal HaSulam, "The Foundations Of Intention," Item 59: …Malchut of the First Restriction is concealed in the "unattainable head" (RADLA) by the secret of the "foundation stone," which the builders neglected. And therein lies the secret of the three heads of which The Book of Zohar speaks, since the first head, RADLA, is corrected as "one above the other," while the head of Arich Anpin is corrected as "one inside the other."
There is a head of a spiritual Partzuf (Rosh) that repels the Light and is therefore called "one above the other," and there is also a head that accepts the Light and sends it downwards as "one inside the other." These two heads stand at the head of the World of Atzilut and constantly balance each other out with their work. This determines the root of the Upper Governance, which comes to us from there.
It says about Malchut, "One above the other"; Malchut is separated from the World of Atzilut and we no longer know what happens there. We don’t understand the First Restriction (Tzimtzum Aleph) since it is at a completely different range.
It’s similar to my ear, which is able to pick up sounds only up to the frequency of 20 kilohertz; I cannot hear anything higher than that. The First Restriction works on "gigahertz" so great, a range so distant that I don’t even suspect its existence. It is unknown and unclear to me.
Such fine qualities of the desire to enjoy and the desire to bestow exist there, and such fine discernments that we don’t even touch it. We aren’t refined and sensitive enough for it. This is called "one above the other."
There is a reverse order of Lights and Kelim, meaning that the desire of Malchut lacks the Light of Keter, Yechida. It turns out that the Light of Hochma ascends into the vessel of Keter, the Light of Bina, into the vessel of Hochma, and so on, until the Light intended for Malchut enters the vessel of Yesod. This is the beginning of the lack of correspondence of the Lights to the desires where all the Lights are not located in their places.
And Arich Anpin is corrected as "one inside the other," meaning that the Light of Hochma fills the desire of Keter. That is why the desire of Keter experiences a lack, a feeling that it is not filled by its Light, since this Light is on a lower level, the Light of Hochma.
However, we have to understand that the only Light that can enter the desire of Keter is the one intended for it. I cannot hear with my eyes or see with my ears! We are talking only about the degree of the Light that fills the desire, and the degree of Light in the desire of Keter is now felt as if it is the Light of Hochma instead of Keter.
From the 3d part of the Daily Kabbalah Lesson 11/18/10, “Beit Shaar Ha-Kavanot”
The Zohar About The Law Of The Integral System