This, then, is the meaning of the statement above, regarding the second principle; that the Zohar does not speak of the world of Atzilut itself.10See section 4, above. This is because Atzilut is like the white in a book. Rather, the Zohar refers to Atzilut in accordance with its illumination into the three worlds of Beria, Yetzira, and Asiya, since they are considered the ink, the letters, and their combinations in the book.
This is so in one of two ways: One way is that the three worlds of Beria, Yetzira, and Asiya receive the illumination of the world of Atzilut in their own place. In this case the light is greatly diminished for them as it passes through the diaphragm that is below the world of Atzilut, until the light is considered merely illumination from the vessels of Atzilut. Alternatively, it occurs through the ascent of the worlds of Beria, Yetzira, and Asiya above the diaphragm, to the place of the sefirot of Bina, Tiferet, and Malkhut of Atzilut, and Beria, Yetzira, and Asiya are found to enclothe the world of Atzilut.
In this case, the lower worlds receive the light in the place of its illumination (as stated in Petiḥa LeḤokhmat HaKabbala (Introduction to the Wisdom of the Kabbala), from section 155 and onward).11This second method for the lower worlds to receive the light of Atzilut is from the process called the second constriction. As a result of this process, the vessels of different levels are able to descend to lower levels and then subsequently pull lower-level vessels back up to higher levels with them.
This process allows for the lower worlds of Beria, Yetzira and Asiya to receive the illumination of Atzilut directly, as opposed to through the diaphragm.