“When the King first desired a world, He engraved its forms in the pure Supernal Light.” (Zohar 1:15a)
The hollow engraved in the Supernal Light was the vacated space, in which all creation subsequently occurred.
This Constriction (tzimtzum) or hollowing of the Divine Essence did not occur in physical spakce, but rather, in conceptual space. It is "hollow" insofar as it contains the possibility for information, but not actual information. As such, it is the "Tohu and Bohu" (chaos and void) mentioned in the account of Creation, where the Scripture states, "the earth was chaos and void" (Bereishit 1:2). Chaos is a state where information can exist, but where it does not exist.
The hollow was made through 32 paths, since letters and digits are the basic bits of information. While random letters and numbers do not actually convey information, as long as they exist, it is also possible for information to exist. The Vacated Space is therefore the state where it is possible for information to exist, but where this possibility has not yet been realized.
These letters were subsequently combined into words, forming the Ten Utterances/Sayings of Creation. Each of these sayings brought information into the Vacated Space, through which creation could take place there.
The order was therefore first "engraving," and then "creation." The Sefer Yetzirah therefore states that the Creator "engraved...and created His universe." (Sefer Yetzirah; Bahir 2; Ramban on Bereishit 1:2)
Physical creation, as reported in the Torah, is not the beginning of the story, but the end of a process that began much earlier and which was totally spiritual at first. It is the essence of what true Kabbalah discusses at length. Kabbalah describes Creation as existing inside a Challal (hollow), a ball like structure in the "center" of the Infinite Light of Ain Sof, surrounded by Ohr Ain Sof on all sides. The creation of the Challal was the first stage in making physical creation possible since it held back the powerful Ohr Ain Sof, which is far too spiritual to allow anything physical to exist. The next stage allowed a stream of Ohr Ain Sof, Kav Ain Sof, to enter the Challal in Divinely measured amounts, creating levels of existence on its way in. By moving towards the center of the Challal the Kav Ain Sof, in effect, was moving away from its Source, the Ohr Ain Sof beyond the Challal, allowing Creation to become increasingly more physical. Ohr Ain Sof resulted first in the Challal, then in the Kav Ain Sof, and eventually in the countless sefirot and partzufim, all just to make a world in which man could exist, exercise free will, and earn his portion in the Olam Haba (World to Come). (Rabbi Pinchas Winston, The Physics of Kabbalah, p. 3, note #10 quoting from Otzrot Chaim, p.5; and p. 17 of The Physics of Kabbalah)
In the beginning, a simple divine light filled the entirety of existence. When there arose in His simple will the desire to create the worlds, He contracted His light, withdrawing it to the sides and leaving a void and an empty space in its center, to allow for the existence of the worlds. (However, this was not an absolute void, for there remained a residue of the divine light within the void.) He then drew a single line of His infinite light into the void to illuminate the worlds. In the teachings of Kabbalah, the act of creation is described as an act of tzimtzum—an act of contraction, concealment and withdrawal. In the beginning, the “light” of G‑d (i.e., the manifest expression of His omnipresence and omnipotence) filled the entirety of existence. A world such as ours—finite, self-defined and independent, with the capacity to turn away from and even deny its Creator—could not exist, for it would have been utterly nullified within the divine light. In order to allow for the existence of the world, G‑d “contracted” His light, creating a “void” and “empty space” within which His infinite being and power is not manifest. Into this void G‑d then allowed a single “line” (kav) of light to penetrate, through which flows a divine energy that is meted out to every level of reality in accordance with its capacity to receive it. (Chabad, Tzimtzum)
