Editing Kav and Chut (section)

== Its Root in Tzimtzum in the Aspect of a Square ==
In Chassidut, it is explained that there are two types of Tzimtzum. The known Tzimtzum from which begins the creation of the worlds and which is mentioned in Etz Chaim, and called there the "First Tzimtzum," and the Tzimtzum in the aspect of a square, which is a hidden root for the worlds, and called briefly in Etz Chaim by the term "empty space." Due to the high concealment of this Tzimtzum, Rabbi Chaim Vital did not want to engage in it, fearing that the concept might be misunderstood in physical terms, but in Chassidut, especially in the teachings of the Maggid of Mezritch and in Chabad Chassidut, they extensively engaged with this realm.

The Rebbe explains that while the Tzimtzum in Etz Chaim was in the aspect of a circle and in the aspect of a point, alluding to complete concealment closed like a point without form, we find that there is another stage of a line that indicates the beginning of measurement in length and width and revelation. Nevertheless, the line is not complete revelation but only the root of revelation, meaning the line is the beginning of the reality of revelation. The line is the power of extension from above to below, but there is still no actual extension from above to below within it.

The root of this line is from the Infinite Light before the Tzimtzum, in which there was an aspect of Tzimtzum in the aspect of a square, meaning that even before there was a complete Tzimtzum in which the Infinite Light was concealed, the Ein Sof, in His essence, assessed, as it were, the divine pleasure that would be revealed in the worlds. According to this pleasure, the Holy One, blessed be He, prepared the Tzimtzum as it was to be in a way that the Infinite Light would later be revealed through the work of the tzaddikim as a result of the illumination of all the Partzufim in the world of Atzilut.

This power both limits and reveals at once: on one hand, it contains the revelation of all the work of the tzaddikim after the Tzimtzum, since this Tzimtzum is, as it were, in His essence, in a place where there is still no concealment. Nevertheless, it is the root of concealment and Tzimtzum, which Tzimtzum comes to revelation through the Reshimu, which is like an extension from the Infinite Light before the Tzimtzum. It limits the length and width of the worlds, meaning that the light in the worlds will be appropriately measured so that the Infinite Light can be revealed in the worlds and the lights will not exceed the vessels. In contrast, the line in the Reshimu is the power of revelation that unifies everything as the Infinite Light was before the Tzimtzum. The difference between this Tzimtzum and the second Tzimtzum in Etz Chaim is that in this Tzimtzum, the revelation is actual and the concealment is only potential, unlike the second Tzimtzum, whose main actual existence is concealment.

While after the Kav the ten Sefirot are realities of lights separate from each other (even if in the world of Akudim they are in the aspect of light in one vessel), before the Kav—in this Tzimtzum in the aspect of a square—the ten Sefirot are in the aspect of being hidden and completely unified.