In the beginning, there was no existence except His presence; the Creator was alone, occupying all space with His light. His light, without end, borders or limit, filled everything. He was not bestowing His influence because there was no one to receive it. When He willed to create; He started to influence. His light being of such holiness and intensity, it is not possible for any being to exist in its proximity.
The “Tsimtsum” is the first act of Ein Sof (Infinite) in the creation. It is the retraction of His light from a certain space and encircling it, so as to reduce its intensity and allow created beings to exist. After this contraction, a ray of His light entered this empty space and formed the first Sephirot.
By these boundaries, He revealed the concepts of rigor and limit needed by the created beings, and gave a space for all the created to exist.