Creation is an emanation from the divine light; its secret is not the coming into existence of something new but the transmutation of the divine reality into something defined and limited–into a world.
This transmutation involves a process, or a mystery, of contraction.
God hides Himself, putting aside His essential infiniteness and withholding His endless light to the extent necessary in order that the world may exist.
Within the actual divine light nothing can maintain its own existence; the world becomes possible only through the special act of divine withdrawal or contraction.
Such divine non-being, or concealment, is thus the elementary condition for the existence of that which is finite.
–Rabbi Adin Steinsaltz
From The Thirteen Petalled Rose by Rabbi Adin Steinsaltz