Part 3: This place or space is said to be empty (חלל, chalal, literally “hollow”) in the sense that it serves as a container to hold others. It is a particular level whose essence is such that it needs others to exist in and depend upon it (like a space waiting to be built up, which is empty as long as it is not filled with buildings). Since the essence of Malchut is to enable worlds to exist and be dependent upon it like branches, we say metaphorically that it has a “container”. And as long as only this level existed and the worlds did not exist, we say that the container was “hollow” and “empty”. Since the worlds dependent upon it came into existence, we say that its hollow is full.
Kalach Pitchei Chokhmah 26:24
Kalach Pitchei Chokhmah 26:24