However, there is a vast difference between the receiving capacity of the fourth level before the constriction and the receiving capacity of the returning light after the constriction. The returning light enclothes only a thin line of the supernal light, containing a beginning and end, as stated. All this was wrought by the partition, due to its impact against the supernal light. Thus, this entire amount of light that was rebuffed from Adam Kadmon on account of the partition, meaning, the entire amount of the supernal light from Ein Sof, blessed be He, that wanted to be enclothed in the fourth level were it not for the partition that prevented it, becomes the surrounding light around Adam Kadmon.
Ein Sof and the First Constriction of Infinite Light
Petichah LeChokhmat HaKabbalah 32:2