We have thoroughly explained the mystical meaning of the surrounding light of Adam Kadmon, which is endless and unlimited in its enormity. This does not mean that Ein Sof, blessed be He, who fills all of reality, is Himself the surrounding light of Adam Kadmon. Rather, the meaning is that when the fusion through collision occurred with the partition that was placed on the Malkhut of the head of Adam Kadmon, the supernal light of Ein Sof struck the partition that was there.
This means that Ein Sof wanted His supernal light to be enclothed in the fourth level of Adam Kadmon, as before the constriction (tzimtzum), but the partition of the Malkhut of the head of Adam Kadmon impacted against His light, meaning that it prevented His light from spreading into the fourth level and so rebuffed it, as stated above in section #14#, so that in truth this returning light that emerged through the rebuffing of the supernal light also became vessels for enclothing the supernal light, as stated above.