Part 11 · Chapter 83

And this is the reason why ZA is called by the name Ze'ir [small], and AVI are called the elders, and Arich is Atika de-Atikin [the Ancient of Ancients], in the secret of the Seivah [hoary old age], which is greater than the Zaken [elder]. And the reason is that Arich is the perfection of mercy, as is written in the Idra of 129: “There is no left in this Atika; everything is right; mercy within mercy; and there is no judgment in it at all.” And AVI have within them a very small revelation toward the judgments, and they are called elders but not Atikin. And ZA, since he is the phase of judgments and Gevurot that are revealed within him — for there is within him right and left, and many mighty red Gevurot are spread within him, even in his head, as mentioned in the Idra of Naso — therefore he is likened to a small one, and is called ZA. Behold, it is clarified that Katnut causes the judgments, and the Zaken and the Seivah indicate mercy.