In order to understand Petach 67 we’d need to know the following. Erich Anpin is the source of everything under discussion here. And so in order for there to be vessels below, they need to be rooted in Erich Anpin — in its lowest triad, that is: it’s Netzach, Hod, and Yesod combination, which is termed Erich Anpin’s “legs”. So, those “legs” need to descend below (to the worlds of Briah, Yetzirah, and Assiyah) in order to allow for Erich Anpin’s lights to enter into them, and to maintain those vessels .
When the vessels need to ascend, though, to Atzilut in the Tikkun process, they do that through Erich Anpin’s “legs”, too. And they go from the lower triad of Netzach, Hod, and Yesod up to the next higher one of Chessed, Gevurah, and Tipheret, which then allows for an even greater degree of Tikkun . As such, this initial descent or “folding-over” of Erich Anpin’s “legs” is the very first phenomenon to allow the broken vessels to ascend and experience Tikkun . (And those “legs” serve as the gateway that connects all.)
Here’s Petach 67 itself with our interpolations.
It was the “folding-over” of Erich Anpin’s “legs”, i.e., its Netzach, Hod, and Yesod elements, that was the first thing that granted the ability to the broken vessels to ascend from Briah, Yetzirah, and Assiyah to Atzilut, and that enabled all their subsequent ascents.
In truth, the vessels depended on those “legs”, and were initially sustained by them below, i.e., in Briah, Yetzirah, and Assiyah. So, when the “legs” were “folded-over” the vessels also had the ability to return upward.
It’s in this sense that Erich Anpin is the source of everything, and that they, i.e., the “legs”, which were the part of Erich Anpin, could serve as the source of the vessels when they descended. In fact, as a result of the “folding-over of the legs”, Chessed, Gevurah, and Tipheret of Erich Anpin also served as their source when the Tikkun became even greater.
 The word used to describe the function of Erich Anpin’s “legs” is k’ful in Hebrew. The term either translates as “double (-functioning)”, or “folded”. We chose to translate it “folding-over” to express the twofold nature of the phenomenon, and to depict the sort of physical shifting the triad would have to go through to allow for both decent and ascent.
 See Klallot HaIlan 4:1. While this seems to be derived from Eitz Chaim 17:2, it’s more likely derived from R’ Sarug’s Derushei Olam HaMalbush (as explicated in Tal Orot 1:8-9) because of the discrepancy between the place of the world of Briah versus Atzilut in the process.
(c) 2014 Rabbi Yaakov Feldman
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