Section 18, entitled “The Tikkunim of Erich Anpin“, encompasses Petachim 101-109.
Now that we’re moving down the order of Partzufim to Erich Anpin itself he’ll be offering “a detailed explanation of the form of the Partzufim” overall, “starting with a general rule” as Ramchal offers in his comments here. This Petach also begins a description of the structure of the Partzufim, and of how they function, beginning with their “heads”.
Petach 101 thus begins with the statement that a Partzuf‘s “head” is always the beginning of its governance system. In fact, Ramchal remarks in his own comments here, that “the ‘head’ itself includes everything in the entire Partzuf – albeit in the form of a beginning” — a source or embryo of everything below it. Still-and-all, “the head’s function is (only actually) completed by the rest of the Partzuf” . That’s analogous to the way our actions always begin in our thoughts, but they only come to fruition through those actions.
The “head” is only complete when it contains a “crown” (Keter) and “brains” (Chochma and Binah). Ramchal makes the point that there have to be those two aspects in order for a Partzuf to govern: an overarching Keter as well as and distinct from the rest of the “head”.
And that only comes about by means of the mystical notion of the entity above dwelling upon the other one below it . Thus, the superior power Keter governs the lower ones.
The Partzuf‘s three “brains” i.e., Keter, Chochma and Binah are all included in its “head”. And it’s there i.e., in the “head”, where the gist of the birth i.e., the beginning of the Partzuf‘s governance system takes place. And that governance extends through the Partzuf’s Chessed, Gevurah, Tipheret, Netzach, Hod, Yesod and Malchut.
 See Petach 90.
 See Da’at Tevunot 2 (in Ginzei Ramchal p. 38), Kinat Hashem Tzivaot (Ibid. p. 116) and Ma’amar Harautin (Ibid. p. 248).
(c) 2017 Rabbi Yaakov Feldman
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Rabbi Feldman’s new annotated translation of Rabbi Yehuda Ashlag’s “Introduction to the Zohar” is available as “The Kabbalah of Self” on Kindle here. His annotated translation of Maimonides’ “Eight Chapters” is available here and his annotated translation of Rabbeinu Yonah’s “The Gates of Repentance” is available here.
He has also translated and commented upon “The Path of the Just” and “The Duties of the Heart” (Jason Aronson Publishers).