Then, when the legs were folded up, this gave the vessels the power to return and go back up. The folding of the legs came about through the power of the arousal of the return (החזרה, hachazarah), and this arousal also reached the vessels that were dependent upon them, and they too ascended.
Part 3: It is in this sense that Arich Anpin (of the first Atzilut) is the root of everything. What relation does Arich Anpin have to the vessels? Arich Anpin is the root of everything, and these vessels must also be rooted in Arich Anpin.