The final understanding of Yerida Tzorech Aliya is introduced here: the Neshama ascends to lifnei HaTzimtzum and the level Kodesh there which is (ultimately) Etzem Ohr Ein Sof and Helem HaAtzmi. This Maamar develops this idea by discussing Shechina and Kadosh and Kodesh as explained in various Maamarim. Shechina is 1) Kav, 2) Atik of A”K, 3) Ohr lifnei HaTzimtzum after the Ratzon for Olomos. Accordingly, Kadosh is 1) Ohr lifnei HaTzimtzum (in general) 2) Kodem Alos Haratzon. And Kadosh is higher than that. Page 516-7, NEW SV p. 680-82.