So, in order to reach the root and source of the Neshomoh as it is in the spiritual world of Atzilus it is achieved as a result of going to Eretz Yisroel.
Background on Likkutei Torah
5572 (1812), covering the books of Bereishis and Shmos, with several Maamorim on Shavuos and Pesach. The second half was published in Zhitomir in 5608 (1848) under the title Likkutei Torah, with Maamorim covering the books of Vayikra, Bamidbor and Devorim, Shir Hashirim, Yomim Tovim, Rosh Hashana & Yom Kippur.
Possuk: Shir Hashirim (1:5)
“I am black but comely, O daughters of Jerusalem! Like the tents of Kedar, like the curtains of Solomon”
I am black but comely: Where the Alter Rebbe explains that even the Neshomos whose roots are in the worlds of Beriyah, Yetzirah or Assiyah also have a root and are originally sourced in the world of Atzilus. (In the words of the Kabbalah the births of these Neshomos are in worlds below Atzilus but their incubation takes place in the world of Atzilus).
Result of Going to Eretz Yisroel
As is explained earlier that Eretz Yisroel is spiritually positioned so that it lines up with the upper Eretz which is from where the Neshomoh of a Jew comes, so in order to reach the highest point from where the Neshomoh comes which is the root and source of the Neshomoh one needs to go to the place that spiritually lines up with that root which is Eretz Yisroel. If one was to attempt to reach his root and source whilst he was in the Diaspora outside Eretz Yisroel and away from his alignment to his root the highest spiritual point that he would only ever be able to reach would be the Supernal sefira of ‘Malchus’ of the spiritual world of ‘Yetzirah’.
