Two Teachings About the Sukkah
From the unpublished "Breslov Tehillim" (BRI)
“Indeed, He will hide me in His shelter (sukkah) on a day of evil.” The sukkah shields a person on a day of evil. That is, when one falls away from Divine service, if he will only strengthen himself and not give up, he will find himself shielded and sheltered by an extremely lofty level of holiness: the aspect of the sukkah, which corresponds to the Supernal Mother. This holiness will encompass him like a protective mother so that he does not fall, God forbid, when he comes to a place of danger. It is also understood from the words of [Rebbe Nachman] that when a person finds himself in a spiritual tailspin, in the very place he has fallen, the greatest holiness is concealed. When he supplicates God and finds Him there, at that very hour he will attain the loftiest sanctity (LH, Rosh Hashanah 4:7).
“All of my bones shall declare, ‘God, who is like You?’ ” The sefirah of Binah is the archetype of the mother; it is where the embryo is formed, as in the verse, “If (IM) you call to understanding (binah)” (Proverbs 2:3). [The word Im is homiletically related to EiM, meaning “mother.”] Binah is also an aspect of the mitzvah of Sukkah, as it is written, “You sheltered me (teSuKeini) in the womb of my mother (IMi)” (Psalms 139:13). When a person prays with intense concentration, and he puts all his force into the letters of prayer, this is an aspect of “All of my bones shall declare, ‘God, who is like You?’ ” This is analogous to the Sukkah, as it is written, “You encompassed me (teSoKhekheini) with bones and sinews” (Job 10:1). The letters of the prayers which one utters with all his might (KoaCh, which has the numerical value of twenty-eight) become the twenty-eight letters of the act of creation (i.e., the number of letters in the first verse of Genesis). Thus, his words are the very words of the Holy One, blessed be He, as in the verse, “I put My words in your mouth” (Isaiah 51:16). [Thus by virtue of prayer with intense concentration, one who prays becomes a “spiritual Sukkah” and an instrument of the Divine speech of creation] (LM I, 48).
 I.e., the sefirah of Binah/Understanding, which is the “mother” of the lower seven sefirot. Associated with the upper letter heh in the Divine Name YHVH, Binah also alludes to the ohr makif, or trancendent plane.
 Rebbe Nachman discusses this concept in Likutey Moharan I, 56. This is also related to the widely-discussed issue of the yeridah le-tzorekh aliyah, “descent for the sake of an ascent.”