Kabbalah sur Ézéchiel 1:4

This is not the case with the barren tree, which does not bear fruit. The reason is that the kelipah²The kelipah (lit. “shell”) refers to those demonic forces which both stand in opposition to the sefirotic realm of holiness and derive their life-energy from it. does not bear fruit. Thus [also] one who studies mistakenly necessarily inclines that study after the “outside” ones. Like the “outside” ones, he bears no fruit. They also surround the stream. The “stream” is Yesod, the locus of mysteries,³On the sefirah Yesod as “locus of mysteries,” see Elliot Wolfson, “Circumcision, Vision of God and Textual Interpretation: From Midrashic Trope to Mystical Symbol”, History of Religions 27 (1987): 189-215, esp. pp. 205-215; idem, “Circumcision and the Divine Name,” Jewish Quarterly Review 78 (1987): 77-112, esp. 100-101, 103-106. for “light” (‘or) is [the numeric equivalent of] “mystery” (raz) This “light,” which is stored away for the righteous,⁴Cf. Zohar I, 31b-32a; II, 148b-149a. departs, [for] the secret of the Lord is to those who fear Him and His covenant (Ps. 25:14). [Covenant] is Yesod, the secret of [the divine name] Yah.⁵See Wolfson, “Circumcision and the Divine Name.” In sum, [these] surround this stream [and] constitute a thin covering (kelipah), about which is written, a brightness was round about it (Ezek. 1:4). This constitutes the foreskin, which had been split and pulled down but not cut off, as has been explained.⁶In a ritual circumcision, there are two parts to the operation, the removal of the foreskin and the tearing (periah) of the mucous membrane. Without both operations, a Jewish circumcision is considered incomplete. The “brightness” is a reference to the kelipah called nogah (“brightness”), which occupies an intermediate position between the realms of the sefirot and the kelipah. It constitutes an aid, border, and covering for the tree that bears fruit. Thus the willows of the stream surround the stream, and there they benefit. Just so, those who err [in their study] form trees there in which the Holy One, blessed be He, rejoices, for ultimately these willows are useful and beautify the stream. They are bound together in the lulav.⁷On the festival of Sukkot, the prayer ritual utilizes “four species”—the etrog (citron), lulav (palm branch), hadas (myrtle), and ‘aravah (willow). The willow was considered the least important of the four, but nonetheless was needed for the set to be complete. See Lev. 23:40.

218. There are four general Kelipot which are alluded to in Ezekiels vision, as written, "And I saw and behold a storm wind coming from the north, a great cloud, and a roaring fire encompassed by a glow". They are also alluded to in Eliyahu's vision, Ruach - Wind, Ra'ash - Earthquake, Esh - Fire, within which G-d was not revealed plus a Kol Dmama Daka - a still small voice.