The Nut Garden
“When King Solomon descended to the depth of the nut, as is written: I descended to the nut garden (Song of Songs 6:11), he took the קְלִפָּה (qelipah), shell, of the אֱגוֹז (egoz), nut, contemplated all those shells, and realized that all the joy and delight of those spirits—shells of the nut—consists solely in clinging to human beings and leading them astray, as is written: The delights of the sons of men: demon after demon (Ecclesiastes 2:8)… The blessed Holy One had to create everything in the world, arraying the world. All consists of a kernel within, with several shells covering the kernel. The entire world is like this, above and below, from the head of the mystery of the primordial point to the end of all rungs: all is this within that, that within this, so that one is the shell of another, which itself is the shell of another” (Zohar 1:19b-20a).
“All those firmaments, one upon the other, are like skins of an onion, some below and some above” (Zohar 3:10a, cf. Maimonides, Mishneh Torah, Hilkhot Yesodei ha-Torah 3:2).