Here’s a part of the explanation given by the Alter Rebbe (it is also cited in the Kuntres Limud HaChasidus, written by the Rebbe Rayatz):
– Eitan is the essence of the soul as it cleaves to the Essence (of G‑d), (Eitan is) a portion of G‑d above. [As we say in the morning blessings:]
“The soul You have placed within me is pure; You created it; You formed it; You breathed it [into me]”.
The four [italicized] terms parallel the Four Worlds [known in the Kabbalah as Atzilut, Briah, Yetzirah, Assiah].
The Midrash (Bereshit Rabbah 14:9) enumerates five gradations of soul:
- nefesh (soul),
- ruach (spirit),
- neshama (soul),
- chaya (living),
- and yechida (single).
The Zohar (Vol. 1, p. 79b.) reckons the first three and the fourth, neshama l’neshama (the soul of the soul), paralleling the four letters of the Holy Name of the Creator – Havayah.
Eitan is the strength of the soul as manifested in the power of self-sacrifice. Eitan also means “ancient, not newly created . . . drawn from G‑d’s Essence” (Sotah 46b).
“The soul You have placed within me is pure” refers to the source of the soul as it is in the world of Atzilut. Emanation is a separation from the illumination of the Infinite, the Emanator. It is not novel, but a revelation of the previously concealed (Cf. Mamaarim 5666, s.v. “Kedoshim.”).
This is maskil, the source that creates and reveals the idea. [It is said:] “Maskil l’Eitan” (lit. “to eitan”), the revelation of maskil is only for eitan. And through the power of maskil, eitan arrives at the state of “ha’ezrachi”, the illumination of all powers and senses.