The sefirot are ten spheres or classes, as it is stated in Sefer Yetzira, "Ten and not nine; ten and not eleven." This is their order: keter (crown); chochma (wisdom); bina (understanding); chesed (kindness); gevura (might); tiferet (beauty); netzach (endurance); hod (splendor); yesod (foundation); malchut (kingship).

In some schemes keter is omitted from the order of the ten sefirot, as will be explained further on. These schemes understand chochma to be the first of the ten and insert daat (knowledge) as a sefira after bina.

As a crown is on top of the head…so keter is on top of all the sefirot

Keter is the highest level or sphere of the sefirot. The term itself denotes its significance: as a crown is on top of the head and encompasses it, so keter is on top of all the sefirot and encompasses them all.

The analogy is carried further: just as the crown is not a part of the head or the body but distinct from it, so keter is essentially distinct from the other sefirot. It is the first emanation, and as such the "lowest level" as it were, of the Emanator Himself. That is why keter is called "the most hidden of all hidden" ("temira dechol temirin"), and is referred to as "naught" ("Ayin"). These terms signify the total concealment of the rank of keter due to its supreme sublimity.

Keter is so sublime and concealed that nothing can be said or postulated of it. While the other sefirot are sometimes represented by various letters of the alphabet, no letter can describe or represent keter. (In the paradigm where the four letters of G‑d's name Havayah represent the ten sefirot, i.e. yud - chochma, hei - bina, vav - the unit of the six middot from chesed to yesod, hei - malchut, keter is represented by the "thorn" of the yud, thus not by any letter but by a mere dot.)

Ein Sof and the sefirot

That is why keter is sometimes excluded from the scheme of the sefirot. It is too sublime to be included. It is a category and class all in itself. In fact it is called the "intermediary" between the Ein Sof and the sefirot, bridging the gap, as it were: it is the "lowest level" of the Light of the Ein Sof and from it, and through it, issue forth the successive divine emanations (thus being the very root or soul of the sefirot). Keter represents the "lever" of divine manifestations and, as such, is called "the Supreme Will" ("Ratzon Ha'elyon") of G‑d: not a particular will focused on some specific goal but the original Divine Willingness (Ratzon) underlying the creative will. It is the "Will of all wills", which precedes all powers or attributes (i.e., the sefirot).

In the metaphorical terminology of the Kabbala and Chasidut, chochma is called Abba and bina is called Imma. Metaphorically speaking, the seed of Abba is implanted in the womb of Imma, and there the rudimentary plant of the seed is developed, expanded, externalized and informed. Daat is called "Ben" ("son"), i.e. the offspring of this union of chochma and bina.

In daat the original idea and concept has matured into corresponding dispositions. Therefore daat is the all-inclusive essence of the middot, the emotive powers or attributes of the lower sefirot. This is because the lower sefirot (from chesed to malchut) express and reveal these dispositions originating in the "intellect".

Thus the middot are called the children of chochma and bina, or, alternatively, the six middot from chesed to yesod as a unit is called "son" and malchut is called "daughter".

It is in this context as "soul (essence) of the middot" that daat is not counted as a separate sefira to replace keter. For as a mere soul without its own independent vessel or body it cannot be included as one of the ten principles of the sefirot (see Etz Chaim 23:5, 8, 40:6).

The Ari is a third opinion to the effect that keter is somewhere in between Or Ein Sof and the sefirot

R. Moses Cordovero always counts keter as part of the ten sefirot and excludes daat as a separate sefira (see Pardes Rimonim 3:1 ff.n and Or Ne'erav 6:1, par. 5). In the system of R. Isaac Luria, daat is usually counted as one of the sefirot while keter is excluded (see Etz Chaim 23:1, 2, 5, 8; 25:6; 42:1).

Their difference in perspective evolves around the interpretation of Zohar I: 31b, where the plain meaning appears to support the opinion of R. Isaac Luria, though R. Moses Cordovero (see ibid., 2:3 ff.) interprets according to his opinion.

In fact this has long been a matter of dispute among the earlier kabbalists. While all are agreed that keter exceedingly excels the sefirot (chochma to malchut), some say that keter is identical with the Ein Sof (rather with the Or Ein Sof) and therefore to be excluded from the scheme of sefirot, while others have it that keter, too, is an emanation and effect having a cause just like the other sefirot and, hence, is to be counted among them (see the discussion of these issues in Pardes Rimonim 3:1 ff., and Etz Chaim 42:1.)

The view of the Ari is a third opinion to the effect that keter is somewhere in between Or Ein Sof and the sefirot, part of both, and bridging or linking them. In his view, keter is the "lowest" level of the Ein Sof as well as the very root or source of the sefirot. This issue relates to the disputed issue whether the term Ein Sof itself has reference to the actual Essence and Being of G‑d as He is in Himself or to G‑d qua First Cause.

In the context of the aforesaid, R. Isaac Luria adds that when speaking of the essential sefirot, keter is included, but when speaking of their general aspects (the "external aspects" of the sefirot) keter is omitted and daat is inserted instead (see Etz Chaim 23:5,8; and the Baal HaTanya's Likutei Torah III: 49c; cf. ibid. II: 46c and V:8a). [Ed. note: the perspective in which keter is omitted and daat is included can be understood as being from the viewpoint after Shevirat haKelim.]

[Adapted from "Mystical Concepts In Chassidism: An Introduction to Kabbalistic Concepts and Doctrines", available as a separate book (Kehot) or together with Likutei Amarim - Tanya, Book IV.]