The first and highest sefira is called keter or "crown". Within this sefira are two main aspects - the inner aspect of keter, called "Atik" or "Atik Yomin" and the outer aspect, called arich anpin. Due to its loftiness Atik Yomin is sometimes referred to as temira d'chol temirin (the most concealed of all) and as ayin (nothingness). The Infinite Light (Or Ein Sof) illuminates atik without any separation. Atik is the source of the Torah, which is referred to as "G-d's delight" and is revealed primarily in the esoteric teachings of the Torah, i.e. in Kabbala. Arich Anpin is essentially the expression of G-d's will. In other words, the outer aspect of the keter of any particular world is the expression of G-d's will and purpose in creating that world.
The will of a human being is the most all-encompassing power of his soul
This can be understood better by comparing this sefira to certain aspects of a human being. The will of a human being is the most all-encompassing power of his soul, since it gives rise to and motivates all of the other powers of the soul. If a person has a will for something he begins to invent ways in which to achieve his goal. Once he has discovered a theoretical method of achieving his goal, he starts to plan out how to achieve this in reality. From there he initiates the action. As long as he has not yet achieved his desire, his will drives him onwards until he does so.
Similarly, keter contains within it the ultimate goal which it seeks to attain. The aim of every plane of reality is to reveal the Infinite Light appropriate to that plane of reality. Thus keter contains within itself the end-point which it desires to achieve. And when it has achieved that desired end-point, it ceases to drive further. This is the meaning of the statement of the Sages in Sefer Yetzira (1:7): "the end is wedged in the beginning, and the beginning is wedged in the end." The purpose of the emanation of the sefirot which is expressed in keter is to unfold the level of Infinite Light appropriate for that plane of reality, all the way through the various stages of development (i.e. through the various sefirot) to the final revelation and manifestation of that light in the sefira of malchut. Thus, keter is "wedged" in the lowest sefira, malchut.. And malchut is wedged in the highest sefira, keter, for it is the end-point which fulfills the purpose of the entire emanation.
Thus keter is the generator and activator of all the other sefirot
Thus keter is the generator and activator of all the other sefirot. For in order to achieve the goal (the revelation of the Infinite Light), the entire range of emanation from its highest point to its lowest is generated and unfolds specifically from keter until the desired objective is achieved.
Just as a person's will transcends any particular aspect of his being and envelops all of him, there is no organ or limb which is the seat of the will. So too, the will and purpose of the Creator in producing a plane of reality is transcendent and envelops the entire inner structure of that world. There is no level of revelation which is outside of the will of G-d as manifested in the keter of that world. Thus keter is the all-encompassing and transcendent sefira of every world. In addition, it is generally beyond human comprehension. The process of immanent, in-dwelling and comprehensible revelation of the Infinite Light appropriate for a plane of reality only begins with the next sefira, the sefira of chochma.
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