The Shechinah (שכינה), God's indwelling Presence, rests in the Holy of Holies. But if God fills the entire world with His glory, what does it mean for the Shechinah to "rest" in one specific place?
Rabbi Schneur Zalman of Liadi answers with an analogy from the human soul. Your soul pervades all 248 organs of your body, from your head to your feet. Yet its principal dwelling place is in the brain. From there, it sends different powers to different organs: the eye receives the power to see, the ear to hear, the mouth to speak, the feet to walk. You can feel this directly, sitting in your brain, conscious of everything that happens throughout the body.
But here is the crucial point: these differences in how the organs receive their power have nothing to do with the soul's essence. The soul is not "more present" in the brain than in the feet. It is a single, simple, spiritual entity with no physical shape or spatial dimension. It cannot be divided into 248 pieces.
Rather, the soul contains 613 distinct powers, corresponding to the 248 positive and 365 negative commandments, and these powers flow outward from concealment through the brain as their primary channel. The brain is not where the soul "is." It is where the soul's life-force first becomes manifest before flowing to the rest of the body.
God's relationship to the universe works the same way. God is equally present everywhere. But the Shechinah, the revealed flow of divine vitality to all worlds, has its primary point of manifestation. In the time of the Temple, that point was the Holy of Holies. The Ark, the Tablets, the Ten Commandments engraved on stone by God's own hand, these were not merely housed there. They were the channel through which infinite light entered finite reality.
To return to, and further to elucidate, the expression of the Yenuka, mentioned earlier,1 Ch. 35. it is necessary first to explain—so that one may understand a little—the subject of the indwelling of the Shechinah, which rested in the Holy of Holies and likewise all other places where the Shechinah rested. What is the meaning of this? Is not the whole world full of His glory? And surely there is no place void of Him. The [clue to the] understanding of this is to be found in the text, “From my flesh I see G–d.”2 Job 9:26. The analogy is from the soul of a human being which pervades all the 248 organs of the body, from head to foot, yet its principal habitation and abode is in his brain, whence it is diffused throughout all the organs, each of which receives from it vitality and power appropriate to it, according to its composition and character: the eye for seeing, the ear for hearing, the mouth for speaking, and the feet for walking—as we clearly sense that in the brain one is conscious of everything that is affected in the 248 organs and everything that is experienced by them. Now, the variation in the acquisition of powers and vitality by the organs of the body from the soul is not due to the [soul’s] essence and being, for this would make its core and essence divisible into 248 diverse parts, vested in 248 loci according to the various forms and locations of the organs of the body. If this were so, it would follow that its essence and core are fashioned in a material design, in a likeness and form resembling the shape of the body, Heaven forfend! Rather, it is entirely a single and simple spiritual entity, which, by its intrinsic essence, is divested of any corporeal shape and of any category and dimension of space, size, or physical limitation. It is, therefore, impertinent to say, in relation to its core and essence, that it is located in the brain of the head more than it is in the feet, since its core and essence are not subject to the dimensions and categories of physical limitation. But there are contained in it, in its intrinsic essence, 613 kinds of powers and vitalities to be actualized and to emerge from concealment in order to animate the 248 organs and 365 veins of the body, through their embodiment in the vivifying soul, which also possesses the corresponding 248 and 365 powers and vitalities. It is with reference to the flow of all the 613 kinds of powers and vitalities from the concealment of the soul into the body in the process of animating it that it has been said that the principal dwelling place and abode of this flow of life and of this manifestation is situated entirely in the brains of the head. Therefore they first receive the power and vitality appropriate to them according to their disposition and character, namely, chabad (chochmah, binah, daat) and the faculty of thought, and all that pertains to the brains; and not only this, but also the sum total of all the streams of vitality flowing to the other organs is also contained and is clothed in the brain that is in the head. It is there that the core and root of the said manifest flow of the light and vitality of the whole soul are to be found. From there a radiation is diffused to all the other organs, each of which receives the power and vitality appropriate to it in accordance with its disposition and character: the faculty of sight reveals itself in the eye, and the faculty of hearing manifests itself in the ear, and so forth. But all the powers flow from the brain, as is known, for therein is located the principal dwelling place of the whole soul, in its manifest aspect, since the sum total of the vitality that is diffused from it is revealed there. Only the [individual] powers of the said general vitality shine forth and are radiated from there into all the organs of the body, much in the same manner as light radiates from the sun and penetrates rooms within rooms. [Even the heart receives vitality from the brain; hence the brain has an intrinsic supremacy over it, as has been explained above.3 Ch. 12.] In a truly like manner, figuratively speaking, does the En Sof, blessed is He, fill all worlds and animate them. And in each world there are creatures without limit or end, myriads upon myriads of various grades of angels and souls, and so on, and likewise, the abundance of the worlds is without end or limit, one higher than the other…. Now, the core and essence of the En Sof, blessed is He, is the same in the higher and lower worlds, as in the example with the soul given above and as is written in the Tikkunim that “He is the Hidden One of all the hidden.”4 Tikkunei Zohar, Introduction 17a. This is to be understood that even in the higher, hidden worlds He is hidden and concealed within them, just as He is hidden and concealed in the lower, for no thought can apprehend Him at all even in the higher worlds. Thus as He is to be found there, so is He found in the very lowest. The difference between the higher and lower worlds is with regard to the stream of vitality which the En Sof, blessed is He, causes to flow and illumine in a category of “revelation out of concealment” [which is one of the reasons why the influence and stream of this vitality is figuratively called “light”], thereby animating the worlds and the creatures therein. For the higher worlds receive, in a somewhat more “revealed” form, than do the lower, and all creatures therein receive each according to its capacity and nature, which is the nature and the form of the particular flow with which the En Sof, blessed is He, imbues and illumines it. But the lower [worlds], even the spiritual ones, do not receive [the light] in quite such a “revealed” form, but only by means of many “garments,” wherein the En Sof, blessed is He, invests the vitality and light which He causes to flow and shine on them in order to animate them. These garments, wherein the En Sof, blessed is He, invests and conceals the light and vitality, are so numerous and powerful that thereby He created this very corporeal and physical world. He gives it existence and animates it by the vitality and light which He causes to flow and shine forth to it—a light that is clothed, hidden, and concealed within the numerous and powerful garments, which hide and screen the light and vitality, so that no light or vitality whatsoever is visibly revealed, but only corporeal and physical things that appear lifeless. Yet they contain light and vitality which constantly give them existence ex nihilo, that they shall not revert and become nothing and nought as they had been. This light comes from the En Sof, blessed is He, except that it is clothed in many garments, as is written in Etz Chaim, that the light and vitality of the physical orb of Earth, which is seen by mortal eyes, is derived from malchut d’malchut d’Asiyah5 The lowest of all the sefirot; for Malchut is the tenth sefirah, and Asiyah—the fourth of the Four Worlds. and in it is contained malchut d’Yetzirah, and so on, so that in all of them are contained the ten sefirot of Atzilut which are united with their Emanator, the En Sof, blessed is He.