As Divided for a Regular Year
Tanya for 20 Adar
Although the substance and essence of the animal soul, in his heart, i.e., its evil middot [its evil emotional character], have still not been absorbed into holiness;
[As explained in chapter 12, only in the case of tzaddikim are the evil middot themselves transformed into holiness. In others, only the animal soul's garments - its faculties of expression by means of which a mitzvah is accomplished - are absorbed into holiness; not the middot which constitute the animal soul's essence. Nevertheless, this fact does not prevent the light of the Shechinah from suffusing the entire body, as the Alter Rebbe concludes shortly].
Yet, because they [the evil middot] are subjugated to holiness and "against their will they say Amen," agreeing and acceding to the performance of the mitzvah, through the strengthening of the divine soul in the brain which masters the heart;
[As discussed in chapter 12, although the emotions of the Beinoni have not been transformed into good, he nevertheless has the power to control them by means of his mind, through contemplating G-d's greatness.
In this way the Beinoni can direct his heart as he chooses, insofar as the actual performance of the mitzvot is concerned].
And [the evil middot] are, at such time [when one exercises the natural mastery of brain over heart by contemplating G-d's greatness], in a state of "exile" and "sleep" [i.e., impotent] as mentioned above [in chapter 12], therefore this [incorrigible nature of the animal soul's evil middot] does not prevent the Shechinah from resting on one's body at this time.
[The Alter Rebbe now goes on to explain how it is possible for one mitzvah to draw the Shechinah upon one's entire body].
This "[resting of the Shechinah]" means that the power of the animal soul clothed in the act that constitutes the mitzvah [e.g., the power in the hand donning Tefillin] is actually absorbed into the divine light, and merges with it in perfect unity.
Thereby one draws down a "ray" [of the light wherein the particular power has been absorbed] upon the totality of the animal soul throughout the body, and [upon] the entire body as well.
[This "ray" of divine light illuminates one's animal soul and his body] in a manner of "encompassing from above," [surrounding them from head to foot].
This explains the expression [appearing in the passage from the Zohar quoted at the beginning of this chapter]: "The Shechinah rests upon his head,"  specifically "upon" [i.e., encompassing him "from above']; and [in a similar vein], the expression "upon EVERY [assembly of] ten [Jews] the Divine Presence rests" [means that the light of the Divine Presence does not permeate them, but illuminates them "from above.]" 
[Heretofore, various levels in the "resting of the Shechinah" have been discussed:
As it rests upon the divine soul; upon the specific faculty of the animal soul that performs a mitzvah;  upon the animal soul as a whole and upon the body -
the latter two only encompassed by, but not permeated with, the light of the Shechinah.
As to the light of the Shechinah encompassing the body, within this level we find further subdivisions:
that level which is the effect of a mitzvah;
that which encompasses any gathering of ten Jews, even when not engaged in a mitzvah;
and perhaps we may distinguish yet another level -
that which rests upon even one individual Jew, even when he is not occupied with a mitzvah.
The Alter Rebbe now goes on to state that this variety of levels at which the Shechinah becomes manifest does not indicate any change or plurality in its light (G-d forbid). The variety means merely that the different objects of the light (the divine soul, the animal soul, the body, and so on) receive it in different ways.
In the Alter Rebbe's words]:
None of these various forms in which the light of the Shechinah is manifested, meaning the ways in which the Ein Sof-light is revealed, can be construed as a change in Himself, or as a plurality.
[G-d the Ein Sof is everywhere; it is only that He is concealed from His creatures. Thus, the uniqueness of the manifestation of the Shechinah lies in the revelation of the Ein Sof.
The fact that the Shechinah manifests itself at some point (e.g., in one's soul, through the performance of a mitzvah), whereas it had previously not been manifest, does not point to any change in G-d; nor do the various forms of manifestation indicate plurality within Him].
As we find in the Tractate Sanhedrin  [where it is recorded] that a certain heretic said to Rabban Gamliel: "You say that the Shechinah rests on every assembly of ten. How many Shechinahs have you?"
And Rabban Gamliel replied with an analogy of the sun's light which enters through many windows, etc.
[Despite the multitude of windows, there is but one light.
The same holds holds true even where the light appears differently from place to place: sunlight shining through stained-glass windows of various hues remains nonetheless unchanged, though it takes on the multicolored appearance of the windows; as does also water in a colored glass - once removed from the glass, it appears in its pristine clarity.
So too with the various modes in which the light of the Shechinah is manifested:
The light remains the same, without change or division; any differences in manifestation are attributable only to the way the light is received by the object in which it is manifest].
And the intelligent will understand - [and, as chassidim would add, "The devout will perceive."
- (Back to text) The Rebbe Shlita notes: "From the fact that the prohibition of walking bareheaded (mentioned in the Zohar) is constant, applying even when one is not engaged in the performance of a mitzvah, it is evident that the reason for the prohibition - that the Shechinah rests on his head - is also constant. Since the Shechinah rests upon the individual constantly, independently of his performance of a mitzvah, the meaning of the Tanya here requires further study."
- (Back to text) The Rebbe Shlita notes: "This, too, is unrelated to the performance of a mitzvah. (Accordingly, we can begin to understand how this [quotation] is relevant here.)"
The explanation of the Rebbe's comment is as follows: At first glance, the statement, "On every [assembly of] ten [Jews] the Divine Presence rests," seems to be totally unrelated to the subject under discussion. Our text is speaking of the light that encompasses the person from above, and descends upon him through the performance of a mitzvah. How is this related to the Shechinah's resting upon any assembly of ten Jews, even when they are not performing a mitzvah?
Quite the contrary, answers the Rebbe; this question in itself begins to provide an answer:
The Alter Rebbe seeks to emphasize that an illumination of the Shechinah encompasses the entire vivifying soul and the entire body ("from head to foot"), not only that organ of the body or the particular faculty of the animal soul that actually performs the mitzvah. He therefore quotes the saying of our Sages which speaks of "every assembly": even when the assembled are at that moment not performing a commandment, the Shechinah nevertheless rests upon them - in an encompassing fashion at least.
- (Back to text) The Rebbe Shlita takes issue with this statement, because the Alter Rebbe states that "[the vital spirit as garbed in the physical body] is absorbed in the Divine light, and furthermore `it is truly absorbed.'"
- (Back to text) 39a.