The cause of this deficiency is the arrogance of the kelipah of the animal soul, which exalts itself above the holiness of the light of the divine soul so that it obscures and darkens its light.
וְהַסִּיבָּה – הִיא גַסּוּת הַקְּלִיפָּה, שֶׁמַּגְבִּיהַּ עַצְמָהּ עַל אוֹר קְדוּשַּׁת נֶפֶשׁ הָאֱלֹהִית, וּמַסְתֶּרֶת וּמַחֲשִׁיכָה אוֹרָהּ.
Therefore, one must crush it and cast it down to the ground, just as in the previously quoted analogy, the beam is splintered so that it will catch fire.
וְלָזֹאת, צָרִיךְ לְבַטְּשָׁהּ וּלְהַשְׁפִּילָהּ לֶעָפָר,
This means that one must crush the sitra achara and cast it to the ground by setting aside appointed times for humbling oneself and considering himself “despicable and contemptible,”4 as it is written.
דְּהַיְינוּ, לִקְבּוֹעַ עִתִּים לְהַשְׁפִּיל עַצְמוֹ, לִהְיוֹת "נִבְזֶה בְעֵינָיו נִמְאָס", כַּכָּתוּב,
Now “a broken heart [leads to] a broken spirit,”5 the “spirit” being the sitra achara, which, in the case of beinonim, is the very man himself.
וְ"לֵב נִשְׁבָּר" – "רוּחַ נִשְׁבָּרָה", הִיא הַסִּטְרָא אָחֳרָא, שֶׁהִיא הִיא הָאָדָם עַצְמוֹ בַּבֵּינוֹנִים,
For in his heart, the vital soul which animates the body is in its full strength as it was at birth; hence, it is indeed the very man himself.
שֶׁנֶּפֶשׁ הַחִיּוּנִית הַמְחַיָּה הַגּוּף, הִיא בְּתָקְפָּהּ כְּתוֹלַדְתָּהּ בְּלִבּוֹ, נִמְצָא – הִיא הִיא הָאָדָם עַצְמוֹ.
With regard to the divine soul within him, it is said: “The soul which You gave within me is pure.”6 The word “(within) me” cannot be understood as referring to the body alone: the body cannot speak for itself as a complete man. Thus, it must refer also to the (animating) soul. Therefore, the words “(which You gave) within me” imply that the man himself who is saying these words is not identified with the “pure soul,” i.e., the divine soul is a thing apart, which has been “placed within” this “me”—the body and animal soul—except in the case of tzaddikim.
וְעַל נֶפֶשׁ הָאֱלֹהִית שֶׁבּוֹ נֶאֱמַר: "נְשָׁמָה שֶׁנָּתַתָּ בִּי טְהוֹרָה הִיא", "שֶׁנָּתַתָּ בִּי" דַּיְיקָא, מִכְּלָל, שֶׁהָאָדָם עַצְמוֹ אֵינֶנּוּ הַנְּשָׁמָה הַטְּהוֹרָה, כִּי אִם בַּצַּדִּיקִים,
With them, the contrary is true: the man himself is the “pure soul,” i.e, the divine soul, while their body is called “the flesh of man,” i.e., secondary to the man himself—the divine soul.
שֶׁבָּהֶם הוּא לְהֵפֶךְ, שֶׁנְּשָׁמָה הַטְּהוֹרָה שֶׁהִיא נֶפֶשׁ הָאֱלֹהִית – הוּא הָאָדָם, וְגוּפָם נִקְרָא – "בְּשַׂר אָדָם".
The Alter Rebbe now proceeds to explain how this is accomplished. He points out that the personality of the beinoni is his animal soul. (When a beinoni says “I,” he is referring to his animal soul.) Thus, by crushing his own spirit, he crushes the sitra achara and thereby enables the light of the soul and intellect to penetrate himself.