This section of Tanya explains the metaphysical basis of bittul as allowing divine unity to seep into the mundane world, emphasizing transformation through connection to God's infinite light.
וְהִנֵּה, שֵׁם ״אֱלֹהִים״, הוּא שֵׁם מִדַּת הַגְּבוּרָה וְהַצִּמְצוּם, וְלָכֵן הוּא גַּם כֵּן בְּגִימַטְרִיָּא ״הַטֶּבַע״, לְפִי שֶׁמַּסְתִּיר הָאוֹר שֶׁלְּמַעְלָה – הַמְהַוֶּה וּמְחַיֶּה הָעוֹלָם, וְנִרְאֶה, כְּאִילּוּ הָעוֹלָם עוֹמֵד וּמִתְנַהֵג בְּדֶרֶךְ הַטֶּבַע. וְשֵׁם ״אֱלֹהִים״ זֶה, הוּא מָגֵן וְנַרְתֵּק לְשֵׁם הֲוָיָ״ה, לְהַעֲלִים הָאוֹר וְהַחַיּוּת הַנִּמְשָׁךְ מִשֵּׁם הֲוָיָ״ה וּמְהַוֶּה מֵאַיִן לְיֵשׁ, שֶׁלֹּא יִתְגַּלֶּה לַנִּבְרָאִים וִיבָּטְלוּ בִּמְצִיאוּת. וְאִם כֵּן, מִמֵּילָא תֵּדַע שֶׁ״בַּשָּׁמַיִם מִמַּעַל וְעַל הָאָרֶץ מִתָּחַת – אֵין עוֹד״, פֵּירוּשׁ, שֶׁגַּם הָאָרֶץ הַחוּמְרִית שֶׁנִּרְאֵית יֵשׁ גָּמוּר לְעֵין כֹּל, הִיא אַיִן וָאֶפֶס מַמָּשׁ לְגַבֵּי הַקָּדוֹשׁ־בָּרוּךְ־הוּא, כִּי שֵׁם ״אֱלֹהִים״ אֵינוֹ מַעֲלִים וּמְצַמְצֵם אֶלָּא לַתַּחְתּוֹנִים, וְלֹא לְגַבֵּי הַקָּדוֹשׁ־בָּרוּךְ־הוּא, מֵאַחַר שֶׁהוּא וּשְׁמוֹ ״אֱלֹהִים״ – אֶחָד, וְלָכֵן, גַּם הָאָרֶץ וּמִתַּחַת לָאָרֶץ הֵן אַיִן וָאֶפֶס מַמָּשׁ לְגַבֵּי הַקָּדוֹשׁ־בָּרוּךְ־הוּא, וְאֵינָן נִקְרָאוֹת בְּשֵׁם כְּלָל, אֲפִילוּ בְּשֵׁם ״עוֹד״ שֶׁהוּא לְשׁוֹן טָפֵל, כְּמַאֲמַר רַבּוֹתֵינוּ־זִכְרוֹנָם־לִבְרָכָה ״יְהוּדָה וְעוֹד לִקְרָא״, וּכְגוּף שֶׁהוּא טָפֵל לַנְּשָׁמָה וְחַיּוּת שֶׁבְּתוֹכוֹ [וְזֶהוּ שֶׁכָּתוּב: ״אֲהַלְלָה ה׳ בְּחַיָּי, אֲזַמְּרָה לֵאלֹהַי בְּעוֹדִי״, שֶׁהַחַיִּים נִמְשָׁכִים מִשֵּׁם הֲוָיָ״ה, וְהָ״עוֹד״ שֶׁהוּא הַגּוּף הַטָּפֵל – מִשֵּׁם ״אֱלֹהִים״], לְפִי שֶׁהַנְּשָׁמָה אֵינָהּ מְהַוָּה הַגּוּף מֵאַיִן לְיֵשׁ, אֲבָל הַקָּדוֹשׁ־בָּרוּךְ־הוּא הַמְהַוֶּה אֶת הַכֹּל מֵאַיִן לְיֵשׁ – הַכֹּל בָּטֵל בִּמְצִיאוּת אֶצְלוֹ, כְּמוֹ אוֹר הַשֶּׁמֶשׁ בַּשֶּׁמֶשׁ. רַק שֶׁהֵן הֵן גְּבוּרוֹתָיו, בְּמִדַּת הַגְּבוּרָה וְהַצִּמְצוּם, לְהַסְתִּיר וּלְהַעֲלִים הַחַיּוּת הַשּׁוֹפֵעַ בָּהֶם, שֶׁיִּהְיוּ נִרְאִים הַשָּׁמַיִם וְהָאָרֶץ וְכָל צְבָאָם כְּאִילּוּ הֵם דָּבָר בִּפְנֵי עַצְמוֹ. אַךְ אֵין הַצִּמְצוּם וְהַהֶסְתֵּר אֶלָּא לַתַּחְתּוֹנִים, אֲבָל לְגַבֵּי הַקָּדוֹשׁ־בָּרוּךְ־הוּא – ״כּוּלָּא קַמֵּיהּ כְּלָא מַמָּשׁ חֲשִׁיבֵי״, כְּאוֹר הַשֶּׁמֶשׁ בַּשֶּׁמֶשׁ, וְאֵין מִדַּת הַגְּבוּרָה מַסְתֶּרֶת חַס וְשָׁלוֹם לְפָנָיו יִתְבָּרֵךְ, כִּי אֵינֶנָּה דָבָר בִּפְנֵי עַצְמוֹ אֶלָּא ״ה׳ הוּא הָאֱלֹהִים״:
Now, the name Elokim is the name which indicates the attribute of gevurah and tzimtzum, hence it is also numerically equal to hateva (nature), for it [Elokim] conceals the supernal light which brings the world into existence and gives it life, and it appears as though the world exists and conducts itself in a natural way. And this name Elokim is a shield and a covering for the name Havaya, to conceal the light and life-force which flows from the name Havaya and brings creation into existence from naught, so that it [the light and life-force] should not be revealed to the creatures, who thereby would become absolutely nullified. Since this is so, you will consequently know that “In the heavens above and on the earth below, en od—there is nothing else [besides G–d].” This means that even the material earth, which appears to the eyes of all to be actually existing, is naught and complete nothingness in relation to the Holy One, blessed is He. For the name Elokim conceals and contracts [the light and life-force] only for the lower [creatures], but not for the Holy One, blessed is He, since He and His Name Elokim are One. Therefore, even the earth and that which is below it are naught and complete nothingness in relation to the Holy One, blessed is He, and are not called by any name at all, not even the name od (else) which is an expression indicating a secondary, subordinate status, as the statement of our Sages of blessed memory, “Yehudah v’od likrah,” [unlike] the body which is subordinate to the soul and life-force within it [and is referred to as od]. [And this is the meaning of the verse: “I will praise Havaya with my life (soul) and will sing to Elokim be’odi” (with my body). For the soul is derived from the name Havaya and the od, which is the body, the subordinate (of the soul), from the name Elokim.] For the soul does not bring the body into existence ex nihilo, [hence it can be called od in relation to the soul], but the Holy One, blessed is He, Who brings everything into existence ex nihilo—everything is absolutely nullified in relation to Him, just as the light of the sun [is nullified] in the sun. Yet these are His restraining powers, to hide and conceal, through the attribute of gevurah and tzimtzum, the life-force which flows into them, so that heaven and earth and all their hosts should appear as if they were independently existing entities. However, the tzimtzum and concealment is only for the lower [worlds], but in relation to the Holy One, blessed is He, “everything before Him is considered as actually naught,” just as the light of the sun in the sun. And the attribute of gevurah does not, Heaven forfend, conceal for Him, blessed be He, for it is not an independent entity—since Havaya is Elokim.