Ever since the Temple was destroyed, “the four cubits of the Halachah”—i.e., study of Jewish law—is the only sanctuary and abode which the Holy One, blessed be He, has in His world; i.e., Torah is the only abode for the revelation of His unity.
וּמִשֶּׁחָרַב בֵּית הַמִּקְדָּשׁ – אֵין לְהַקָּדוֹשׁ־בָּרוּךְ־הוּא בְּעוֹלָמוֹ מִשְׁכָּן וּמָכוֹן לְשִׁבְתּוֹ, הוּא יִחוּדוֹ יִתְבָּרֵךְ, אֶלָּא אַרְבַּע אַמּוֹת שֶׁל הֲלָכָה,
For the halachot set out before us are the actual embodiment of G-d’s will and wisdom, which are one with G-d; the halachic ruling represents the Divine will, and what underlies it is Divine wisdom. Hence, in the Torah, G-d’s unity stands revealed.
שֶׁהוּא רְצוֹנוֹ יִתְבָּרֵךְ וְחָכְמָתוֹ הַמְלוּבָּשִׁים בַּהֲלָכוֹת הָעֲרוּכוֹת לְפָנֵינוּ.
Therefore, after one meditates deeply, according to his ability, on the subject of this abovementioned self-nullification, let him reflect in his heart as follows:
וְלָכֵן, אַחַר שֶׁיַּעֲמִיק הָאָדָם מַחֲשַׁבְתּוֹ בְּעִנְיַן בִּיטּוּל הַנִּזְכָּר לְעֵיל כְּפִי יְכָלְתּוֹ, זֹאת יָשִׁיב אֶל לִבּוֹ:
“The capacity of my intelligence and of my soul’s root is too limited to constitute a chariot and an abode for G-d’s unity in perfect truth,
"כִּי מִהְיוֹת קָטָן שִׂכְלִי וְשֹׁרֶשׁ נִשְׁמָתִי מֵהָכִיל, לִהְיוֹת מֶרְכָּבָה וּמִשְׁכָּן לְיִחוּדוֹ יִתְבָּרֵךְ בֶּאֱמֶת לַאֲמִיתּוֹ,
for my thought cannot grasp or apprehend His unity at all with any degree of comprehension in the world,
מֵאַחַר דְּלֵית מַחֲשָׁבָה דִילִי תְּפִיסָא וּמַשֶּׂגֶת בּוֹ יִתְבָּרֵךְ כְּלָל וּכְלָל שׁוּם הַשָּׂגָה בָּעוֹלָם,
not an iota, in fact, of that which was grasped by the Patriarchs and Prophets, who were G-d’s chariot and abode by virtue of their awareness of G-d’s unity, as they grasped it.
וְלֹא שֶׁמֶץ מֶנְהוּ מֵהַשָּׂגַת הָאָבוֹת וְהַנְּבִיאִים,
“This being so, I will make Him a sanctuary and an abode by studying Torah at fixed times by day and by night, to the extent of my free time,
אֵי לָזֹאת, אֶעֱשֶׂה לוֹ מִשְׁכָּן וּמָכוֹן לְשִׁבְתּוֹ, הוּא הָעֵסֶק בְּתַלְמוּד תּוֹרָה כְּפִי הַפְּנַאי שֶׁלִּי, בִּקְבִיעוּת עִתִּים בַּיּוֹם וּבַלַּיְלָה,
as stipulated by the law governing each individual’s situation, set forth in the Laws of Torah Study.
כְּדָת הַנִּיתְּנָה לְכָל אֶחָד וְאֶחָד בְּהִלְכוֹת תַּלְמוּד תּוֹרָה,
“As our Sages say, ‘Even one chapter in the morning [and one at night…]’6 suffice, for one who can manage no more, for him to be regarded as ‘engaging in Torah study day and night.’ Therefore, by fulfilling this minimal quota, I, too, will become an abode for G-dliness.”
וּכְמַאֲמַר רַבּוֹתֵינוּ־זִכְרוֹנָם־לִבְרָכָה: 'אֲפִילוּ פֶּרֶק אֶחָד שַׁחֲרִית כוּ''"
Thereby, his heart shall rejoice; he shall be glad and offer joyous thanks for his fortune
וּבָזֶה יִשְׂמַח לִבּוֹ וְיָגִיל, וְיִתֵּן הוֹדָאָה עַל חֶלְקוֹ בְּשִׂמְחָה וּבְטוּב לֵבָב,
in meriting to be “a host to the Almighty”7 through his study of Torah, which causes him to be a “sanctuary” for G-d twice each day, according to the extent of his available time and according to the capacity which G-d has granted him.
עַל שֶׁזָּכָה לִהְיוֹת אוּשְׁפְּזִיכָן לַגְּבוּרָה פַּעֲמַיִם בְּכָל יוֹם, כְּפִי הָעֵת וְהַפְּנַאי שֶׁלּוֹ, כְּמִסַּת יָדוֹ אֲשֶׁר הִרְחִיב ה' לוֹ:
The Alter Rebbe points out below that when one specific place is singled out as an abode for G-d’s presence, despite the fact that “His glory fills the entire earth,” the uniqueness of this site lies in the revelation of G-dliness which occurs there. In contrast to the rest of the world, where G-d’s unity as the sole existing being stands concealed, in “the abode of G-d’s presence,” it is clearly apparent that “there is naught besides Him.” We thus see that the revelation of G-d’s unity which the Jewish people experienced at Mount Sinai, but which they could not endure, was continued by means of the Sanctuary.