תניא, חלק ראשון; ליקוטי אמרים ה׳ — ד"ה כִּי עַל יְדֵי כָּל הַמִּצְוֹת שֶׁבְּדִבּוּר
The chapter explains the special bond formed through Torah study, in which the divine wisdom studied becomes united with the soul. This is a classic chassidic source for Torah's personal transformative power.
כִּי עַל יְדֵי כָּל הַמִּצְוֹת שֶׁבְּדִבּוּר וּמַעֲשֶׂה, הַקָּדוֹשׁ־בָּרוּךְ־הוּא מַלְבִּישׁ אֶת הַנֶּפֶשׁ, וּמַקִּיפָהּ אוֹר ה׳ מֵרֹאשָׁהּ וְעַד רַגְלָהּ, וּבִידִיעַת הַתּוֹרָה, מִלְּבַד שֶׁהַשֵּׂכֶל מְלוּבָּשׁ בְּחָכְמַת ה׳, הִנֵּה גַּם חָכְמַת ה׳ בְּקִרְבּוֹ – מַה שֶּׁהַשֵּׂכֶל מַשִּׂיג וְתוֹפֵס וּמַקִּיף בְּשִׂכְלוֹ מַה שֶּׁאֶפְשָׁר לוֹ לִתְפּוֹס וּלְהַשִּׂיג מִידִיעַת הַתּוֹרָה, אִישׁ כְּפִי שִׂכְלוֹ וְכֹחַ יְדִיעָתוֹ וְהַשָּׂגָתוֹ בִּפְשַׁט־רֶמֶז־דְּרוּשׁ־סוֹד. וּלְפִי שֶׁבִּידִיעַת הַתּוֹרָה, הַתּוֹרָה מְלוּבֶּשֶׁת בְּנֶפֶשׁ הָאָדָם וְשִׂכְלוֹ וּמוּקֶּפֶת בְּתוֹכָם, לָכֵן נִקְרֵאת בְּשֵׁם ״לֶחֶם״ וּ״מְזוֹן הַנֶּפֶשׁ״. כִּי כְּמוֹ שֶׁהַלֶּחֶם הַגַּשְׁמִי זָן אֶת הַגּוּף כְּשֶׁמַּכְנִיסוֹ בְּתוֹכוֹ וְקִרְבּוֹ מַמָּשׁ, וְנֶהְפָּךְ שָׁם לִהְיוֹת דָּם וּבָשָׂר כִּבְשָׂרוֹ, וַאֲזַי יִחְיֶה וְיִתְקַיֵּם, כָּךְ בִּידִיעַת הַתּוֹרָה וְהַשָּׂגָתָהּ בְּנֶפֶשׁ הָאָדָם שֶׁלּוֹמְדָהּ הֵיטֵב בְּעִיּוּן שִׂכְלוֹ עַד שֶׁנִּתְפֶּסֶת בְּשִׂכְלוֹ וּמִתְאַחֶדֶת עִמּוֹ וְהָיוּ לַאֲחָדִים – נַעֲשָׂה מָזוֹן לַנֶּפֶשׁ וְחַיִּים בְּקִרְבָּהּ, מֵחַיֵּי הַחַיִּים אֵין־סוֹף בָּרוּךְ־הוּא הַמְלוּבָּשׁ בְּחָכְמָתוֹ וְתוֹרָתוֹ שֶׁבְּקִרְבָּהּ.
For, through all the commandments involving speech or action, the Holy One, blessed is He, clothes the soul and envelops it from head to foot with the Divine light. However, with regard to knowledge of the Torah, apart from the fact that the intellect is clothed in Divine wisdom, this Divine wisdom is also contained in it, to the extent that his intellect comprehends, grasps, and encompasses, as much as it is able so to do, of the knowledge of the Torah, every man according to his intellect, his knowledgeable capacity, and his comprehension in Pardes. Since, in the case of knowledge of the Torah, the Torah is clothed in the soul and intellect of a person and is absorbed in them, it is called “bread” and “food” of the soul. For just as physical bread nourishes the body as it is absorbed internally, in his very inner self, where it is transformed into blood and flesh of his flesh, whereby he lives and exists—so, too, it is with the knowledge of the Torah and its comprehension by the soul of the person who studies it well, with a concentration of his intellect, until the Torah is absorbed by his intellect and is united with it, and they become one. This becomes nourishment for the soul and its inner life from the Giver of life, the En Sof, blessed is He, Who is clothed in His wisdom and in His Torah that are [absorbed] in it [the soul].