10(The tzimtzum and concealing of the life-force is called in Kabbalistic terminology kelim [“vessels”], and the life-force itself is called or [“light”],11 which signifies revelation.
[וְהִנֵּה, בְּחִינַת הַצִּמְצוּם וְהֶסְתֵּר הַחַיּוּת – נִקְרָא בְּשֵׁם "כֵּלִים", וְהַחַיּוּת עַצְמוֹ – נִקְרָא בְּשֵׁם "אוֹר",
For just as a vessel covers that which is within it, so does the tzimtzum cover and conceal the light and the life-force that flows into created beings, and this tzimtzum makes it impossible for them to perceive the G-dliness that is vested within them.
שֶׁכְּמוֹ שֶׁהַכְּלִי מְכַסֶּה עַל מַה שֶּׁבְּתוֹכוֹ, כָּךְ בְּחִינַת הַצִּמְצוּם מְכַסֶּה וּמַסְתִּיר הָאוֹר וְהַחַיּוּת הַשּׁוֹפֵעַ;
The kelim are verily the letters of the ten Divine utterances (or their substitutions and transpositions, etc.), which are the life-force of created beings,
וְהַכֵּלִים – הֵן הֵן הָאוֹתִיּוֹת,
and [all these letters] are rooted in the five letters12 מנצפ"ך
שֶׁשָּׁרְשָׁן ה' אוֹתִיּוֹת מנצפ"ך,
since they represent five degrees of gevurah i.e., five restraining forces that divide and separate the breath and voice in the five organs of speech, thus enabling the twenty-two letters to be formed.
שֶׁהֵן ה' גְּבוּרוֹת הַמְחַלְּקוֹת וּמַפְרִידוֹת הַהֶבֶל וְהַקּוֹל בְּה' מוֹצָאוֹת הַפֶּה לְהִתְהַוּוֹת כ"ב אוֹתִיּוֹת,
Just as the five physical organs of speech divide sounds and letters into five separate categories (labial, guttural, etc.), so, too, do the five spiritual levels of gevurah give rise to the twenty-two supernal letters.
The source of the five levels of gevurah is termed in the Kabbalah Butzina deKardunita, which is Aramaic for (lit.) “light from darkness,’’ the darkness being a level of concealment that transcends light.13
וְשֹׁרֶשׁ הַה' גְּבוּרוֹת – הוּא "בּוּצִינָא דְקַרְדּוּנִיתָא",
This is the supernal gevurah of Atik Yomin, the spiritual level of keter that transcends all Worlds, including Atzilut,
שֶׁהִיא גְּבוּרָה עִילָּאָה דְּ"עַתִּיק יוֹמִין",
and, correspondingly, the source of [the various levels of Divine] kindness is chesed of Atik Yomin,
וְשֹׁרֶשׁ הַחֲסָדִים – הוּא גַּם כֵּן חֶסֶד דְּ"עַתִּיק יוֹמִין",
as is known to the students of the Kabbalah.)14
כַּיָּדוּעַ לְיוֹדְעֵי חֵן]:
Since the tzimtzum and the letters (on one hand) and the revelation of the Divine light and life-force (on the other hand) both emanate from the level of Atik Yomin, it follows that the tzimtzum does not effect an objective concealment as viewed from their common source Above, for, as previously explained, “No entity can conceal itself from itself.”
Thus, tzimtzum affects and is only felt by created beings, who because of this concealment are unable to perceive the Divine life-force that continuously creates them. This is necessary in order for them to think of themselves as independently existing—a state which must be felt by them if they are to “tangibly exist.”
In truth, however, they are utterly nullified within their source Above.
It is explained in the Kabbalah that these are the source of all letters,