In order for Hashem’s Chochma of Atzilus to come into the Torah passages in the Tefillin, the level of Kesser needs to be expressed. So, when a Jewish man puts on Tefillin, he actually connects to Hashem’s Chochma on a deeper level than Chochma of Atzilus does, since the Jew is also connecting to Hashem through Kesser which transcends Atzilus.
Therefore, a Unification Above is affected through mitzvos performed specifically with physical objects, וְלָכֵן נַעֲש ָה יִּחו ד עֶלְיוֹן עַל יְדֵי םיִּ יִּמְ שַ ג םיִּרָבְד ,
The term “Unification Above” means: The Sefiros of Atzilus are spiritually Above the created words. When two Sefiros unite with each other, (generally speaking, either Chochma with Bina or Ze’eir Anpin with Malchus,) on a deeper level than they usually are united, this is a called a “Unification Above.”
This deeper level of connection between the Sefiros (either of Chochma with Bina or Ze’eir Anpin with Malchus) is dependent on the service of Hashem from the person below in this physical world.
such as through tzedakah, which effects a Unification Above in the world of Atzilus, כ ְמוֹ עַל יְדֵי צְדָקָה נַעֲש ָה יִּחו ד עֶלְיוֹן ב ַ אֲצִּילו ת –
Through giving tzedakah-charity to the poor in this world, this has a ripple affect back to the cosmic source of the poor person and the person giving, as they exist in the levels of Ze’eir Anpin and Malchus. Ze’eir Anpin, the level of Hashem’s Emotive Attributes of Kindness and Severity, are the level that is “giving,” and Malchus, the level of Speech and Creation is “receiving” the additional flow of Hashem’s Light and Power from Ze’eir Anpin, corresponding to the poor person receiving life-sustaining funds from his benefactor.
