The left hand is receiving and right hand giving. The hand that Tefillin is worn on is the weak left hand in order to tame egoism. It symbolizes the correction that a person should have on his upper spiritual degree.
This is a very high level in the world of Atzilut – Arich Anpin. There are Tefillin Jacob, Tefillin Rachel, Tefillin Leah, and Tefillin Israel.
Torah, Deuteronomy 11:18: …and they shall be for ornaments between your eyes…
Eyes are the quality of the level of Hochma in the head part of the world of Atzilut, meaning they are very high corrections. To reach such states we must do serious work on ourselves.
But there are also support programs that help implement a common program. It is like recording a new program on our desires. After all, nothing was created in the universe apart from desire. And the Upper Light gradually, like a laser, records the new program on our previous program without canceling the previous one.
In other words, all our egoism remains and just begins to work according to the different program. Therefore Tefillin, Tallit, and all other attributes symbolize the spiritual connections that we must restore between us over our shattered desire.
Question: Do these material attributes help us?
Answer: Unfortunately they just distract us. The fact is that by realizing commandments on the material level, a person thinks that he does everything required. However, it is good if along with performing physical actions that explanations are given: why, what for, and what is behind them, so they remind a person about his inner abilities of implementing the correction.
And it is bad if he thinks that by tying the Tefillin boxes he already fulfills the commandments.
From KabTV’s “Secrets of the Eternal Book” 6/15/16