The tefillin are the conduit, the instrument for the connection between the divine powers of wisdom and understanding, and human wisdom and understanding.
The meaning of this connection is that human wisdom and understanding are subsumed and incorporated into divine wisdom and understanding.
“Incorporation” means that a persons wisdom and understanding, as well as the higher forces of wisdom and understanding, are engaged in the same matter, so to speak.
At that moment, a person’s wisdom and understanding are solely an expression of God’s wisdom and understanding.