Many of the laws and details regarding the creation of tefillin are oral traditions that trace back to Moses, known as halachah leMoshe miSinai.1 Received from G‑d atop Mount Sinai, they were passed down by Moses to Joshua, and from there down to the leaders and sages of each generation.

These specifications are not hinted at in Scripture, nor can they be deduced logically. Yet they are far from arbitrary. As Maimonides writes, it is appropriate to contemplate these decrees and provide an explanation for them whenever possible. With this in mind, here are just a few explanations that the mystics give as to why tefillin needs to be made of animal hide.

Harnessing Impulses

When we put on tefillin, we place one box upon the left arm (signifying action) opposite the heart (the seat of the emotions) and the other upon the head (the seat of the intellect). When doing so, we have in mind the submission of one's mind, heart and actions to the Almighty. On the one hand, we do not simply follow the impulses of the heart (since we can easily be tempted), but on the other hand, we can’t simply follow our intellect (as that path can be harsh and cold).

Based on this, some explain that by placing sacred leather parchments in a box made of animal hide, we subdue and transform our animalistic desires and impulses and use them in our service of G‑d.

Elevating All of Creation

The mystics explain that the world can be separated into four major components: domem (inanimate/mineral), tzomeach (vegetation), chai (animal) and medaber (humankind).

In the process of preparing the hides and making the tefillin, certain herbs (tzomeach) and water (domem) are used to process the hides (chai). When the person (medaber) performs the mitzvah of tefillin, he is gathering and elevating all four components of creation and demonstrating how G‑d is the master and creator of all.2