We now encounter something new. Until now, we have seen continuing narratives in the books of Bereisheet and Shemot, but in Parashat Bo we begin to find sections of mitzoth. Most of those in our parasha appear to be clearly connected to the Exodus from Egypt. Tefillin seems to be an exception. Drawing on traditional works of halakha and Jewish thought, we examine this mitzvah and contrast it with the mitzvoth of sukka and tzitzith.