We learn how there can be four passages in the Tefilin yet only three names in the the Sh'ma reading. The numerology of the 25 letters in the Sh'ma, the 24 letters in the unification that begins with "Blessed be the name," the 49 gates of Binah and the 25 things used to complete the building of the tabernacle are all explained in detail.
Rabbi Aba asks Rabbi Shimon about the leather straps of the Tefilin, comparing it to skin. Rabbi Shimon gives him an explanation, and then says that when a person studies the Torah all night and then puts on the Tefilin in the morning, when he goes out of his house wearing the Tzitzit and passing the Mezuzah on his doorpost, then he is escorted by four holy angels that go with him to the synagogue. We are also told about the artistic work of people who create the Tefilin, the Tzitzit, and the Mezuzah. Rabbi Shimon closes by saying that if people really knew the Torah they would know that there isn't a single letter or word of it that does not contain supernal secrets.