The Head Tefillin

THE HEAD TEFILLIN

דברים פרק כח, י וְרָאוּ כָל-עַמֵי הָאָרֶׁץ כִׁי שֵם ה 'נִׁקְרָא עָלֶׁיךָ וְיָרְ אוּ מִׁמֶׁךָ:

“Then all the nations of the world will see that the Name of G-d is upon you, and they will fear you.”

The Gemara Menochos 35b and the Medrash Shir Hashirim 7:6 (see also Targum Yonoson ben Uziel) say that this refers to the tefillin "she'b'rosh," literally IN one's head. (Rabbi Yosef Soloveitchik tz”l states every Jewish man wears a crown, not because he is powerful, but because he is committed.)

We have a halacha l'Moshe miSinai that the exterior of the tefillin housing of the shel rosh has the letter shin twice on it.

1. Why the letter "shin"?
2. Why does one of the two "shinin" have four strokes and four heads rather than the normal three headed "shin"?

Why the letter "shin"?

1. An allusion from our verse, the first letters of the words "SHeim-HaShem (Yud)-Nikra" create "shin."
2. The shin is indicative of HaShem's name as the four letter name of HaShem, yud, kay, vov, kay equals 26, and their corresponding letters in the "atbash transpermutation system” is mem, tzaddi, pei, tzaddi which equal 300, the numerical value of the letter shin (Beis Yoseif on the Tur Orach Chaim #32 in the name of the R"I Askandrani).
3. The Beis Yoseif in the name of the Orchos Chaim #27 says that "shin" equals 300 and this is the number of days per year that a person wears Tefillin (Not worn on Shabbos or Yom Tovim). This last reason is found in the Rabbeinu Bachyei as well.
4. The Toras Chaim #101 says that since we have knots in the Tefillin straps that form a dalet and a yud, we create a shin on the shel rosh to complete the name of HaShem, Shin-Dalet-Yud.