A Dispute as Old as the Sources The Gemara in Menachot 34b discusses the order of the placement of the Tefillin. The first two parshiyot in which the Torah mentions tefillin are from the right, and the next two are from the left. Rashi reads this as two sets: to the person facing the wearer, the first set will begin from the right, and the second set will be to the left of that. So, the order is Kadesh, V'hayah, Shema, V'hayah (Menachot 34b, Rashi s.v. V'hakorei). Tosafot brings the opinion of Rabbeinu Tam that the first two parshiyot indeed begin from the reader's right, Kadesh and V'hayah, but the next set "begins" from left to right, Shema and V'hayah. This results in the two parshiyot that begin with the word V'hayah being in the center chambers (Tosafot, Menachot 34b s.v. V'hakorei). Tosafot cites R' Hai Gaon and R' Yosef Tov Elem (Joseph Bonfils) who preceded Rabbeinu Tam and ruled the same way (Tosafot ibid.). However, Rambam a...