R. Yossi says: We find that the right hand, too, is called "hand," as it is written (Bereshith 48:17) "And Joseph saw that his father had placed his right hand on the head of Ephraim and it was wrong in his eyes, and he took hold of his father's hand to remove it, etc." (If so, how is "upon your hand" to be understood, if it can signify either right or left)? To include an amputee (of the left hand), that he places it on the right.
"And you shall bind them as a sign upon your hand and they shall be totafoth between your eyes.": Once the hand-piece is upon your arm, place the head-piece upon your head — whence they ruled: In donning the tefillin, he dons the hand-piece first and then the head-piece. And when he removes them, he removes the head-piece first and then the hand-piece.