Look deeply and you will see that the Torah does not know of man and woman as separate beings. Each act is performed once through a single body—a body that in our world may appear as two, but which the Torah sees as one. On the contrary, for both to be assigned the same mitzvah would be redundant, for why should one half of the body do that which the other has already accomplished? Just as a man fulfills the mitzvah to be fruitful and multiply through the agency of his female counterpart, so does a woman wrap tefillin or wear tzitzit on the body of her male counterpart. For just as man and woman were first created as a single form, so...