The occasional visitor to Israel, or, indeed, to any predominantly Jewish neighborhood, is bound to have a lot of questions about the at-times bewildering surroundings. It could be something as mundane as those strings hanging out of someone’s shirt or that funny little box glued to the doorjamb of the hotel room.
The mezuzah is one of the more prominent examples of Jewish material culture; others include tefillin, tzitzit and tallit and a kippah. The word mezuzah literally means doorpost, but it has come to mean the parchment scroll placed on the doorpost that is inscribed with the verses from Deuteronomy that start with, “Hear O Israel, the Lord our God, the Lord is One. And thou shalt love the LORD thy God with all thy heart, and with all thy soul, and with all thy might.” And then we read a few verses later: “And thou shalt write them upon the door-posts of thy house, and upon thy gates.”
Tellingly, “doorpost” comes up earlier in the Torah in a very different context. In Exodus 12, Israelite homeowners in Egypt were told to daub their doorpost with the blood of a sacrificed lamb, as a signal to the Angel of Death to “pass over” the house. The mezuzah is both a religious amulet and a means to spiritually elevate every entry to and exit from the house.
The law calls for a mezuzah to be placed on every doorpost of the home, with the exception of bathrooms and closets. The parchment (klaf in Hebrew) must be written by hand by a scribe, on animal skin. Mezuzahs are nearly always housed in a case that is itself mounted on the doorpost. These cases range from no-frills plastic utilitarian to gorgeous ceramic and silver works of art.
Sephardic Jews affix their mezuzahs vertically, but the Ashkenazi custom is to position them on a slant. Why? One opinion holds that this was a countermove by Jews with anti-Semitic Christian neighbors who would occasionally incite trouble by forming a cross by painting a short horizontal line across the vertical mezuzah. Ashkenazi Jews attempted to prevent this defacement by installing the mezuzah on an angle.