From: Judaism 101
Signs and Symbols
MezuzahOn the doorposts of traditional Jewish homes (and many not-so-traditional homes!), you will find a small case like the one pictured at left.
This case is commonly known as a mezuzah (Heb.: doorpost), because it is placed upon the doorposts of the house. The mezuzah is not, as some suppose,
a good-luck charm, nor does it have any connection with the lamb's blood placed on the doorposts in Egypt. Rather, it is a constant reminder of
G-d's presence and G-d's mitzvot.
The mitzvah to place mezuzot on the doorposts of our houses is derived from Deut. 6:4-9, a passage commonly known as the Shema (Hear, from the first
word of the passage). In that passage, G-d commands us to keep His words constantly in our minds and in our hearts, by (among other things) writing
them on the doorposts of our house. The words of the Shema are written on a tiny scroll of parchment, along with the words of a companion passage,
Deut. 11:13-21. On the back of the scroll, a name of G-d is written. The scroll is then rolled up placed in the case, so that the first letter of the
Name (the letter Shin) is visible (or, more commonly, the letter Shin is written on the outside of the case).
The scroll must be handwritten in a special style of writing and must be placed in the case to fulfill the mitzvah. It is commonplace for gift shops
to sell cases without scrolls, or with mechanically printed scrolls, because a proper scroll costs more than even an elaborately decorated case
($30-$50 for a valid scroll is quite reasonable). According to traditional authorities, mechanically printed scrolls do not fulfill the mitzvah of the
mezuzah, nor does an empty case.
The case and scroll are then nailed or affixed to the right side doorpost on an angle, with a small ceremony called Chanukkat Ha-Bayit (dedication of
the house - yes, this is the same word as Chanukkah, the holiday celebrating the rededication of the Temple after the Maccabean revolt against
Greece). A brief blessing is recited. See the text of the blessing at Affixing the Mezuzah.
Why is the mezuzah affixed at an angle? The rabbis could not decide whether it should be placed horizontally or vertically, so they compromised!
Every time you pass through a door with a mezuzah on it, you touch the mezuzah and then kiss the fingers that touched it, expressing love and respect
for G-d and his mitzvot and reminding yourself of the mitzvot contained within them.
It is proper to remove a mezuzah when you move, and in fact, it is usually recommended. If you leave it in place, the subsequent owner may treat it
with disrespect, and this is a grave sin. I have seen many mezuzot in apartment complexes that have been painted over by subsequent owners, and it
breaks my heart every time I see that sort of disrespect to an object of religious significance.
Or, just Google "Mezuzah"
I'm guessing that your house was once occupied by a Jewish family who either left the mezuzah as a gift or blessing or they just didn't bother to
have it removed when they left. Technically, only a Rabbi is supposed to attach or remove it.
Your house may be "haunted" but it's not likely that it's connected to the mezuzah. In fact, the mezuzah may be what is protecting you from even
more hauntings. ;-)