The mezuzah is a small, often decorative box that contains a scroll with the words of the Torah. It is really like a mini Torah, because it is written in the same manner and with the same materials as the full scroll. Its origins are in the Torah, in the paragraph of the Shema that we say twice a day. “And these words which I command you will be on your heart…and you will write them on the door posts and lintels of your home.”
These words were originally taken quite literally, and people wrote them right on the door posts themselves. The mezuzah as we know it today was developed to give the words greater dignity and permanence.
Many people think of the mezuzah as a good luck charm, some to such an extent that when something bad happens, they check to see whether the scroll of the mezuzah is flawed. This was never the intent.
The mezuzah is a statement of the values of the home. When we go out into the world in the morning it is a reminder to live by our values of compassion and honesty. When we return home it is a reminder of how we are supposed to treat the people inside the house. We may have had a long day, but it is not excuse for taking it out on our loved ones. We take a look at the mezuzah, perhaps kiss it, take a breath, and then go to work or school or anything else we have to do that day, and again when we return.
Let me say something about kissing the mezuzah, and the Torah during the Torah service, and when saying the blessings over the Torah. The original reason for kissing the Torah or mezuzah was not as a sign of affection, though that is certainly a good thought to have in mind while doing it. The purpose for kissing the Torah is as a sign of agreement, showing that we believe in and agree to live by its words. It is to help us remember who we are and where we came from. It is a sign that we are a people created by the values of the Torah, a people that on a daily basis is to embrace the challenges of life with patience, kindness and persistence.
Rabbi Aaron Bergman's Blog 