Guardian Angel Maven
The Torah itself accentuates the great power of mezuzah observance to guard our lives and the lives of our young offspring:
You shall write them on the doorposts of your house and upon your gates. So that your days and the days of your children shall be prolonged…
Conversely, the Sages derive from this verse an implied warning about the negative consequences that could arise from the neglect of the mitzvah.
Clearly, as with every mitzvah, one’s primary intention in affixing a mezuzah should be solely to fulfill
…it may seem as if one intends to make for himself a talisman for protection! Rather, he should perform the mitzvah correctly to fulfill the word of the Creator, Blessed be He, and He will guard us and save us by our right hand.
The Zohar teaches that the mezuzah protects the inhabitants of the house not only in their home but also from the time they leave the house until they return home. Kol Bo suggests that the letters of the Divine name ש-ד-י, customarily inscribed on the outside of the mezuzah parchment (see the Mezuzah Maven column in Ohrnet Vayetze titled “What’s In a Name?”), also allude to the phrase שומר דלתות ישראל (Guardian of the doors of Israel). The daubing of the blood of the Pesach offering on the night of the Exodus on the doorposts and lintels of Jewish homes to prevent destructive forces from penetrating is the first instance of this theme.
In a famous story the Talmud relates how the Roman convert Onkelos fell afoul of his uncle, the Roman Emperor, because of his conversion to Judaism. Soldiers were sent to arrest him, but they abandoned their task, indeed converting to Judaism instead. Finally, in exasperation:
Again he (the Roman Emperor) sent another cohort, ordering them not to enter into any conversation whatsoever with him (Onkelos). So, they took hold of him, and as they were walking on, he saw the mezuzah which was fixed on the door-frame and he placed his hand on it, saying to them: “Now what is this?” They replied: “You tell us, then.” He said, “According to universal custom, a mortal king dwells within, and his servants keep guard on him without; but (in the case of) the Holy One, Blessed be He, it is His servants who dwell within while He keeps guard on them from without, as it is written: “G-d shall guard your going out and your coming in, from this time forth and for evermore.” Then they too converted to Judaism.
The nature of this “guarding” is interpreted in several ways by the commentaries. Basing himself on an Aggadic teaching, Rambam writes that the protection is from sin. As we encounter the “angelic” mezuzah and its message on our doorposts, we are reminded of
Whoever wears tefillin on his head and arm, wears tzitzit on his garment, and has a mezuzah on his entrance, can be assured that he will not sin because he has many who will remind him. These are the angels who will prevent him from sinning, as the verse states: "The angel of
Seemingly, according to this approach, the protective blessing of the mezuzah is fully realized only if one heeds its reminder and is spurred to lead a virtuous life.
Rabbi Yehudah Loew (Maharal of Prague) writes that
The Talmud advises that we should place the mezuzah on the outer handbreadth of the doorpost so that the whole house will benefit from its protection.
- Sources: Devarim 11:20-21; Shabbat 32b; Rosh, Hilchot Mezuzah 18; Avodah Zarah 11a; Menachot 33b, 43b; Rambam, Hilchot Sefer Torah 6:13; Tehillim 34:8; Maharal, Netivot Olam, Netiv HaAvodah 15; Kol Bo 90