1) HALACHAH: THE CUSTOM TO TOUCH AND KISS THE MEZUZAH
OPINIONS: The Gemara relates that Onkelus, hunted by the Caesar for converting to Judaism, confronted battalion after battalion of troops who came to his house and successfully convinced each battalion of the merits of Judaism. The Caesar finally instructed his troops not to talk to Onkelus at all, but just to arrest him. They arrived at Onkelus' home and ordered him to come with them. Upon leaving, he touched the Mezuzah on his door post and asked the Roman soldiers, "What is this?" They replied, "You tell us." He explained to them that it is the manner of an earthly king to sit inside while his servants guard him from outside. Hash-m, however, is different. His servants sit inside and He guards them from the outside, as it says, 'Hashem will guard you as you leave and as you enter, from now and forever" (Tehilim 121:8). The soldiers were deeply moved by this lesson and they, too, converted. After this set of troops was defeated, the Caesar stopped sending more troops.
Many Poskim cite this Gemara as the source for the custom to touch and kiss the Mezuzah when one leaves or enters his home.
(a) The DARCHEI MOSHE (YD 285) quotes the MAHARIL who infers from the Gemara that one should place his hand on the Mezuzah when he leaves his home and say, "Hash-m Yishmor Tzeisi u'Vo'i me'Atah v'Ad Olam" -- "Hash-m should guard my leaving and coming from now and forever," a paraphrase of the verse in Tehilim. This custom is recorded by the REMA (YD 285:2). However, the Rema does not write that one should recite the prayer both when he leaves and enters his home, but only when he leaves. The Rema writes that when one enters, "he should place his hand on the Mezuzah." Perhaps the Rema maintains that the prayer is not said when one enters his home, because the source for such a prayer is the incident with Onkelus, who said the verse only when he was leaving his home.
The SHACH quotes additional words of the Maharil, which the Rema does not cite (although the Rema does quote them in DARCHEI MOSHE): When one leaves his house in order to embark on a trip outside of his city, he should place his hand on the Mezuzah and say, "b'Shimcha Tal Etleh." The Shach explains that "Tal" is the Gematriya of the Divine name written on the back of the Mezuzah, "Kuzu."
Although these sources do not mention that one should kiss the Mezuzah after he places his hand on it, other sources mention that it is praiseworthy to kiss objects of Mitzvos, and this certainly is true of something as holy as a Mezuzah. (See PISCHEI TESHUVAH YD 285:3, who writes in the name of REBBI AKIVA EIGER that one may touch the Mezuzah with his bare skin only when it is within an encasement.)
(b) The KITZUR SHULCHAN ARUCH (11:24) explicitly writes that one should kiss the Mezuzah when he leaves and enters his house. When he leaves his house he should say, "Hash-m Shomri Hash-m Tzili Al Yad Yemini, Hash-m Yishmor Tzeisi u'Vo'i me'Atah v'Ad Olam" -- "Hash-m is my Guard, Hash-m is my Shade at my right hand, Hash-m should guard my leaving and coming from now and forever." The Kitzur Shulchan Aruch mentions this prayer only with regard to one who leaves his house, perhaps because Onkelus said this verse only when he left his house.
(c) The BIRKEI YOSEF quotes a different version of this custom in the name of the ARIZAL. He says that a person should place his middle finger on the name "Shakai" of the Mezuzah, kiss his finger (see ARUCH HA'SHULCHAN YD 285:4), and pray to Hash-m that He guard him with the name Shakai, and that He save him from the Yetzer ha'Ra with the name of Hash-m formed with the letters that follow the letters of Shakai -- "Tav (after Shin), Kaf (after Yud), Heh (after Dalet)."
It should be noted that none of Poskim mention that one must place his hand on or kiss any Mezuzah other than the one on the door of his home. (Y. MONTROSE)
2) AGADAH: "WOE TO THIS ONE WHEN THIS ONE RISES"
QUESTION: The Gemara relates that once every seventy years, a holiday would be celebrated in Rome, on which a healthy man would ride on the back of a cripple. The healthy man would wear the clothes of Adam ha'Rishon and the scalp of Rebbi Yishmael, and he would hold an expensive rod made of a type of gold. The people would decorate the marketplaces and proclaim in front of the pair of men: "The officer's calculation is nonsense! The brother of our master is a forger! Whoever sees will see, and whoever does not see will not see! What does the liar gain with his trickery, and the forger with his forgery?" They would conclude, "Woe to this one when this one rises!"
The commentaries explain that this ceremony was intended to demonstrate Esav's supposed triumph over Yakov, who gained nothing by stealing the birthright and blessings from Esav. However, the ceremony seems to end on an ominous note for Rome. The conclusion, "Woe to this one when this one rises," implies that Rome fears the rising of Yakov. Why would they add that ominous statement?
(a) The KOS YESHU'OS explains that the last statement was not part of their proclamation. Rather, it is the Gemara's response to their boasting. The Gemara responds by saying that although they are mightier now, woe to them when Hash-m will again elevate the status of the Jewish people.
(b) The AVODAS AVODAH and the ETZ YOSEF record testimony from a person who actually saw this ceremony, and who insisted that the Romans themselves made this last statement. However, it was the Roman elders who said it in Hebrew in order that the masses not understand that their triumph is only temporary.
(c) The AVODAH BERURAH explains that it is not unreasonable to say that the Romans themselves made this statement. It is the nature of evildoers to persist in their evil ways even when they know that they likely will be punished for their deeds after they die. Although the evildoers boast that they are triumphant in this world, they admit that if Hash-m elevates the Jewish people at the end of the days, they are going to face serious judgment. (Y. MONTROSE)