Q:

"Why do we dip the challah in salt on Shabbat? And why three times?"

A:

Actually, it has nothing to do with Shabbat; it applies whenever we eat bread. Tradition cites four reasons: two are found in Midrash/Talmud and two in Kabbalah. The first three are quoted in the Code of Law.1 It is desirable to have all of these ideas in mind while performing the dipping.

1) Judaism is primarily home-centered, not synagogue-centered. Each Jewish home is (or should be!) a miniature Holy Temple. The dining table parallels the altar in the Temple,2 and the meals we eat are like the offerings that were brought there. This theme is strongly emphasized with bread, our most basic staple food-item, which is singled out for dipping in salt reminiscent of the offerings which had to be be accompanied by salt [Lev. 2:13].

2) During the leisure of a sit-down meal, we are expected to speak words of Torah (see Avot 3:3]. However, while washing our hands and waiting for the first bite of bread we must be silent, so at that time we do not have the merit of Torah study. But the salt on the table, a natural preservative, is a reminder of G-d's eternal covenant with us [Num. 18:19], and thus provides protection for us at this vulnerable moment. With this in mind, it is easy to understand why it is recommended to leave the salt dish on the table the entire meal, even if we don't use it!

3) The Hebrew word for salt is spelled mem-lamed-chet.3 Its numerical value, 78, is three times that of G-d's four-letter name. Therefore, we dip the bread in the salt exactly three times. (While dipping, some people have the custom to focus on the prayer, "G-d was, G-d is, G-d always will be king".4 Some also have the custom to shake the bread after each dipping.5) Furthermore, we put the bread in the salt and not the salt on the bread, since bread is a manifestation of chesed ("kindness"), while salt symbolizes gevurah ("strictness").

4) For non-vegetarians, there is a nother layer of meaning. In the traditional Jewish classification system of physical life, "still" - "growing" - "moving" - "speaking" [mineral-vegetable-animal-human], man represents the highest of the four divisions. At our meals we have the opportunity to elevate the other three levels through proper eating. Salt represents the mineral kingdom. (In the old days, they didn't eat chemicals at every meal!)

Yrachmiel Tilles

1. Shulchan Aruch, Orach Chayim 167:5 with Rema and Magen Avraham. See there sources for first two reasons; for sources for third reason, see Marei Makomot v'Tziyunim l'Shulchan Aruch Admur HaZaken I, 167:8.
2. If any bugs are discovered on your table, don't kill them, just remove them. The altar provided sanctuary! [ibid]
3. The same letters as the word for bread, lamed-chet- mem.
4. Sephardic tradition (note the similarity of the Hebrew words for "salt" and "king": melach-melech, with 'king' spelled with a chof at the end instead of a chet).
5. The triple dipping affects a sweetening of the three "strictnesses," which in turn enables the removal of the "impure shells" from the table [Ohr Tzadikim, quoted in Taamei Minhagim #182].