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!
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
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!)
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.
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,
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].