[The celebrant] should not slice [the loaf] before they set before him salt or savoury (Rashi explains ['savoury'] as meaning anything that is eaten together with the bread) to give taste to the slice; but if it was quality bread or spiced or salted as ours is, or if it was his intention to eat dry bread he need not wait. Note: nevertheless, it is a mitzvah to put salt on every table before breaking [bread] because the table is likened to the altar and food to an offering, and it says "you shall offer salt with all your offerings".
In Mishnaic and Talmudic times bread was baked from many different kinds of grain and it was usually coarse and very bland. When the bread was intended for a mitzvah - such as ĥallah on Shabbat and festivals or the matzah for the Seder service on Pesaĥ - 'quality' bread was baked, almost invariably from wheat. Since, on a weekday at least, the bread was so very bland it was considered appropriate to sprinkle it with salt (or to dip it in salt) so that it would have some taste and thus be worthy of its benediction. Seeing that the purpose of the salt was to give the bread flavour it is obvious that any other foodstuff that would achieve the same result was acceptable in place of salt. This is what Rabbi Karo calls a 'savoury', and the parenthetical reference to Rashi's commentary makes it clear that anything that will give taste to the bread is acceptable. (The reference in all probability is to what Rashi wrote on Eruvin 29a.)
By the end of the middle ages bread was already spiced with salt or similar flavouring during the baking and bread from wheat was much more common, especially on Shabbat and YomTov. Thus, according to the rationale explained above it should no longer be necessary to add salt to the bread as we approach modern times. However, by this time the adding of salt to the bread had become so customary that it was emotionally difficult to dispense with the habit even if it was realized intellectually that it was no longer needed. It is a commonplace in Jewish lore - as in the lore of all peoples - that when a cherished custom loses its raison d'être a new one will be found.
In Jewish thought the dining table was considered to be be possessed of quasi sanctity. Many different mitzvot are fulfilled before we can put food into our mouths and the knowledge of the performance of these mitzvot accords the meal an aura of sacred ritual. Tithes have been taken, kashrut has been observed, hands have been washed, benedictions have been recited: all these raise even the humblest of tables into incipient sanctity. An accepted epithet for the altar in the Bet Mikdash was Shulĥan Gavo'ah, the Table of the Most High. (We discussed various aspects of this kind of thinking when we studied Tractate Tamid.) With the destruction of the Bet Mikdash this concept was gradually transferred to our own dining tables. In the Gemara [Berakhot 55a] we read:
As long as the Bet Mikdash was standing the altar atoned for [the sins of] Israel; now it is a person's table which atones for him.
This teaching was based on a previous dictum which praised the person who prolongs sitting at the table, thus prolonging the meal
in case a poor person might come along and one can give him
from the food still on the table. It was this constant consideration of mitzvot - both ritual and social - that caused the verse [Ezekiel 41:22] associated with the altar of the Temple in Jerusalem to be applied also to the dining table in every Jewish home:
This is the table that stands before the Lord.
Thus the dining table is invested with and aura of sanctity and is likened to an altar. It is but one small step thereafter to liken the meal served on that table to the offerings made to God on the altar in the Bet Mikdash. Every time we eat we offer all the mitzvot that have been observed in connection with the meal as our modern offering to God. The commandments that have been observed start with the ploughing of the field and go through the whole gamut of observances until we reach the mitzvah of entertaining the needy at our table as an honoured guest. The Torah [Leviticus 2:13] orders that
You shall season your every offering of meal with salt; you shall not omit from your meal offering the salt of your covenant with God; with all your offerings you must offer salt.
We have been discussing the benediction ha-motzi. I wrote that the celebrant slices the ĥallot. This prompted Ze'ev Orzech to write:
I am gratified to read that the hallot should be sliced (that is, cut with a knife) for that is how I was brought up. It was only as much later that I encountered the custom of tearing chunks out of the hallah. I have seen whole groups grasp a hallah and tear it to pieces. This is justified in terms of "breaking bread." Whether hallot are sentient or not, I wince every time I see this happen. Any comment?
I am sorry to disappoint you! I used the term 'sliced' because it seemed the most appropriate English term to use. However, the original Hebrew term does not necessarily indicate 'slicing': it indicates, as Ze'ev writes, the "breaking of bread" - in any suitable manner. Halakhically speaking there is no objection at all if people wish to "break bread" with their bare hands rather than slice it with a knife. The "breaking of bread" can be done in an aesthetic manner just as the slicing of bread can be done in a non-aesthetic manner. As long as the bread is served in a manner appropriate to the sancity of the table, which we described earlier in this shiur, it makes no matter how it is done. Let me add that it is the custom of my family to "break bread". But then we usually use small home-baked ĥallot; when we have occasion to use large ĥallot we slice them with a knife.
Uri Sobel writes concerning the leĥem mishneh that we mentioned in Shabbat 043:
Regarding the "double rations", it has always seemed to me that the timing of the exodus narrative you cited is inconsistent with how we do our ritual. The isralites gathered the manna in the morning. Thus they had a double portion on Friday morning. But, by day's end, presumably, they would have eaten some of it, leaving them with less than a double portion for Shabbat. Certainly, by lunch the next day, there would be at most 1 ration left (calling into question needing two loaves on shabbat day), but even for dinner Friday night, I would think they no longer had a full double portion (otherwise, what did they eat on Friday day?)
The custom of having two ĥallot on Shabbat and YomTov is not in imitation of the manna in the desert; it is in commemoration of the manna in the desert - zekher la-man. By having two loaves instead of just one we recall God's providential care of the Israelites in the desert even to the extent of ensuring that they would have enough manna to last throughout Shabbat even though it would not be available to them on Shabbat itself.
In connection with the same topic, Mark Lehrman writes:
If the rationale for the 2 hallot on Shabbat is the double portion of manna described in Exodus, then is it appropriate (or required) to have 2 hallot at Festival meals as well?
Yes. As I wrote in response to Uri above we may assume that "double rations" were provided on YomTov as well.