The twelve loaves of Lechem Hapanim symbolize the twelve tribes. They simultaneously represent a prayer for sustenance of the twelve shevatim and an expression of our gratitude to the Almighty for His sustenance. From the word “tamid“, “always,” we derive that the Shulchan, Table, is never to be without its twelve loaves. Just as the Kohanim were about to remove the past week’s bread in order to eat it, other Kohanim were at the same moment arranging the new weeks Lechem Hapanim on the table. What is the significance of the coincidence of these two actions? If a minute had passed without bread on the Table, would it have been so bad?
Horav Avigdor Miller, Shlita, explains that the concept of “tamid” in regard to bread implies Hashem’s Providence. Although all living creatures are constantly consuming bread/food, yet Hashem continues to supply additional amounts of food constantly. Never are we without Hashem’s sustenance. If He were to halt this process for just a moment, we would have a food shortage. He provides all of the time. It is just that we have become accustomed to taking our bread/sustance for granted. Only when our bread is endangered, do we respond to Hashem’s wake- up call.