Our Gemara on Amud Beis records a dispute regarding the shape of the showbread in the Beis HaMikdash:

“Rabbi Ḥanina says: It was rectangular, with a wide base and two parallel walls with an open space between them, like a box that is open on two sides.”

“Rabbi Yoḥanan says that the shewbread was like a rocking boat, i.e., a triangular-shaped boat with a narrow base from which two walls rise at angles. Since the boat does not have a wide base, it rocks from side to side.”

Sefer Bamidbar Yehuda (end of Emor) notes that the Table in the Beis HaMikdash is the vehicle for channeling God’s blessings for sustenance, which is obvious in its ritual regarding bread. The boat-like shape that rocks to and fro is also reminiscent of the uneasy and fluctuating nature of the pursuit of livelihood. In agrarian times, it was the temperament of the weather; in our times, less so, but more the fluctuations of the economy and market dynamics. Likewise, the open box shape hints at the ease of obtaining divine intervention if one merits—a container with a wide opening up top.

Rav Hirsch in Parashas Terumah explains an additional symbolic idea. The two walls jointly were equal to the flat surface area. The bread is piled one on the other, and therefore each bread is held by the one below it, with walls that are equal to the surface. Rav Hirsch says this alludes to the interdependency of each person’s sustenance on the other and the need for brotherhood and harmony. Sefer Daf al Daf notes that even more striking is the opinion that the bread was V-shaped. In that case, the smallest portion of the area was surface (i.e., self-gratification), and the largest part was supporting the other bread.

I wonder if this final position is a hint to a halachic opinion about tzedakkah. Ordinarily, it is forbidden to give more than one-fifth of one’s income to charity, so as not to be self-destructive. However, some hold that if one is mega-wealthy and needs only a small amount of his total fortune, he may give a much larger percentage (see Shulchan Aruch YD 249:1 and Chochmas Adam 144:10). This is reminiscent of the small surface area that is flat, while almost all the area goes into supporting the other bread.