The agony of exile and the destruction of Jerusalem are captured through the visceral, physical torment of eating ruined food and being cast into the dirt. As the people were driven from their homes, they experienced a profound degradation that affected their most basic means of survival.
The primary approach among commentators traces these events to the harsh historical reality of the initial exile. Stripped of their possessions and driven out without basic cooking utensils, the exiles were forced to dig shallow pits in the earth just to knead their dough. Naturally, small stones and pebbles became mixed into the food. As the starving people ate, they broke and blunted their teeth on the gravel [רש״י, תורה תמימה, צאינה וראינה]. This desperate situation carried a bitter irony. God had previously commanded the prophet Ezekiel to prepare gear for exile in order to warn the people and help them prepare for this exact fate. Instead of listening, the people mocked the prophet, only to eventually face the harsh consequences and break their teeth on stone-filled bread [רש״י].
The degradation extended beyond the ruined food to the feeling of being completely overturned and pressed into the ashes. Commentators offer nuanced views on this suffering. Some describe it as being forcefully flipped upside down, much like an overturned vessel [רש״י]. Others view it as being deeply soiled and dirtied [אבן עזרא], or being firmly pressed and submerged into the ashes [ביאור שטיינזלץ]. A fascinating causal link between the ruined bread and the ashes is found in the practices of desert travelers. Typically, wanderers would bake their bread upon a thick layer of ash, which acted as a barrier to keep the dough clean from the desert sand and rocks. However, because God cast the people themselves into the ashes, there was no ash left to protect their food. Forced to bake directly on the bare ground, the bread became encrusted with pebbles, leading directly to their shattered teeth [אלשיך].
Beyond the physical reality, the imagery serves as a powerful allegory for sin and its consequences. At first glance, sin may appear as soft, pleasant flour, but it secretly contains hard stones that ultimately break a person, leading to a punishment where the entire body is cast into the ashes [פלגי מים]. Another allegorical approach views the teeth as a symbol for the Torah scholars, who provide the nation with its strength and structure. As long as these leaders remain united, enemies cannot overpower Israel. However, when strife and division act as gravel wedged between them, their protective power shatters. This internal friction ultimately results in the nation being thrown into the ashes, representing the death or exile of the generation's leaders due to their own infighting [אלון בכות].
The profound sorrow captured in these events left a lasting mark on Jewish practice. It became the foundation for the customs surrounding the final meal eaten before the fast of Tisha B'Av. To physically connect with the pain of the destruction and fulfill the imagery of this tragedy, it became a tradition to eat bread dipped in ashes as the centerpiece of the mourning meal before the fast begins [תורה תמימה].