In Section One, Werner and Jutta discover the Professor—a man who hosts a radio show that discusses science and nature in a manner that sparks the imaginations of both children. During one such show, the Professor tells a tale of the creation of coal that allegoricizes the relationship at the heart of the novel:
Consider a single piece glowing in your family’s stove. See it, children? That chunk of coal
was once a green plant, a fern or reed that lived one million years ago, or maybe two million, or
maybe one hundred million. [...] And eventually the peat dried and became like stone, and someone dug it up, and the coal man brought it to your house, and maybe you yourself carried it to the stove, and now that sunlight—sunlight one hundred million years old—is heating your home tonight . . .
This geological narrative is an allegory for Werner and Marie-Laure's relationship, which hinges on coincidence, random chance, and the benevolence of strangers. Werner and Marie-Laure are simply lumps of coal in the ground, each having no significant meaning to the other, until circumstances bring them to a moment of collision—a moment where each becomes significant to the other, a lump of coal turned into light and heat and life.
In the following passage from Section 5, Marie-Laure's Uncle Etienne clashes with Madame Manec, who believes he should be doing more to resist German occupation. Madame Manec utilizes an allegorical description of their situation to attempt to spur Etienne to action:
“Do you know what happens, Etienne,” says Madame Manec from the other side of the kitchen, “when you drop a frog in a pot of boiling water?”
“You will tell us, I am sure.”
“It jumps out. But do you know what happens when you put the frog in a pot of cool water and then slowly bring it to a boil? You know what happens then?”
Marie-Laure waits. The potatoes steam.
Madame Manec says, “The frog cooks."
In this instance of allegory, Madame Manec compares Uncle Etienne to a frog, slowly cooking in a pot of boiling water. In Madame Manec's allegory, the frog first sits in a pot of cool water, unaware of the danger surrounding him because the heat increases incrementally instead of in a single instant. Madame Manec represents Uncle Etienne's situation as that of the frog's: he has gradually grown accustomed to life under Nazi rule, remaining complacent in his inaction despite the steadily increasing danger of his surroundings.