“And will we tell the mayor what’s in the box?”

The tired assistant builder asks this of the equally weary chief builder centuries before the story begins. The simple question broaches the topic of disclosure—and its response opens both the underlying conflict of the story and the theme of “The Complexity of Tightly-Held Secrets.” Keeping their instructions secret and relying on only the passage of time to open the box, the Builders make a critical error in judgement that threatens the future.

“This was where she wanted to be, up here where everything happened, not down underground.”

Lina’s interior monologue is full of irony; as the city of Ember is all she knows, she thinks she is aboveground under a dark sky. The bustle of the city feels busy and interesting, prompting her desire for a role as a messenger. Ironically, Lina will eventually learn that the secrets of Ember and the solution for their plight are deep underground.

“The city of Ember was made for us long ago by the Builders […] It is the only light in the dark world. Beyond Ember, the darkness goes on forever in all directions.”

Lina, Doon, and all children in Ember grow up reading and learning from The Book of the City of Ember, in which this line appears. At the start of the story, Lina cannot see any symbolic or double meaning in the lines, but DuPrau indicates to readers that Ember is full of secrets. The “darkness” around Ember represents a void of knowledge.