Personal mementos appear as a recurring motif in the story and relate to the theme of The Heart’s Memories. All of the humans who boarded the spacecraft were allowed to bring along personal belongings that held sentimental value. As the Collective evolves over the centuries the ship has been in flight, it attempts to eradicate all signs of individuality among its members. New generations are created in laboratories rather than through natural reproduction, and everyone looks and dresses alike.

Consequently, the mementos brought by the original humans in stasis have no place in a brave new world of absolute uniformity. With no such objects of their own, the Collective fails to realize the tremendous psychological significance of these simple items. Since they aren’t perceived to be particularly threatening, they are shoved into a storage room and forgotten. However, the mementos have the curious power to awaken memories. This process begins when Voxy innocently handles an old copy of a book. Even though he is a member of the Collective, the book sparks a glimmer of imagination in the boy. He then tells Petra about the book, and she unlocks the room that contains the treasure trove of humanity’s past.