The central theme of Number the Stars is the difficulty of growing up. One could make the case that Lowry uses the context of World War II as a way of making these difficulties stand out clearly. The novel focuses on Annemarie Johansen's personal experiences with growing up, but her experiences are common to most young people. Growing up is presented as a struggle for identity. Does Annemarie belong to the world of adults or to the world of children? Such distinctions are always difficult to make, but the situations the war creates makes these distinctions even more difficult. The roles Annemarie must play blur the line between a child's responsibilities and an adult's responsibilities. Lowry uses the war to demonstrate how confusing the separation between childhood and adulthood can be. Because of the war, Annemarie needs greater protection, but at the same time has to learn things that one normally does not learn until later life.
Annemarie is frequently compared and contrasted to other characters in the novel, particularly Kirsti and Peter Neilsen. Kirsti's complete state of innocence and stream of childish requests is juxtaposed with Annemarie's growing sense of responsibility. Innocence, perhaps the most prominent feature of childhood, is no longer possible for Annemarie. Because of this, she does not identify with her little sister. But Annemarie is not sure she belongs with the adults, either. Her observation that Peter has "taken his place in the world of adults" makes it clear that Annemarie does not feel like a member of that world. Annemarie's concerns about her ability to be brave also make her feel that she is mature. Yet she is beyond the point where her youth will protect her from being called on for help.
The role of knowledge and concealment adds to the conflict of childhood versus adulthood. Again, the war plays a part in complicating this issue. It is not appropriate for a child to be told certain things, particularly concerning war. But in order for Annemarie to process what is happening around her, she wants to know more. This curiosity is also a fundamental part of growing up. But in Number the Stars, ignorance can be a form of self-protection. So Annemarie struggles with differentiating between the information that is being withheld for her own safety and the information that is being hidden because she is so young.
Physical and mental voyages run throughout Number the Stars. The novel centers around the trip that the Rosen's and the other Jews must make across the ocean to safety. That voyage takes place in three parts: the trip from Copenhagen to Gilleleje, the walk from the house to the boat, and the final crossing to Sweden. Parallel to this voyage is the journey of Annemarie's growth. As she makes physical trips from place to place, she is developing new ideas and new ways of viewing herself. The trip she makes through the woods to deliver the packet to Henrik is particularly symbolic. The passage into the woods marks a transformation. Annemarie is taking on a job that an adult would normally perform; thus, she makes literal and figurative steps towards maturity. Peter Neilsen is another character we see transformed. His interactions with Mrs. Johansen shift. Toward the end of the novel, Peter and Mrs. Johansen become equals.
The reality of war is at times so terrible and strange that it feels unreal. Annemarie sometimes has difficulty accepting the events of the war as real. She fictionalizes them, making the war into a fairy tale reality. At other times, fairytales are contrasted to the war. For example, Annemarie says that everything has changed except the fairy tales. The fairy tales are also used as a means of showing that Annemarie is leaving her childhood behind. Kirsti loves stories about kings and queens, but Annemarie does not care for them. She even wants to correct her sister's overactive imagination at times. Despite herself, though, Annemarie finds support in the world of fiction. Fairy tales are often used as a way of explaining something that is hard to understand or cope with. So when her life becomes truly frightening or confusing, Annemarie reverts to seeing the war as if it were a fairy tale. As she goes to deliver the packet to Henrik, Annemarie makes the trip into the story of Little Red Riding-Hood. By turning her own life into fiction, Annemarie is able to deal with her fear and get the packet to her uncle. In the end, of course, reality is nothing like the fairy tales, things do not always end well, and the heroes do not live happily ever after. Peter Neilsen dies. It is revealed that Lise's death was a product of the war, too. Even Kristi grows out of fairy tales.
Within the theme of growing up, the truth becomes an important issue. A large part of being a child is discovery. The process of discovering the way the world works and understanding other people is central to maturation. In Number the Stars, the war makes it necessary for the truth to be concealed at times. As Henrik explains, knowing too much can make bravery harder and therefore put a person at risk. This, however, creates a contradiction for the process of growing up. Not knowing is usually equated with being a child. But in the story, not knowing means being able to face danger, which is a mature trait. Thus Annemarie must find a balance between demanding the truth and protecting herself from it.
Annemarie learns that judgments based on appearances are not always correct. This lesson is related to the theme of growing up, since learning to avoid judging on appearances alone is part of maturing. Particularly concerning pride, Annemarie discovers that what you see at first may not be a manifestation of what is actually so. At first, Annemarie thinks that the Rosens have lost their pride because they wear shabby clothing and make a forced escape. But she quickly realizes this is not true. Their pride is intact and is not attached to the objects they possess. The casket, too, is an instance of miscalculation based on appearance. A casket normally contains a dead person, but in this case it holds items that will help the escaping Jews to survive.
The war forces individuals to conceal their true identities and actions. In various situations, the characters of Number the Stars must pretend to be someone they are not. Ellen's desire to go to acting school is painfully echoed by the events of her own life, in which acting becomes a matter of survival. Ellen must act as if she is Lise Johansen in order to save herself. Annemarie also finds herself playing roles. While Mrs. Johansen is taking the Rosens to Henrik's boat, Annemarie takes on the role of the mother. Then she plays the part of the silly little girl when the soldiers stop her in the woods. Role-playing can also be connected to the process of growing up. Children play at being adults in order to try on the responsibilities of the grown-up world without having to assume them in reality.
The seashell that Peter Neilsen gives Annemarie represents several different things. Because it comes from the se,a it is a clue to the work that Peter had been doing and the adventure that Annemarie will take part in. A shell is also protection for a sea creature. The characters of Number the Stars must each find a way protecting themselves. Visually, the shell is also representative of the hidden appearances that come up through out the novel. A shell conceals something, but one cannot be sure just by looking at it what it might conceal. A shell is often full of surprises, just as the characters and events of the novel are.
The Star of David appears in several places during the course of Number the Stars. The Star of David is a central symbol in the Jewish tradition. In the novel, it represents the necessity for Ellen and all the Jews to hide their religion. Until the end of the war, Annemarie keeps the Star of David necklace that Ellen wears. The necklace symbolizes Annemarie's devotion to her friend and her stance against the Germans. Stars also appear in the psalm that Peter reads before the voyage to Sweden. In this case, the stars represent Annemarie's tainted view of the world. To her the stars demonstrate the vastness and hopelessness of existence.
The woods symbolize a right of passage for Annemarie. They operate as part of the theme of voyage and transformation. When Annemarie passes through the woods on her way to the boat, she is undergoing a transformation. She is discovering her own ability to do the job of an adult. For the Rosens, the woods are part of the passage from danger to safety.