Throughout the novel, the reader is presented with various symbols. The symbols are clearly made evident by Holden's constant repetition of their importance. The symbols are so important and their symbolism is directly related to the major themes of the novel. Allie, Holden's young brother who died several years earlier, was a key symbol throughout the story.
When Holden remembers incidents from his past involving Allie, his attitude changes, such as when he writes the composition about Allie's baseball glove or when Holden broke his hand after punching all of the windows after Allie died. He feels that Allie was one of the few people who were not phony in a world full of phonies. More importantly, Allie represents the innocence and childhood that Holden strives to find throughout his multi-day journey. In Holden's opinion, Allie represents the purity that Holden looks for in the world. Holden admits that he admires Allie more than he admires Jesus, and even prays to Allie at one point, rather than Jesus.
Allie is Holden's role model, whom he judges the rest of the world according to. When Allie dies, it creates turbulence in Holden's life. At various points during the course of the novel, Holden inquires as to what happens to the ducks who are normally on a pond in Central Park, when winter comes and the water freezes. As he inquires, the answers he receives range from as farfetched answers as the idea that the ducks still remain there under the ice, just as the fish do, to uncaring answers such as a simple 'What a stupid question!' remark. Despite the answer he gets, Holden is never satisfied with the reply. Holden doesn't consciously realize that the ducks relate to him.
Whether he will admit it or not, Holden is scared. He has been kicked out of numerous schools, he can't get good grades, his parents are angry with him, and he spends his days wandering through New York City. He doesn't know where he is going to go, reflecting his question about the ducks. Perhaps if he knew where the ducks went, he could follow their example. While walking through New York City, Holden arrives at the Museum of Natural History. He remarks about the museum that he likes the glass cases that the museum officials place all of their exhibits in.
He wishes he could place parts of his life in glass cases because they won't change. In the end, he decides not to go into the museum. He likes the museum because he used to go there in his childhood, a time that he remembers with happiness. Since the glass cases inside the museum don't allow anyone to change anything, it would be the one place for Holden to go if he wanted everything to be as it was during his childhood.
However, he elects to remain outside because he is afraid that there is a chance that the museum might have changed. Jane Gallagher changed since his childhood and Holden thought that was unbelievable, so if Jane could change, perhaps the museum could change, as well. Holden knows that if the museum does not remain the same, it could hurt him, so he makes a conscious decision not to enter, even if his reasons are subconscious. Catcher in the Rye was a very powerful and symbolic book written from the position of a troubled teenager. The themes are clearly illustrated through the symbols, which Holden makes sure the reader recognizes..