Another theme is the development of maturity. Holden slowly matures throughout the novel, finally growing up in the park at the carousel. They start to accept responsibilities for their actions, but they try to change themselves to impress others. They put on phony airs, and are less open to learning. Holden sees adults as people who have given in to society and become something they're not.
Adults think that they are always right, because they have conformed to the norm.
There are certain responsibilities and ideals that adults are expected to have. In reaching these, they become phony and untrue to themselves and others. Holden wants to hold on to the innocence and truth of youth, and this means not becoming one of the phony adults he despises. Holden knows this and has learned that the recognition of these concepts is different in young people and adults. Holden wants to preserve the innocence of children because he sees children as the only people who are able to see the truth behind the illusions of the world.