While talking with Phoebe, she asks Holden what he would want to be when he grows up. He responds saying: "I keep picturing all these little kids playing some game in this big field of rye and all. Thousands of little kids, and nobody's around--nobody big, I mean--except me. And I"m standing on the edge of some crazy cliff. What I have to do, I have to catch everybody if they start to go over the cliff--I mean if they"re running and they don't look where they"re going I have to come out from somewhere and catch them. That's all I"d do all day. I"d just be the catcher in the rye and all." Holden wants to protect the innocence of his sister and every other innocent child in the world. Before Holden met Sally for their date, he stops in front of the Museum of Natural History and begins to reminisce. He thinks about the way he visited the museum when he was younger. He also says that every time one visits the museum, he is changed in some way, but the figures in the exhibits always stay the same. He wants to be able to preserve some things in the glass: "Certain things they should stay the way they are. You ought to be able to stick them in one of those big glass cases and just leave them alone,". Holden wants the innocence of children to be frozen behind that glass. .
When he visits Phoebe's school to give her a note, Holden notices two instances of graffiti on the walls. He succeeds in rubbing one of them off cannot rub off the other. It depresses Holden to think that someday this kind of graffiti will spoil his sister Phoebe and all of her friends. Holden believes that his main reason in this world is to protect the young and innocent from the horrors of the real world. He soon realizes that this is impossible. Holden sees that becoming the Catcher in the Rye is an unattainable and highly unrealistic. When he meets Phoebe during her lunch break at school, he has made up his mind to leave and hitchhike out west.