Why does Holden ask Sally to run away with him without thinking his entire plan through?

Holden is a sixteen year old boy. His brain is still not fully developed and this includes his prefrontal cortex, or the part of his brain that makes decisions. He's sitting down talking to Sally about why he doesn't like school and loathes phonies, then he get's an idea that if he wanted to he could just run away, take Sally with him and go out west to find a job. He has this idea and, at that moment it is the best idea of his life, there has never been any thing better than running away and taking Sally with him. He doesn't think everything through, he just asks Sally and can tell that she hates every detail of it. Sally would prefer for him to stay in school and become rich like their fathers, which is the opposite of what Holden wants because he knows his father is a phony. Holden doesn't think any of this when he asks Sally, he thinks he's in love with her one moment and out the next, but he is just in love with the idea of her, very much like Jay Gatsby and Daisy. Right after he suggested running away he regretted it, but he tried again. Sally proves herself to be a phony at this point, only interested in money and looks rather than actual people. Holden proves that he does not think things through before blurting out what is on his mind. Holden's prefrontal cortex is not developed and he makes rash, and bad decisions, because he does not think things through.

Why does Holden refuse to go into the museum?

Holden's whole life has changed since the last time he went in the museum with his class. He is not a little kid anymore, D.B. moveed away, Phoebe is older, and Allie is gone. Holden has been sent to private school after boarding school and has lost his faith in people, but the museum is the same for him. Nothing should be moved or added, the indians should be canoeing and the eskimo should be fishing. If Holedn were to go inside the museum and it were different, he wouldn't know how to react. After all these years, and memories of going into that museum every Saturday,  he doesn't want it to change. Holden wants one thing after all these to be the same. His memories of the musuem include Allie being alive and D.B. being there, and that is what he wants. Holden wants to go back in time and spend every second with his family before his world is torn apart by disease.

Why does Holden give the nuns so much money?

Holden meets the nuns in a cafe and they start talking toeach other. The talk about school and books. Holden insists on paying for their food and then gave them ten dollars in their basket. Holden is so used to people being mean and fake, he meets these nuns and he realizes that they aren't fake and that they genuinely enjoy talking to him. Holden had thought that all the real people had left to be replaced by their falsely sweet masks. The nuns and their kindeness was real and he wanted to help them.

Why doesn't Holden have sex with the prostitute?

Earlier in the book Holden described himself as "yellow". Then we learned that he cared about those who couldn't take care of themselves, espeacially the ducks. He wanted to know that even when he couldn't see them that they'd be okay and survive. The same is aplicable to the prostitute. He described her as looking no older than he is. At sixteen, this girl had to become a prostitute, had to do horrible things for unknown reasons. We do not learn why she had to do what she did, but we do learn that she never wanted to hurt Holden, prove when Maurice came to collect the money and Sunny stopped him from seriously injuring Holden. Holden could not sleep with Sunny because even after she told him she worked every night, she is still a girl, she is young and childish, but Holden wants toprtect her.

What does "yellow" mean and why does Holden describe himself as "one of those very yellow guys"?

During Chapter 13, Holden admits to readers that he is "yellow". From the content yellow means that he is scared of fights and that he pretends to be tough. The informal definition on dictionary.com is cowardly. Holden describes himself as "yellow" when he is explaining to the reader that his gloves were stolen and that even if he knew who took them, he wouldn't fight for them. Maybe because his parents are rich and can just buy him new ones, but he leads readers to believe that it is because, for all his talk, he does not act. He goes on to tell us how he doesn't mind the fact that he'll get punched, so much as he doesn't want to look at the other person while he punches. Once again Holden shows us his compassion, he would rather be hurt than see the pain on another persons face. While Holden, and many others call this cowardice, I feel that if any one were ever in a dire situation, Holden would do all he could to help them, rather than run away screaming.

Why does Holden care about the ducks?

Holden has a strange companionship with people and things that do not seem to be able to take care of themselves. The ducks are just one example in this story, in Chapter 12, Holden asks his taxi driver, Horwitz, "...does somebody come around in a truck or something and take them away, or do they fly away by themselves?"(81, Salinger). Holden is genuinely worried for the safety of these animals, which he feels can not take care of themselves. Unlike so many people he has met, at all the schools he has gone to and places he's been, he worries about the innocent animals and children, not the phonies who constantly surround him. Over the course of the book we find out that his brother, Allie, died at a young age. Holden, being his big brother, had tried to protect Allie because Allie was one of the only people in the world he truly liked. Allie was innocent and did not deserve to die, but still he was taken from his family. Holden may believe that if he nurtured him more, protected him more that perhaps he'd still be here, which is why, anything that can't seem to take care of itself or needs a bit of protection, Holden automatically feels it falls on him to defend, even if it is a duck.