In The Catcher in the Rye, author J. D. Salinger uses the stream-of-consciousness style to give us detailed views of Holden’s thinking. Holden essentially has an ongoing monologue with himself that jumps around from one scene to another, depending on what memory an incident spurs for him. In this particular passage, the question of who was the best war poet, Rupert Brooke or Emily Dickinson, causes Holden to begin thinking about war itself and what the life of a soldier would be like. He equates the regimented life in the army to the Boy Scouts, which also has an extensive set of rules that boys must follow in their troops.
The passage contributes to the development of themes in the novel by emphasizing Holden’s contempt for war and violence and conformity. Holden begins by saying that he was once in the Boy Scouts and only lasted “for about a week.” He could not stand looking at the back of the guy's neck in front of him. This is not to be taken literally, but essentially means that Holden could not stand the regimented rules and uniformity that required that he stand in line behind the other scout.
Holden does not want to conform as boy scouts or soldiers do. To underscore how much he does not want to be a follower, he says,
I swear if there's ever another war, they better just take me out and stick me in front of a firing squad.
He does not mean this literally. He also says that he does not see how D. B. could hate the army and war and still "like a phony like that," referring to Hemingway’s A Farewell to Arms. In thinking about this, Holden he also specifically mentions The Great Gatsby.
I was crazy about The Great Gatsby. Old Gatsby. Old sport. That killed me.
This allusion to The Great Gatsby is a bit of satire. In The Great Gatsby, Gatsby’s frequent use of the term “old sport” is an affectation that Gatsby uses to further the image he has created of himself as someone born to wealth and privilege. The reader of The Catcher in the Rye understands the satire here if he or she is familiar with The Great Gatsby. Holden then says,
Anyway, I'm sort of glad they've got the atomic bomb invented. If there's ever another war, I'm going to sit right the hell on top of it. I'll volunteer for it, I swear to God I will.
Again, this is also Salinger's use of both satire and metaphor. Just as the reference to being placed in front of a firing squad is not to be taken literally, Holden does not really believe that he could sit on top of an atomic bomb. Salinger uses this satire as a device to convey Holden's views of violence. The image of Holden on top of the bomb is a metaphor for his disdain of war and instruments of war. The entire passage underscores Holden’s contempt for war, hypocrisy, and the negative passions that drag people into war, which are then portrayed romantically in certain novels.