Wow! So I have been totally mind blown with how different my perspective is on this book and have been compelled to write here and see what others think of my view point and understanding of it....
Firstly ill start by saying that my first impression of the narrator was not to believe everything that he is saying because within the first few pages he openly admits that he is a liar and often gives out false names, so therefore I expected nothing to be as it seems whilst reading.
In summary I feel that Holden is not alive. He was depression and committed suicide and jumped out of the window as a result - the window he says James Castle jumped out of. He is talking to us from purgatory and whilst he reflects on actual events that contributed to this, he also battles with his emotions and we are listening to his emotional and confused journey. I came to this conclusion because of the following points:
Consistent and unusual references to "it killed me" throughout the entire book from the start - this led me to think more carefully about whether this character was actually alive.
There is a clear census that the character is 'depressed'. He is very negative and never appears to be happy, only when talking to or about his younger sister.
His younger sister I think is actually him. The child is 'his voice of reason' and represents him before the depression set in and clouded his judgement and character. His love for the way he used to be.
He touches on religion and Catholicism - but he resists acknowledging what religion he is.
'James Castle' wore Holden's black turtleneck jumper... I think this just represents the depression struggles and the burden that he felt strangled around his neck.
When talking to Mr Antolini - language used is "I have a feeling that you're riding for some terrible, terrible fall" "This fall i think your riding for - It's a special kind of fall, a horrible kind"
"The man falling isn't permitted to feel or hear himself hit bottom" - later Holden says he would pretend to be a mute and want a deaf and mute girlfriend.... A sign to me of the lack of acceptance to the fall he took. To forever live in Purgatory.
"I can clearly see you dying nobly, for some highly unworthy cause" - I think this is reference to when he jumped out of the window. The characteristics of James 'standing his ground' with those boys was the same as Holden did with Maurice. I feel Holden and James are the same person and this comment fro Mr Antolini is him trying to make Holden realise that he jumped. He then says " you're going to have to find out where you want to go. And then youve got to start going there." - referencing a choice to move on to the next life"
When Mr Antolini places his hand on his forehead, I think this is a memory from when Mr Antolini went to pick him up from the floor after he jumped.
"every time I came to the end of a block and stepped off the goddam curb, I had this feeling that I'd never get t the other side of the street. I thought I'd just go down, down, down, down and nobody'd ever see me again'.
"Allie don't let me disappear"
Finally I decided I'd go away. I decided I'd never go home again and I'd never go away to another school. I decided I would go see Pheobe and say goodye"
No school today, the kid that did all the talking said. He was lying, sure as I'm alive, the little 'person of dubious parentage''.
"I was the only one left in the tomb then. I sort if liked it, in a way."
Crucially, when saying what would make him happy he said "If a body catch a body", "I have to catch everybody if they start going over the cliff". He says children, so i think he is reflecting on how innocent and happy he was as a child until life made him cynical and depressed, so he wants to 'save' people before they fall and 'hit the bottom'. I also think that he beginning to regret jumping, beginning to wish someone caught him before he hit the bottom.
There were many more references and quotes that led me to this perspective but too many to post here. I hope you can see where I am coming from and would be fascinated to hear your point of view!