My favourite quote from Catcher In The Rye isn't by Salinger, it is a quote that he had a character read on page 169:
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one
- Wilhelm Stekel
In this quote Salinger is trying to save himself from taking a lonely path or one that results in his younger self sacrificing too much for too little. Something he seemed to do many times in his life.