Mr. Antolini is one of Holden's former teachers from Elkton Hills. Mr. Antolini had been to Holden's home for dinner many times, so the two know each other very well. This places Mr. Antolini in a position to help Holden understand what is going on in his life as he approaches adulthood. Further, Mr. Antolini must be held in high regard by Holden because he would rather stay at Antolini's house than tell his parents that he has recently gotten kicked out of Pencey. While there, Holden receives some of the best advice from someone who really cares for his future.
First, Mr. Antolini asks about Holden's current grades and discovers that he got kicked out of Pencey. Then he really makes an effort to give Holden some perspective on life. He knows that Holden doesn't like phonies and wants to live a noble life; so, he decides to write down a quote that he hopes will help Holden to understand what a noble life is.
"The mark of the immature man is that he wants to die nobly for a cause, while the mark of the mature man is that he wants to live humbly for one" (188).
This gives great perspective into how a person should behave in order to live nobly, rather than hoping to die for a noble cause. This pegs Holden correctly because he only sees the phonies in life and has a difficult time finding anything noble. Mr. Antolini gives more advice that shows he really knows Holden and what Holden is going through.
"Among other things, you'll find that you're not the first person who was ever confused and frightened and even sickened by human behavior. . . many men have been just as troubled morally and spiritually as you are right now" (189).
Holden doesn't say much about his reaction to all of this advice because he is desperately tired and wants to go to sleep. It's too bad Mr. Antolini ruins his relationship with Holden by stroking his hair after he falls asleep, but the advice was still good. Holden must have remembered the advice well because he writes it down afterwards while describing his adventures in the hospital in California.