Mr. Antolini is one of only three numbers in Holden's address book (the other two are Jane and his father's office).
After visiting Phoebe, Holden decides to call Mr. Antolini. He used to be his teacher at Elkton Hills, he says, but he's now an English instructor at N.Y.U.
So Holden calls him up and tells him he's flunked out of Pencey. Mr. Antolini invites him to come over, even though it's the middle of the night. (By this time, it has to be at least 3am.)
We get some key information about Mr. Antolini: he's one of those teachers you can joke around with, he's not much older than D.B., and when James Castle committed suicide by jumping out the window, he was the only one to do anything about it (he checked for a pulse and then carried the body over to the infirmary).
While Holden heads over to Mr. Antolini's place, he tells us more. He used to see the guy quite frequently after he left Elkton Hills. Once Mr. Antolini got married, the three of them used to play tennis.
Mrs. Antolini, he says, is "about sixty years older than Mr. Antolini" and has a lot of money.
When Holden gets to their apartment, Mr. Antolini is drinking and Mrs. Antolini is in a different room. Both of these, we are told, are par for the course.
Mr. Antolini and Holden have an key discussion about digressions. When his former teacher makes the argument that you should pick a topic and stick to it, Holden counters that the most interesting bits of a conversation often come out by accident, and that you never really know what you need to talk about until you get started and it comes out by accident. (Check out Shmoop's discussion of "Tone" and "Writing Style," by the way.)
When Mrs. Antolini brings in coffee, Mr. Antolini gives her a kiss – Holden says they're always doing this in public.
And now for the big and important lecture: Mr. Antolini begins by saying he worries that Holden will end up thirty years old and hating everyone. He thinks Holden is in for a special fall of some sort, and that he'll end up dying nobly for an unworthy cause.
He busts out a favorite quote of his, one written by a psychoanalyst: "The mark of an 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."
He continues on to the importance of education. Mr. Antolini insists that once Holden gets past the lousy classes and the lousy teachers, he'll realize what a beautiful and symbiotic relationship can form when people teach and learn from one another.
While you can be smart on your own, he says, you're much more likely to do something meaningful if you cultivate your native abilities, namely via education.
Meanwhile, Antolini has been knocking back drinks like you can't believe.
Seeing Holden yawn, he laughs and sets up the couch for him to sleep on before going to bed himself.
Holden wakes up to find Mr. Antolini sitting next to him on the floor, with his hand on Holden's head.
When Holden freaks out, Mr. Antolini says he was "Just admiring–" but Holden cuts him off. Even so, Mr. Antolini stays very calm about the whole thing. He seems to think it's no big deal.
He tells Holden to hurry back as soon as he picks up his bags from Grand Central Station.
Shortly after, Holden thinks about what happens and wonders if maybe Mr. Antolini was just being a good friend. He feels bad that he left in such a huff after Mr. Antolini had been nice enough to let him come over and stay so late at night.