In chapter 19 of The Catcher in the Rye, Holden Caulfield meets an acquaintance that he refers to as “Old Luce” in a bar. Luce is older than Holden. At one point they were both at Wooten together and Luce was Holden’s student advisor. Luce is now a student at Columbia.
Holden is feeling lonely in the bar when he spots Luce, and he tries desperately to hold a conversation with him. Luce isn’t particularly interested in talking to Holden and chastises him repeatedly. At one point, Holden jokes about seeing a “flit” (homosexual) in the bar. He tells Luce that he saved the “flit” for him. Luce says,
Very funny. Same old Caulfield. When are you going to grow up?
Much of the rest of their conversation revolves around sex, as Holden attempts to get Luce to discuss his sex life, which Luce does not want to do. Their exchange shows Holden’s immaturity as he continues to badger Luce about his sex life after Luce repeatedly asks him to drop the subject.
Near the end of the conversation, Luce says, “Your mind is immature.” Holden responds with,
It is. It really is. I know it.
At least Holden recognizes his own immaturity, but then he lapses back into the topic of sex.
Finally, Luce suggests that Holden see a psychoanalyst to help him “recognize the patterns of his mind.”
Luce, as a character, is moving into adulthood. He is having a relationship with a mature woman and thinking about things like Eastern philosophy. Holden is still behaving in a childish way with his preoccupation about discussing sex with someone who doesn’t want to talk about it. He also fails to understand how Luce could be interested in an older Chinese woman unless it was for sexual reasons.