I kept walking and walking up Fifth Avenue, without any tie on or anything. Then all of a sudden, something very spooky started happening. 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 to the other side of the street. I thought I’d just go down, down, down, and nobody’d ever see me again. Boy, did it scare me. You can’t imagine. I started sweating like a bastard – my whole shirt and underwear and everything. Then I started doing something else. Every time I’d get to the end of a block I’d make believe I was talking to my brother Allie. I’d say to him, “Allie, don’t let me disappear. Allie, don’t let me disappear. Allie, don’t let me disappear. Please, Allie.” And then when I’d reach the other side of the street without disappearing, I’d thank him. Then it would start all over again as soon as I got to the next corner. But I kept going and all. I was sort of afraid to stop, I think – I don’t remember, to tell you the truth. I know I didn’t stop till I was way up in the Sixties, past the zoo and all. Then I sat down on this bench. I could hardly get my breath, and I was still sweating like a bastard. I sat there, I guess, for about an hour.
– J. D. Salinger
The Catcher in the Rye. Chapter 25. Holden is at rock-bottom here. He thinks about his dead brother Allie and his own mortality and pleads with Allie not to let him disappear. Holden has these imaginary conversations with Allie, it is a form of escapism for him.