Lost Season 3 Episode 20

Ben: (to an empty chair) Jacob, this is John. (to Locke) Aren't you going to say, "Hello," John?
Locke: What?
Ben: (to the chair) I told you he wouldn't.
Locke: Who - What are you talking about?
Ben: You can't see him?
Locke: See who?
Ben: Jacob. He's sitting right here, in this chair. (to the chair) Yes, I know, but he insisted.
Locke: What is this?
Ben: You wanted the secrets of the island, well here they are. This is the man who can answer every single - (to the chair) I am not. He made me bring him here. Did you think that that was my - Sir, may I finish?
Locke: You're crazy.