He mentions in the book how authors can fool you and distract you which is part of it.He also talks about how authors can make you feel things. How they can make you frustrated, sad, happy ect. Or make you turn the book sideways and upside down too read it. I think the joke was partially too make you believe that whatever you found wasn't it. Which in and of itself was enlightening. It brought you the wisdom that Alcatraz can make you do what he wants. I think that's it that he can make you do what he wants when your reading. That I believe is hte secret too make you do what he wants.