Nick and Jordan encounter the owl-eyed spectacled man in the library at Gatsby’s house. The man is quite shocked to find that the books on the shelves are real. He says he had expected them to be cardboard facsimiles of books, such as one might today find in a store display. Nick notes that the man takes it for granted that he and Jordan do not believe him, so he takes a book to show them.
He mentions that Gatsby never read the books. “Knew when to stop too—didn’t cut the pages.” Owl Eyes (as Nick later calls him) does not seem surprised by this fact. Gatsby has earned a reputation as a mysterious man so far, and numerous rumors circulate about him. Most do not have positive things to say about him. The man’s comment, “What do you expect?” refers to these rumors. He is saying that a man who is so mysterious keeps up appearances, and nothing is real; he is pointing out that Gatsby knowingly set up the library so as to present a false face. So, while the real books keep up the appearance of a well-read and sophisticated man, they also reflect a falseness in Gatsby, since he only has them to fool others.
Interestingly, Owl Eyes seizes the book from Nick’s hand and puts it back on the shelf, “muttering that if one brick was removed the whole library was liable to collapse.” This comment directly relates to Gatsby. He has spent years creating a persona, but all it takes is one slip-up and his entire façade can come tumbling down. We might view this scene as foreboding the tumult that is to come in Gatsby’s life, as he is soon to lose everything.