When concerning chapter three of The Great Gatsby, we meet a character refered to as Owl Eyes. What happens in the library with Owl Eyes and what does it mean?

Jordan and Nick go looking for Gatsby in his mansion; instead, they find a grotesque little man in enormous eyeglasses (Nick calls him "Owl Eyes") skimming through the books in Gatsby's library. Both Owl Eyes and Jordan initially think that the books are false, designed only to give the appearance of a library; both are surprised to find that the books are real.