Who is owl-eyes? what surprises him about gatsby's library? why would this impress him?

Owl-eyes refer to the old man wearing eyeglasses. He was the only one keen enough to investigate so he was the only one who knew who Gatsby really is. What surprised Owl-eyes are the books displayed in his library were real. They may be actual book but not a single page was read. This made him impressed since Gatsby was really good when it comes to deceiving people.