The sky is the limit. 

"You can never get a cup of tea large enough or a book long enough to suit me." 
 C.S. Lewis

"What really knocks me out is a book that, when you're all done reading it, you wish the author that wrote it was a terrific friend of yours and you could call him up on the phone whenever you felt like it. That doesn't happen much, though." 
J.D. Salinger

"The person, be it gentleman or lady, who has not pleasure in a good novel, must be intolerably stupid." 
Jane Austen