" Give a book 50 pages. When you get to the bottom of Page 50, ask yourself if you're really liking the book.... And if, at the bottom of Page 50, all you are really interested in is who marries whom, or who the murderer is, then turn to the last page and find out. If it's not on the last page, turn to the penultimate page, or the antepenultimate page, or however far back you have to go to discover what you want to know… When you are 51 years of age or older, subtract your age from 100, and the resulting number (which, of course, gets smaller every year) is the number of pages you should read before you can guiltlessly give up on a book…When you turn 100, you are authorized (by the Rule of 50) to judge a book by its cover. "

― Nancy Pearl