How do you know that what you read is good? I assume that if I did enough reading in a particular field, a few authors and books would stand out as The Best or The Most Important Works In This Discipline. I've always found it very difficult to judge a book's value, since I tend to take everything I read at face value. Some people can read a book and immediately see its symbolism, recognize that it mirrors another author's style ("this is Pynchon-esque," "clearly, this is applied Derrida"), and see through the author's writing to understand what he or she is really saying.