Do You Need to Know?

Well, do you?

Referring to the question I asked earlier on twitter: Can you read a book without knowing anything about it or do you need to at least know the premise to help you establish tone and purpose?

I'm wondering because, I absolutely have to know what the book is about. All the time. I recently finished The Mysterious Benedict Society and just started Michael Chabon's Wonder Boys. I realized that I experienced the same moment with both books - I read the first two pages, started to feel slightly uncomfortable and confused, realized I had no clue what the stories were about, and promptly flipped the books over to read the back cover copy. Without context or knowing some sort of general purpose, I find I'm completely unable to establish the correct tone. The words somehow seem muddled. It's all Morse code, or something equally difficult to read if you don't know how to read it.

Basically, I need some sort of direction in order to more thoroughly enjoy and understand a book.

Do you?
(Repetition is key, right?)