haven't i read this before?

i'm reading to kill a mockingbird that my lovely friend, ellie, lent me, but as i read each page, i seem to know what's going to happen. i don't even remember what the book is really about, or what will happen later in the book, but as each scene develops, it seems really familiar. so have i read it before? maybe. 

anyway, i really like this line.

there are some kind of men who - who're so busy worrying about the next world they've never learned to live in this one...