The Stranger: A Review
The Stranger, by Albert Camus, gives you that feeling. The main character seems to live like that all the time, completely detached from life.
The philosophical question that this book centers around (in my opinion anyway, you could teach a class on this book) is how far a person should go in order to fit into society's norms. The protagonist does not make any effort to live up to the expectations of others and is completely honest in all situations. On its face this seems admirable and an ideal we all strive to, in practice and in this novel it can at times make him seem like a monster. I try to tell myself I'm an absolutist when it comes to being honest and not hurting feelings but this novel made it clear to me that it's not true at all.
Even though it's a philosophical book it really doesn't feel like it, Camus is wonderful in that way. The book isn't that long and moves along very quickly. Give it a read, I'm sure you'll get totally different lessons out of it than I will.