The Nicomachean Ethics [AKA Ethica Nicomachea] by Aristotle
This is a difficult book to describe. Pretty much it seems like common sense. Aristotle goes through and describes each of our emotional attributes and describes the extremes of them (i.e. bravery to cowardice). The result of his analysis was that the middle of the road response in most cases was the "good" response and that most people should strive for them to be "good" people. Overall I felt like I was reading a treatise on the seven deadly sins and I did not gain much afterwards. I would have to recommend this to go on people's skip list.