It's hard to realistically label something as a "Classic" but I'm OK - You're OK totally qualifies. The author, Thomas Harris, MD, opens up a window into how we relate to others by discussing "Transactional Analysis" . His philosophy is totally opposed to the traditional "I" centered Freudian approach. Harris expands this to identify encounters between two or more people as "Transactions", I don't think I could do it justice. Buy a copy, read it and keep it on your bookshelf.