If we are to love, help, persuade or oppose other people, we must gauge what they think and what they want. Human interaction depends on what has been called ‘a theory of mind.’ One crucial component of that theory is an understanding of emotion. If we cannot understand what will upset or delight another person, we cannot fully participate in social life. This book traces the development of that understanding in the child, highlighting the child’s increasing insight into the complexity and subtlety of our mental life.