Mind, Self, and Society (1934) by George Mead
When
I read this during my doctoral studies.
Why
In addition to moral development, I am also a scholar of social development. When preparing for my oral exams, this book was very influential. In the earlier years of my program, specifically, I was really interested in the psychology of role taking or perspective taking, which Mead devotes sufficient attention to.
How
Although Mead is a social behaviorist, at a general level, the book contributed to my interests in understanding how people attempt to understand the viewpoints of others. I think about perspective-taking and understanding others differently now, but I appreciate the role this book played in my emerging understanding of these phenomena.