Cain’s Introduction begins with the well-known story of Rosa Parks refusing to give up her seat on a bus in 1955. This led to Parks’s arrest, which sparked the Montgomery Bus Boycott—a milestone in the civil rights movement that gave Dr. Martin Luther King, Jr., his first brush with fame. Cain views this event, however, through a psychological rather than historical lens. The two civil rights leaders, Parks and King, represent different personality types: introverted and extroverted, respectively. Together, they made a formidable team. Parks’s behavior was all the more powerful given that she was a quiet, unimposing woman, while King’s outgoing nature and powerful rhetoric inspired others to fight the system.

Yet the qualities of introverts like Parks are given short shrift in the United States. Cain argues that introversion is treated as “a second-class personality trait, somewhere between a disappointment and a pathology” (4), and that our society values what she calls the Extrovert Ideal. Research shows that traits of extroversion are often valued over those of introversion. However, the world has been greatly enriched by the contributions of introverts—such as the science of Albert Einstein and the art of Vincent van Gogh.