Greene begins his discussion of humanity’s natural irrationality by telling the story of the Second Peloponnesian War. In 432 BC, representatives from Sparta arrived in Athens to persuade the Athenian council to agree to their terms of peace; otherwise, Sparta would declare war on Athens. Though Athens did not want to risk losing their democracy and wealth in a war with militaristic Sparta, they felt they had no choice. 

The male citizens held an assembly where they debated fighting or seeking peace. Pericles— a renowned philosopher and elder statesman who ushered Athens into a golden age—convinced the other Athenians to welcome the Spartans and allow them to exhaust themselves until the Athenians could gain the advantage. However, this strategy didn’t work, and a plague arrived and killed many, including Pericles. Without him, the Athenians responded more aggressively to Sparta’s attacks, leading to a lengthy, brutal war. Eventually, the Spartans exhausted the Athenians of their resources and men, and in 405 BC, the Athenians agreed to Spartan control over Greece.

Greene explains that while the Athenians believed themselves to be highly rational people, they were susceptible to the human weaknesses of rage, greed, and lust for power. Pericles, however, avoided these shortcomings by revering the mind and the Greek goddess of wisdom, Athena. This allowed him to practice control over his emotions and open his mind, including toward his enemies. Greene encourages the reader to practice rationality by examining their emotions and practicing calm thinking.

Greene states that when humans’ plans fail, they naturally tend to blame a person or force beyond their control when their own lack of awareness and inability to control their emotions are often the true cause. He uses the impulsive, short-term financial bubbles in the 1929 and 2008 American economic crashes and the 1720s South Sea crash as examples of this natural irrationality. He argues that while emotions are an important method of communicating danger, these emotions tend to stem from early childhood triggers like abandonment. In addition, instead of people becoming more rational over time, he believes that humans’ irrationality has worsened with advanced technology and social media, including manipulative advertising. While everyone has irrational thoughts, one can recognize a rational person by their productivity and focus on collective well-being, not just on their desires.

Greene tells the reader they can practice rationality by identifying common biases that limit rationality, understanding irrationality—especially as it reaches its more severe levels—and practicing strategies to gain rationality. He explains several common types of bias: confirmation bias, or searching for ideas and answers that one wants, regardless of logic and reasonability; conviction bias, or the idea that something must be true because the person who says it strongly believes it; appearance bias, or the tendency to see people’s masks rather than their true selves; group bias, or having one’s logic bound by their lies to the ideas and thoughts of their group; blame bias, or the ignoring of one’s failings and mistakes to avoid confronting their role in it; and superiority bias, the idea that one’s ideas are more rational and moral than the ideas of others. 

Greene also addresses the factors contributing to irrationality, particularly early childhood triggers such as toxic parenting, abandonment, and abuse; immediate gains and losses in life that throw one’s life into chaos; increased pressure and stress in one’s life; people whose charisma or narcissism influence other people; and the power of group-think on the individual. To combat irrational thought, Greene encourages the reader to know themselves fully, find the roots of their emotions, understand people neutrally, and balance their logic and emotions.

Greene begins the chapter with the idea that humans can empathize with others, allowing them to help and care for them, but must combat a natural tendency toward narcissism. He argues that every human is a narcissist to some degree, stemming from the desire for their mother’s attention as infants. The inability to form a strong sense of self during early childhood can lead to higher levels of narcissism. Narcissistic people often have narcissistic parents or parents who gave too little or too much attention. 

Greene calls people with unhealthy levels of narcissism “deep narcissists.” Deep narcissists’ external and internal lives revolve around fantasies that completely differ from reality. They are also extremely sensitive and insecure, unable to handle any sort of criticism or challenge, and see others as tools for their use, leading to toxic relationships. Greene says, however, that the most dangerous form of deep narcissism, however, is the “narcissistic leader,” who gains traction and power through grandiose self-confidence and charisma but destroys everything they encounter through their need to control.

Most people, Greene clarifies, are functional in their narcissism, and they must detect the different types of narcissists to be cautious and aware of their own self-absorption. He encourages the reader to develop empathy by focusing on others, especially those they don’t agree with, and understanding their emotions and inner workings. Greene offers examples of four narcissist types, using Soviet dictator Joseph Stalin as an example of a narcissist who needs complete control, using charm and violent intimidation interchangeably; infamous nun Jeanne de Belciel as an example of a theatrical narcissist whose cravings for attention create a series of lies and manipulation for praise; Russian author Leo Tolstoy and his wife, Sonya, as examples of a toxic narcissistic couple whose inability to empathize fully led them to worsen their marriage and each other’s lives; and explorer Sir Ernest Henry Shackleton as an example of a healthy narcissist whose empathetic leadership kept his crew’s morale up, allowing them to survive treacherous months on an ice floe until their rescue.

In this chapter, Greene explains that humans naturally mask their true emotions, but these masks cannot completely hide people’s emotions, which are identifiable through expressions, gestures, and body language. He encourages the reader to gain the ability to understand people’s true feelings by studying the traits that betray their social masks. He then tells the story of psychologist Milton Erickson, who became temporarily paralyzed from polio as a teenager. During his recovery, Erickson took an interest in reading his sisters’ and parents’ body language and expressions, finding contradictions between them and the words they said. This inspired him to become a psychologist, using his keen eye to diagnose his patients. For example, he was able to gather that one of his patients was having an affair by how she said the word “abroad” as “a-broad” (77). Greene says that Erickson mastered this ability by focusing more on people’s unconscious communication rather than relying on their words to determine their moods and attitudes. Greene tells the reader that they can master this skill, too, by realizing their self-absorption and observing other people more closely.

Humans learn masking in early childhood, realizing early on that they must hide their true feelings and thoughts from others to avoid punishment, humiliation, or marginalization. This behavior is so inherent to human socialization that most people are not aware of how much they mask. However, our desire to express our feelings and thoughts is so strong that these feelings and thoughts appear through facial expressions, gestures, and body language—impulses developed early in human evolution. 

Greene wants the reader to embrace this truth about humanity’s performativity and become skilled in observation to avoid falling for people’s outward appearances. Children are excellent observers because of their vulnerability, but over time, they become more self-conscious and less aware of people’s true feelings. To become a better observer, one must be calm and open-minded but also discreet, mirroring the person who is under observation. Greene recommends that the reader observe the person doing an exciting activity. He says that the observer should look for mixed signals but not fall into emotional biases, citing Othello’s distrust of his wife Desdemona and subsequent misreading of her emotions in Othello as an example. 

Greene offers examples of what to look for: signs of liking someone, such as leaning closer, or disliking someone, such as pursing lips while one is talking. In addition, he distinguishes dominant signs, like a calm, confident disposition, from submissive signs, such as pausing and increased blinking, and discusses deception signs, such as overtly big smiles. Greene then recommends the reader play their role in their social setting by giving dominant signs, bringing forth wanted emotions, adapting to others around them, making good first impressions, intriguing people with dramatic traits, and showing their good values to others.