Memoirs of Extraordinary Popular Delusions and the Madness of Crowds

The book is divided into three main parts: National Delusions: This section explores cases of mass hysteria and irrational behavior on a large scale including the witch trials the Crusades and other instances of societal mania. Peculiar Follies: Here Mackay discusses various bizarre and irrational beliefs and practices that have captured the public's attention such as alchemy fortune-telling and belief in the philosopher's stone. Philosophical Delusions: This section delves into instances of intellectual and philosophical fads that have captivated people's minds including the study of phrenology (the study of the shape of the skull to determine personality traits) and the obsession with apocalyptic prophecies. Mackay's work is often cited as a classic exploration of mass psychology and the dynamics of group behavior. He uses historical examples to illustrate how emotions and irrational thinking can spread within a population leading to actions that might appear illogical when viewed from a rational perspective.