Gustave Le Bon

Charles-Marie Gustave Le Bon was a leading French polymath whose areas of interest included anthropology, psychology, sociology, medicine, invention, and physics. He is best known for his 1895 work The Crowd: A Study of the Popular Mind, which is considered one of the seminal works of crowd psychology. A native of Nogent-le-Rotrou, Le Bon qualified as a doctor of medicine at the University of Paris in 1866. 

He opted against the formal practice of medicine as a physician, instead beginning his writing career the same year of his graduation. He published a number of medical articles and books before joining the French Army after the outbreak of the Franco-Prussian War. Defeat in the war, coupled with being a first-hand witness to the Paris Commune of 1871, strongly shaped Le Bon's worldview. He then traveled widely, touring Europe, Asia, and North Africa. 

He analyzed the peoples and the civilizations he encountered under the umbrella of the nascent field of anthropology, developing an essentialist view of humanity, and invented a portable cephalometer during his travels. In the 1890s, he turned to psychology and sociology, in which fields he released his most successful works. Le Bon developed the view that crowds are not the sum of their individual parts, proposing that within crowds, there forms a new psychological entity, the characteristics of which are determined by the "racial unconscious" of the crowd. 

At the same time, he created his psychological and sociological theories, performed experiments in physics, and published popular books on the subject, anticipating the mass–energy equivalence and prophesizing the Atomic Age. Le Bon maintained his eclectic interests up until his death in 1931. Ignored or maligned by sections of the French academic and scientific establishment during his life due to his politically conservative and reactionary views, Le Bon was critical of majoritarianism and socialism.

George Lachmann Mosse claimed that fascist theories of leadership that emerged during the 1920s owed much to Le Bon's theories of crowd psychology. Adolf Hitler is known to have read The Crowd and, in Mein Kampf, drew on the propaganda techniques proposed by Le Bon. Benito Mussolini also made a careful study of Le Bon. Some commentators have drawn a link between Le Bon and Vladimir Lenin/the Bolsheviks.

Just prior to World War I, Wilfred Trotter introduced Wilfred Bion to Le Bon's writings and Sigmund Freud's work Group Psychology and the Analysis of the Ego. Trotter's book Instincts of the Herd in Peace and War (1919) forms the basis for the research of both Wilfred Bion and Ernest Jones, who established what would be called group dynamics. During the first half of the twentieth century, Le Bon's writings were used by media researchers such as Hadley Cantril and Herbert Blumer to describe the reactions of subordinate groups to media.

Edward Bernays, a nephew of Sigmund Freud, was influenced by Le Bon and Trotter. In his influential book Propaganda, he declared that a major feature of democracy was the manipulation of the electorate by the mass media and advertising. Theodore Roosevelt, as well as Charles G. Dawes, and many other American progressives in the early 20th century were also deeply affected by Le Bon's writings.