Gustave Le Bon (May 7, 1841 – December 13, 1931) was a French social psychologist, sociologist, and amateur physicist. He was the author of several works in which he expounded theories of national traits, racial superiority, herd behavior and crowd psychology. His work on crowd psychology became important during the first half of the twentieth century when it was used by media researchers such as Hadley Cantril and Herbert Blumer to describe the reactions of subordinate groups to media. He also contributed to controversy about the nature of matter and energy. His book The Evolution of Matter was very popular in France (having twelve editions), and though some of its ideas — notably that all matter was inherently unstable and was constantly and slowly transforming into luminiferous ether — were used by some physicists of the time (including Henri Poincaré), his specific formulations were not given much consideration. During 1896 he reported observing a new kind of radiation, which he termed "black light" (not the same as what modern people call black light today), though it was later discovered not to exist.[1] Le Bon was born in Nogent-le-Rotrou, France (near Chartres), and died in Marnes-la-Coquette. He studied medicine and toured Europe, Asia, and North Africa during the 1860s to 1880s while writing about archeology and anthropology, making some money from the design of scientific apparatus. His first great success however was the publication of Les Lois psychologiques de l'évolution des peuples (1894; The Psychology of Peoples), the first work in which he used a popularizing style that was to make his reputation secure. His best selling work, La psychologie des foules (1895; English translation The Crowd: A Study of the Popular Mind, 1896), was published soon afterward. During 1902, he began a series of weekly luncheons (les déjeuners du mercredi) to which prominent people of many professions were invited to discuss topical issues. The strength of Le Bon's personal networks is apparent from the guest list: participants included Henri and Raymond Poincaré (cousins, physicist and President of France respectively), Paul Valéry and Henri Bergson. Le Bon was one of the great popularizers of theories of the unconscious at a critical time during the formation of new theories of social action. Wilfred Trotter, a famous surgeon of University College Hospital, London, wrote similarly in his famous book Instincts of the Herd in Peace and War, just before the beginning of World War I; he has been referred to as 'Le Bon's popularizer in English.' Trotter also introduced Wilfred Bion, who worked for him at the hospital, to Sigmund Freud's work Massenpsychologie und Ich-Analyse (1921; English translation Group Psychology and the Analysis of the Ego, 1922), which was based explicitly on a critique of Le Bon's work. Ultimately both Bion and Ernest Jones became interested in what would later be called group psychology. Both of these men became associated with Freud when he fled Austria soon after the Anschluss. Both men were closely associated with the Tavistock Institute as important researchers of the topic of group dynamics. It is arguable that the fascist theories of leadership that emerged during the 1920s owed much to Le Bon's theories of crowd psychology. Indeed, Adolf Hitler's Mein Kampf drew largely on the propaganda techniques proposed in Le Bon's 1895 book[2][3][4][5]. In addition, Benito Mussolini made a careful study of Le Bon's crowd psychology book, apparently keeping the book by his bedside.[6] Edward Bernays, a nephew of Sigmund Freud, was influenced by Le Bon and Trotter. In his famous book Propaganda he declared that a major feature of democracy was the manipulation of the mass mind by media and advertising.