"Group Psychology and The Analysis of The Ego" by Sigmund Freud is a book published in 1921. Drawing on sociologist Gustave Le Bon's work, Freud explores the psychological mechanisms within mass movements. He examines how individuals in crowds lose conscious personality, act on impulses, and become controlled by the unconscious. Freud argues that masses are held together by libidinal bonds and identification with leaders. The work distinguishes between temporary fads and enduring organized groups, revealing how both operate through similar mental processes. (This is an automatically generated summary.)