"Massenpsychologie und Ich-Analyse" by Sigmund Freud is an essay written in 1921. Freud explores the psychological mechanisms at work within mass movements, examining how individuals in crowds experience feelings of unlimited power that allow them to express drives they would normally suppress. Drawing on Gustave Le Bon's work, he distinguishes between short-lived revolutionary masses and permanent organized groups like churches or militaries, arguing that libidinal bonds hold masses together through identification with other members and idealization of leaders.