Group Psychology and the Analysis of the Ego is a 1921 book by Sigmund Freud, the founder of psychoanalysis.
In this monograph, Freud describes psychological mechanisms at work within mass movements. A mass, according to Freud, is a "temporary entity, consisting of heterogeneous elements that have joined together for a moment." He refers heavily to the writings of sociologist and psychologist Gustave Le Bon (1841-1931), summarizing his work at the beginning of the book in the chapter Le Bon ...