Gustave Le Bon 1

The disappearance of conscious personality and the turning of feelings and thoughts in a definite direction, which are the primary characteristics of a crowd about to become organised, do not always involve the simultaneous presence of a number of individuals on one spot. Thousands of isolated individuals may acquire at certain moments, and under the influence of certain violent emotions—such, for example, as a great national event—the characteristics of a psychological crowd."

― from "The Crowd; study of the popular mind"