"The vigor of a mass movement stems from the propensity of its followers for united action and self-sacrifice. When we ascribe the success of a movement to its faith, doctrine, propaganda, leadership, ruthlessness and so on, we are but referring to instruments of unification and to means used to inculcate a readiness for self-sacrifice. It is perhaps impossible to understand the nature of a mass movement unless it is recognized that their chief preoccupation is to foster, perfect and perpetuate a facility for united action and self-sacrifice."