One Voice

I think that one voice can move a crowd to action provided some other details. The masses would have to have faith that the person had some sort of power; Young succeeded in causing such a strife because the group believed that he was receiving word from a higher authority. Additionally, the crowd must at least somewhat agree with the person. Not only did Young represent an authority, but also he seemed to be an ardent supporter of something they already believed in. Were he a Republican trying to have influence over the Communists, they would probably have just ignored him.

When speaking of a larger group of people, that "one person" would ultimately not be a single individual. If a group is trying to change the world, it needs a representative to serve as a face for them. Say for the Communists, that's Pamela Anderson. Pamela Anderson will give speeches, talk to papers and TV stations, and sign the books she wrote, but it won't be her who's making people rise to action. The real power is in her colleagues because they are the ones whose ideas she's spreading. Pamela Anderson could know nothing about Communism other than what the true believers have written for her to say into the mic, but whenever people think of the party, they'll think of her. One person cannot be responsible for calling people to action, but the group who is responsible needs a face to put on their message if they want to be remembered.