As for the momentum of a movement, that's very much related to people.. at the start of a movement, a “critical mass” for a certain number of the right people that stay zealous as the core of the cause, and then for the momentum to continue and/or grow, it's some intangible combination of more people joining the movement and growing awareness of the movement among the >a href=en.wikipedia.org/wiki/Hoi_polloi>hoi polloi.