The Influence of Periferal Movements on the Mainstream

If everything spreads like a virus, how is it some ideas don't leap from group to group? Damon was exposed to ideas about social justice at home. So why didn't they leap through him to his classmates? Why didn't he infect them with those concepts? Damin also noticed something else. Overtime, some ideas that were popular in one community did spread to others. But the way this happened did not look anything like a virus. It took decades for those ideas to spread.