Typically, public health uses top-down strategies. The most effective messages are believed to come from the experts, 'from the top.' The people who know the most about the subject, the people who are paid to sit around and think about the subject, it turns out, though, that if you look at the Sheen effect and if you look at these other examples of organic media events ... that's not the case. These messages, they come from the bottom; they come from ordinary people. People who aren't health experts. Sheen might be a celebrity, but he's not a health expert. Angelina Jolie is not a health expert.