[Tycho]

One added benefit of seeing a speaker rather than just reading an essay is that you can better judge the conviction in their statements. Lots of people trim their essays/articles to a state of dry assertiveness, because it's the expected style. But in person they're more likely to add things like 'and i spent a long time trying to work this out, and to be honest I'm not sure I've got it right, but my working conclusion is that...'