Visiting Quora is striking because it seems to be one of the rare places on the Internet where a diverse group of people come out of the woodwork to try to be smart and thoughtful. That just doesn’t happen very often. But then, it can be easy to forget to visit Quora, with its random jumble of writings on topics that are interesting but not crucial.

As Quora’s co-founder, CEO and also a significant investor, Adam D’Angelo is the driving force behind the site as it expands from Q&A to other kinds of writing. In an interview last week at the company’s new Mountain View, Calif., headquarters, the former Face