Susan Cain is a lawyer and negotiations consultant. She is also an introvert who has noticed that institutions like business and education are stacked against people like her. So for the past seven years, she has been writing Quiet, a book on that subject. It was published earlier this year. She knew that to promote it she would have to undertake something difficult for introverts: lots of public speaking. She braced herself for ‘a year of speaking dangerously.’ Her dream venue was scariest stage of all: TED, which has become for intellectuals and artists the equivalent of what Johnny Carson’s couch once was for comedians.