If we think about emotion this way - as outside-in, not inside out - it is possible to understand how some people can have an enormous amount of influence over others. Some of us, after all, are very good at expressiing emotions and feelings, which means that we are far more emotionally contagious than the rest of us.

The Tipping Point: How Little Things Can Make a Big Difference (ed. Little, Brown, 2006) - ISBN: 9780759574731