It shapes every interaction we have, whether we're trying to get a two-year-old to eat green vegetables or ask for a promotion at work. But how do we really gain and maintain power - through coercion or cooperation? What does it do to our behaviour? And what makes us lose power? In twenty revolutionary 'power principles', renowned psychologist Dacher Keltner turns everything we thought we knew about influence and status upside down, redefining power for our times.