In honor of Nelson Mandela's 90th birthday, Richard Stengel, managing editor of Time magazine, put together Mandela's eight lessons of leadership. Stengel writes: "[The lessons] are cobbled together from…conversations old and new and from observing [Mandela] up close and from afar. Many of them stem directly from his personal experience. All of them are calibrated to cause the best kind of trouble: the trouble that forces us to ask how we can make the world a better place."

Here are Mandela's eight lessons of leadership:

1. Courage is not the absence of fear—it's inspiring others to move beyond it.
   
2. Lead from the front—but don't leave your base behind.
   
3. Lead from the back—and let others believe they are in front.
   
4. Know your enemy—and learn about his favorite sport. [In order to work more effectively with Afrikaners, Mandela learned their language and all about their most cherished sport: rugby.
   
5. Keep your friends close—and your rivals even closer.
   
6. Appearances matter—and remember to smile.
   
7. Nothing is black or white.
   
8. Quitting is leading too.