Talk of the Nation, April 20, 2010 Time editor Richard Stengel spent nearly three years traveling with Nelson Mandela, collecting hours of conversation about his life for Mandela's autobiography. Stengel calls prison Mandela's greatest teacher. He remembers gasping when he first saw the Mandela's tiny prison cell in Robben Island, where he spent the majority of his 27 years in jail. "Nelson Mandela, as you know, is a big man," Stengel tells host Neal Conan, "larger than life, in a literal and figurative way." The cell was so small, Stengel remembers, "he couldn't even lie down and stretch out his legs. It could barely contain him." But, says Stengel, Mandela's imprisonment taught him "how to contain himself, how to practice the self control that he actually didn't have before he went into prison."