The Screwtape Letters is excellent, I read it years ago. I'm currently working on The Worst Journey in the World, by Apsley Cherry-Garrard. it's the story of Sir Robert Scott's journey to the South Pole, and his attempted return. I've read South, which is Shackleton's story of his attempt to traverse the Antarctic continent, and Endurance, which is the story of Shackleton's attempt written by Alfred Lansing. I suppose I should find something about Amundsen's journey, since he succeeded where Scott and Shackleton did not.