Nick Paumgarten writes about the Swiss climber Ueli Steck, who made a name for himself climbing mountains at high speed with no ropes. In a recent climb, on Mt. Everest, Steck and his climbing partners got into a violent confrontation with Nepalese Sherpas. Here, Sasha Weiss talks with Paumgarten and staff writer Peter Hessler about lure and lore of mountaineering, how the influence of corporate sponsorship has changed the sport, and the complicated relationship between Sherpas and Western climbers on Everest. Also, why David Sedaris is on his best behavior around guests.