What makes a person abandon the world and become a hermit? Was Chris Knight merely an anti-social loner? Or does he have something important to teach us? These are some of the questions journalist Michael Finkel, who has written for National Geographic, asks in his book The Stranger in the Woods: The Extraordinary Story of the Last True Hermit. Speaking by phone , Finkel discusses what makes someone become a hermit, and why Knight finally got caught.