"Early on a difficult climb, especially a solo climb, you’re hyper-aware of the abyss pulling at your back, constantly feeling its call, its immense hunger. To resist takes tremendous conscious effort, you don’t dare let your guard down for an instant. The void puts you on edge, makes your movements tentative and clumsy. But as the climb continues, you grow accustomed to the exposure, you get used to rubbing shoulders with doom, you come to believe in the reliability of your hands and feet and head. You learn to trust your self-control."