All that held me to the mountainside, all that held me to the world, were two thin spikes of chrome molybdenum stuck half an inch into a smear of frozen water, yet the higher I climbed, the more comfortable I became. Early on a difficult climb, especially a difficult solo-climb, you constantly feel the abyss pulling at your back. To resist takes a tremendous conscious effort; you don’t dare let your guard down for an instant. The siren song of the void puts you on edge; it makes your movements tentative, clumsy, herky-jerky. But as the climb goes on, 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.
Jon Krakauer, climb on Devils Thumb, Alaska, Into the Wild, p. 142 (1996)
Jon Krakauer, Into the Wild, concerns the wilderness trek of Christopher McCandless into the Alaskan back country, ending in his death. Krakauer, in the quote I have excerpted above, juxtaposes his own experience on the side of Devils Thumb with that of McCandless. Krakauer came out alive. Unfortunately, McCandless did not.
Addendum, November 27, 2010: If you have not clicked on the hyperlink to Devils Thumb, do so because it takes you to the Google map in Alaska.