Timmy O'Neill is guiding Steve Baskis through ancient yellow pines that almost touch the sky. They're hiking all day to base camp in California's Yosemite National Park, 2,000 feet up in Little Yosemite Valley.
Taking Baskis by the hand, O'Neill traces the distant ridge of Half Dome, a bald rock rising almost a mile from the valley floor. That's tomorrow's challenge.
Baskis can't actually see the peak. Four years ago, a bomb blast in Iraq took his eyesight. So O'Neill is guiding Baskis along the trail, providing directions and warning him away from steep drops.