We revisit our earlier conversation about life on the vertical with Mark Synnott, elite climber and author of "The Impossible Climb: Alex Honnold, El Capitan, and the Climbing Life." The book describes Synnott's personal climbing history, beginning with his early days at Cathedral Ledge in N.H., and documents the preparation involved in Alex Honnold's historic free solo climb of Yosemite's El Capitan.