As a guide, I’m often asked what I carry on my harness. In addition to standard climbing hardware, plus prussic cords, a Tibloc, and a Micro-Traxion for glacier travel, I carry a knife. Once my clients see the knife, they often reference Joe Simpson’s classic mountaineering epic, Touching the Void. Unlike the moment of decision in the book when Simon cuts the rope to free himself while letting Simpson fall into a crevasse, I carry a knife for other reasons: these include to cut tat, add cordage to existing anchors, and cut the free ends from a stuck rope.