Sometimes a solution just appears out of nowhere. You bring your multipage spreadsheet to the finance department, and within seconds the accountant tells you something isn't quite right without being able to say what. You're perched on a narrow ledge halfway up Half Dome in Yosemite Valley, 1,000 feet above deck, searching for the continuation of the climb on the granite wall that appears featureless, when your senior climbing partner quickly points to a tiny series of flakes: “Trust me, this is it.”

Author: Christof Koch