You are always alone atop a mountain, even in a crowd. At a beach - any beach - a solitary figure standing at the edge of your vision can make you feel intruded upon. On the summit of an Alpine mountain, a chairlift dumping out bystanders six at a time will offer you no companionship. I stand next to my wife at nearly 11,000 feet of altitude, in the St. Moritz region of Switzerland, on the highest skiable peak of the formidable Corvatsch massif. I have known my wife for over a quarter century, but she has momentarily become a phantom of herself, unable to interrupt my solitude with even the best of our mutual intentions.