The others have gone back down, and I am alone on the mountaintop with a strange young woman, dressed all in white, who shows me how to survive on nothing but snow left over from the long winter. The snow stands two feet deep among stone ruins built by a vanished race of miners, and it is gritty with dust from the atmosphere. Those are aerial plankton, she says, the microscopic corpses of our only real angels. The snow keeps them fresh. Eat it and live.