There is a moment, if you trip or slip, before your hand shoots out to break your fall, when you feel the earth rushing up at you and you cannot help yourself, a passing, fraction-of-a-second terror. I felt that way hour after hour after hour. Being anxious at this extreme level is bizarre. You feel all the time that you want to do something, that there is some affect that is unavailable to you, that there's a physical need of impossible urgency and discomfort for which there is no relief, as though you were constantly vomiting from your stomach but had no mouth.