The average American has at least one unexplained symptom every week or two, and less than one-fifth of survey subjects report no symptoms at all during the three days prior to a random query. Headache, tingling, pain, dizziness, briefly blurred vision, a slight imbalance when walking, loss of train of thought, feelings of jabs and jolts: these are the most common symptoms, and they befall any healthy nervous system, then disappear and are forgotten.
