Consider then the small, unnoticed turning of the steering wheel, perhaps the exertion of only one pound for each motion, the varying pressure of foot on accelerator, not more than half a pound perhaps but an enormous total over a period of six hours. Then there are the muscles of shoulders and neck, constantly if unconsciously flexed for emergency, the eyes darting from road to rear-view mirror, the thousand decisions so deep that the conscious mind is not aware of them.
This in a day before power steering and power brakes.
