Aching, throbbing, searing, excruciating – pain is difficult to describe and impossible to see. So how can doctors measure it? ... During that period of convalescence, as I watched her grimace and clench her teeth and let slip little cries of anguish until a long regimen of combined ibuprofen and codeine finally conquered the pain, several questions came into my head. Chief among them was: Can anyone in the medical profession talk about pain with any authority? From the family doctor to the surgeon, their remarks and suggestions seemed tentative, generalised, unknowing – and potentially dangerous: Was it right for the doctor to tell my wife that her level of pain didn’t sound like appendicitis when the doctor didn’t know whether she had a high or low pain threshold? Should he have advised her to stay in bed and risk her appendix exploding into peritonitis? How could surgeons predict that patients would feel only ‘discomfort’ after such an operation when she felt agony – an agony that was aggravated by fear that the operation had been a failure? ... There seemed to be a chasm of understanding in human discussions of pain. I wanted to find out how the medical profession apprehends pain – the language it uses for something that’s invisible to the naked eye, that can’t be measured except by asking for the sufferer’s subjective description, and that can be treated only by the use of opium derivatives that go back to the Middle Ages.