Pain has been described as the gift no one wants. There cannot be a single reader who has not, at some time, wished not to experience pain.

But we are better off with the capacity to suffer pain than without it. A few people are born with a genetic deficiency that leaves them completely free of pain. They rarely survive to adult life. Leprosy has for thousands of years been the most dreaded disease. Only in the 20th century was it realised that the disfigurement was not the result of the illness itself but of inadvertent injuries caused to soft tissues by damaged nerve endings that did not allow the sufferer to register pain.