Why is pain so poorly understood? Why do we distinguish between mental pain and physical pain, when pain is always an emotional experience? How can it be that science is about to clone a human being but still can't cure the pain of a bad back? If pain is the reason most people visit the doctor, why are most doctors so bad at addressing the problem of suffering? Marni Jackson sets out in Pain- the fifth vital sign to understand this most elusive of subjects. In the questing and narrative manner of Oliver Sacks, Jackson takes us back into the history of pain and forward into the possibility of pain genetics. She brings us stories of both people in pain and the pain pioneers- eccentrics and artists, wrestlers and writers, psychologists and philosophers, nurses and doctors. Above all, Pain makes an elusive subject vivid and readable. We all know what pain is - now Marni Jackson has given it a voice.