Professor Patrick Wall changed the way we think about pain. Until the middle of the 20th Century, pain was considered primarily to be a symptom of disease or injury. Pain was classically viewed in terms of a single mechanism consisting of a modality-specific, hard-wired system of nerve fibres running between the periphery and a specific pain centre in the brain. The implication of this view was that pain could only result from clear tissue pathology, with the result that physiotherapy treatment was often directed at the peripheral source of the pain. However, this does not fit with clinical observation, in that there is little correlation between the amount of tissue damage suffered by patients and the degree of pain that they feel