On the relation of injury to pain. The John J. Bonica lecture.

Pain is better classified as an awareness of a need-state than as a sensation. It serves more to promote healing than to avoid injury. It has more in common with the phenomena of hunger and thirst than it has with seeing or hearing. The period after injury is divided into the immediate, acute and chronic stages. In each stage it is shown that pain has only a weak connection to injury but a strong connection to the body state.