1911 Encyclopædia Britannica/Pain

PAIN (from Lat. poena, Gr. ποίνη, penalty, that which must be paid: O. Fr. peine), a term used loosely (1) for the psychological state, which may be generally described as “unpleasantness,” arising, e.g. from the contemplation of a catastrophe or of moral turpitude, and (2) for physical (or psycho-physical) suffering, a specific sensation localized in a particular part of the body. The term is used in both senses as the opposite of “pleasure,” though it is doubtful whether the antithesis between physical and psychical pleasure can be equally well attested. The investigation of the pleasure-pain phenomena of consciousness has taken a prominent place in psychological and ethical speculation, the terms “hedonics” and “algedonics” ἀλγηδίον, pain of body or mind) being coined to express different aspects of the subject. So in aesthetics attempts have been made to assign to pain a specific psychological function as tending to increase pleasure by contrast (so Fechner): pain, e.g. is a necessary element in the tragic. Scientists have experimented elaborately with a view to the precise localization of pain-sensations, and “pain-maps” can be drawn showing the exact situation of what are known as “pain-spots.” For such experiments instruments known as “aesthesiometers” and “algometers” have been devised. The great variety of painful sensations—throbbing, dull, acute, intermittent, stabbing—led to the conclusion among earlier investigators that pains differ in quality. It is, however, generally agreed that all pain is qualitatively the same, though subject to temporal and intensive modification. (See Psychology; Aesthetics; Nervous System; Sympathetic System.)