after lowering the arm the shoulder-muscle aches, much as it does in rheumatism. Pain is an effect upon consciousness, which absorbs, engulfs, and therefore obliterates sensation. To use an ancient phrase, “It is less that I feel pain than that I am pain.” If we speak of the capacity for pain as a sense, we may call it for the purpose of our present argument the “sense of damage.” The nerves of the skin are acutely affected by any agent which is likely to do harm. It is their business to convey to the central nervous system an influence which so affects it as to set up in consciousness the condition of pain. Sensations of damage evoke reflex movements by means of which the part of the body likely to be injured, or the whole body, is removed to a safe distance. It being the duty of the skin to give this warning, a service of nerves sensitive to noxious agents has been developed which scouts in co-operation with the services devoted to the recognition of physical contact and heat and cold (_cf._ p. 425). If, imagining that the fire has not been lighted, I touch an almost red-hot stove, I acquire quite a considerable amount of information of which I am able to make use. I gain an accurate notion of the situation of the stove, and I put the right part of my finger in my mouth. The skin sends to the brain the ordinary sensations of touch and pressure before the condition of pain is established. In seeking for a definition of pain, we must eliminate the two attributes which have characterized all the forms of stimulation which we have considered up to the present time: (1) The tendency to provoke movement; (2) the supply of information. If I am suffering from a whitlow, the last thing that I am disposed to do is to jerk my finger about. Although it enhances the urgency of skin-reflexes, pain, in general, inhibits movement instead of provoking it. This is well illustrated in pleurisy. So long as a man is healthy he is quite unconscious of the fact that at each respiration the lower part of the lung slides on the lining of the chest-wall; but commencing inflammation on the surface of one of the lungs causes intense susceptibility to friction, and the pain produces an effect which the man is quite unable to produce by an effort of will; it stops the movements of the chest on the damaged side. Pain is inhibitory, not stimulant. It is not, properly speaking, a sensation. Frequently being mixed with sensational elements, it conveys topographical information; but pure pain approaches in quality the nebulous sense of distress of a patient who, when asked where he felt it, replied: “Nowhere; but there is a deal of it in the room.”