THE NERVOUS SYSTEM 313 



matism. 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 pro- 

 voke 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 in- 

 hibitory, not stimulant. It is not, properly speaking, a sen- 

 sation. Frequently being mixed with sensational elements, it 

 conveys topographical information ; but pure pain approaches 



