466 THE SENSORY FUNCTIONS OF THE SKIN 



tion to them they gradually become more and more unpleasant and, finally, actu- 

 ally painful. 



In diseases accompanied by pain, the pain is often more severe at night than 

 during the day. This is probably due to the fact that in the daytime our atten- 

 tion is distracted by many things outside ourselves, and is not directed so exclu- 

 sively to the body. 



By purposely fixing one's attention on a definite object or idea it is possible 

 to suppress not only the expression of pain, but to a large extent the pain itself. 

 The following story of Immanuel Kant is much to the point. Kant suffered 

 from time to time with attacks of gout which, as many know, may be very 

 painful. " Out of patience at feeling myself deprived of sleep," he writes, " I 

 soon seized upon the stoical expedient of fixing my thought intently on some 

 chance object, whatever it might be (e. g., on the many ideas associated with 

 the name of Cicero), and of consequently diverting my attention from all sen- 

 sations. In this way the sensation speedily became blunted, so that the natural 

 tendency to sleep overcame them. And this I could repeat with equally good 

 results each time in the little interruptions in my night's rest occasioned by 

 recurring attacks. But in the morning the shiny redness of the toes of my left 

 foot was sufficiently convincing to myself that these sensations had not been 

 purely fanciful." 



Although all men have not the same will power as Kant had, we may never- 

 theless learn from his example that it is possible actually to suppress pain to a 

 certain extent, just as it is possible for us to accustom ourselves to bear a neces- 

 sary pain without sounding it abroad with loud wailings. 



The expression of pain, therefore, is not to be accepted as a measure of its 

 intensity. A strong-willed person may feel very severe pain without wincing, 

 while another may cry out at a pin prick. On the other hand, we must not 

 forget the experience oft confirmed in animals as well as in men that sensitive- 

 ness to pain is very different in different individuals. And since nobody can 

 tell with certainty how strong is the pain which another feels, we ought not to 

 withhold our sympathy from others when they give expression to pain. 



It is very difficult to decide just whereinjies the real physiological cause 

 of pain. Since we know that the pain aroused by any adequate stimulus has 

 an altogether different character in different parts of the body as, e. g., those 

 aroused by a high temperature differ from those aroused by a low temperature, 

 as the pain of muscle cramps is of a different kind from that of high pressure 

 inside the eye, and the pains occurring in inflammatory processes differ accord- 

 ing to the organ inflamed the assumption is undoubtedly suggested that pain 

 is produced by an excessive excitation of the ordinary afferent nerves from 

 different parts of the body. 



The fact that in certain diseases of the nervous system the sensations of pain 

 are lost while the ordinary tactile sensations do not suffer any considerable 

 diminution, does not militate against this hypothesis. One might readily im- 

 agine that the maximum excitation necessary for the production of pain were 

 not reached, although the threshold stimulus remained approximately the same; 

 and this supposition could be brought into line with Schiff's observation that 

 section of the gray matter of the spinal cord abolishes sensations of pain with- 

 out affecting the tactile sensations. 



Proceeding from this observation it has repeatedly been conjectured that 

 painful impressions are conducted through the gray matter, and that the 



