WHAT IS PAIN? 351 



possessing a nervous system must feel pain, because 

 pain belongs to the nervous system, I ask. To what 

 part of that system ? We are certain that it does not 

 belong to every part. We have endless nerve-actions 

 incessantly going forward, without a vestige of pain 

 accompanying them. There is no pain in seeing, hear- 

 ing, thinking, breathing, digesting, &c. If not every 

 part of the nervous mechanism, then only some special 

 part, or parts, must be credited with sensibility under 

 the form of Pain ; and the mere fact of an animal's 

 possessing a nervous system, will aid the argument 

 only when proof is afforded that this system also in- 

 cludes the special part or parts endowed with sensi- 

 bility to Pain * 



As far as I can see into this obscure question, Pain 

 is only a specialisation of that Sensibility which is 

 common to all animals. It is a specialisation result- 

 ing from a high degree of differentiation of the nervous 

 system, consequently found only in the more complex 

 animals, and in them increasing as we ascend the scale. 

 Out of a primordial basis of Sensibility (one of the 

 vital properties — an ultimate fact, therefore), various 

 special forms are developed. In the ascending series 

 we have first reflex action, we have next the organic 

 sensations, then the special sensations of seeing, hear- 

 ing, tasting, smelling, touching ; we have, further, the 

 sensations of shivering, tickling, fatigue, hunger, thirst, 



* In the Proceedinffs of the Liverpool Literary and PhilosopJucal So- 

 ciety, No. IV. (1848), will be found an interesting essay by Dr Inman, 

 entitled "On the Non-existence of Pain in the Lower Animals," in 

 which many curious facts are collected. 



