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holds equally as regards the other ; and we may have pain as 

 uncertain in its outward development as any other emotion 

 of the mind. 



" It becomes necessary, therefore, to inquire more at length 

 into the evidences we have of the existence of this feeling in 

 any particular case, and the extent to which they may be 

 trusted. 



" If we trace, step by step, the course of argument we adopt 

 to convince ourselves, or others, of the existence of pain in 

 those who cannot communicate with us in words, we shall find 

 that we invariably commence by a delineation of its effects 

 upon ourselves. We know, that when the surgeon has politely 

 poked his knife through our tender skin, or when we have 

 torn ourselves by a rusty nail or a savage thorn, we have felt 

 a disposition to shrink from the infliction, to turn and writhe 

 the body about to distract our attention, and reduce the pain- 

 ful smarting from which we suffer ; and that if the irritating 

 cause has been prolonged, as in the case of severe surgical 

 operations, the body has become almost convulsed, that the 

 limbs are thrown wildly about, and the whole frame seems 

 to be lashed with agony. Knowing this, we infer that when- 

 ever a similar cause is operating upon others, and the same 

 effects are produced as were produced in us, they must be 

 attended by the same feelings of pain and suffering, and vice 

 versa. 



"Do we not, for example, in spite of ourselves, judge that 

 the pain which the surgeon is inflicting with his instruments, 

 or that nature is imposing in disease, is great or small in pro- 

 portion to the outward manifestation of suffering? Do we 

 not, when we hear a string of groans or cries, and witness an 

 inordinate amount of writhing and convulsion, believe that 

 there is a larger extent of suffering present, than when we 

 see a patient silently bearing what would be to us the greatest 

 torture ? 



"Who, for example, when they see a caterpillar wriggling 



