PLEASURES AND PAINS. 109 



Thus, then, we see that the affixing of painful or disagree- 

 able states of consciousness to deleterious changes of the 

 organism, and the reverse states to reverse changes, has been 

 a necessary function of the survival of the fittest. We may 

 further see that in bringing about this adjustment or corre- 

 spondence, the zoological principle of the survival of the 

 fittest must have been largely assisted by the physiological 

 principle that Pleasure tends to accompany the normal 

 activity of an organ and Pain to accompany its abnormal. 

 For as organs are invariably of use to the organism, their 

 normal activity must always be beneficial to it ; while, con- 

 versely, their abnormal activity, tending to cause or being 

 caused by their own disintegration, must always be harmful 

 to the organism. Survival of the fittest is thus provided 

 with a ready-formed condition or tendency of psycho-physio- 

 logy on which to work — a tendency which survival of the 

 fittest may itself in earlier times have been instrumental 

 in producing ; but which, in any case, when once established 

 must gTeatly assist survival of the fittest in apportioning the 

 appropriate state of consciousness to any particular organic 

 process. 



Another principle of pyscho-physiology must likewise 

 have greatly assisted natural selection in its execution of 

 this work. This principle is that which obtains in so-called 

 acquired tastes and distastes. Thus, as Mr. Spencer observes, 

 14 Pleasures and Pains may be acquired — may be, as it were, 

 superimposed on certain feelings which did not originally 

 yield them. Smokers, snuff-takers, and those who chew 

 tobacco, furnish familiar instances of the way in which long 

 persistence in a sensation not originally pleasurable, makes it 

 pleasurable — the sensation itself remaining unchanged. The 

 like happens with various foods and drinks, which, at first 

 distasteful, are afterwards relished if frequently taken. 

 Common sayings about the effects of habit imply recognition 

 tit this truth as holding with feelings of other orders. That 

 acute pain can be superinduced on feelings originally agree- 

 able or indifferent, we have no proof. But we have proof 

 that tin- state of consciousness called disgust may be made 

 inseparable from a feeling that once was pleasurable:" so 



that even in the life-time of the individual the states of 



consciousness as pleasurable or painful may reverse their 

 character with reference to the same organic changes or sen- 



