PLEASURE, PAIN AND INTELLIGENCE 149 



ent relish and alcoholic liquors are readily imbibed even by such 

 primitive creatures as bees and wasps upon their very first ac- 

 quaintance with these intoxicants. But aside from exceptional 

 cases pleasure in the animal world is a sufficiently good index of 

 what is beneficial that under conditions which ordinarily present 

 themselves it seldom leads to injurious courses of action. 



The relation between the pleasant and the beneficial is, however, 

 probably not a primary one, and it is not improbable that it 

 represents a connection established by natural selection, as was 

 first maintained by Herbert Spencer. 



If the states of consciousness which a creature endeavors to maintain 

 are the correlatives of injurious actions, and if the states of consciousness 

 which it endeavors to expel are the correlatives of beneficial actions, it 

 must quickly disappear through persistence in the injurious and avoid- 

 ance of the beneficial. In other words, those races of beings only can 

 have survived in which, on the average, agreeable or desired feelings went 

 along with activities conducive to the maintenance of life, while disagree- 

 able and habitually-a voided feelings went along with activities directly or 

 indirectly destructive of life; and there must ever have been, other things 

 equal, the most useful and long-continued survivals among races in which 

 these adjustments of feelings to actions were the best, tending ever to 

 bring about perfect adjustment. 



This explanation which has become widely accepted leaves a 

 fundamental question unanswered. It does not explain why cer- 

 tain acts are stamped in and certain others stamped out. Of 

 the mechanism of this process, which is the real problem involved 

 in the pleasure-pain reaction, we are as ignorant as before. The 

 explanation means that animals which took pleasure in following 

 acts that brought them benefit were preserved and those that 

 did not behave in this manner were eliminated. But why does 

 an animal tend to repeat an act that brings it pleasure and avoid 

 one that produces pain? It seems so natural for creatures to 

 behave in this way that the existence of any problem here is 

 usually unsuspected, but this is the problem that confronts us 

 when we endeavor to obtain a clear understanding of the way in 

 which intelligence develops out of instinct. 



In the pleasure-pain response we have two problems of a quite 



