THE KOOT-PRINCIPLES OF MIND. 53 



physiologically considered, the emotions are the activities of 

 highly wrought nervous mechanisms, and these activities are 

 only excited by tlie very special stimuli which, on their sub- 

 jective side, we recognize as the particular kind of ideas 

 which are appropriate to call up particular emotions. We 

 do not laugh at a painful sight, nor does a ludicrous sight 

 cause us to weep ; and this, physiologically considered, 

 merely means that the nervous machinery whose action is 

 accompanied by one emotion, will only respond to one kind of 

 very specialized and complex stimulation ; it will not respond 

 to another and probably in many respects very similar kind of 

 stimulation, which, nevertheless, is competent to evoke re- 

 sponses from another and probably very similar piece of nervous 

 machinery. And thus, also, it is with Eeasoning and Judg- 

 ment. Eeasoning, on its physiological side, is merely a series 

 of highly complicated nervous changes, regarding which the , 

 only thing we certainly know is, that not one of them can ; 

 take place without an adequate physical accompaniment, and ■ 

 therefore that on its physiological side a train of reasoning is 

 a series of nervous changes, every one of wdiich must be 

 produced by physical antecedents. And hence on its objec- 

 tive side every step in a train of reasoning consists in a 

 selective discrimination among all those exceedingly delicate 

 stimuli w^hich, on their subjective side, we know as argu- 

 ments. Similarly regarded. Judgment is likewise nothing 

 more than the final result of the incidence of a vast number 

 of very delicate stimuli ; and this final result, like all the 

 intermediate steps of the reasoning which led to it, is nothing 

 more than the exercise of a power to discriminate between 

 the stimulus which on its subjective side we recognize as the 

 right, and that which w^e similarly recognize as the wrong. 

 Lastly, Volition, subjectively considered, is the faculty of 

 consciously selecting motives ; and motives, objectively con- 

 sidered, are nothing more than immensely complex and 

 inconceivably refined stimuli to nervous action. 



If we turn from the ascending scale of mental faculties 

 in man, to the ascending^ scale of mind in the animal king^- 

 dom, we shall meet with further and still more definite evi- 

 dence that the distinguishing property of mind, on its 

 physiological side, consists in this power of discriminating 

 between different kinds of stimuli, irrespective of their 

 degrees of mechanical intensity. But, before giving a brief 



