734 THE POPULAR SCIENCE MONTHLY. 



drifted, but pursued tlie course in which her head was set until she 

 arrived at her predestined port. 



The second of my inquiries was into the life-histories of twins, in 

 the course of which I collected cases where the pair of twins resem- 

 bled each other so closely that they behaved like one person, thought 

 and spoke alike, and acted, similar parts when separated. Whatever 

 spontaneous feeling the one twin may have had, the other twin at the 

 very same moment must have had a spontaneous feeling of exactly 

 the same kind. Such habitual coincidences, if they had no common 

 cause, would be impossible ; we are therefore driven to the conclusion 

 that, whenever twins think and speak alike, there is no spontaneity in 

 either of them, in the popular acceptation of the word, but that they 

 act mechanically and in like ways, because their mechanisms are alike. 

 I need not reiterate my old arguments, and will say no more about 

 the twins, except that new cases have come to my knowledge which 

 corroborate former information. It follows that, if we had in our 

 keeping the twin of a man, who was his "double," we might obtain a 

 trustworthy forecast of what the man would do under any new condi- 

 tions, by first subjecting that twin to the same conditions and watch- 

 ing his conduct. 



My third inquiry is more recent. It was a course of introspective 

 search into the operations of my own mind, whenever I caught myself 

 engaged in a feat of what at first sight seemed to be free-will. The 

 inquiry was carried on almost continuously for three weeks, and pro- 

 ceeded with, off and on, for many subsequent months. After I had 

 mastered the method of observation, a vast deal of apparent mystery 

 cleared away, and I ultimately reckoned the rate of occurrence of per- 

 plexing cases, during the somewhat uneventful but pleasant months of 

 a summer spent in the country, to be less than one a day. All the rest 

 of my actions seemed clearly to lie within the province of normal cause 

 and consequence. The general results of my introspective inquiry sup- 

 port the views of those who hold that man is little more than a con- 

 scious machine, the larger part of whose actions are predicable. As 

 regards such residuum as there may be, which is not automatic, and 

 which a man, however wise and well-informed, could not possibly 

 foresee, I have nothing to say ; but I have found that the more care- 

 fully I inquired, whether it was into hereditary similarities of conduct, 

 into the life-histories of twins, or now introspectively into the pro- 

 cesses of what I should have called my own free-will, the smaller seems 

 the room left for the possible residuum. 



I conclude from these three inquiries that the motives of the will 

 are mostly normal, and that the character which shapes our conduct is 

 a definite and durable "something," and therefore that it is reasonable 

 to attempt to measure it. We must guard ourselves against suppos- 

 ing that the moral faculties which we distinguish by different names, 

 as courage, sociability, niggardliness, are separate entities. On the con- 



