HEREDITY 295 



Nurture, when the Nurtures of the persons compared 

 were not exceedingly different. It appeared that 

 when twins who had been closely alike had after- 

 wards grown dissimilar, the date of divergence was 

 usually referred to a time when one of them had a 

 serious illness, sufficient to modify his constitution. 



Many years later I was so harassed with the old 

 question of Determinism, which would leave every 

 human action under the control of Heredity and 

 Environment, that I made a series of observations on 

 the actions of my own mind in relation to Free Will. 

 I employ the word not merely as meaning " un- 

 hindered "' but in the special sense of an uncaused and 

 creative action. It was carried on almost continuously 

 for six weeks, and off and on for many subsequent 

 months [55]. The procedure was this. Whenever I 

 caught myself in an act of what seemed to be " Free 

 Will " in the above sense, I checked myself and tried 

 hard to recollect what had happened before, made rapid 

 notes, and then wrote a full account of the case. To 

 my surprise, I found, after some days' work, that the 

 occasions were rare on which there seemed room for 

 the exercise of Free Will as defined above. I 

 subsequently reckoned that they did not occur oftener 

 than once a day. Motives for all the other events 

 could be traced backwards in succession, by orderly 

 and continuous steps, until they led into a tangle of 

 familiar paths. It was curious to watch the increase 

 of power given by practice, of recalling mental actions 

 which being usually overlooked give the false idea 

 that much has been performed through a creative act, 

 or by inspiration, which is really due to straight- 

 forward causation. The subject is too complex to be 



