The Evidence of Mind 33 



very gradually have his muscles acquired the strength to 

 do it as it should be done. Now among the lower animal 

 forms we sometimes meet with learning by experience that 

 is very slow ; that requires a hundred or more repetitions 

 of the stimulus before the new reaction is acquired. In 

 such a case we can find analogical reasons for suspecting 

 that a gradual change in the tissues of the body has taken 

 place, of the sort which, like the attuning of the violin wood 

 or the slow development of a muscle, have no conscious 

 accompaniment. 



We must then ask the question : What kind of learning 

 by experience never, so far as we know, occurs unconsciously ? 

 ■ Suppose a human being shut up in a room from which he can 

 escape only by working a combination lock. As we shall see 

 later, this is one of the methods by which the learning power 

 of animals has been tested. The man, after prolonged 

 investigation, hits upon the right combination and gets out. 

 Suppose that he later finds himself again in the same pre- 

 dicament, and that without hesitation or fimibling he opens' 

 the lock at once, and performs the feat again and again, to 

 show that it was not a lucky accident. But one interpreta- 

 tion of such behavior is possible. We know from our own 

 experience that the man could not have worked the lock the 

 second time he saw it, unless he consciously remembered the 

 movements he made the first time ; that is, unless he had in 

 mind some kind of idea as a guide. Here, at least, there can 

 have been no change in the structure of the muscles, for such 

 changes are gradual ; the change must have taken place in 

 the most easily alterable portion of the organism, the ner- 

 vous system ; and further, it must have taken place in the 

 most unstable and variable part of the nervous system, the 

 higher cortical centres whose activity is accompanied by 

 consciousness. In other words, we may be practically 



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