60 MENTAL EVOLUTION IN MAN. 



wooden floor of an apple-room, and, as each bag of apples 

 was shot, it produced through the rest of the house a noise 

 resembling that of distant thunder. My dog became terror- 

 stricken at the sound ; but as soon as I brought him to the 

 apple-room and showed him the true cause of the noise, he 

 became again buoyant and cheerful as usual." * 



The importance of clearly perceiving that animals have a 

 generic, as distinguished from an abstract, idea of causation 

 — and, indeed, must have such an idea if they are in any way 

 at all to adjust their actions to their circumstances — the 

 importance of clearly perceiving this is, that it carries with it 

 a proof of the logic of recepts being able to reach generic 

 ideas o{ principles, as well as of objects, qualities, and actions. 

 In order to prove this important fact still more unquestionably, 

 I will here quote a passage from the biography of the cebus 

 which I kept for the express purpose of observing his intelli- 

 gence. 



" To-day he obtained possession of a hearth-brush, one of 

 the kind which has the handle screwed into the brush. He 

 soon found the way to unscrew the handle, and, having done 

 that, he immediately began to try to find out the way to screw 

 it in again. This he in time accomplished. At first he put 

 the wrong end of the handle into the hole, but turned it round 

 and round the right way for screwing. Finding it did not 

 hold, he turned the other end of the handle, carefully stuck it 

 into the hole, and began again to turn it the right way. It 

 was, of course, a very difficult feat for him to perform, for he 

 required both liis hands to hold the handle in the proper 

 position, and to turn it between his hands in order to screw 

 it in ; and the long bristles of the brush prevented it from 

 remaining steady, or with the right side up. He held the 



* I may here observe that the earliest age in the infant at which I have 

 observed such appreciation of causality to occur is during the sixth month. With 

 my own children at that age I noticed that if I made a knocking sound with my 

 concealed foot, they would look round and round the room with an obvious desire 

 to ascertain the cause that was producing the sound. Compare, also, Mental 

 Evolution in Animals, pp. 156-158, on emotions aroused in brutes by sense of the 

 mysterious — i.e. the unexplained. 



