152 The Study of Animal Life part ii 



stated that a monkey that had learned to screw and 

 unscrew a handle from a broom had learned " the principle 

 of the screw." This is entirely erroneous. The monkey 

 merely observed that a certain movement given to the 

 handle caused it to separate from the broom, and inferred 

 perceptually that the same result would always follow from 

 the same action. 



It is evident that a sound comparative psychology of 

 the animal kingdom, or even of a few of the highest 

 species, is beyond the present possibilities of science. 



