224 MENTAL FACULTIES sec. 



This effect of habit greatly facilitates our daily life, for it 

 includes a number of actions which we perform from morning 

 till night as it were involuntarily, although we have once 

 had to take pains to learn them, from the actions we perform 

 on rising in the morning to those of going to bed. Thus the 

 brain is left at liberty to work in other directions, to acquire 

 new faculties. 



Such acquired automatic actions can be inherited. Instinct 

 is inherited faculty, especially is inherited habit. Or to state 

 it more accurately, instinct is the power of habitually acting 

 without reflection so as to attain a given object — in such a 

 way as intelligence or even reason might dictate — in response 

 to internal stimuli depending on the condition of the body, 

 and to external, or without the latter. 



!N'o other scientific explanation of instinct seems to me 

 possible. 



I divide instincts into perfect and imperfect. The former 

 are those w^hich are inherited in such a complete manner 

 that thev need no further stimulation, no kind of ouidance, 

 no practice. These are inherited automatisms. They include, 

 for instance, the collection of honey by bees and other insects, 

 the formation of the cocoon by caterpillars, numerous "building 

 instincts," the impulse in young water-birds to seek the water 

 and their power of swimming immediately, the love of parents 

 for their children, brooding instincts, and so on. 



Imperfect instincts require to be called into action by an 

 external stimulus, or to be developed by guidance and prac- 

 tice. In these there is merely an inherited capacity for 

 automatic action. To this class beloncj the buildino: of suit- 

 able nests by birds, and for the most part the instincts of 

 game -dogs. Here also belong many other faculties called 

 forth by very short experience (compare the following). 



Imperfect instinct passes, without any limit which can be 

 distinctly defined, into faculty acquired during life. 



