CHAPTER I. 



HEREDITY OF INSTINCTS. 

 I. 



WHEN we speak of instinct, our first difficulty is to define the 

 term. Not to enumerate here all the various significations of 

 the word as used in ordinary language, it is employed in at least 

 three different senses even by naturalists and philosophers, whose 

 language has to be more precise than that of other people. Some- 

 times instinct is intended to signify the automatic, almost mechan- 

 ical, and probably unconscious action of animals, in pursuance of 

 an object determined by their organization, and specific characters. 

 Again, instinct is made synonymous with desire, inclination, pro- 

 pensity ; as when we speak of good or evil instincts, a thievish or 

 murderous instinct. Finally, we sometimes comprise under the term 

 instinct all the psychological phenomena occurring in animals, and 

 all forms of mental activity inferior to those of man. This latter 

 signification of the word is plainly the result of our unwillingness 

 to attribute intellect to brutes ; and thus, contrary to all reason, 

 we confound with blind and unconscious impulses the conscious 

 acts which every animal performs under the guidance of its indi- 

 vidual experience, 1 and which, consequently, are analogous to those 

 which, in our own case, we call intelligent or intellectual acts. 



Although, in our opinion, instinct and intelligence are one and 

 the same, as we will try hereafter to show, and though the differ- 

 ence between them is one not of kind, but only of degree j still 

 we will employ the word instinct here in its first signification only 

 which alone we hold to be exact and in conformity with etymology. 

 We must, for the sake of greater precision, begin with a good defi- 

 nition of this term ; but, unfortunately, no such definition has yet 



1 For instance, the act performed by a dog carried far from his home, when 

 from among a score of roads he selects the one which will bring him back. 



