306 Heredity. 



to effects, that is to say, from sentiments and ideas to acts, and 

 from acts to social institutions. We will therefore study the influ- 

 ence of heredity, first on the constitution of the human soul, on 

 its intellectual states, its sentiments and passions, then on the 

 acts which give outward expression to these inner states ; lastly, on 

 the institutions which result from these acts, and which not only 

 regulate, but also consolidate them. Thus we shall have to con- 

 sider, successively, the psychological, the moral, and the social 

 consequences of heredity. 



CHAPTER II. 



THE PSYCHOLOGICAL CONSEQUENCES OF HEREDITY. 



THE study of the psychological consequences of heredity must 

 begin with the instincts. We will not here discuss a question 

 already treated, 1 since it will be enough to state briefly the certain 

 or probable results already obtained. 



If heredity acted merely the part of a conservator, its conse- 

 quences, psychological or otherwise, would present no difficulty 

 whatever. On the hypothesis of individual types created once for 

 all with their physical and moral attributes, the only consequence 

 of heredity would be the indefinite repetition of these types, with 

 some accidental deviations unimportant facts of spontaneity. 

 But the case is very different Notwithstanding the character of 

 immutability usually assigned to instincts, they may vary as we 

 have seen, and their variations are transmissible. Hence the first 

 consequence of heredity, that it renders possible the acquisition of 

 new instincts. This consequence rests on facts, and is certain and 

 indisputable. 



Another consequence, one that is merely possible, and which 

 we have stated only as an hypothesis, is the genesis of all instinct 

 whatever by way of heredity. Instincts, regarded as hereditary 



1 See Part I. ch. i. 



