288 Heredity. 



primitive type. Thus there is established in the individual, between 

 the heredity of the natural characters and that of the acquired 

 characters, a conflict, in which nature must win if art does not 

 counteract it. Bacon's saying is true of heredity, as of all natural 

 laws : Natura non nisi parendo wnrilur. But with the aid of art, 

 under the constant influence of education, or of the same moral 

 environment, acquired characters become fixed; and then there 

 is established in our psychical constitution a second nature, so 

 intimately blended with the former, that usually they cannot be 

 7 distinguished. 



To sum up : without the law of evolution, nothing is simpler 

 than to determine the consequences of heredity. It would not be 

 worth while to study them separately, for they would consist only 

 in the indefinite conservation of the same specific characters. But 

 with evolution all is different The living being tends incessantly 

 to be modified by causes both internal and external. The internal 

 causes determine those spontaneous modifications of the organism 

 and of the dynamism which, as we have seen, some authors explain 

 by a law of spontaneity, such as a new physical character, or a new 

 mental aptitude. By external causes we mean the action of cir- 

 cumstances, which have as strong an influence on the moral as on 

 the physical being, and which in time tend to fashion it in a certain 

 manner. In the battle of life, the struggle for existence, that great 

 biological fact which Darwin has so well established that his 

 adversaries themselves have accepted it, these modifications con- 

 stitute for the individual a probability of its survival, if by them 

 it is better adapted to new conditions. They render it possible 

 for the living being in the first place to subsist, and then to 

 perpetuate itself. Heredity, which is essentially a conservative 

 force, tends to transmit to the descendants the whole nature of 

 their parents ; as well every deterioration, physical, mental, and 

 moral, as every physical, mental, and moral amelioration. The 

 blind fatality of its laws regulates not alone progress, but also 

 decay. 



Man, therefore, as he comes into the world, is not the impres- 

 >; sionless statue dreamt of by Bonnet and Condillac. Not only is 

 he possessed of a certain constitution, a certain nervous organi- 

 zation, which predisposes him to feel, to think, and to act after a 



