380 Heredity, 



back to it, is only apparent Reversion takes place when the race 

 is left to itself. It does not occur in a race which, by the long- 

 continued action of natural or artificial instrumentalities, has been 

 adapted to its new surroundings. For every being, physical or 

 moral, the condition of existence is a harmony between itself and 

 its moral or physical surroundings. For every being the essential 

 characteristics are those which are entirely in accord with its 

 circumstances ; accidental characteristics are those which are more 

 or less so. Consequently the former are stable, as being sustained 

 from within and from without ; the latter are unstable, because, 

 though sustained from within, they are opposed, or at least not 

 sustained, from without Reversion to the physical or mental 

 type is therefore the result of natural laws, and by no means of a 

 mysterious power or occult influence. 



But if the natural or artificial surroundings favour the fixity of 

 the acquired character, and make it a habit for heredity is only a 

 specific habit it then becomes a second nature, which is so firmly 

 grounded in the original nature that it cannot be distinguished 

 from it Heredity, which seemed divided against itself, comes into 

 agreement with itself, and two cases apparently contradictory fall 

 under one law. Other characteristics, however, cannot be fixed, 

 and they appear but for a moment 



If this be understood, it is interesting to see how a contemporary 

 philosopher infers from the two laws of heredity and of evolution 

 the future progress of the human race. At the conclusion of his 

 Principles of Biology, Mr. Herbert Spencer ingeniously shows that, 

 in virtue of natural laws, civilization, the cause of which has been 

 an excess of population, must result in a diminution of population. 

 These considerations are so closely bound up with the consequences 

 of psychological heredity that we shall be pardoned if we state 

 them here in detail. 



As the perfectness of a being consists in its more and more 

 complete adaptation to its environment, it is logical to infer that 

 all the progress of humanity will consist in an adjustment of this 

 kind. But by what means, and by the development of what 

 faculties ? 



' Will it be by the development of physical strength ? Probably 

 not to any considerable degree. Mechanical appliances are fast 



