DEVELOPMENT OF THE MORAL SENSE. 209 



PEOGKESS NOT AN INVAEIABLB BULB. 



Descent ^® must remember tliat progress is no in- 



of Man, variable rule. It is very difficult to say why 

 ^*°* ■ one civilized nation rises, becomes more pow- 

 erful, and spreads more widely, than another ; or why the 

 same nation progresses more quickly at one time than at 

 another. We can only say that it depends on an increase 

 in the actual number of the population, on the number 

 of the men endowed with high intellectual and moral 

 faculties, as well as on their standard of excellence. Cor- 

 poreal structure appears to have little influence, except 

 so far as vigor of body leads to vigor of mind. 



It has been urged by several writers that, as high in- 

 tellectual powers are advantageous to a nation, the old 

 Greeks, who stood some grades higher in intellect than 

 any race that has ever existed,- ought, if the power of 

 natural selection were real, to have risen still higher in 

 the scale, increased in number, and stocked the whole of 

 Europe. Here we have the tacit assumption, so often 

 made with respect to corporeal structures, that there is 

 some innate tendency toward continued development in 

 mind and body. But development of all kinds depends 

 on many concurrent favorable circumstances. Natural 

 selection acts only tentatively. Individuals and races 

 may have acquired certain indisputable advantages, and 

 yet have perished from failing in other characters. The 

 Greeks may have retrograded from a want of coherence 

 between the many small states, from the small size of 

 their whole country, from the practice of slavery, or 

 from extreme sensuality ; for they did not succumb until 

 "they were enervated and corrupt to the very core." 

 The Western nations of Europe, who now so immeasura- 

 bly surpass their former savage progenitors, and stand at 



