PREFACE xi 



the application of natural selection to moral codes and social 

 ideals. That moral code which works best, which fits the people 

 who follow it to survive by making them strong and efficient is 

 per se the best moral code. Whether we like it or not, such 

 people will rule the earth and crowd out of existence other people 

 who follow different codes which make for less efficiency. As the 

 present writer has said elsewhere, one might as well say that he 

 is unable to perceive a hygienic order of the universe merely 

 because what he has believed to be hygienic practice does not 

 secure him good health, or that he does not discover a harmony 

 between the order of the universe and his supposedly hygienic 

 practices. If morality is social hygiene, then we must apply the 

 same test to our moral practices and belief s that we are compelled 

 to apply to our hygienic practices and beliefs. If our hygienic 

 beliefs do not seem to work in matters of health, we will, if we 

 are wise, change our beliefs, rather than try to change the uni- 

 verse. Similarly, if our moral practices and beliefs do not seem 

 to work, we must change our moral practices and beliefs rather 

 than try to change the universe. 



It will require a much greater mental revolution to adjust our- 

 selves to this new doctrine of social evolution than it ever took 

 to adjust ourselves to a biological doctrine of evolution. The 

 beliefs that were involved then were only traditional beliefs 

 regarding the Creation. These beliefs were never very deep- 

 seated, and a single generation was sufficient to bring about the 

 discarding of the old and the adoption of the new; but our 

 fundamental notions of right and wrong are very much older 

 than the Biblical story of the Creation, and very much more 

 deep-seated. To have to give up, for example, a cherished belief 

 regarding democracy, or socialism, or individualism, or culture, 

 or gentlemanly conduct, or as to what constitutes virtue, in order 

 to square ourselves with the facts of the universe, will involve 

 such a mental struggle that very few can be expected to come 

 through it very successfully in any single generation. Neverthe- 

 less, the process is going on. They will rule the world who are 

 best fitted to rule the world by virtue of their strength and effi- 

 ciency, not by virtue of the assumed beauty or persuasive power of 



