106 ORGANIC EVOLUTION 



development involve not progress, not even con- 

 servatism or stagnation, but positive deterioration. 

 Yet it is always the fittest that have survived, 

 such as the tapeworm, the tubercle bacillus, and the 

 « dry-rot." Plainly the fittest are not infrequently 

 the worst. 



It is now many years since John Stuart Mill 

 rebuked the common habit of speech which avers 

 that there is an essential difference between practice 

 and theory. Erroneous theory on matters of prac- 

 tical bearing means erroneous practice, and con- 

 versely. Now the nature of evolution is a matter 

 which has a practical bearing, and men cannot 

 afford to hold erroneous theoretical views thereupon. 

 Hence we find that the common error of regarding' 

 evolution as something that may be trusted to " go 

 on by itself," always making for progress meanwhile, 

 is showing signs of disastrously affecting practice. 

 If it has not done so to any large extent hitherto, 

 that is merely because a belief in this conception of 

 evolution is not widespread — not because practice 

 and theory are separable, save in the abstract. The 

 obvious inference from this erroneous view of organic 

 evolution is that our motto should be laissez-faire. 

 The thing is in " higher hands than ours " : we may 

 fold our hands and leave it to follow its appointed 

 course. As we shall observe in greater detail later, 

 this view, were it generally accepted, would be 

 utterly disastrous. Organic evolution does not pro- 

 ceed without causes or factors. If, then, these factors, 

 for one reason or another, be thrown out of action, 

 the process will entirely cease. Plainly they cannot 

 all be thrown out of action in the case of the human 



