THE STRUGGLE FOR LIFE. 207 



so both negatively and positively. In the first place 

 it produces fitness by killing off the unfit. Without 

 the rigorous weeding out of the imperfect the progress 

 of the world had not been possible. If fit and unfit in- 

 discriminately had been allowed to live and reproduce 

 their kind, every improvement which any individual 

 might acquire would be degraded to the common level 

 in the course of a few generations. Progress can only 

 start by one or two individuals shooting ahead of their 

 species ; and their life-gain can only be conserved by 

 their being shut off from their species or by their 

 species being shut off from them. Unless shut off 

 from their species their acquisition will either be neu- 

 tralized in the course of time by the swamping effect 

 of inter-breeding with the common herd, or so diluted 

 as to involve no real advance. The only chance for 

 Evolution, then, is either to carry off these improved 

 editions into " physiological isolation," or to remove 

 the unimproved editions by wholesale death. The 

 first of these alternatives is only occasionally possible ; 

 the second always. Hence the death of the unevolved, 

 or of the unadapted in reference to some new and 

 higher relation with environment, is essential to the 

 perpetuation of a useful variation. Although Natural 

 Selection by no means invariably works in the direc- 

 tion of progress, in parasites it has consummated al- 

 most utter degeneration, no progress can take place 

 without it. It is only when one considers the work- 

 ing of the Struggle for Life on the large scale, and 

 realizes its necessity to the Evolution of the world as 

 a whole, that one can even begin to discuss its ethical 

 or teleological meanings. To make a fit world, the 

 unfit at every stage must be made to disappear ; and 



