48 PROLEGOMENA 



to remember that evolution is not an explanation of the 

 cosmic process, but merely a generalised statement of 

 the method and results of that process. And, further, 

 that, if there is proof that the cosmic process was set 

 going by any agent, then that agent will be the creator 

 of it and of all its products, although supernatural inter- 

 vention may remain strictly excluded from its further 

 course. 



So far as that limited revelation of the nature of 

 things, which we call scientific knowledge, has yet gone, 

 it tends, with constantly increasing emphasis, to the 

 belief that, not merely the world of plants, but that of 

 animals; not merely living things, but the whole fabric 

 of the earth; not merely our planet, but the whole solar 

 system; not merely our star and its satellites, but the 

 millions of similar bodies which bear witness to the 

 order which pervades boundless space, and has endured 

 through boundless time; are all working out their pre- 

 destined courses of evolution. 



With none of these have I anything to do, at present, 

 except with that exhibited by the forms of life which 

 tenant the earth. All plants and animals exhibit the 

 tendency to vary, the causes of which have yet to be 

 ascertained; it is the tendency of the conditions of life, 

 at any given time, while favouring the existence of the 

 variations best adapted to them, to oppose that of the 

 rest and thus to exercise selection; and all living things 

 tend to multiply without limit, while the means of sup- 

 port are limited; the obvious cause of which is the pro- 

 duction of offspring more numerous than their progeni- 

 tors, but with equal expectation of life in the actuarial 

 sense. Without the first tendency there could be no 

 evolution. Without the second, there would be no good 

 reason why one variation should disappear and another 

 take its place; that is to say there would be no selection. 



