424 ON THE ORIGIN OF SPECIES 



groups subordinate to groups, all within a few great 

 classes, which we now see everywhere around us, 

 and which has prevailed throughout all time. This 

 grand fact of the grouping of all organic beings 

 seems to me utterly inexplicable on the theory of 

 creation. 



As natural selection acts solely by accumulating 

 slight, successive, favourable variations, it can produce 

 no great or sudden modification ; it can act only by 

 very short and slow steps. Hence the canon of 'Natura 

 non facit saltum,' which every fresh addition to our 

 knowledge tends to make truer, is on this theory simply 

 intelligible. We can plainly see why nature is prodigal 

 in variety, though niggard in innovation. But why 

 this should be a law of nature if each species has been 

 independently created, no man can explain. 



Many other facts are, as it seems to me, explicable 

 on this theory. How strange it is that a bird, under 

 the form of woodpecker, should have been created to 

 prey on insects on the ground ; that upland geese, 

 which never or rarely swim, should have been created 

 with webbed feet ; that a thrush should have been 

 created to dive and feed on sub-aquatic insects ; and 

 that a petrel should have been created with habits and 

 structure fitting it for the life of an auk or grebe ! and 

 so on in endless other cases. But on the view of each 

 species constantly trying to increase in number, with 

 natural selection always ready to adapt the slowly vary- 

 ing descendants of each to any unoccupied or ill-occu- 

 pied place in nature, these facts cease to be strange, 

 or perhaps might even have been anticipated. 



As natural selection acts by competition, it adapts 

 the inhabitants of each country only in relation to the 

 degree of perfection of their associates ; so that we 

 need feel no surprise at the inhabitants of any one 

 country, although on the ordinary view supposed to 

 have been specially created and adapted for that coun- 

 try, being beaten and supplanted by the naturalised 

 productions from another land. Nor ought we to 

 marvel if all the contrivances in nature be not, as far 



