WHAT WE OWE TO DARWIN 21 



shall be able, perhaps, to return to the transcen- 

 dental formula with intelligence. 



In regard to the proposition that science ofEers 

 not explanations but formulations, it is important 

 to bear in mind (1) that the biologist, for instance, 

 postulates simple living creatures with which 

 to start his story of evolution ; (2) that he also 

 takes for granted throughout the organism's 

 power of varying and trading with time ; (3) 

 that he does not account, as yet, for the " big 

 lifts " in the process of evolution, or for the direc- 

 tion in which the tree has grown (vertically, so 

 to speak, as well as horizontally) — a direction 

 which gives the whole process greater significance ; 

 and (4) that the biologist's causal equation is not 

 like those of mechanics, where causa aequat effectum. 

 Bergson distinguishes (a) a cause acting par 

 impulsion, as when one billiard-ball strikes an- 

 other (where the quantity and quality of the 

 effect vary with the quantity and quality of 

 the cause) ; (&) a cause acting par delanchement, 

 as when a spark makes the powder explode (where 

 the invariable effect has no relation to the quantity 

 and quality of the cause) ; and (c) a cause acting 

 par deroulement, as when the spring which 

 works the gramophone unrolls the tune on the 

 cylinder (where the quantity of the effect is pro- 

 portionate to the quantity of the cause). In the 

 first case only does the cause explain the effect, 

 but living is not such an effect. 



Darwin's Argument. — What did Darwin really 

 do in regard to the general doctrine of organic 

 evolution ? He showed that it rationalises our 

 whole outlook. He took a wide sweep of things 

 as they are and showed that they admit of evo- 



