PROGRESS, BIOLOGICAL AND OTHER 33 



gress. Some biologists have lumped it, together 

 with all other evolutionary processes which seem to 

 show us a development along predetermined lines, 

 under the head of orthogenesis — the (hypothetical!) 

 tendency of organisms to unfold just one type of 

 hidden potentiality. Bergson has been particularly 

 struck with it : refuses to allow that it can have any- 

 thing to do with Natural Selection or any determin- 

 ist process, and ascribes it to his elan vital. 



Here, as so often elsewhere, Bergson reveals him- 

 self as a good poet but a bad scientist. His intellec- 

 tual vision of evolution as a fact, as something hap- 

 pening, something whole, to be apprehended in a 

 unitary way — that is unsurpassed. He seems to see 

 it as vividly as you or I might see a hundred yards 

 race, holding its different incidents and movements 

 all in his mind together to form one picture. But he 

 then goes on to give a symbolic description of what 

 he sees — and then thinks that his symbols will serve 

 in place of analytic explanations. There is an "urge 

 of life"; and it is, as a matter of fact, urging life up 

 the steps of progress. But to say that biological 

 progress is explained by the elan vital is to say that 

 the movement of a train is ''explained" by an elan 

 locomotif of the engine: it is to fall into the error, so 

 often condemned in scientists by philosophers, and 

 ridiculed in both by satirists, of hanging or at least 

 disposing of a difficulty by giving it a long name. 



Let us think of the condition of life on earth at 

 any given moment of her evolution. Certain possi- 



