The History of Things 69 



the story of an individual development. It is the 

 same earth all through, just as it is the same or- 

 ganism all through. In organic evolution, how- 

 ever, we have to do with races, with a succession 

 of new forms, arising out of old forms, which either 

 disappear or continue to exist alongside of their 

 descendants. We may perhaps speak of the evo- 

 lution of the chemical elements, of which we know 

 very little, but we cannot accurately speak of the 

 evolution of the earth. It is not the survivor 

 among many earths which arose from the womb 

 of a Protogsea. It has had a long development, 

 that is all. This may seem verbal pedantry, and 

 yet fallacy is apt to arise from confusing con- 

 tinuous individual development with racial evo- 

 lution. 



In the development of an individual organism 

 we always start with a more or less rich inheritance 

 which is the product of a long evolution in previous 

 ages. We regard the development as a gradual 

 realization of the "given" potentiality, as a gradual 

 expression of what is already there. We believe 

 that in an appropriate environment stage succeeds 

 stage in an absolutely predetermined fashion. 

 There is an identity of essential substance through- 

 out, and the stage of to-day contains that of to- 

 morrow, and must, in normal conditions, give rise 

 to it: New properties, new modes of behaviour, 

 emerge day after day, and although we do not 



