10 DOCTRINE OF EVOLUTION 



sive process comprising all the transformations which 

 can be observed now and which have occurred in the 

 past. 



At a certain time in the earth's history, after the hard 

 outer crust had been formed, it became possible for 

 living materials to arise and for simple primitive 

 creatures to exist. Thus began the process of organic 

 evolution — the natural history of living things — with 

 which we are concerned in this and later addresses. 

 Organic evolution is thus a part of the greater cosmic 

 process. As such it does not deal with the origin of 

 life, but it begins with hfe, and concerns itself with the 

 evolution of living things. And while the investigator 

 is inevitably brought to consider the fundamental 

 question as to the way the first life began, as a student 

 of organic forms he takes life for granted and studies 

 only the relationships and characteristics of animals 

 and plants, and their origins. 



But even as a preliminary definition, the statement 

 that organic evolution means natural change does 

 not satisfy us. We need a fuller statement of what it 

 is and what it involves, and I think that it would be 

 best to begin, not with the human being in which we 

 are so directly interested, nor even with one of the 

 lower creatures, but with something, as an analogy, 

 which will make it possible for us to understand im- 

 mediately what is meant by the evolution of a man, 

 or of a horse, or of an oak tree. The first steam loco- 

 motive that we know about, like that of Stephenson, was 

 a crude mechanism with a primitive boiler and steam- 

 chest and drive-wheels, and as a whole it had but a low 

 degree of efficiency measured by our modern standard ; 



