30 FROM THE GREEKS TO DARWIN 



passed from direct observation to speculation 

 upon the causes of things, drew their suggestions 

 and inspiration largely from these great philoso- 

 phers. 



This need not lead us into the history of the 

 discussion of primary causes, nor of the mechan- 

 ical and monistic versus the dualistic view of Na- 

 ture. The evolution of life as an organic law, 

 more complex but comparable to any inorganic 

 law, such as gravitation, is one phase of natural 

 causation. For whatever principle regulates the 

 rapid fall of a wounded bird to the earth is the 

 same in kind, so far as our philosophy of Nature 

 is concerned, as that which, during millions of 

 years, has slowly evolved the bird from the earth. 



Some of the Greeks early saw this truth; yet 

 in the progress of later thought in Europe, the 

 living world was the last to come under this prin- 

 ciple of natural causation. The battle for it had 

 to be fought out first in cosmogony, then in 

 geology. So keen a philosopher as Kant believed 

 that he saw two principles in Nature ; one of nat- 

 ural causes reigning in lifeless matter, one of 

 teleological causes reigning in living matter. This 

 was because he could not conceive of any natural 

 principle which could explain the beautiful adap- 

 tations and designs of Nature. From geology the 

 spread of the truth of natural causation reached 

 the origin of the lower forms of life, and finally 



