82 FROM THE GREEKS TO DARWIN 



phy was therefore anthropocentric : "Plants are 

 evidently for the sake of animals and animals 

 for the sake of man; thus Nature, which does 

 nothing in vain, has done all things for the sake 

 of man." 



Aristotle's concept of an internal perfecting 

 tendency is brought out clearly and emphatically 

 in the most striking passage of all his writings, 

 where he undertakes to refute an argument at- 

 tributed to Empedocles. This is of the greatest 

 interest today, because Aristotle clearly states 

 and rejects a chance theory of the origin or adap- 

 tive structures in animals altogether similar to 

 that of Darwin. 



In Empedocles' crude suggestion of the sur- 

 vival of adapted beings and the extinction of in- 

 adapted beings Aristotle perceived the gist of an 

 argument which might be applied not only to 

 entire organisms but to parts of organisms, to 

 explain purposive structures, and which might 

 thus become a dangerous rival to his own concept 

 of the origin of purposive structures by the di- 

 rect operation of his ^perfecting principle.' 



In the following passages, selected from the 

 early books of his Physics, we seem to gain a 

 clear insight into Aristotle's whole chain of rea- 

 soning, in a manner which enables us to compare 

 it with modern lines of thought. The headings 

 and brackets are my own; the passages are se- 



