AMONG THE GREEKS 73 



Empedocles' interpretation of the segmented 

 structure of the backbone ; the same doctrine had 

 been discussed with great abihty even in the dia- 

 logues of Plato (427-347 B.C.). Brooks^ calls 

 this to our attention as follows: 



Belief that something is added to our nature by 

 experience, and training, and education, rests on de- 

 liberate or unconscious acceptance of some such defi- 

 nition of nature as that which Alciphron gives ; and, 

 as the modern zoologist . . . seems to lose sight of 

 Eupliranor's analysis of this definition, I beg leave 

 to refresh his memory by a short quotation from the 

 old dialogue. 



'^Euphranor, You seem very much taken with the 

 beauty of nature. Be pleased to tell me, Alciphron, 

 what those things are which you esteem natural^ or 

 by what mark I may know them. 



^^Alciphron. For a thing to be natural, for in- 

 stance, to the mind of man, it must appear originally 

 therein: it must be universal in all men: it must be 

 invariably the same in all nations and ages. These 

 limitations of original, universal, and invariable ex- 

 clude all those notions of the human mind which are 

 the effect of custom and education." 



Aristotle also discussed the proto-Darwinian 

 survival hypothesis of Empedocles and Democ- 

 ritus in application to the adaptive origin of the 

 front teeth of man — that is, the cutting or incisor 

 teeth and the piercing eye teeth. He rejects the 



iWilliam Keith Brooks: The Foundations of Zoology, p. 62. 



