Aristotle's biology 



characters, not common to the species, are not 

 due to a final cause; that is to say, they are 

 not useful or conducive to the end which is the 

 life of the animal. 



" For whenever things are not the product 

 of Nature working upon the animal kingdom 

 as a whole, nor yet characteristic of each 

 separate kind, then none of these things is such 

 as it is or is so developed for any final cause. 

 The eye, for instance, exists for a final cause, 

 but it is not blue for a final cause unless this 

 condition be characteristic of the kind of 

 animal." 



In other words, when a character is common 

 to all animals of an established group, then it 

 exists for a purpose; but fluctuating characters 

 are not so developed. Such characters have 

 " no connection with the essence of the animal's 

 being, but we must refer the causes to the 

 material and the motive principle or efficient 

 cause, on the view that these things come into 

 being by necessity." Apparently Aristotle 

 means that the formal or final cause cannot 

 always control the material and the efficient 

 causes, and variations from the perfect type 

 arise.*^ 



Every animal with its essential or constant 



[69] 



