PARTS OF ANIMALS, III. ii. 



been unable to bend ; and the bull has no hands ; so 

 they had to be where they are — on the head. And 

 being there, they offer the least possible hindrance 

 to the movements of the body in general. 



Deer alone have horns that are solid throughout ; 

 and deer alone shed their horns : this is done (a) on 

 purpose to get the advantage of the extra lightness, 

 (b) of necessity, owing to the weight of the horns. 

 In other animals the horns are hollow up to a certain 

 distance, but the tips are solid because solid tips are 

 an advantage when striking. And to prevent undue 

 weakness even in the hollow part, which grows out 

 from the skin, the solid piece which is fitted into it 

 comes up from the bones. In this way the horns 

 are rendered most serviceable for offensive pur- 

 poses and least hampering during the rest of the 

 time. 



This completes our statement of the purpose for 

 which horns exist and the reason why some animals 

 have them and some have not. 



We must now describe the character of that 

 ** necessary nature," owing to which certain things 

 are present of necessity, things which have been 

 used by " rational nature " to subserve a " purpose." ** 



To begin with, then : the larger the animal, the 

 greater the quantity of corporeal or earthy matter 

 there is in it. We know no really small homed 

 animal — the smallest known one is the gazelle. (To 

 study Nature we have to consider the majority of 

 cases, for it is either in what is universal or what 

 happens in the majority of cases that Nature's 

 ways are to be found. Now all the bone in animals' 



" rational nature" see above 640 b 8-29, G41 a 25 ff., 642 a 

 1 fiF., and cf. G.A. (Loeb edn.), Introd. § 14. 



223 



