PARTS OF ANIMALS, I. in. 



number, or some higher value of 2" ; and there will 

 be an identical number of species." 



(The species is the differentia in the Matter. There 

 is no animal part which exists without matter ; nor 

 on the other hand is there any which is matter only, 

 for body in any and every condition cannot make an 

 animal or any part of an animal, as I haΛ"e often 

 pointed out.*) 



(e) Again, the di\"ision ought to be made according 

 to points that belong to the Essence of a thing and 

 not according to its essential (inseparable) attributes. 

 For instance, in making di\-isions of geometrical 

 figures, it would be ^^τong to di^ide them into those 

 whose angles are together equal to two right angles 

 and those Λvhose angles are together greater than two 

 right angles ; because it is only an attribute of the 

 triangle that its angles are together equal to two 

 right angles.'' 



(/) Again, di\'ision should be by opposites, 

 opposites being mutually " different," e.g. pale and 

 dark, straight and curved. Therefore, provided the 

 tΛvo terms are truly " different," di%-ision should be 

 by means of opposites, and should not characterize 

 one side by ability to SΛvim and the other side by 

 some colour. And besides this, di^^sion of U\-ing 

 creatures, at any rate, by the functions which are 

 common functions of body and soul,** such as we 

 actually find done in the dixisions mentioned above, 

 where animals are divided into " walkers " and 

 " fliers " — for there are some groups, such as that of 

 the Ants, which have both attributes, being both 



locomotive, and thought (see Be an. 414 a 38 ff.). His point 

 is that the correct way to divide and classify animals is rather 

 by bodily characteristics, which is what he himself does. 



87 



