PARTS OF ANIMALS, I. v. 



which are common, and those which belong (6) to a 

 group, or (c) to a species. By " common " I mean 

 those that are present in all animals ; by " those 

 which belong to a group " I mean those of animals 

 whose differences we see to be differences " of 

 excess " " in relation to one another : an example of 

 this is the group Birds. Man is an example of a 

 species ; so is every class which admits no differ- 

 entiation of its general definition. These three sorts 

 of common attributes are, respectively, (1) analogous, 

 (2) generic, (3) specific. 



Now it is evident that when one action is for the 

 sake of another action, then the instruments which 

 perform the two actions differ exactly as the two 

 actions differ : and if one action is " prior " to another 

 and is the " end " of that other action, then the part 

 of the body to which it belongs wdll be " prior " to 

 the part to which the other action belongs. There 

 is also a third possibility, viz. that the action and its 

 organ are there simply because the presence of others 

 necessarili) involves them.^ (By affections and actions 

 I mean Generation, Growth, Copulation, Waking, 

 Sleep, Locomotion, and the other similar ones that 

 are found in animals. Examples of parts are : Nose, 

 Eye, Face ; each of these is named a " limb " or 

 " member." And the same holds for the rest too.) 



Let this suffice concerning the method of our 

 inquiry, and let us now endeavour to describe the 

 causes of all these things, particular as well as 

 common ; and, according to the principles laid down, 

 we will begin with the first ones first. 



105 



