i8 i. 5. 



As every instrument and every bodily member subserves some 

 partial end, that is to say, some special action, so the whole body 

 must be destined to minister to some plenary sphere of action. 

 Thus the saw is made for sawing, for this is its function, and not 

 sawing for the saw. Similarly the body too must somehow or 

 other be made for the soul, and each part of it for some sub- 

 ordinate function, to which it is adapted. 



We have, then, first to describe the common functions, common, 

 that is, to the whole animal kingdom, or to certain large groups, 

 or to the members of a species. In other words, we have to 

 describe the attributes common to all animals, or to assemblages, 

 like the class of Birds, of closely allied groups differentiated by 

 gradation, or to groups like Man not differentiated into subordinate 

 groups. In the first case the common attributes may be called 

 analogous, in the second generic, in the third specific. 



When a function is ancillary to another, a like relation mani- 

 festly obtains between the organs which discharge these functions ; 

 and similarly if one function is the end of another, their respective 

 organs will stand to each other in the same relation. Other 

 phenomena there are that are [neither ancillary to higher ones, 

 nor the end of lower ones, but] the inevitable results of the 

 existing conditions [under which the animal is living]. 



Instances of what I mean by functions and affections are Re- 

 production, Growth, Copulation, Waking, Sleep, Locomotion, and 

 other similar vital actions. Instances of what I mean by parts are 

 Nose, Eye, Face, and other so-called members or limbs, and also 

 the more elementary parts of which these are made. So much 

 for the method to be pursued. Let us now try to set forth the 

 causes of all vital phenomena, whether universal or particular, and 

 in so doing let us follow that order of exposition, which conforms, 

 as we have indicated, to the order of nature. 



646 a. 



