PARTS OF ANIMALS, II. x. 



An animal can neither exist nor grow without food. 

 Therefore in all living creatures of perfect formation <* 

 there are two parts most necessary above all : one by 

 which food is taken in and the other by which residues 

 are eliminated. (Plants — which also we include 

 under the head of living things — have, it is true, no 

 place for the useless residue, but this is because their 

 food, M'hich they get out of the earth, is already con- 

 cocted before it enters them, and instead of this 

 residue they yield their fruit and seeds.) And in all 

 creatures there is a third part intermediate between 

 these indispensable two, and this is the seat of the 

 source and principle of life. Plants, again, are so made 

 as to remain in one place, and thus they do not exhibit 

 a great variety of non-uniform substances ; they have 

 few actions to perform, and therefore but few organs 

 are needed to perform them. For this reason we must 

 consider plants and their formations separately. But 

 with creatures that not only live but also have the 

 power of sensation, the formations are more varied, 

 and there is more diversity in some than in others, the 

 greatest variety being found in those creatures which 

 in addition to living have the capability of living the 

 good life, as man has. Man is the only one of the 

 animals known to us who has something of the di\'ine 

 in him, or if there are others, he has most. This is 

 one reason why we ought to speak about man first, 

 and another is that the shape of his external parts is 

 better kno\vnthan that of other animals. Another and 

 obvious reason is that in man and in man alone do the 

 natural parts appear in their natural situation : the 



733 b 1 and 737 b 16, 26, the " perfect " animals are the 

 viviparous ones. For the " most highly finished " animals 

 see 666 a 28. 



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