PROGRESSION OF ANIMALS, v. 



V. Animals in which the superior and the front are 

 differentiated, man, for example, and the birds, are 

 bipeds (two of the four points being wings in birds, 

 and hands and arms in man). But the animals in 

 which the superior and the front are in the same 

 position " are four-footed (quadrupeds), many-footed 

 (polypods), and footless. By " foot " I mean the part 

 that is at a point which has connexion with the ground 

 and gives movement from place to place ; for the 

 feet (TToSes) seem to have derived their name from 

 the ground (-eSov). Some animals have their front 

 and their back in the same position, for example the 

 molluscs and the stromboid testaceans ; with these 

 we have already dealt elsewhere.^ 



Now since there are three regions, the superior, 

 the middle, and the inferior, bipeds have their 

 superior part in a position corresponding to the 

 superior region of the universe, polypods and footless 

 animals in a position corresponding to the middle 

 region, and plants in a position corresponding to the 

 inferior region. The reason is that plants lack 

 movement, and the superior part is situated with a 

 view to nutriment, and their nutriment comes from 

 the earth. Quadrupeds, polypods, and footless 

 animals have their superior part in a position corre- 

 sponding to the middle region because they are not 

 erect ; bipeds have it in a position corresponding to 

 the superior region because they are erect, especially 

 man, the biped most in accordance with nature. And 

 it is only reasonable that the origins <' should come 

 from these parts ; for the origin is honourable, and 

 the superior is more honourable than the inferior, and 

 the front than the back, and the right than the left. 

 It is also true if we reverse the proposition and assert 



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