ARISTOTLE'S BIOLOGY 



two we may regard pretty much as one and 

 the same); thirdly, the material; and fourthly, 

 the moving principle or efficient cause." 88 



" Now that with which the ancient writers, 

 who first philosophized about nature, busied 

 themselves, was the material principle and the 

 material cause. They inquired what this is, 

 and what its character; how the universe is 

 generated out of it, and by what motor in- 

 fluence, whether, for instance, by antagonism 

 or friendship, whether by intelligence or spon- 

 taneous action, 39 — the substratum of matter 

 being assumed to have certain inseparable 

 properties; fire, for instance, to have a hot 

 nature, earth, a cold one; the former to be 

 light, the latter heavy. For even the genesis 

 of the universe is thus explained by them. 

 After a like fashion they deal with the develop- 

 ment of plants and of animals. They say, for 

 instance, that the water contained in the body 

 causes by its currents the formation of the 

 stomach and the other receptacles of food or of 

 excretion; and that the breath by its passage 

 breaks open the outlets of the nostrils; air and 

 water being the materials of which bodies are 

 made; for all represent nature as composed of 

 such or similar substances. 

 [63] 



