GENERATION OF ANIMALS, I. x^'ui. 



of this sort the source of the movement is within 

 the things themselves, as in the ones just quoted 

 (where slander is actually one part of the whole 

 to-do) ; in others it is external to them ; e.g., crafts- 

 manship of every kind is external to the works 

 which the craftsman produces, and the torch is 

 external to the house which is set on fire. 



Now it is clear that the case of semen falls under 

 one or other of these two senses " : the offspring is 

 formed " from " it either (a) as " from " material, 

 or (b) as " from " a prime mover (a source of move- 

 ment). It is definitely not an instance of (1) above, 

 where " from " means " after," e.g., " from the 

 Panathenaean festival comes the sea-voyage " ; nor 

 of (3), i.e., of coming into being " from " a contrary ; 

 for the one contrary is destroyed as the other comes 

 into being from it, and so there must be present 

 besides them some primary substrate, from which 

 the new contrary is to come into being. ** Thus we 

 now have to discover in which of the two classes 

 semen is to be placed : Is it to be regarded as matter, 

 i.e., as something which is acted upon, or as a form, 

 i.e., as something which acts of itself — or even as 

 both ? for perhaps at the same time it will also be 

 clear in what way formation from contraries has its 

 place in all things that arise from semen. (After 

 all, formation from contraries as well as the other 

 methods of formation is found in nature ; sonxg ani- 

 mals are formed from contraries — male and female, 

 though some are formed from one parent only, as are 

 plants and certain of the animals in which there is no 

 definite separation of male and female.) 



out the change. Clearly, says Aristotle, this is not the 

 meaning of yiyveaOai required here. 



75 



