GENERATION OF ANIMALS, II. i. 



account of B which is next to it, or is it rather the 

 case that B is formed after A ? I mean, for instance, 

 not that the heart, once it is formed, fashions the 

 liver, and then the hver fashions something else ; 

 but that the one is formed after the other [just as a 

 man is formed after a child], not by it. The reason 

 of this is that, so far as the things formed by nature 

 or by human art are concerned, the formation of 

 that which is potentially is brought about by that 

 which is in actuality ; so that the Form, or con- 

 formation, of B would have to be contained in A,' 

 e.g., the Form of the liver would have to be in the 

 heart — -which is absurd. And there are other ways 

 too in which the theory is absurd and fondly in- 

 vented. But besides, for any part of the animal 

 or plant to be present from the outset ready foi-med 

 within the semen or seed, whether it has the power 

 to fashion the other parts or not — even this is impos- 

 sible if everything is formed out of semen or seed ; 

 because it is plain that it was formed by that which 

 fashioned the semen if it is present within the semen 

 from the outset ; but semen must be formed before 

 (any part), and that is the business of the parent. 

 Therefore no part can be present within the semen. 

 Therefore it does not contain in itself that which 

 fashions the parts. And yet this cannot be external 

 to the semen either " : and it must be either ex- 

 ternal to it or inside it. 



Well, we must endeavour to solve this difficulty. 

 Maybe there is some statement of ours, made without 

 qualification, which ought to be qualified : e.g., if we 

 ask, in irhat sense exactly is it impossible for the parts 

 to be formed by something external ? we see that 

 in one sense it is possible, though in another it is not. 



149 



