95 



ad infinitum. There is, therefore, that which moves 

 immoveably, and which is perpetual. 



But from hence it is evident, that all things are 

 not moved; for there is also something which is 

 immoveable. Nor are all things at rest ; for there 

 are also things which are moved. Nor are some 

 things always at rest, but others always moved ; 

 for there are also things which are sometimes at 

 rest, and sometimes moved, such as are things 

 which are moved from contraries into contraries. 

 Nor are all things sometimes at rest, and some- 

 times moved ; for there is that which is perpetu- 

 ally moved, and also that which is perpetually im- 

 moveable. 



THEOREM 12. 



Everything which is moved, is moved by some- 

 thing. 



Demonstration. Let A be that which is moved, 

 I say that A is moved by something : for it is either 

 moved according or contrary to nature. If, there- 

 fore, it is moved according to nature, that which 

 moves is nature ; but, if contrary to nature, that 

 which employs violence moves ; for every motion 

 contrary to nature is violent. 



THEOREM 13. 



That which first moves a circular motion is im- 

 partible, or without parts. 



