MOVEMENT OF ANIMALS, v.-vi. 



corruption is a different one ; for if there is, as we 

 assert, a primary movement, this would be the cause 

 of coming into being and wasting away, and per- 

 haps of all the other movements as well. And as in 

 the universe, so in the animal, this is primary motion, 

 when the animal comes to perfection ; so that it is 

 itself the cause of its own growth, if this ever takes 

 place, and of any alteration which occurs ; otherwise 

 it is not necessary that something should remain at 

 rest." But the first growth and alteration occur 

 through another's agency and by other means, and 

 nothing can in any way be itself the cause of its own 

 coming into being and wasting away ; for that \vhich 

 moves must be prior to that which is moved, and that 

 which begets to that which is begotten, and nothing 

 is prior to itself. 



VI. Now whether soul is moved or not, and if 

 it is moved, how it is moved, has already been 

 discussed in our treatise On Soul. But since all 

 inanimate things are moved by something else — and 

 how that which is primarily and eternally moved is 

 moved, and how the prime mover moves it, has been 

 already set forth in our work on First Philosophy ^ — 

 it remains to inquire how the soul moves the body 

 and what is the origin of movement in an animal. 

 For, if we exclude the movement of the universe, 

 animate things are the cause of movement in every- 

 thing else, except in things which are moved by one 

 another through coming into coUision with one 

 another. Therefore all their movements have a 

 limit ; for the movements of animate things have a 

 limit. For all animals move and are moved with 

 some object, and so this, namely their object, is the 

 limit of all their movement. Now we see that the 



457 



