Kitap 12
5
Now if a thing is moved, it can be otherwise than it is. Therefore if the actuality of the heaven is primary locomotion, then in so far as the heaven is moved, in this respect at least it is possible for it to be otherwise; i.e. in respect of place, even if not of substantiality. But since there is something—X—which moves while being itself unmoved, existing actually, X cannot be otherwise in any respect.
6
For the primary kind of change is locomotion,Proved in Aristot. Physics 8.7. and of locomotion circular locomotion Aristot. Physics 8.9 ; and this is the motion which X induces. Thus X is necessarily existent; and qua necessary it is good, and is in this sense a first principle.The argument is: X (the prime mover), since it imparts the primary motion, cannot be liable to motion (or change) of any kind. Therefore it exists of necessity, and must be good (cf. Aristot. Met. 5.5.6); and it is qua good, i.e., the object of desire, that X is a first principle. For the necessary has all these meanings: that which is by constraint because it is contrary to impulse; and that without which excellence is impossible; and that which cannot be otherwise, but is absolutely necessary.Cf. Aristot. Met. 5.5
6
Such, then, is the first principle upon which depend the sensible universe and the world of nature.
