What is in potential but changing needs something else to explain the change.
-If someone asks “how did the cow become steak?” you need to say more than “because it could be one”. If someone asks how Eddie learned to play piano, you need to say something more than “because he was able” or even “because he had talent”.
But what is changing is potential.
-Nothing considered as actual is seen as becoming something else. It is not seen relative to anything other than what it is or the state it’s in.
So what is changing needs something else to explain the change.
Omne quod movetur ab alio movetur is a claim about potential being, i.e. the referent for the “quod” is “potential being”.
The “something else” is either in motion or not. Assume it’s not. This means there is some entity that both moves things and cannot be located on a timeline relative to a later state. Everything in the universe is the first but not the second; and the universe itself is the second but not the first. So there is some cause of motion that is neither the universe nor in the universe. And this all can recognize as God.
Assume the “something else” is in motion. Let the sum of these something else’s be taken. If all are moved by another with nothing else, then all movers are secondary and derivative sorts of things with nothing primary, which is impossible (like having copies from no original). So there is something whose substance and nature both moves things and cannot be located on a timeline relative to some later state.