1. If the series were infinite there would be no first mover and no motion.
2. Some things are moved.
3. If something is moved, then it was potentially (not actually) in motion.
4. If something moves, then it is actually (not potentially) in motion.
5. Conclusion 1 is a contradiction.
6. If self-motion is impossible, then if something moves then it is moved by something else.
7. There is a first mover AKA God.
8. If something were to move itself, it would be both potentially and actually in motion.
9. It is not possible for something to move itself.
10. If something moves, then it is moved by something else.
11. If something moves, then it is moved by something else, which is moved by something else…