Would you like to read Aquinas?
"Regarding the unity of the divine essence, we must first believe that God exists. This is a truth clearly known by reason. **We observe that** all things that move are moved by other things, the lower by the higher. The elements are moved by heavenly bodies; and among the elements themselves, the stronger moves the weaker; and even among the heavenly bodies, the lower are set in motion by the higher. This process cannot be traced back into infinity. For everything that is moved by another is a sort of instrument of the first mover. Therefore, if a first mover is lacking, all things that move will be instruments. But if the series of movers and things moved is infinite, there can be no first mover. In such a case, these infinitely many movers and things moved will all be instruments. But even the unlearned perceive how ridiculous it is to suppose that instruments are moved, unless they are set in motion by some principal agent. This would be like fancying that, when a chest or a bed is being built, the saw or the hatchet performs its functions without the carpenter. Accordingly there must be a first mover that is above all the the rest; and this being we call God."
